localhost ring fixes

Pipeline + MLX Ring worked with 2 nodes but failed to initialize with
3 or more nodes. The MLX ring backend requires each node to know its
specific left and right neighbors in the ring, but the previous
implementation provided a single flat host list shared by all nodes.

With 2 nodes, a flat list [host0, host1] accidentally worked because
each node could find its only neighbor. With 3+ nodes, each node needs
a customized view:
- Rank 0: [self, right_neighbor, placeholder]
- Rank 1: [left_neighbor, self, right_neighbor]
- Rank 2: [placeholder, left_neighbor, self]

Changed MlxRingInstance from `hosts: list[Host]` to
`hosts_by_node: dict[NodeId, list[Host]]` with `ephemeral_port: int`.

Added `get_mlx_ring_hosts_by_node()` which generates per-node host
lists where:
- Self position uses 0.0.0.0 for local binding
- Left/right neighbors use actual connection IPs
- Non-neighbors use 198.51.100.1 (RFC 5737 TEST-NET-2 placeholder)

Also added IP prioritization (en0 > en1 > non-Thunderbolt > any) to
prefer stable network interfaces.

TODO.md

@@ -19,7 +19,6 @@
 25. Rethink retry logic
 26. Task cancellation. When API http request gets cancelled, it should cancel corresponding task.
 27. Log cleanup - per-module log filters and default to DEBUG log levels
-28. Validate RDMA connections with ibv_devinfo in the info gatherer
 
 Potential refactors:
 

dashboard/src/lib/stores/app.svelte.ts

@@ -96,7 +96,7 @@ interface RawNodeProfile {
 
 interface RawTopologyNode {
 	nodeId: string;
-	nodeProfile?: RawNodeProfile;
+	nodeProfile: RawNodeProfile;
 }
 
 interface RawTopologyConnection {
@@ -105,13 +105,9 @@ interface RawTopologyConnection {
 	sendBackMultiaddr?: { multiaddr?: string; address?: string; ip_address?: string } | string;
 }
 
-// Connection can be an object or a tuple [source, target, metadata]
-type RawConnectionItem = RawTopologyConnection | [string, string, { sinkMultiaddr?: { ip_address?: string; address?: string } }?];
-
 interface RawTopology {
-	// nodes can be array of strings (node IDs) or array of objects with nodeId/nodeProfile
-	nodes: (string | RawTopologyNode)[];
-	connections?: RawConnectionItem[];
+	nodes: RawTopologyNode[];
+	connections?: RawTopologyConnection[];
 }
 
 type RawNodeProfiles = Record<string, RawNodeProfile>;
@@ -202,17 +198,9 @@ function transformTopology(raw: RawTopology, profiles?: RawNodeProfiles): Topolo
 	const nodes: Record<string, NodeInfo> = {};
 	const edges: TopologyEdge[] = [];
 
-	// Handle nodes - can be array of strings (node IDs) or array of objects with nodeId/nodeProfile
 	for (const node of raw.nodes || []) {
-		// Determine the node ID - could be a string or an object with nodeId property
-		const nodeId = typeof node === 'string' ? node : node.nodeId;
-		if (!nodeId) continue;
-		
-		// Get the profile - from the separate profiles map or from the node object itself
-		const profileFromMap = profiles?.[nodeId];
-		const profileFromNode = typeof node === 'object' ? node.nodeProfile : undefined;
-		const profile = { ...(profileFromNode ?? {}), ...(profileFromMap ?? {}) };
-		
+		const mergedProfile = profiles?.[node.nodeId];
+		const profile = { ...(node.nodeProfile ?? {}), ...(mergedProfile ?? {}) };
 		const ramTotal = profile?.memory?.ramTotal?.inBytes ?? 0;
 		const ramAvailable = profile?.memory?.ramAvailable?.inBytes ?? 0;
 		const ramUsage = Math.max(ramTotal - ramAvailable, 0);
@@ -250,7 +238,7 @@ function transformTopology(raw: RawTopology, profiles?: RawNodeProfiles): Topolo
 			}
 		}
 
-		nodes[nodeId] = {
+		nodes[node.nodeId] = {
 			system_info: {
 				model_id: profile?.modelId ?? 'Unknown',
 				chip: profile?.chipId,
@@ -272,34 +260,14 @@ function transformTopology(raw: RawTopology, profiles?: RawNodeProfiles): Topolo
 		};
 	}
 
-	// Handle connections - can be objects with localNodeId/sendBackNodeId or tuples [source, target, metadata]
 	for (const conn of raw.connections || []) {
-		let localNodeId: string | undefined;
-		let sendBackNodeId: string | undefined;
-		let sendBackMultiaddr: { multiaddr?: string; address?: string; ip_address?: string } | string | undefined;
-		
-		// Check if it's a tuple format [source, target, metadata]
-		if (Array.isArray(conn)) {
-			localNodeId = conn[0] as string;
-			sendBackNodeId = conn[1] as string;
-			const metadata = conn[2] as { sinkMultiaddr?: { ip_address?: string; address?: string } } | undefined;
-			if (metadata?.sinkMultiaddr) {
-				sendBackMultiaddr = metadata.sinkMultiaddr;
-			}
-		} else {
-			// Object format with localNodeId/sendBackNodeId
-			localNodeId = conn.localNodeId;
-			sendBackNodeId = conn.sendBackNodeId;
-			sendBackMultiaddr = conn.sendBackMultiaddr;
-		}
-		
-		if (!localNodeId || !sendBackNodeId) continue;
-		if (localNodeId === sendBackNodeId) continue;
-		if (!nodes[localNodeId] || !nodes[sendBackNodeId]) continue;
+		if (!conn.localNodeId || !conn.sendBackNodeId) continue;
+		if (conn.localNodeId === conn.sendBackNodeId) continue;
+		if (!nodes[conn.localNodeId] || !nodes[conn.sendBackNodeId]) continue;
 
 		let sendBackIp: string | undefined;
-		if (sendBackMultiaddr) {
-			const multi = sendBackMultiaddr;
+		if (conn.sendBackMultiaddr) {
+			const multi = conn.sendBackMultiaddr;
 			if (typeof multi === 'string') {
 				sendBackIp = extractIpFromMultiaddr(multi);
 			} else {
@@ -308,8 +276,8 @@ function transformTopology(raw: RawTopology, profiles?: RawNodeProfiles): Topolo
 		}
 
 		edges.push({
-			source: localNodeId,
-			target: sendBackNodeId,
+			source: conn.localNodeId,
+			target: conn.sendBackNodeId,
 			sendBackIp
 		});
 	}

src/exo/master/api.py

@@ -207,7 +207,6 @@ class API:
                     instance_meta=instance_meta,
                     min_nodes=min_nodes,
                 ),
-                node_profiles=self.state.node_profiles,
                 topology=self.state.topology,
                 current_instances=self.state.instances,
             )
@@ -263,7 +262,6 @@ class API:
                             instance_meta=instance_meta,
                             min_nodes=min_nodes,
                         ),
-                        node_profiles=self.state.node_profiles,
                         topology=self.state.topology,
                         current_instances=self.state.instances,
                     )
@@ -428,8 +426,9 @@ class API:
         """Calculate total available memory across all nodes in bytes."""
         total_available = Memory()
 
-        for profile in self.state.node_profiles.values():
-            total_available += profile.memory.ram_available
+        for node in self.state.topology.list_nodes():
+            if node.node_profile is not None:
+                total_available += node.node_profile.memory.ram_available
 
         return total_available
 

src/exo/master/main.py

@@ -158,7 +158,6 @@ class Master:
                                 command,
                                 self.state.topology,
                                 self.state.instances,
-                                self.state.node_profiles,
                             )
                             transition_events = get_transition_events(
                                 self.state.instances, placement
@@ -201,7 +200,9 @@ class Master:
     async def _plan(self) -> None:
         while True:
             # kill broken instances
-            connected_node_ids = set([x for x in self.state.topology.list_nodes()])
+            connected_node_ids = set(
+                [x.node_id for x in self.state.topology.list_nodes()]
+            )
             for instance_id, instance in self.state.instances.items():
                 for node_id in instance.shard_assignments.node_to_runner:
                     if node_id not in connected_node_ids:

src/exo/master/placement.py

@@ -6,11 +6,10 @@ from typing import Sequence
 from loguru import logger
 
 from exo.master.placement_utils import (
-    NodeWithProfile,
     filter_cycles_by_memory,
-    get_hosts_from_subgraph,
+    get_mlx_ibv_devices_matrix,
     get_mlx_jaccl_coordinators,
-    get_mlx_jaccl_devices_matrix,
+    get_mlx_ring_hosts_by_node,
     get_shard_assignments,
     get_smallest_cycles,
 )
@@ -20,10 +19,9 @@ from exo.shared.types.commands import (
     DeleteInstance,
     PlaceInstance,
 )
-from exo.shared.types.common import Host, NodeId
 from exo.shared.types.events import Event, InstanceCreated, InstanceDeleted
 from exo.shared.types.memory import Memory
-from exo.shared.types.profiling import NodePerformanceProfile
+from exo.shared.types.topology import NodeInfo
 from exo.shared.types.worker.instances import (
     Instance,
     InstanceId,
@@ -52,16 +50,19 @@ def place_instance(
     command: PlaceInstance,
     topology: Topology,
     current_instances: Mapping[InstanceId, Instance],
-    node_profiles: Mapping[NodeId, NodePerformanceProfile],
 ) -> dict[InstanceId, Instance]:
     all_nodes = list(topology.list_nodes())
 
-    cycles = topology.get_cycles() + [[node] for node in all_nodes]
-    candidate_cycles = list(filter(lambda it: len(it) >= command.min_nodes, cycles))
-    cycles_with_sufficient_memory = filter_cycles_by_memory(
-        candidate_cycles, node_profiles, command.model_meta.storage_size
+    logger.info("finding cycles:")
+    cycles = topology.get_cycles()
+    singleton_cycles = [[node] for node in all_nodes]
+    candidate_cycles = list(
+        filter(lambda it: len(it) >= command.min_nodes, cycles + singleton_cycles)
     )
-    if len(cycles_with_sufficient_memory) == 0:
+    cycles_with_sufficient_memory = filter_cycles_by_memory(
+        candidate_cycles, command.model_meta.storage_size
+    )
+    if not cycles_with_sufficient_memory:
         raise ValueError("No cycles found with sufficient memory")
 
     smallest_cycles = get_smallest_cycles(cycles_with_sufficient_memory)
@@ -69,15 +70,13 @@ def place_instance(
     smallest_tb_cycles = [
         cycle
         for cycle in smallest_cycles
-        if topology.get_subgraph_from_nodes(
-            [node.node_id for node in cycle]
-        ).is_thunderbolt_cycle([node.node_id for node in cycle])
+        if topology.get_subgraph_from_nodes(cycle).is_thunderbolt_cycle(cycle)
     ]
 
     if smallest_tb_cycles != []:
         smallest_cycles = smallest_tb_cycles
 
-    cycles_with_leaf_nodes: list[list[NodeWithProfile]] = [
+    cycles_with_leaf_nodes: list[list[NodeInfo]] = [
         cycle
         for cycle in smallest_cycles
         if any(topology.node_is_leaf(node.node_id) for node in cycle)
@@ -86,7 +85,11 @@ def place_instance(
     selected_cycle = max(
         cycles_with_leaf_nodes if cycles_with_leaf_nodes != [] else smallest_cycles,
         key=lambda cycle: sum(
-            (node.node_profile.memory.ram_available for node in cycle),
+            (
+                node.node_profile.memory.ram_available
+                for node in cycle
+                if node.node_profile is not None
+            ),
             start=Memory(),
         ),
     )
@@ -95,16 +98,14 @@ def place_instance(
         command.model_meta, selected_cycle, command.sharding
     )
 
-    cycle_digraph: Topology = topology.get_subgraph_from_nodes(
-        [node.node_id for node in selected_cycle]
-    )
+    cycle_digraph: Topology = topology.get_subgraph_from_nodes(selected_cycle)
 
     instance_id = InstanceId()
     target_instances = dict(deepcopy(current_instances))
 
     if len(selected_cycle) == 1:
         logger.warning(
-            "You have likely selected jaccl for a single node instance; falling back to MlxRing"
+            "You have likely selected ibv for a single node instance; falling back to MlxRing"
         )
 
         command.instance_meta = InstanceMeta.MlxRing
@@ -112,32 +113,33 @@ def place_instance(
     # TODO: Single node instances
     match command.instance_meta:
         case InstanceMeta.MlxJaccl:
-            mlx_jaccl_devices = get_mlx_jaccl_devices_matrix(
+            mlx_ibv_devices = get_mlx_ibv_devices_matrix(
+                selected_cycle,
                 cycle_digraph,
             )
             mlx_jaccl_coordinators = get_mlx_jaccl_coordinators(
-                coordinator=selected_cycle[0].node_id,
+                selected_cycle,
                 coordinator_port=random_ephemeral_port(),
                 cycle_digraph=cycle_digraph,
             )
             target_instances[instance_id] = MlxJacclInstance(
                 instance_id=instance_id,
                 shard_assignments=shard_assignments,
-                jaccl_devices=mlx_jaccl_devices,
+                ibv_devices=mlx_ibv_devices,
                 jaccl_coordinators=mlx_jaccl_coordinators,
             )
         case InstanceMeta.MlxRing:
-            hosts: list[Host] = get_hosts_from_subgraph(cycle_digraph)
+            ephemeral_port = random_ephemeral_port()
+            hosts_by_node = get_mlx_ring_hosts_by_node(
+                selected_cycle=selected_cycle,
+                cycle_digraph=cycle_digraph,
+                ephemeral_port=ephemeral_port,
+            )
             target_instances[instance_id] = MlxRingInstance(
                 instance_id=instance_id,
                 shard_assignments=shard_assignments,
-                hosts=[
-                    Host(
-                        ip=host.ip,
-                        port=random_ephemeral_port(),
-                    )
-                    for host in hosts
-                ],
+                hosts_by_node=hosts_by_node,
+                ephemeral_port=ephemeral_port,
             )
 
     return target_instances

src/exo/master/placement_utils.py

@@ -1,4 +1,5 @@
-from collections.abc import Generator, Mapping
+from collections.abc import Generator
+from typing import TypeGuard, cast
 
 from loguru import logger
 from pydantic import BaseModel
@@ -8,7 +9,7 @@ from exo.shared.types.common import Host, NodeId
 from exo.shared.types.memory import Memory
 from exo.shared.types.models import ModelMetadata
 from exo.shared.types.profiling import NodePerformanceProfile
-from exo.shared.types.topology import RDMAConnection, SocketConnection
+from exo.shared.types.topology import NodeInfo
 from exo.shared.types.worker.runners import RunnerId, ShardAssignments
 from exo.shared.types.worker.shards import (
     PipelineShardMetadata,
@@ -23,32 +24,27 @@ class NodeWithProfile(BaseModel):
     node_profile: NodePerformanceProfile
 
 
+def narrow_all_nodes(nodes: list[NodeInfo]) -> TypeGuard[list[NodeWithProfile]]:
+    return all(node.node_profile is not None for node in nodes)
+
+
 def filter_cycles_by_memory(
-    cycles: list[list[NodeId]],
-    node_profiles: Mapping[NodeId, NodePerformanceProfile],
-    required_memory: Memory,
-) -> list[list[NodeWithProfile]]:
-    filtered_cycles: list[list[NodeWithProfile]] = []
+    cycles: list[list[NodeInfo]], required_memory: Memory
+) -> list[list[NodeInfo]]:
+    filtered_cycles: list[list[NodeInfo]] = []
     for cycle in cycles:
-        if not all(node in node_profiles for node in cycle):
+        if not narrow_all_nodes(cycle):
             continue
 
         total_mem = sum(
-            (node_profiles[node].memory.ram_available for node in cycle), start=Memory()
+            (node.node_profile.memory.ram_available for node in cycle), start=Memory()
         )
         if total_mem >= required_memory:
-            filtered_cycles.append(
-                [
-                    NodeWithProfile(node_id=node, node_profile=node_profiles[node])
-                    for node in cycle
-                ]
-            )
+            filtered_cycles.append(cast(list[NodeInfo], cycle))
     return filtered_cycles
 
 
-def get_smallest_cycles(
-    cycles: list[list[NodeWithProfile]],
-) -> list[list[NodeWithProfile]]:
+def get_smallest_cycles(cycles: list[list[NodeInfo]]) -> list[list[NodeInfo]]:
     min_nodes = min(len(cycle) for cycle in cycles)
     return [cycle for cycle in cycles if len(cycle) == min_nodes]
 
@@ -139,9 +135,11 @@ def get_shard_assignments_for_tensor_parallel(
 
 def get_shard_assignments(
     model_meta: ModelMetadata,
-    selected_cycle: list[NodeWithProfile],
+    selected_cycle: list[NodeInfo],
     sharding: Sharding,
 ) -> ShardAssignments:
+    if not narrow_all_nodes(selected_cycle):
+        raise ValueError("All nodes must have profiles to create shard assignments")
     match sharding:
         case Sharding.Pipeline:
             return get_shard_assignments_for_pipeline_parallel(
@@ -178,16 +176,17 @@ def get_hosts_from_subgraph(cycle_digraph: Topology) -> list[Host]:
         current_node = cycle[i]
         next_node = cycle[(i + 1) % len(cycle)]
 
-        for src, sink, connection in cycle_digraph.list_connections():
-            if not isinstance(connection, SocketConnection):
-                continue
-
-            if src == current_node and sink == next_node:
+        for connection in cycle_digraph.list_connections():
+            if (
+                connection.local_node_id == current_node.node_id
+                and connection.send_back_node_id == next_node.node_id
+            ):
                 if get_thunderbolt and not connection.is_thunderbolt():
                     continue
+                assert connection.send_back_multiaddr is not None
                 host = Host(
-                    ip=connection.sink_multiaddr.ip_address,
-                    port=connection.sink_multiaddr.port,
+                    ip=connection.send_back_multiaddr.ip_address,
+                    port=connection.send_back_multiaddr.port,
                 )
                 hosts.append(host)
                 break
@@ -195,7 +194,8 @@ def get_hosts_from_subgraph(cycle_digraph: Topology) -> list[Host]:
     return hosts
 
 
-def get_mlx_jaccl_devices_matrix(
+def get_mlx_ibv_devices_matrix(
+    selected_cycle: list[NodeInfo],
     cycle_digraph: Topology,
 ) -> list[list[str | None]]:
     """Build connectivity matrix mapping device i to device j via RDMA interface names.
@@ -204,7 +204,6 @@ def get_mlx_jaccl_devices_matrix(
     to device j, or None if no connection exists or no interface name is found.
     Diagonal elements are always None.
     """
-    selected_cycle = list(cycle_digraph.list_nodes())
     num_nodes = len(selected_cycle)
     matrix: list[list[str | None]] = [
         [None for _ in range(num_nodes)] for _ in range(num_nodes)
@@ -215,55 +214,208 @@ def get_mlx_jaccl_devices_matrix(
             if i == j:
                 continue
 
-            for conn in cycle_digraph.get_all_connections_between(node_i, node_j):
-                if isinstance(conn, RDMAConnection):
-                    matrix[i][j] = conn.source_rdma_iface
+            # Find the IP J uses to talk to I
+            for connection_ip, _ in _find_connection_ip(node_j, node_i, cycle_digraph):
+                # This is a local IP on I, which is attached to an interface: find that interface
+                if interface_name := _find_interface_name_for_ip(connection_ip, node_i):
+                    matrix[i][j] = interface_name
+                    logger.info(
+                        f"Interface name for {connection_ip} on {node_i.node_id}: {interface_name}"
+                    )
                     break
             else:
+                logger.warning(
+                    f"Failed to find interface name between {node_i.node_id} and {node_j.node_id}"
+                )
                 raise ValueError(
-                    "Current jaccl backend requires all-to-all RDMA connections"
+                    "Current ibv backend requires all-to-all rdma connections"
                 )
 
     return matrix
 
 
 def _find_connection_ip(
-    node_i: NodeId,
-    node_j: NodeId,
+    node_i: NodeInfo,
+    node_j: NodeInfo,
     cycle_digraph: Topology,
-) -> Generator[str]:
-    """Find all IP addresses that connect node i to node j."""
-    # TODO: Prioritise ETHERNET > ??WIFI > TB for coordinator
-    for connection in cycle_digraph.get_all_connections_between(node_i, node_j):
-        if isinstance(connection, SocketConnection):
-            yield connection.sink_multiaddr.ip_address
+) -> Generator[tuple[str, bool]]:
+    """Find all IP addresses that connect node i to node j, with thunderbolt flag."""
+    for connection in cycle_digraph.list_connections():
+        if (
+            connection.local_node_id == node_i.node_id
+            and connection.send_back_node_id == node_j.node_id
+        ):
+            yield connection.send_back_multiaddr.ip_address, connection.is_thunderbolt()
+
+
+def _find_interface_name_for_ip(
+    ip_address: str,
+    node_info: NodeInfo,
+) -> str | None:
+    if node_info.node_profile is None:
+        return None
+
+    logger.info(f"Searching {node_info.node_id} for ip {ip_address}:")
+    for interface in node_info.node_profile.network_interfaces:
+        if interface.name not in ["en2", "en3", "en4", "en5", "en6", "en7"]:
+            continue
+        logger.info(f" | {interface.name}: {interface.ip_address}")
+        if interface.ip_address != ip_address:
+            continue
+
+        logger.info("Found")
+        return f"rdma_{interface.name}"
+
+    return None
+
+
+def _find_general_interface_name_for_ip(
+    ip_address: str,
+    node_info: NodeInfo,
+) -> str | None:
+    """Find the interface name for an IP address on a node (any interface)."""
+    if node_info.node_profile is None:
+        return None
+
+    for interface in node_info.node_profile.network_interfaces:
+        if interface.ip_address == ip_address:
+            return interface.name
+
+    return None
+
+
+def _find_ip_prioritised(
+    node: NodeInfo, other_node: NodeInfo, cycle_digraph: Topology
+) -> str | None:
+    """Find an IP address between nodes with prioritization.
+
+    Priority order:
+    1. en0 (Ethernet on Mac Studio, WiFi on MacBook)
+    2. en1 (WiFi on Mac Studio, Ethernet on MacBook)
+    3. Non-Thunderbolt connections
+    4. Any other IP address
+    """
+    ips = list(_find_connection_ip(node, other_node, cycle_digraph))
+    interface_names = [
+        _find_general_interface_name_for_ip(ip, other_node) for ip, _ in ips
+    ]
+
+    en0_ip = next(
+        (
+            ip
+            for (ip, _), interface_name in zip(ips, interface_names)
+            if interface_name == "en0"
+        ),
+        None,
+    )
+    if en0_ip:
+        return en0_ip
+
+    en1_ip = next(
+        (
+            ip
+            for (ip, _), interface_name in zip(ips, interface_names)
+            if interface_name == "en1"
+        ),
+        None,
+    )
+    if en1_ip:
+        return en1_ip
+
+    non_thunderbolt_ip = next(
+        (ip for (ip, is_thunderbolt) in ips if not is_thunderbolt), None
+    )
+    if non_thunderbolt_ip:
+        return non_thunderbolt_ip
+
+    if ips:
+        return ips[0][0]
+
+    return None
+
+
+def get_mlx_ring_hosts_by_node(
+    selected_cycle: list[NodeInfo],
+    cycle_digraph: Topology,
+    ephemeral_port: int,
+) -> dict[NodeId, list[Host]]:
+    """Generate per-node host lists for MLX ring backend.
+
+    Each node gets a list where:
+    - Self position: Host(ip="0.0.0.0", port=ephemeral_port)
+    - Left/right neighbors: actual connection IPs
+    - Non-neighbors: Host(ip="198.51.100.1", port=0) placeholder (RFC 5737 TEST-NET-2)
+    """
+    world_size = len(selected_cycle)
+    if world_size == 0:
+        return {}
+
+    logger.info(f"[RING3DBG] get_mlx_ring_hosts_by_node: world_size={world_size}, ephemeral_port={ephemeral_port}")
+    logger.info(f"[RING3DBG] cycle node_ids: {[n.node_id for n in selected_cycle]}")
+
+    hosts_by_node: dict[NodeId, list[Host]] = {}
+
+    for rank, node in enumerate(selected_cycle):
+        node_id = node.node_id
+        left_rank = (rank - 1) % world_size
+        right_rank = (rank + 1) % world_size
+        logger.info(f"[RING3DBG] rank={rank} node_id={node_id} left_rank={left_rank} right_rank={right_rank}")
+
+        hosts_for_node: list[Host] = []
+
+        for idx, other_node in enumerate(selected_cycle):
+            if idx == rank:
+                hosts_for_node.append(Host(ip="0.0.0.0", port=ephemeral_port))
+                continue
+
+            if idx not in {left_rank, right_rank}:
+                # Placeholder IP from RFC 5737 TEST-NET-2
+                hosts_for_node.append(Host(ip="198.51.100.1", port=0))
+                continue
+
+            connection_ip = _find_ip_prioritised(node, other_node, cycle_digraph)
+            logger.info(f"[RING3DBG] rank={rank} idx={idx} connection_ip={connection_ip}")
+            if connection_ip is None:
+                logger.warning(
+                    f"Failed to find prioritised connection IP between {node_id} and {other_node.node_id}"
+                )
+                raise ValueError(
+                    "MLX ring backend requires connectivity between neighbouring nodes"
+                )
+
+            hosts_for_node.append(Host(ip=connection_ip, port=ephemeral_port))
+
+        logger.info(f"[RING3DBG] rank={rank} final hosts_for_node={hosts_for_node}")
+        hosts_by_node[node_id] = hosts_for_node
+
+    return hosts_by_node
 
 
 def get_mlx_jaccl_coordinators(
-    coordinator: NodeId,
+    selected_cycle: list[NodeInfo],
     coordinator_port: int,
     cycle_digraph: Topology,
 ) -> dict[NodeId, str]:
-    """Get the coordinator addresses for MLX JACCL (rank 0 device).
+    """Get the coordinator addresses for MLX Jaccl (rank 0 device).
 
     Select an IP address that each node can reach for the rank 0 node. Returns
     address in format "X.X.X.X:PORT" per node.
     """
-    selected_cycle = list(cycle_digraph.list_nodes())
-    logger.info(f"Selecting coordinator: {coordinator}")
+    rank_0_node = selected_cycle[0]
+    logger.info(f"Selecting coordinator from rank 0 node: {rank_0_node.node_id}")
 
-    def get_ip_for_node(n: NodeId) -> str:
-        if n == coordinator:
+    def get_ip_for_node(n: NodeInfo) -> str:
+        if n.node_id == rank_0_node.node_id:
             return "0.0.0.0"
 
-        for ip in _find_connection_ip(n, coordinator, cycle_digraph):
+        for ip, _ in _find_connection_ip(n, rank_0_node, cycle_digraph):
             return ip
 
         logger.warning(
-            f"Failed to find directly connected ip between {n} and {coordinator}"
-        )
-        raise ValueError(
-            "Current jaccl backend requires all participating devices to be able to communicate"
+            f"Failed to find directly connected ip between {n.node_id} and {rank_0_node.node_id}"
         )
+        raise ValueError("Current ibv backend requires all-to-all rdma connections")
 
-    return {n: f"{get_ip_for_node(n)}:{coordinator_port}" for n in selected_cycle}
+    return {
+        n.node_id: f"{get_ip_for_node(n)}:{coordinator_port}" for n in selected_cycle
+    }

src/exo/master/tests/conftest.py

@@ -1,36 +1,67 @@
+from typing import Callable
+
+import pytest
+
+from exo.shared.types.common import NodeId
 from exo.shared.types.multiaddr import Multiaddr
 from exo.shared.types.profiling import (
-    MemoryUsage,
+    MemoryPerformanceProfile,
     NodePerformanceProfile,
     SystemPerformanceProfile,
 )
-from exo.shared.types.topology import RDMAConnection, SocketConnection
+from exo.shared.types.topology import Connection, ConnectionProfile, NodeInfo
 
 
-def create_node_profile(memory: int) -> NodePerformanceProfile:
-    return NodePerformanceProfile(
-        model_id="test",
-        chip_id="test",
-        friendly_name="test",
-        memory=MemoryUsage.from_bytes(
-            ram_total=1000,
-            ram_available=memory,
-            swap_total=1000,
-            swap_available=1000,
-        ),
-        network_interfaces=[],
-        system=SystemPerformanceProfile(),
-    )
+@pytest.fixture
+def create_node():
+    def _create_node(memory: int, node_id: NodeId | None = None) -> NodeInfo:
+        if node_id is None:
+            node_id = NodeId()
+        return NodeInfo(
+            node_id=node_id,
+            node_profile=NodePerformanceProfile(
+                model_id="test",
+                chip_id="test",
+                friendly_name="test",
+                memory=MemoryPerformanceProfile.from_bytes(
+                    ram_total=1000,
+                    ram_available=memory,
+                    swap_total=1000,
+                    swap_available=1000,
+                ),
+                network_interfaces=[],
+                system=SystemPerformanceProfile(),
+            ),
+        )
+
+    return _create_node
 
 
 # TODO: this is a hack to get the port for the send_back_multiaddr
-def create_connection(ip: int, sink_port: int = 1234) -> SocketConnection:
-    return SocketConnection(
-        sink_multiaddr=Multiaddr(address=f"/ip4/169.254.0.{ip}/tcp/{sink_port}"),
-    )
+@pytest.fixture
+def create_connection() -> Callable[[NodeId, NodeId, int | None], Connection]:
+    port_counter = 1235
+    ip_counter = 1
 
+    def _create_connection(
+        source_node_id: NodeId, sink_node_id: NodeId, send_back_port: int | None = None
+    ) -> Connection:
+        nonlocal port_counter
+        nonlocal ip_counter
+        # assign unique ips
+        ip_counter += 1
+        if send_back_port is None:
+            send_back_port = port_counter
+            port_counter += 1
+        return Connection(
+            local_node_id=source_node_id,
+            send_back_node_id=sink_node_id,
+            send_back_multiaddr=Multiaddr(
+                address=f"/ip4/169.254.0.{ip_counter}/tcp/{send_back_port}"
+            ),
+            connection_profile=ConnectionProfile(
+                throughput=1000, latency=1000, jitter=1000
+            ),
+        )
 
-def create_rdma_connection(iface: int) -> RDMAConnection:
-    return RDMAConnection(
-        source_rdma_iface=f"rdma_en{iface}", sink_rdma_iface=f"rdma_en{iface}"
-    )
+    return _create_connection

src/exo/master/tests/test_master.py

@@ -19,13 +19,15 @@ from exo.shared.types.events import (
     ForwarderEvent,
     IndexedEvent,
     InstanceCreated,
-    NodeGatheredInfo,
+    NodePerformanceMeasured,
     TaskCreated,
 )
 from exo.shared.types.memory import Memory
 from exo.shared.types.models import ModelId, ModelMetadata
 from exo.shared.types.profiling import (
-    MemoryUsage,
+    MemoryPerformanceProfile,
+    NodePerformanceProfile,
+    SystemPerformanceProfile,
 )
 from exo.shared.types.tasks import ChatCompletion as ChatCompletionTask
 from exo.shared.types.tasks import TaskStatus
@@ -81,14 +83,21 @@ async def test_master():
                 origin=sender_node_id,
                 session=session_id,
                 event=(
-                    NodeGatheredInfo(
+                    NodePerformanceMeasured(
                         when=str(datetime.now(tz=timezone.utc)),
                         node_id=node_id,
-                        info=MemoryUsage(
-                            ram_total=Memory.from_bytes(678948 * 1024),
-                            ram_available=Memory.from_bytes(678948 * 1024),
-                            swap_total=Memory.from_bytes(0),
-                            swap_available=Memory.from_bytes(0),
+                        node_profile=NodePerformanceProfile(
+                            model_id="maccy",
+                            chip_id="arm",
+                            friendly_name="test",
+                            memory=MemoryPerformanceProfile(
+                                ram_total=Memory.from_bytes(678948 * 1024),
+                                ram_available=Memory.from_bytes(678948 * 1024),
+                                swap_total=Memory.from_bytes(0),
+                                swap_available=Memory.from_bytes(0),
+                            ),
+                            network_interfaces=[],
+                            system=SystemPerformanceProfile(),
                         ),
                     )
                 ),
@@ -152,34 +161,38 @@ async def test_master():
         assert events[0].idx == 0
         assert events[1].idx == 1
         assert events[2].idx == 2
-        assert isinstance(events[0].event, NodeGatheredInfo)
+        assert isinstance(events[0].event, NodePerformanceMeasured)
         assert isinstance(events[1].event, InstanceCreated)
-        runner_id = list(
-            events[1].event.instance.shard_assignments.runner_to_shard.keys()
-        )[0]
-        assert events[1].event.instance == MlxRingInstance(
-            instance_id=events[1].event.instance.instance_id,
-            shard_assignments=ShardAssignments(
-                model_id=ModelId("llama-3.2-1b"),
-                runner_to_shard={
-                    (runner_id): PipelineShardMetadata(
-                        start_layer=0,
-                        end_layer=16,
+        created_instance = events[1].event.instance
+        assert isinstance(created_instance, MlxRingInstance)
+        runner_id = list(created_instance.shard_assignments.runner_to_shard.keys())[0]
+        # Validate the shard assignments
+        expected_shard_assignments = ShardAssignments(
+            model_id=ModelId("llama-3.2-1b"),
+            runner_to_shard={
+                (runner_id): PipelineShardMetadata(
+                    start_layer=0,
+                    end_layer=16,
+                    n_layers=16,
+                    model_meta=ModelMetadata(
+                        model_id=ModelId("llama-3.2-1b"),
+                        pretty_name="Llama 3.2 1B",
                         n_layers=16,
-                        model_meta=ModelMetadata(
-                            model_id=ModelId("llama-3.2-1b"),
-                            pretty_name="Llama 3.2 1B",
-                            n_layers=16,
-                            storage_size=Memory.from_bytes(678948),
-                        ),
-                        device_rank=0,
-                        world_size=1,
-                    )
-                },
-                node_to_runner={node_id: runner_id},
-            ),
-            hosts=[],
+                        storage_size=Memory.from_bytes(678948),
+                    ),
+                    device_rank=0,
+                    world_size=1,
+                )
+            },
+            node_to_runner={node_id: runner_id},
         )
+        assert created_instance.shard_assignments == expected_shard_assignments
+        # For single-node, hosts_by_node should have one entry with self-binding
+        assert len(created_instance.hosts_by_node) == 1
+        assert node_id in created_instance.hosts_by_node
+        assert len(created_instance.hosts_by_node[node_id]) == 1
+        assert created_instance.hosts_by_node[node_id][0].ip == "0.0.0.0"
+        assert created_instance.ephemeral_port > 0
         assert isinstance(events[2].event, TaskCreated)
         assert events[2].event.task.task_status == TaskStatus.Pending
         assert isinstance(events[2].event.task, ChatCompletionTask)

src/exo/master/tests/test_placement.py

@@ -1,3 +1,5 @@
+from typing import Callable
+
 import pytest
 from loguru import logger
 
@@ -5,20 +7,14 @@ from exo.master.placement import (
     get_transition_events,
     place_instance,
 )
-from exo.master.tests.conftest import (
-    create_connection,
-    create_node_profile,
-    create_rdma_connection,
-)
 from exo.shared.topology import Topology
 from exo.shared.types.commands import PlaceInstance
 from exo.shared.types.common import CommandId, NodeId
 from exo.shared.types.events import InstanceCreated, InstanceDeleted
 from exo.shared.types.memory import Memory
 from exo.shared.types.models import ModelId, ModelMetadata
-from exo.shared.types.multiaddr import Multiaddr
-from exo.shared.types.profiling import NetworkInterfaceInfo
-from exo.shared.types.topology import SocketConnection
+from exo.shared.types.profiling import NetworkInterfaceInfo, NodePerformanceProfile
+from exo.shared.types.topology import Connection, NodeInfo
 from exo.shared.types.worker.instances import (
     Instance,
     InstanceId,
@@ -30,6 +26,11 @@ from exo.shared.types.worker.runners import ShardAssignments
 from exo.shared.types.worker.shards import Sharding
 
 
+@pytest.fixture
+def topology() -> Topology:
+    return Topology()
+
+
 @pytest.fixture
 def instance() -> Instance:
     return MlxRingInstance(
@@ -37,7 +38,8 @@ def instance() -> Instance:
         shard_assignments=ShardAssignments(
             model_id=ModelId("test-model"), runner_to_shard={}, node_to_runner={}
         ),
-        hosts=[],
+        hosts_by_node={},
+        ephemeral_port=50000,
     )
 
 
@@ -73,33 +75,34 @@ def test_get_instance_placements_create_instance(
     available_memory: tuple[int, int, int],
     total_layers: int,
     expected_layers: tuple[int, int, int],
+    topology: Topology,
     model_meta: ModelMetadata,
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+    create_connection: Callable[[NodeId, NodeId], Connection],
 ):
     # arrange
     model_meta.n_layers = total_layers
     model_meta.storage_size.in_bytes = sum(
         available_memory
     )  # make it exactly fit across all nodes
-    topology = Topology()
 
     cic = place_instance_command(model_meta)
     node_id_a = NodeId()
     node_id_b = NodeId()
     node_id_c = NodeId()
-    profiles = {
-        node_id_a: create_node_profile(available_memory[0]),
-        node_id_b: create_node_profile(available_memory[1]),
-        node_id_c: create_node_profile(available_memory[2]),
-    }
-    topology.add_node(node_id_a)
-    topology.add_node(node_id_b)
-    topology.add_node(node_id_c)
-    topology.add_connection(node_id_a, node_id_b, create_connection(1))
-    topology.add_connection(node_id_b, node_id_c, create_connection(2))
-    topology.add_connection(node_id_c, node_id_a, create_connection(3))
+    topology.add_node(create_node(available_memory[0], node_id_a))
+    topology.add_node(create_node(available_memory[1], node_id_b))
+    topology.add_node(create_node(available_memory[2], node_id_c))
+    # Add bidirectional connections for ring topology
+    topology.add_connection(create_connection(node_id_a, node_id_b))
+    topology.add_connection(create_connection(node_id_b, node_id_a))
+    topology.add_connection(create_connection(node_id_b, node_id_c))
+    topology.add_connection(create_connection(node_id_c, node_id_b))
+    topology.add_connection(create_connection(node_id_c, node_id_a))
+    topology.add_connection(create_connection(node_id_a, node_id_c))
 
     # act
-    placements = place_instance(cic, topology, {}, profiles)
+    placements = place_instance(cic, topology, {})
 
     # assert
     assert len(placements) == 1
@@ -125,11 +128,12 @@ def test_get_instance_placements_create_instance(
     assert shards_sorted[-1].end_layer == total_layers
 
 
-def test_get_instance_placements_one_node_exact_fit() -> None:
+def test_get_instance_placements_one_node_exact_fit(
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+) -> None:
     topology = Topology()
     node_id = NodeId()
-    topology.add_node(node_id)
-    profiles = {node_id: create_node_profile(1000 * 1024)}
+    topology.add_node(create_node(1000 * 1024, node_id))
     cic = place_instance_command(
         ModelMetadata(
             model_id=ModelId("test-model"),
@@ -138,7 +142,7 @@ def test_get_instance_placements_one_node_exact_fit() -> None:
             n_layers=10,
         ),
     )
-    placements = place_instance(cic, topology, {}, profiles)
+    placements = place_instance(cic, topology, {})
 
     assert len(placements) == 1
     instance_id = list(placements.keys())[0]
@@ -149,11 +153,12 @@ def test_get_instance_placements_one_node_exact_fit() -> None:
     assert len(instance.shard_assignments.runner_to_shard) == 1
 
 
-def test_get_instance_placements_one_node_fits_with_extra_memory() -> None:
+def test_get_instance_placements_one_node_fits_with_extra_memory(
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+) -> None:
     topology = Topology()
     node_id = NodeId()
-    topology.add_node(node_id)
-    profiles = {node_id: create_node_profile(1001 * 1024)}
+    topology.add_node(create_node(1001 * 1024, node_id))
     cic = place_instance_command(
         ModelMetadata(
             model_id=ModelId("test-model"),
@@ -162,7 +167,7 @@ def test_get_instance_placements_one_node_fits_with_extra_memory() -> None:
             n_layers=10,
         ),
     )
-    placements = place_instance(cic, topology, {}, profiles)
+    placements = place_instance(cic, topology, {})
 
     assert len(placements) == 1
     instance_id = list(placements.keys())[0]
@@ -173,11 +178,12 @@ def test_get_instance_placements_one_node_fits_with_extra_memory() -> None:
     assert len(instance.shard_assignments.runner_to_shard) == 1
 
 
-def test_get_instance_placements_one_node_not_fit() -> None:
+def test_get_instance_placements_one_node_not_fit(
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+) -> None:
     topology = Topology()
     node_id = NodeId()
-    topology.add_node(node_id)
-    profiles = {node_id: create_node_profile(1000 * 1024)}
+    topology.add_node(create_node(1000 * 1024, node_id))
     cic = place_instance_command(
         model_meta=ModelMetadata(
             model_id=ModelId("test-model"),
@@ -188,7 +194,7 @@ def test_get_instance_placements_one_node_not_fit() -> None:
     )
 
     with pytest.raises(ValueError, match="No cycles found with sufficient memory"):
-        place_instance(cic, topology, {}, profiles)
+        place_instance(cic, topology, {})
 
 
 def test_get_transition_events_no_change(instance: Instance):
@@ -233,103 +239,179 @@ def test_get_transition_events_delete_instance(instance: Instance):
     assert events[0].instance_id == instance_id
 
 
-def test_placement_prioritizes_leaf_cycle_with_less_memory(
+def test_placement_selects_cycle_with_most_memory(
+    topology: Topology,
     model_meta: ModelMetadata,
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+    create_connection: Callable[[NodeId, NodeId], Connection],
 ):
-    # arrange
-    topology = Topology()
+    # Arrange two 3-node cycles with different total memory.
+    # With bidirectional connections for ring topology, both cycles have non-leaf nodes.
+    # The algorithm should select the cycle with the most available memory.
 
-    model_meta.storage_size = Memory.from_bytes(1000)
+    # Model requires more than any single node but fits within a 3-node cycle
+    model_meta.storage_size.in_bytes = 1500
+    model_meta.n_layers = 12
 
+    # Create node ids
     node_id_a = NodeId()
     node_id_b = NodeId()
     node_id_c = NodeId()
     node_id_d = NodeId()
+    node_id_e = NodeId()
+    node_id_f = NodeId()
 
-    profiles = {
-        node_id_a: create_node_profile(500),
-        node_id_b: create_node_profile(600),
-        node_id_c: create_node_profile(600),
-        node_id_d: create_node_profile(500),
-    }
+    # A-B-C cycle total memory = 1600 (< D-E-F total)
+    topology.add_node(create_node(400, node_id_a))
+    topology.add_node(create_node(400, node_id_b))
+    topology.add_node(create_node(800, node_id_c))
 
-    topology.add_node(node_id_a)
-    topology.add_node(node_id_b)
-    topology.add_node(node_id_c)
-    topology.add_node(node_id_d)
+    # D-E-F cycle total memory = 1800 (> A-B-C total)
+    topology.add_node(create_node(600, node_id_d))
+    topology.add_node(create_node(600, node_id_e))
+    topology.add_node(create_node(600, node_id_f))
 
-    # Daisy chain topology
-    topology.add_connection(node_id_a, node_id_b, create_connection(1))
-    topology.add_connection(node_id_b, node_id_a, create_connection(1))
-    topology.add_connection(node_id_b, node_id_c, create_connection(1))
-    topology.add_connection(node_id_c, node_id_b, create_connection(1))
-    topology.add_connection(node_id_c, node_id_d, create_connection(1))
-    topology.add_connection(node_id_d, node_id_c, create_connection(1))
+    # Build bidirectional cycles for ring topology
+    topology.add_connection(create_connection(node_id_a, node_id_b))
+    topology.add_connection(create_connection(node_id_b, node_id_a))
+    topology.add_connection(create_connection(node_id_b, node_id_c))
+    topology.add_connection(create_connection(node_id_c, node_id_b))
+    topology.add_connection(create_connection(node_id_c, node_id_a))
+    topology.add_connection(create_connection(node_id_a, node_id_c))
 
-    logger.info(list(topology.list_connections()))
+    topology.add_connection(create_connection(node_id_d, node_id_e))
+    topology.add_connection(create_connection(node_id_e, node_id_d))
+    topology.add_connection(create_connection(node_id_e, node_id_f))
+    topology.add_connection(create_connection(node_id_f, node_id_e))
+    topology.add_connection(create_connection(node_id_f, node_id_d))
+    topology.add_connection(create_connection(node_id_d, node_id_f))
 
     cic = place_instance_command(
         model_meta=model_meta,
     )
 
-    # act
-    placements = place_instance(cic, topology, {}, profiles)
+    # Act
+    placements = place_instance(cic, topology, {})
 
-    # assert
+    # Assert: D-E-F cycle should be selected as it has more total memory
     assert len(placements) == 1
-    instance = list(placements.values())[0]
+    instance_id = list(placements.keys())[0]
+    instance = placements[instance_id]
 
     assigned_nodes = set(instance.shard_assignments.node_to_runner.keys())
-    assert assigned_nodes == set((node_id_a, node_id_b)) or assigned_nodes == set(
-        (node_id_c, node_id_d)
-    )
+    less_memory_cycle_nodes = {node_id_a, node_id_b, node_id_c}
+    more_memory_cycle_nodes = {node_id_d, node_id_e, node_id_f}
+
+    assert more_memory_cycle_nodes.issubset(assigned_nodes)
+    assert assigned_nodes.isdisjoint(less_memory_cycle_nodes)
 
 
 def test_tensor_rdma_backend_connectivity_matrix(
+    topology: Topology,
     model_meta: ModelMetadata,
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+    create_connection: Callable[[NodeId, NodeId], Connection],
 ):
-    topology = Topology()
     model_meta.n_layers = 12
     model_meta.storage_size.in_bytes = 1500
 
-    node_a = NodeId()
-    node_b = NodeId()
-    node_c = NodeId()
+    node_id_a = NodeId()
+    node_id_b = NodeId()
+    node_id_c = NodeId()
 
-    profiles = {
-        node_a: create_node_profile(500),
-        node_b: create_node_profile(500),
-        node_c: create_node_profile(500),
-    }
+    node_a = create_node(500, node_id_a)
+    node_b = create_node(500, node_id_b)
+    node_c = create_node(500, node_id_c)
 
     ethernet_interface = NetworkInterfaceInfo(
         name="en0",
         ip_address="192.168.1.100",
     )
-    ethernet_conn = SocketConnection(
-        sink_multiaddr=Multiaddr(address=f"/ip4/192.168.1.{100}/tcp/{8000}")
-    )
 
-    profiles[node_a].network_interfaces = [ethernet_interface]
-    profiles[node_b].network_interfaces = [ethernet_interface]
-    profiles[node_c].network_interfaces = [ethernet_interface]
+    assert node_a.node_profile is not None
+    assert node_b.node_profile is not None
+    assert node_c.node_profile is not None
+
+    conn_a_b = create_connection(node_id_a, node_id_b)
+    conn_b_c = create_connection(node_id_b, node_id_c)
+    conn_c_a = create_connection(node_id_c, node_id_a)
+
+    conn_b_a = create_connection(node_id_b, node_id_a)
+    conn_c_b = create_connection(node_id_c, node_id_b)
+    conn_a_c = create_connection(node_id_a, node_id_c)
+
+    assert conn_a_b.send_back_multiaddr is not None
+    assert conn_b_c.send_back_multiaddr is not None
+    assert conn_c_a.send_back_multiaddr is not None
+
+    assert conn_b_a.send_back_multiaddr is not None
+    assert conn_c_b.send_back_multiaddr is not None
+    assert conn_a_c.send_back_multiaddr is not None
+
+    node_a.node_profile = NodePerformanceProfile(
+        model_id="test",
+        chip_id="test",
+        friendly_name="test",
+        memory=node_a.node_profile.memory,
+        network_interfaces=[
+            NetworkInterfaceInfo(
+                name="en3",
+                ip_address=conn_c_a.send_back_multiaddr.ip_address,
+            ),
+            NetworkInterfaceInfo(
+                name="en4",
+                ip_address=conn_b_a.send_back_multiaddr.ip_address,
+            ),
+            ethernet_interface,
+        ],
+        system=node_a.node_profile.system,
+    )
+    node_b.node_profile = NodePerformanceProfile(
+        model_id="test",
+        chip_id="test",
+        friendly_name="test",
+        memory=node_b.node_profile.memory,
+        network_interfaces=[
+            NetworkInterfaceInfo(
+                name="en3",
+                ip_address=conn_c_b.send_back_multiaddr.ip_address,
+            ),
+            NetworkInterfaceInfo(
+                name="en4",
+                ip_address=conn_a_b.send_back_multiaddr.ip_address,
+            ),
+            ethernet_interface,
+        ],
+        system=node_b.node_profile.system,
+    )
+    node_c.node_profile = NodePerformanceProfile(
+        model_id="test",
+        chip_id="test",
+        friendly_name="test",
+        memory=node_c.node_profile.memory,
+        network_interfaces=[
+            NetworkInterfaceInfo(
+                name="en3",
+                ip_address=conn_a_c.send_back_multiaddr.ip_address,
+            ),
+            NetworkInterfaceInfo(
+                name="en4",
+                ip_address=conn_b_c.send_back_multiaddr.ip_address,
+            ),
+            ethernet_interface,
+        ],
+        system=node_c.node_profile.system,
+    )
 
     topology.add_node(node_a)
     topology.add_node(node_b)
     topology.add_node(node_c)
-    topology.add_connection(node_a, node_b, create_rdma_connection(3))
-    topology.add_connection(node_b, node_c, create_rdma_connection(4))
-    topology.add_connection(node_c, node_a, create_rdma_connection(5))
-    topology.add_connection(node_b, node_a, create_rdma_connection(3))
-    topology.add_connection(node_c, node_b, create_rdma_connection(4))
-    topology.add_connection(node_a, node_c, create_rdma_connection(5))
-
-    topology.add_connection(node_a, node_b, ethernet_conn)
-    topology.add_connection(node_b, node_c, ethernet_conn)
-    topology.add_connection(node_c, node_a, ethernet_conn)
-    topology.add_connection(node_a, node_c, ethernet_conn)
-    topology.add_connection(node_b, node_a, ethernet_conn)
-    topology.add_connection(node_c, node_b, ethernet_conn)
+    topology.add_connection(conn_a_b)
+    topology.add_connection(conn_b_c)
+    topology.add_connection(conn_c_a)
+    topology.add_connection(conn_b_a)
+    topology.add_connection(conn_c_b)
+    topology.add_connection(conn_a_c)
 
     cic = PlaceInstance(
         sharding=Sharding.Tensor,
@@ -339,7 +421,7 @@ def test_tensor_rdma_backend_connectivity_matrix(
         min_nodes=1,
     )
 
-    placements = place_instance(cic, topology, {}, profiles)
+    placements = place_instance(cic, topology, {})
 
     assert len(placements) == 1
     instance_id = list(placements.keys())[0]
@@ -347,10 +429,10 @@ def test_tensor_rdma_backend_connectivity_matrix(
 
     assert isinstance(instance, MlxJacclInstance)
 
-    assert instance.jaccl_devices is not None
+    assert instance.ibv_devices is not None
     assert instance.jaccl_coordinators is not None
 
-    matrix = instance.jaccl_devices
+    matrix = instance.ibv_devices
     assert len(matrix) == 3
 
     for i in range(3):
@@ -359,15 +441,15 @@ def test_tensor_rdma_backend_connectivity_matrix(
     assigned_nodes = list(instance.shard_assignments.node_to_runner.keys())
     node_to_idx = {node_id: idx for idx, node_id in enumerate(assigned_nodes)}
 
-    idx_a = node_to_idx[node_a]
-    idx_b = node_to_idx[node_b]
-    idx_c = node_to_idx[node_c]
+    idx_a = node_to_idx[node_id_a]
+    idx_b = node_to_idx[node_id_b]
+    idx_c = node_to_idx[node_id_c]
 
     logger.info(matrix)
 
-    assert matrix[idx_a][idx_b] == "rdma_en3"
-    assert matrix[idx_b][idx_c] == "rdma_en4"
-    assert matrix[idx_c][idx_a] == "rdma_en5"
+    assert matrix[idx_a][idx_b] == "rdma_en4"
+    assert matrix[idx_b][idx_c] == "rdma_en3"
+    assert matrix[idx_c][idx_a] == "rdma_en3"
 
     # Verify coordinators are set for all nodes
     assert len(instance.jaccl_coordinators) == 3

src/exo/master/tests/test_placement_utils.py

@@ -1,48 +1,56 @@
+from typing import Callable
+
 import pytest
 
 from exo.master.placement_utils import (
-    NodeWithProfile,
     filter_cycles_by_memory,
     get_hosts_from_subgraph,
     get_mlx_jaccl_coordinators,
     get_shard_assignments,
     get_smallest_cycles,
 )
-from exo.master.tests.conftest import create_connection, create_node_profile
 from exo.shared.topology import Topology
 from exo.shared.types.common import Host, NodeId
 from exo.shared.types.memory import Memory
 from exo.shared.types.models import ModelId, ModelMetadata
+from exo.shared.types.profiling import NetworkInterfaceInfo, NodePerformanceProfile
+from exo.shared.types.topology import Connection, NodeInfo
 from exo.shared.types.worker.shards import Sharding
 
 
-def test_filter_cycles_by_memory():
+@pytest.fixture
+def topology() -> Topology:
+    topology = Topology()
+    return topology
+
+
+def test_filter_cycles_by_memory(
+    topology: Topology,
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+    create_connection: Callable[[NodeId, NodeId], Connection],
+):
     # arrange
     node1_id = NodeId()
     node2_id = NodeId()
-    topology = Topology()
 
-    node1 = create_node_profile(1000 * 1024)
-    node2 = create_node_profile(1000 * 1024)
-    node_profiles = {node1_id: node1, node2_id: node2}
+    node1 = create_node(1000 * 1024, node1_id)
+    node2 = create_node(1000 * 1024, node2_id)
 
-    topology.add_node(node1_id)
-    topology.add_node(node2_id)
+    topology.add_node(node1)
+    topology.add_node(node2)
 
-    connection1 = create_connection(1)
-    connection2 = create_connection(2)
+    connection1 = create_connection(node1_id, node2_id)
+    connection2 = create_connection(node2_id, node1_id)
 
-    topology.add_connection(node1_id, node2_id, connection1)
-    topology.add_connection(node2_id, node1_id, connection2)
+    topology.add_connection(connection1)
+    topology.add_connection(connection2)
 
     cycles = topology.get_cycles()
     assert len(cycles) == 1
     assert len(cycles[0]) == 2
 
     # act
-    filtered_cycles = filter_cycles_by_memory(
-        cycles, node_profiles, Memory.from_bytes(1)
-    )
+    filtered_cycles = filter_cycles_by_memory(cycles, Memory.from_bytes(1))
 
     # assert
     assert len(filtered_cycles) == 1
@@ -50,65 +58,64 @@ def test_filter_cycles_by_memory():
     assert set(n.node_id for n in filtered_cycles[0]) == {node1_id, node2_id}
 
 
-def test_filter_cycles_by_insufficient_memory():
+def test_filter_cycles_by_insufficient_memory(
+    topology: Topology,
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+    create_connection: Callable[[NodeId, NodeId], Connection],
+):
     # arrange
     node1_id = NodeId()
     node2_id = NodeId()
-    topology = Topology()
 
-    node1 = create_node_profile(1000 * 1024)
-    node2 = create_node_profile(1000 * 1024)
-    node_profiles = {node1_id: node1, node2_id: node2}
+    node1 = create_node(1000 * 1024, node1_id)
+    node2 = create_node(1000 * 1024, node2_id)
 
-    topology.add_node(node1_id)
-    topology.add_node(node2_id)
+    topology.add_node(node1)
+    topology.add_node(node2)
 
-    connection1 = create_connection(1)
-    connection2 = create_connection(2)
+    connection1 = create_connection(node1_id, node2_id)
+    connection2 = create_connection(node2_id, node1_id)
 
-    topology.add_connection(node1_id, node2_id, connection1)
-    topology.add_connection(node2_id, node1_id, connection2)
+    topology.add_connection(connection1)
+    topology.add_connection(connection2)
 
     # act
     filtered_cycles = filter_cycles_by_memory(
-        topology.get_cycles(), node_profiles, Memory.from_kb(2001)
+        topology.get_cycles(), Memory.from_kb(2001)
     )
 
     # assert
     assert len(filtered_cycles) == 0
 
 
-def test_filter_multiple_cycles_by_memory():
+def test_filter_multiple_cycles_by_memory(
+    topology: Topology,
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+    create_connection: Callable[[NodeId, NodeId], Connection],
+):
     # arrange
     node_a_id = NodeId()
     node_b_id = NodeId()
     node_c_id = NodeId()
-    topology = Topology()
 
-    node_a = create_node_profile(500 * 1024)
-    node_b = create_node_profile(500 * 1024)
-    node_c = create_node_profile(1000 * 1024)
-    node_profiles = {
-        node_a_id: node_a,
-        node_b_id: node_b,
-        node_c_id: node_c,
-    }
+    node_a = create_node(500 * 1024, node_a_id)
+    node_b = create_node(500 * 1024, node_b_id)
+    node_c = create_node(1000 * 1024, node_c_id)
 
-    topology.add_node(node_a_id)
-    topology.add_node(node_b_id)
-    topology.add_node(node_c_id)
+    topology.add_node(node_a)
+    topology.add_node(node_b)
+    topology.add_node(node_c)
 
-    topology.add_connection(node_a_id, node_b_id, create_connection(1))
-    topology.add_connection(node_b_id, node_a_id, create_connection(2))
-    topology.add_connection(node_a_id, node_c_id, create_connection(3))
-    topology.add_connection(node_c_id, node_b_id, create_connection(4))
+    topology.add_connection(create_connection(node_a_id, node_b_id))
+    topology.add_connection(create_connection(node_b_id, node_a_id))
+
+    topology.add_connection(create_connection(node_a_id, node_c_id))
+    topology.add_connection(create_connection(node_c_id, node_b_id))
 
     cycles = topology.get_cycles()
 
     # act
-    filtered_cycles = filter_cycles_by_memory(
-        cycles, node_profiles, Memory.from_kb(1500)
-    )
+    filtered_cycles = filter_cycles_by_memory(cycles, Memory.from_kb(1500))
 
     # assert
     assert len(filtered_cycles) == 1
@@ -120,38 +127,31 @@ def test_filter_multiple_cycles_by_memory():
     }
 
 
-def test_get_smallest_cycles():
+def test_get_smallest_cycles(
+    topology: Topology,
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+    create_connection: Callable[[NodeId, NodeId], Connection],
+):
     # arrange
     node_a_id = NodeId()
     node_b_id = NodeId()
     node_c_id = NodeId()
-    topology = Topology()
 
-    node_a = create_node_profile(500 * 1024)
-    node_b = create_node_profile(500 * 1024)
-    node_c = create_node_profile(1000 * 1024)
-    node_profiles = {
-        node_a_id: node_a,
-        node_b_id: node_b,
-        node_c_id: node_c,
-    }
+    node_a = create_node(500 * 1024, node_a_id)
+    node_b = create_node(500 * 1024, node_b_id)
+    node_c = create_node(1000 * 1024, node_c_id)
 
-    topology.add_node(node_a_id)
-    topology.add_node(node_b_id)
-    topology.add_node(node_c_id)
+    topology.add_node(node_a)
+    topology.add_node(node_b)
+    topology.add_node(node_c)
 
-    topology.add_connection(node_a_id, node_b_id, create_connection(1))
-    topology.add_connection(node_b_id, node_a_id, create_connection(2))
-    topology.add_connection(node_a_id, node_c_id, create_connection(3))
-    topology.add_connection(node_c_id, node_b_id, create_connection(4))
-
-    cycles = [
-        [NodeWithProfile(node_id=nid, node_profile=node_profiles[nid]) for nid in cycle]
-        for cycle in topology.get_cycles()
-    ]
+    topology.add_connection(create_connection(node_a_id, node_b_id))
+    topology.add_connection(create_connection(node_b_id, node_c_id))
+    topology.add_connection(create_connection(node_c_id, node_a_id))
+    topology.add_connection(create_connection(node_b_id, node_a_id))
 
     # act
-    smallest_cycles = get_smallest_cycles(cycles)
+    smallest_cycles = get_smallest_cycles(topology.get_cycles())
 
     # assert
     assert len(smallest_cycles) == 1
@@ -168,6 +168,9 @@ def test_get_smallest_cycles():
     ],
 )
 def test_get_shard_assignments(
+    topology: Topology,
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+    create_connection: Callable[[NodeId, NodeId], Connection],
     available_memory: tuple[int, int, int],
     total_layers: int,
     expected_layers: tuple[int, int, int],
@@ -176,25 +179,19 @@ def test_get_shard_assignments(
     node_a_id = NodeId()
     node_b_id = NodeId()
     node_c_id = NodeId()
-    topology = Topology()
 
-    node_a = create_node_profile(available_memory[0] * 1024)
-    node_b = create_node_profile(available_memory[1] * 1024)
-    node_c = create_node_profile(available_memory[2] * 1024)
-    node_profiles = {
-        node_a_id: node_a,
-        node_b_id: node_b,
-        node_c_id: node_c,
-    }
+    node_a = create_node(available_memory[0] * 1024, node_a_id)
+    node_b = create_node(available_memory[1] * 1024, node_b_id)
+    node_c = create_node(available_memory[2] * 1024, node_c_id)
 
-    topology.add_node(node_a_id)
-    topology.add_node(node_b_id)
-    topology.add_node(node_c_id)
+    topology.add_node(node_a)
+    topology.add_node(node_b)
+    topology.add_node(node_c)
 
-    topology.add_connection(node_a_id, node_b_id, create_connection(1))
-    topology.add_connection(node_b_id, node_c_id, create_connection(2))
-    topology.add_connection(node_c_id, node_a_id, create_connection(3))
-    topology.add_connection(node_b_id, node_a_id, create_connection(4))
+    topology.add_connection(create_connection(node_a_id, node_b_id))
+    topology.add_connection(create_connection(node_b_id, node_c_id))
+    topology.add_connection(create_connection(node_c_id, node_a_id))
+    topology.add_connection(create_connection(node_b_id, node_a_id))
 
     model_meta = ModelMetadata(
         model_id=ModelId("test-model"),
@@ -202,11 +199,7 @@ def test_get_shard_assignments(
         n_layers=total_layers,
         storage_size=Memory.from_kb(1000),
     )
-
-    cycles = [
-        [NodeWithProfile(node_id=nid, node_profile=node_profiles[nid]) for nid in cycle]
-        for cycle in topology.get_cycles()
-    ]
+    cycles = topology.get_cycles()
     selected_cycle = cycles[0]
 
     # act
@@ -235,21 +228,28 @@ def test_get_shard_assignments(
     )
 
 
-def test_get_hosts_from_subgraph():
+def test_get_hosts_from_subgraph(
+    topology: Topology,
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+    create_connection: Callable[[NodeId, NodeId, int | None], Connection],
+):
     # arrange
     node_a_id = NodeId()
     node_b_id = NodeId()
     node_c_id = NodeId()
-    topology = Topology()
 
-    topology.add_node(node_a_id)
-    topology.add_node(node_b_id)
-    topology.add_node(node_c_id)
+    node_a = create_node(500, node_a_id)
+    node_b = create_node(500, node_b_id)
+    node_c = create_node(1000, node_c_id)
 
-    topology.add_connection(node_a_id, node_b_id, create_connection(1))
-    topology.add_connection(node_b_id, node_a_id, create_connection(2))
-    topology.add_connection(node_a_id, node_c_id, create_connection(3))
-    topology.add_connection(node_c_id, node_b_id, create_connection(4))
+    topology.add_node(node_a)
+    topology.add_node(node_b)
+    topology.add_node(node_c)
+
+    topology.add_connection(create_connection(node_a_id, node_b_id, 5001))
+    topology.add_connection(create_connection(node_b_id, node_c_id, 5002))
+    topology.add_connection(create_connection(node_c_id, node_a_id, 5003))
+    topology.add_connection(create_connection(node_b_id, node_a_id, 5004))
 
     # act
     hosts = get_hosts_from_subgraph(topology)
@@ -257,47 +257,108 @@ def test_get_hosts_from_subgraph():
     # assert
     assert len(hosts) == 3
     expected_hosts = [
-        Host(ip=("169.254.0.2"), port=1234),
-        Host(ip=("169.254.0.3"), port=1234),
-        Host(ip=("169.254.0.4"), port=1234),
+        Host(ip=("169.254.0.2"), port=5001),
+        Host(ip=("169.254.0.3"), port=5002),
+        Host(ip=("169.254.0.4"), port=5003),
     ]
     for expected_host in expected_hosts:
         assert expected_host in hosts
 
 
-def test_get_mlx_jaccl_coordinators():
+def test_get_mlx_jaccl_coordinators(
+    topology: Topology,
+    create_node: Callable[[int, NodeId | None], NodeInfo],
+    create_connection: Callable[[NodeId, NodeId, int | None], Connection],
+):
     # arrange
     node_a_id = NodeId()
     node_b_id = NodeId()
     node_c_id = NodeId()
-    topology = Topology()
 
-    topology.add_node(node_a_id)
-    topology.add_node(node_b_id)
-    topology.add_node(node_c_id)
+    node_a = create_node(500 * 1024, node_a_id)
+    node_b = create_node(500 * 1024, node_b_id)
+    node_c = create_node(1000 * 1024, node_c_id)
 
-    topology.add_connection(node_a_id, node_b_id, create_connection(1))
-    topology.add_connection(node_b_id, node_a_id, create_connection(2))
-    topology.add_connection(node_a_id, node_c_id, create_connection(3))
-    topology.add_connection(node_c_id, node_b_id, create_connection(4))
+    conn_a_b = create_connection(node_a_id, node_b_id, 5001)
+    conn_b_a = create_connection(node_b_id, node_a_id, 5002)
+    conn_b_c = create_connection(node_b_id, node_c_id, 5003)
+    conn_c_b = create_connection(node_c_id, node_b_id, 5004)
+    conn_c_a = create_connection(node_c_id, node_a_id, 5005)
+    conn_a_c = create_connection(node_a_id, node_c_id, 5006)
 
-    conn_a_b = create_connection(1)
-    conn_b_a = create_connection(2)
-    conn_b_c = create_connection(3)
-    conn_c_b = create_connection(4)
-    conn_c_a = create_connection(5)
-    conn_a_c = create_connection(6)
+    # Update node profiles with network interfaces before adding to topology
+    assert node_a.node_profile is not None
+    assert node_b.node_profile is not None
+    assert node_c.node_profile is not None
 
-    topology.add_connection(node_a_id, node_b_id, conn_a_b)
-    topology.add_connection(node_b_id, node_a_id, conn_b_a)
-    topology.add_connection(node_b_id, node_c_id, conn_b_c)
-    topology.add_connection(node_c_id, node_b_id, conn_c_b)
-    topology.add_connection(node_c_id, node_a_id, conn_c_a)
-    topology.add_connection(node_a_id, node_c_id, conn_a_c)
+    node_a.node_profile = NodePerformanceProfile(
+        model_id="test",
+        chip_id="test",
+        friendly_name="test",
+        memory=node_a.node_profile.memory,
+        network_interfaces=[
+            NetworkInterfaceInfo(
+                name="en3",
+                ip_address=conn_a_b.send_back_multiaddr.ip_address,
+            ),
+            NetworkInterfaceInfo(
+                name="en4",
+                ip_address=conn_a_c.send_back_multiaddr.ip_address,
+            ),
+        ],
+        system=node_a.node_profile.system,
+    )
+    node_b.node_profile = NodePerformanceProfile(
+        model_id="test",
+        chip_id="test",
+        friendly_name="test",
+        memory=node_b.node_profile.memory,
+        network_interfaces=[
+            NetworkInterfaceInfo(
+                name="en3",
+                ip_address=conn_b_a.send_back_multiaddr.ip_address,
+            ),
+            NetworkInterfaceInfo(
+                name="en4",
+                ip_address=conn_b_c.send_back_multiaddr.ip_address,
+            ),
+        ],
+        system=node_b.node_profile.system,
+    )
+    node_c.node_profile = NodePerformanceProfile(
+        model_id="test",
+        chip_id="test",
+        friendly_name="test",
+        memory=node_c.node_profile.memory,
+        network_interfaces=[
+            NetworkInterfaceInfo(
+                name="en3",
+                ip_address=conn_c_b.send_back_multiaddr.ip_address,
+            ),
+            NetworkInterfaceInfo(
+                name="en4",
+                ip_address=conn_c_a.send_back_multiaddr.ip_address,
+            ),
+        ],
+        system=node_c.node_profile.system,
+    )
+
+    topology.add_node(node_a)
+    topology.add_node(node_b)
+    topology.add_node(node_c)
+
+    topology.add_connection(conn_a_b)
+    topology.add_connection(conn_b_a)
+    topology.add_connection(conn_b_c)
+    topology.add_connection(conn_c_b)
+    topology.add_connection(conn_c_a)
+    topology.add_connection(conn_a_c)
+
+    cycle = [node_a, node_b, node_c]
 
     # act
     coordinators = get_mlx_jaccl_coordinators(
-        node_a_id, coordinator_port=5000, cycle_digraph=topology
+        cycle, coordinator_port=5000, cycle_digraph=topology
     )
 
     # assert
@@ -326,11 +387,11 @@ def test_get_mlx_jaccl_coordinators():
 
     # Non-rank-0 nodes should use the specific IP from their connection to rank 0
     # node_b uses the IP from conn_b_a (node_b -> node_a)
-    assert coordinators[node_b_id] == (f"{conn_b_a.sink_multiaddr.ip_address}:5000"), (
-        "node_b should use the IP from conn_b_a"
-    )
+    assert coordinators[node_b_id] == (
+        f"{conn_b_a.send_back_multiaddr.ip_address}:5000"
+    ), "node_b should use the IP from conn_b_a"
 
     # node_c uses the IP from conn_c_a (node_c -> node_a)
-    assert coordinators[node_c_id] == (f"{conn_c_a.sink_multiaddr.ip_address}:5000"), (
-        "node_c should use the IP from conn_c_a"
-    )
+    assert coordinators[node_c_id] == (
+        f"{conn_c_a.send_back_multiaddr.ip_address}:5000"
+    ), "node_c should use the IP from conn_c_a"

src/exo/master/tests/test_topology.py

@@ -1,14 +1,13 @@
 import pytest
 
 from exo.shared.topology import Topology
-from exo.shared.types.common import NodeId
 from exo.shared.types.multiaddr import Multiaddr
 from exo.shared.types.profiling import (
-    MemoryUsage,
+    MemoryPerformanceProfile,
     NodePerformanceProfile,
     SystemPerformanceProfile,
 )
-from exo.shared.types.topology import SocketConnection
+from exo.shared.types.topology import Connection, ConnectionProfile, NodeId, NodeInfo
 
 
 @pytest.fixture
@@ -17,15 +16,20 @@ def topology() -> Topology:
 
 
 @pytest.fixture
-def connection() -> SocketConnection:
-    return SocketConnection(
-        sink_multiaddr=Multiaddr(address="/ip4/127.0.0.1/tcp/1235"),
+def connection() -> Connection:
+    return Connection(
+        local_node_id=NodeId(),
+        send_back_node_id=NodeId(),
+        send_back_multiaddr=Multiaddr(address="/ip4/127.0.0.1/tcp/1235"),
+        connection_profile=ConnectionProfile(
+            throughput=1000, latency=1000, jitter=1000
+        ),
     )
 
 
 @pytest.fixture
 def node_profile() -> NodePerformanceProfile:
-    memory_profile = MemoryUsage.from_bytes(
+    memory_profile = MemoryPerformanceProfile.from_bytes(
         ram_total=1000, ram_available=1000, swap_total=1000, swap_available=1000
     )
     system_profile = SystemPerformanceProfile()
@@ -39,85 +43,162 @@ def node_profile() -> NodePerformanceProfile:
     )
 
 
-def test_add_node(topology: Topology):
+@pytest.fixture
+def connection_profile() -> ConnectionProfile:
+    return ConnectionProfile(throughput=1000, latency=1000, jitter=1000)
+
+
+def test_add_node(topology: Topology, node_profile: NodePerformanceProfile):
     # arrange
     node_id = NodeId()
 
     # act
-    topology.add_node(node_id)
+    topology.add_node(NodeInfo(node_id=node_id, node_profile=node_profile))
 
     # assert
-    assert topology.node_is_leaf(node_id)
+    data = topology.get_node_profile(node_id)
+    assert data == node_profile
 
 
-def test_add_connection(topology: Topology, connection: SocketConnection):
+def test_add_connection(
+    topology: Topology, node_profile: NodePerformanceProfile, connection: Connection
+):
     # arrange
-    node_a = NodeId()
-    node_b = NodeId()
-
-    topology.add_node(node_a)
-    topology.add_node(node_b)
-    topology.add_connection(node_a, node_b, connection)
+    topology.add_node(
+        NodeInfo(node_id=connection.local_node_id, node_profile=node_profile)
+    )
+    topology.add_node(
+        NodeInfo(node_id=connection.send_back_node_id, node_profile=node_profile)
+    )
+    topology.add_connection(connection)
 
     # act
-    data = list(conn for _, _, conn in topology.list_connections())
+    data = topology.get_connection_profile(connection)
 
     # assert
-    assert data == [connection]
+    assert data == connection.connection_profile
 
-    assert topology.node_is_leaf(node_a)
-    assert topology.node_is_leaf(node_b)
+
+def test_update_node_profile(
+    topology: Topology, node_profile: NodePerformanceProfile, connection: Connection
+):
+    # arrange
+    topology.add_node(
+        NodeInfo(node_id=connection.local_node_id, node_profile=node_profile)
+    )
+    topology.add_node(
+        NodeInfo(node_id=connection.send_back_node_id, node_profile=node_profile)
+    )
+    topology.add_connection(connection)
+
+    new_node_profile = NodePerformanceProfile(
+        model_id="test",
+        chip_id="test",
+        friendly_name="test",
+        memory=MemoryPerformanceProfile.from_bytes(
+            ram_total=1000, ram_available=1000, swap_total=1000, swap_available=1000
+        ),
+        network_interfaces=[],
+        system=SystemPerformanceProfile(),
+    )
+
+    # act
+    topology.update_node_profile(
+        connection.local_node_id, node_profile=new_node_profile
+    )
+
+    # assert
+    data = topology.get_node_profile(connection.local_node_id)
+    assert data == new_node_profile
+
+
+def test_update_connection_profile(
+    topology: Topology, node_profile: NodePerformanceProfile, connection: Connection
+):
+    # arrange
+    topology.add_node(
+        NodeInfo(node_id=connection.local_node_id, node_profile=node_profile)
+    )
+    topology.add_node(
+        NodeInfo(node_id=connection.send_back_node_id, node_profile=node_profile)
+    )
+    topology.add_connection(connection)
+
+    new_connection_profile = ConnectionProfile(
+        throughput=2000, latency=2000, jitter=2000
+    )
+    connection = Connection(
+        local_node_id=connection.local_node_id,
+        send_back_node_id=connection.send_back_node_id,
+        send_back_multiaddr=connection.send_back_multiaddr,
+        connection_profile=new_connection_profile,
+    )
+
+    # act
+    topology.update_connection_profile(connection)
+
+    # assert
+    data = topology.get_connection_profile(connection)
+    assert data == new_connection_profile
 
 
 def test_remove_connection_still_connected(
-    topology: Topology, connection: SocketConnection
+    topology: Topology, node_profile: NodePerformanceProfile, connection: Connection
 ):
     # arrange
-    node_a = NodeId()
-    node_b = NodeId()
-
-    topology.add_node(node_a)
-    topology.add_node(node_b)
-    topology.add_connection(node_a, node_b, connection)
+    topology.add_node(
+        NodeInfo(node_id=connection.local_node_id, node_profile=node_profile)
+    )
+    topology.add_node(
+        NodeInfo(node_id=connection.send_back_node_id, node_profile=node_profile)
+    )
+    topology.add_connection(connection)
 
     # act
-    topology.remove_connection(node_a, node_b, connection)
+    topology.remove_connection(connection)
 
     # assert
-    assert list(topology.get_all_connections_between(node_a, node_b)) == []
+    assert topology.get_connection_profile(connection) is None
 
 
-def test_remove_node_still_connected(topology: Topology, connection: SocketConnection):
+def test_remove_node_still_connected(
+    topology: Topology, node_profile: NodePerformanceProfile, connection: Connection
+):
     # arrange
-    node_a = NodeId()
-    node_b = NodeId()
-
-    topology.add_node(node_a)
-    topology.add_node(node_b)
-    topology.add_connection(node_a, node_b, connection)
-    assert list(topology.out_edges(node_a)) == [(node_b, connection)]
+    topology.add_node(
+        NodeInfo(node_id=connection.local_node_id, node_profile=node_profile)
+    )
+    topology.add_node(
+        NodeInfo(node_id=connection.send_back_node_id, node_profile=node_profile)
+    )
+    topology.add_connection(connection)
 
     # act
-    topology.remove_node(node_b)
+    topology.remove_node(connection.local_node_id)
 
     # assert
-    assert list(topology.out_edges(node_a)) == []
+    assert topology.get_node_profile(connection.local_node_id) is None
 
 
-def test_list_nodes(topology: Topology, connection: SocketConnection):
+def test_list_nodes(
+    topology: Topology, node_profile: NodePerformanceProfile, connection: Connection
+):
     # arrange
-    node_a = NodeId()
-    node_b = NodeId()
-
-    topology.add_node(node_a)
-    topology.add_node(node_b)
-    topology.add_connection(node_a, node_b, connection)
-    assert list(topology.out_edges(node_a)) == [(node_b, connection)]
+    topology.add_node(
+        NodeInfo(node_id=connection.local_node_id, node_profile=node_profile)
+    )
+    topology.add_node(
+        NodeInfo(node_id=connection.send_back_node_id, node_profile=node_profile)
+    )
+    topology.add_connection(connection)
 
     # act
     nodes = list(topology.list_nodes())
 
     # assert
     assert len(nodes) == 2
-    assert all(isinstance(node, NodeId) for node in nodes)
-    assert {node for node in nodes} == {node_a, node_b}
+    assert all(isinstance(node, NodeInfo) for node in nodes)
+    assert {node.node_id for node in nodes} == {
+        connection.local_node_id,
+        connection.send_back_node_id,
+    }

src/exo/shared/apply.py

@@ -11,8 +11,10 @@ from exo.shared.types.events import (
     IndexedEvent,
     InstanceCreated,
     InstanceDeleted,
+    NodeCreated,
     NodeDownloadProgress,
-    NodeGatheredInfo,
+    NodeMemoryMeasured,
+    NodePerformanceMeasured,
     NodeTimedOut,
     RunnerDeleted,
     RunnerStatusUpdated,
@@ -25,23 +27,13 @@ from exo.shared.types.events import (
     TopologyEdgeCreated,
     TopologyEdgeDeleted,
 )
-from exo.shared.types.profiling import NodePerformanceProfile
+from exo.shared.types.profiling import NodePerformanceProfile, SystemPerformanceProfile
 from exo.shared.types.state import State
 from exo.shared.types.tasks import Task, TaskId, TaskStatus
-from exo.shared.types.topology import RDMAConnection
+from exo.shared.types.topology import NodeInfo
 from exo.shared.types.worker.downloads import DownloadProgress
 from exo.shared.types.worker.instances import Instance, InstanceId
 from exo.shared.types.worker.runners import RunnerId, RunnerStatus
-from exo.utils.info_gatherer.info_gatherer import (
-    MacmonMetrics,
-    MacTBConnections,
-    MacTBIdentifiers,
-    MemoryUsage,
-    MiscData,
-    NodeConfig,
-    NodeNetworkInterfaces,
-    StaticNodeInformation,
-)
 
 
 def event_apply(event: Event, state: State) -> State:
@@ -55,12 +47,16 @@ def event_apply(event: Event, state: State) -> State:
             return apply_instance_created(event, state)
         case InstanceDeleted():
             return apply_instance_deleted(event, state)
+        case NodeCreated():
+            return apply_topology_node_created(event, state)
         case NodeTimedOut():
             return apply_node_timed_out(event, state)
+        case NodePerformanceMeasured():
+            return apply_node_performance_measured(event, state)
         case NodeDownloadProgress():
             return apply_node_download_progress(event, state)
-        case NodeGatheredInfo():
-            return apply_node_gathered_info(event, state)
+        case NodeMemoryMeasured():
+            return apply_node_memory_measured(event, state)
         case RunnerDeleted():
             return apply_runner_deleted(event, state)
         case RunnerStatusUpdated():
@@ -192,7 +188,7 @@ def apply_runner_deleted(event: RunnerDeleted, state: State) -> State:
 
 
 def apply_node_timed_out(event: NodeTimedOut, state: State) -> State:
-    topology = copy.deepcopy(state.topology)
+    topology = copy.copy(state.topology)
     state.topology.remove_node(event.node_id)
     node_profiles = {
         key: value for key, value in state.node_profiles.items() if key != event.node_id
@@ -200,12 +196,8 @@ def apply_node_timed_out(event: NodeTimedOut, state: State) -> State:
     last_seen = {
         key: value for key, value in state.last_seen.items() if key != event.node_id
     }
-    downloads = {
-        key: value for key, value in state.downloads.items() if key != event.node_id
-    }
     return state.model_copy(
         update={
-            "downloads": downloads,
             "topology": topology,
             "node_profiles": node_profiles,
             "last_seen": last_seen,
@@ -213,69 +205,103 @@ def apply_node_timed_out(event: NodeTimedOut, state: State) -> State:
     )
 
 
-def apply_node_gathered_info(event: NodeGatheredInfo, state: State) -> State:
-    topology = copy.deepcopy(state.topology)
-    topology.add_node(event.node_id)
-    info = event.info
-    profile = state.node_profiles.get(event.node_id, NodePerformanceProfile())
-    # TODO: should be broken up into individual events instead of this monster
-    match info:
-        case MacmonMetrics():
-            profile.system = info.system_profile
-            profile.memory = info.memory
-        case MemoryUsage():
-            profile.memory = info
-        case NodeConfig():
-            pass
-        case MiscData():
-            profile.friendly_name = info.friendly_name
-        case StaticNodeInformation():
-            profile.model_id = info.model
-            profile.chip_id = info.chip
-        # TODO: makes me slightly sad
-        case NodeNetworkInterfaces():
-            profile.network_interfaces = info.ifaces
-        case MacTBIdentifiers():
-            profile.tb_interfaces = info.idents
-        case MacTBConnections():
-            conn_map = {
-                tb_ident.domain_uuid: (nid, tb_ident.rdma_interface)
-                for nid in state.node_profiles
-                for tb_ident in state.node_profiles[nid].tb_interfaces
-            }
-            as_rdma_conns = [
-                (
-                    conn_map[tb_conn.sink_uuid][0],
-                    RDMAConnection(
-                        source_rdma_iface=conn_map[tb_conn.source_uuid][1],
-                        sink_rdma_iface=conn_map[tb_conn.sink_uuid][1],
-                    ),
-                )
-                for tb_conn in info.conns
-                if tb_conn.source_uuid in conn_map
-                if tb_conn.sink_uuid in conn_map
-            ]
-            topology.replace_all_out_tb_connections(event.node_id, as_rdma_conns)
-
-    last_seen = {**state.last_seen, event.node_id: datetime.fromisoformat(event.when)}
-    new_profiles = {**state.node_profiles, event.node_id: profile}
+def apply_node_performance_measured(
+    event: NodePerformanceMeasured, state: State
+) -> State:
+    new_profiles: Mapping[NodeId, NodePerformanceProfile] = {
+        **state.node_profiles,
+        event.node_id: event.node_profile,
+    }
+    last_seen: Mapping[NodeId, datetime] = {
+        **state.last_seen,
+        event.node_id: datetime.fromisoformat(event.when),
+    }
+    state = state.model_copy(update={"node_profiles": new_profiles})
+    topology = copy.copy(state.topology)
+    # TODO: NodeCreated
+    if not topology.contains_node(event.node_id):
+        topology.add_node(NodeInfo(node_id=event.node_id))
+    topology.update_node_profile(event.node_id, event.node_profile)
     return state.model_copy(
         update={
             "node_profiles": new_profiles,
-            "last_seen": last_seen,
             "topology": topology,
+            "last_seen": last_seen,
         }
     )
 
 
+def apply_node_memory_measured(event: NodeMemoryMeasured, state: State) -> State:
+    existing = state.node_profiles.get(event.node_id)
+    topology = copy.copy(state.topology)
+
+    if existing is None:
+        created = NodePerformanceProfile(
+            model_id="unknown",
+            chip_id="unknown",
+            friendly_name="Unknown",
+            memory=event.memory,
+            network_interfaces=[],
+            system=SystemPerformanceProfile(
+                # TODO: flops_fp16=0.0,
+                gpu_usage=0.0,
+                temp=0.0,
+                sys_power=0.0,
+                pcpu_usage=0.0,
+                ecpu_usage=0.0,
+                ane_power=0.0,
+            ),
+        )
+        created_profiles: Mapping[NodeId, NodePerformanceProfile] = {
+            **state.node_profiles,
+            event.node_id: created,
+        }
+        last_seen: Mapping[NodeId, datetime] = {
+            **state.last_seen,
+            event.node_id: datetime.fromisoformat(event.when),
+        }
+        if not topology.contains_node(event.node_id):
+            topology.add_node(NodeInfo(node_id=event.node_id))
+            # TODO: NodeCreated
+        topology.update_node_profile(event.node_id, created)
+        return state.model_copy(
+            update={
+                "node_profiles": created_profiles,
+                "topology": topology,
+                "last_seen": last_seen,
+            }
+        )
+
+    updated = existing.model_copy(update={"memory": event.memory})
+    updated_profiles: Mapping[NodeId, NodePerformanceProfile] = {
+        **state.node_profiles,
+        event.node_id: updated,
+    }
+    # TODO: NodeCreated
+    if not topology.contains_node(event.node_id):
+        topology.add_node(NodeInfo(node_id=event.node_id))
+    topology.update_node_profile(event.node_id, updated)
+    return state.model_copy(
+        update={"node_profiles": updated_profiles, "topology": topology}
+    )
+
+
+def apply_topology_node_created(event: NodeCreated, state: State) -> State:
+    topology = copy.copy(state.topology)
+    topology.add_node(NodeInfo(node_id=event.node_id))
+    return state.model_copy(update={"topology": topology})
+
+
 def apply_topology_edge_created(event: TopologyEdgeCreated, state: State) -> State:
-    topology = copy.deepcopy(state.topology)
-    topology.add_connection(event.source, event.sink, event.edge)
+    topology = copy.copy(state.topology)
+    topology.add_connection(event.edge)
     return state.model_copy(update={"topology": topology})
 
 
 def apply_topology_edge_deleted(event: TopologyEdgeDeleted, state: State) -> State:
-    topology = copy.deepcopy(state.topology)
-    topology.remove_connection(event.sink, event.source, event.edge)
+    topology = copy.copy(state.topology)
+    if not topology.contains_connection(event.edge):
+        return state
+    topology.remove_connection(event.edge)
     # TODO: Clean up removing the reverse connection
     return state.model_copy(update={"topology": topology})

src/exo/shared/constants.py

@@ -38,7 +38,6 @@ EXO_TEST_LOG = EXO_CACHE_HOME / "exo_test.log"
 
 # Identity (config)
 EXO_NODE_ID_KEYPAIR = EXO_CONFIG_HOME / "node_id.keypair"
-EXO_CONFIG_FILE = EXO_CONFIG_HOME / "config.toml"
 
 # libp2p topics for event forwarding
 LIBP2P_LOCAL_EVENTS_TOPIC = "worker_events"

src/exo/shared/logging.py

@@ -24,8 +24,6 @@ class _InterceptHandler(logging.Handler):
         except ValueError:
             level = record.levelno
 
-        return
-
         logger.opt(depth=3, exception=record.exc_info).log(level, record.getMessage())
 
 

src/exo/shared/tests/test_apply/test_apply_node_download.py

@@ -19,7 +19,7 @@ def test_apply_node_download_progress():
         NodeDownloadProgress(download_progress=event), state
     )
 
-    assert new_state.downloads == {NodeId("node-1"): [event]}
+    assert new_state == State(downloads={NodeId("node-1"): [event]})
 
 
 def test_apply_two_node_download_progress():
@@ -39,4 +39,7 @@ def test_apply_two_node_download_progress():
         NodeDownloadProgress(download_progress=event2), state
     )
 
-    assert new_state.downloads == {NodeId("node-1"): [event1, event2]}
+    # TODO: This test is failing. We should support the following:
+    # 1. Downloading multiple models concurrently on the same node (one per runner is fine).
+    # 2. Downloading a model, it completes, then downloading a different model on the same node.
+    assert new_state == State(downloads={NodeId("node-1"): [event1, event2]})

src/exo/shared/tests/test_state_serialization.py

@@ -1,7 +1,7 @@
 from exo.shared.types.common import NodeId
 from exo.shared.types.multiaddr import Multiaddr
 from exo.shared.types.state import State
-from exo.shared.types.topology import SocketConnection
+from exo.shared.types.topology import Connection
 
 
 def test_state_serialization_roundtrip() -> None:
@@ -11,12 +11,14 @@ def test_state_serialization_roundtrip() -> None:
     node_a = NodeId("node-a")
     node_b = NodeId("node-b")
 
-    connection = SocketConnection(
-        sink_multiaddr=Multiaddr(address="/ip4/127.0.0.1/tcp/10001"),
+    connection = Connection(
+        local_node_id=node_a,
+        send_back_node_id=node_b,
+        send_back_multiaddr=Multiaddr(address="/ip4/127.0.0.1/tcp/10001"),
     )
 
     state = State()
-    state.topology.add_connection(node_a, node_b, connection)
+    state.topology.add_connection(connection)
 
     json_repr = state.model_dump_json()
     restored_state = State.model_validate_json(json_repr)

src/exo/shared/topology.py

@@ -1,219 +1,203 @@
 import contextlib
-from collections.abc import Mapping, Sequence
-from dataclasses import dataclass, field
 from typing import Iterable
 
 import rustworkx as rx
 from pydantic import BaseModel, ConfigDict
 
 from exo.shared.types.common import NodeId
-from exo.shared.types.topology import RDMAConnection, SocketConnection
+from exo.shared.types.profiling import ConnectionProfile, NodePerformanceProfile
+from exo.shared.types.topology import Connection, NodeInfo
 
 
 class TopologySnapshot(BaseModel):
-    nodes: Sequence[NodeId]
-    connections: Mapping[
-        NodeId, Mapping[NodeId, Sequence[SocketConnection | RDMAConnection]]
-    ]
+    nodes: list[NodeInfo]
+    connections: list[Connection]
 
-    model_config = ConfigDict(frozen=True, extra="forbid")
+    model_config = ConfigDict(frozen=True, extra="forbid", strict=True)
 
 
-@dataclass
 class Topology:
-    # the _graph can be used as a int -> NodeId map.
-    _graph: rx.PyDiGraph[NodeId, SocketConnection | RDMAConnection] = field(
-        init=False, default_factory=rx.PyDiGraph
-    )
-    _vertex_indices: dict[NodeId, int] = field(init=False, default_factory=dict)
+    def __init__(self) -> None:
+        self._graph: rx.PyDiGraph[NodeInfo, Connection] = rx.PyDiGraph()
+        self._node_id_to_rx_id_map: dict[NodeId, int] = dict()
+        self._rx_id_to_node_id_map: dict[int, NodeId] = dict()
+        self._edge_id_to_rx_id_map: dict[Connection, int] = dict()
 
     def to_snapshot(self) -> TopologySnapshot:
         return TopologySnapshot(
-            nodes=list(self.list_nodes()), connections=self.map_connections()
+            nodes=list(self.list_nodes()),
+            connections=list(self.list_connections()),
         )
 
     @classmethod
     def from_snapshot(cls, snapshot: TopologySnapshot) -> "Topology":
         topology = cls()
 
-        for node_id in snapshot.nodes:
+        for node in snapshot.nodes:
             with contextlib.suppress(ValueError):
-                topology.add_node(node_id)
+                topology.add_node(node)
 
-        for source in snapshot.connections:
-            for sink in snapshot.connections[source]:
-                for conn in snapshot.connections[source][sink]:
-                    topology.add_connection(source, sink, conn)
+        for connection in snapshot.connections:
+            topology.add_connection(connection)
 
         return topology
 
-    def add_node(self, node_id: NodeId) -> None:
-        if node_id in self._vertex_indices:
+    def add_node(self, node: NodeInfo) -> None:
+        if node.node_id in self._node_id_to_rx_id_map:
             return
-        rx_id = self._graph.add_node(node_id)
-        self._vertex_indices[node_id] = rx_id
+        rx_id = self._graph.add_node(node)
+        self._node_id_to_rx_id_map[node.node_id] = rx_id
+        self._rx_id_to_node_id_map[rx_id] = node.node_id
 
     def node_is_leaf(self, node_id: NodeId) -> bool:
         return (
-            node_id in self._vertex_indices
-            and len(self._graph.neighbors(self._vertex_indices[node_id])) <= 1
+            node_id in self._node_id_to_rx_id_map
+            and len(self._graph.neighbors(self._node_id_to_rx_id_map[node_id])) == 1
         )
 
     def neighbours(self, node_id: NodeId) -> list[NodeId]:
         return [
-            self._graph[rx_id]
-            for rx_id in self._graph.neighbors(self._vertex_indices[node_id])
+            self._rx_id_to_node_id_map[rx_id]
+            for rx_id in self._graph.neighbors(self._node_id_to_rx_id_map[node_id])
         ]
 
-    def out_edges(
-        self, node_id: NodeId
-    ) -> Iterable[tuple[NodeId, SocketConnection | RDMAConnection]]:
-        if node_id not in self._vertex_indices:
+    def out_edges(self, node_id: NodeId) -> list[tuple[NodeId, Connection]]:
+        if node_id not in self._node_id_to_rx_id_map:
             return []
-        return (
-            (self._graph[nid], conn)
-            for _, nid, conn in self._graph.out_edges(self._vertex_indices[node_id])
-        )
+        return [
+            (self._rx_id_to_node_id_map[nid], conn)
+            for _, nid, conn in self._graph.out_edges(
+                self._node_id_to_rx_id_map[node_id]
+            )
+        ]
 
     def contains_node(self, node_id: NodeId) -> bool:
-        return node_id in self._vertex_indices
+        return node_id in self._node_id_to_rx_id_map
+
+    def contains_connection(self, connection: Connection) -> bool:
+        return connection in self._edge_id_to_rx_id_map
 
     def add_connection(
         self,
-        source: NodeId,
-        sink: NodeId,
-        connection: SocketConnection | RDMAConnection,
+        connection: Connection,
     ) -> None:
-        if connection in self.get_all_connections_between(source, sink):
+        if connection.local_node_id not in self._node_id_to_rx_id_map:
+            self.add_node(NodeInfo(node_id=connection.local_node_id))
+        if connection.send_back_node_id not in self._node_id_to_rx_id_map:
+            self.add_node(NodeInfo(node_id=connection.send_back_node_id))
+
+        if connection in self._edge_id_to_rx_id_map:
             return
 
-        if source not in self._vertex_indices:
-            self.add_node(source)
-        if sink not in self._vertex_indices:
-            self.add_node(sink)
+        src_id = self._node_id_to_rx_id_map[connection.local_node_id]
+        sink_id = self._node_id_to_rx_id_map[connection.send_back_node_id]
 
-        src_id = self._vertex_indices[source]
-        sink_id = self._vertex_indices[sink]
+        rx_id = self._graph.add_edge(src_id, sink_id, connection)
+        self._edge_id_to_rx_id_map[connection] = rx_id
 
-        _ = self._graph.add_edge(src_id, sink_id, connection)
+    def list_nodes(self) -> Iterable[NodeInfo]:
+        return (self._graph[i] for i in self._graph.node_indices())
 
-    def get_all_connections_between(
-        self, source: NodeId, sink: NodeId
-    ) -> Iterable[SocketConnection | RDMAConnection]:
-        if source not in self._vertex_indices:
-            return []
-        if sink not in self._vertex_indices:
-            return []
+    def list_connections(self) -> Iterable[Connection]:
+        return (connection for _, _, connection in self._graph.weighted_edge_list())
 
-        src_id = self._vertex_indices[source]
-        sink_id = self._vertex_indices[sink]
+    def get_node_profile(self, node_id: NodeId) -> NodePerformanceProfile | None:
         try:
-            return self._graph.get_all_edge_data(src_id, sink_id)
-        except rx.NoEdgeBetweenNodes:
-            return []
+            rx_idx = self._node_id_to_rx_id_map[node_id]
+            return self._graph.get_node_data(rx_idx).node_profile
+        except KeyError:
+            return None
 
-    def list_nodes(self) -> Iterable[NodeId]:
-        return self._graph.nodes()
+    def update_node_profile(
+        self, node_id: NodeId, node_profile: NodePerformanceProfile
+    ) -> None:
+        rx_idx = self._node_id_to_rx_id_map[node_id]
+        self._graph[rx_idx].node_profile = node_profile
 
-    def map_connections(
-        self,
-    ) -> Mapping[NodeId, Mapping[NodeId, Sequence[SocketConnection | RDMAConnection]]]:
-        base: dict[NodeId, dict[NodeId, list[SocketConnection | RDMAConnection]]] = {}
-        for src_id, sink_id, connection in self._graph.weighted_edge_list():
-            source = self._graph[src_id]
-            sink = self._graph[sink_id]
-            if source not in base:
-                base[source] = {}
-            if sink not in base[source]:
-                base[source][sink] = []
-            base[source][sink].append(connection)
-        return base
+    def update_connection_profile(self, connection: Connection) -> None:
+        rx_idx = self._edge_id_to_rx_id_map[connection]
+        self._graph.update_edge_by_index(rx_idx, connection)
 
-    def list_connections(
-        self,
-    ) -> Iterable[tuple[NodeId, NodeId, SocketConnection | RDMAConnection]]:
-        return (
-            (
-                self._graph[src_id],
-                self._graph[sink_id],
-                connection,
-            )
-            for src_id, sink_id, connection in self._graph.weighted_edge_list()
-        )
+    def get_connection_profile(
+        self, connection: Connection
+    ) -> ConnectionProfile | None:
+        try:
+            rx_idx = self._edge_id_to_rx_id_map[connection]
+            return self._graph.get_edge_data_by_index(rx_idx).connection_profile
+        except KeyError:
+            return None
 
     def remove_node(self, node_id: NodeId) -> None:
-        if node_id not in self._vertex_indices:
+        if node_id not in self._node_id_to_rx_id_map:
             return
 
-        rx_idx = self._vertex_indices[node_id]
+        for connection in self.list_connections():
+            if (
+                connection.local_node_id == node_id
+                or connection.send_back_node_id == node_id
+            ):
+                self.remove_connection(connection)
+
+        rx_idx = self._node_id_to_rx_id_map[node_id]
         self._graph.remove_node(rx_idx)
 
-        del self._vertex_indices[node_id]
+        del self._node_id_to_rx_id_map[node_id]
+        del self._rx_id_to_node_id_map[rx_idx]
 
-    def replace_all_out_tb_connections(
-        self, source: NodeId, new_connections: Sequence[tuple[NodeId, RDMAConnection]]
-    ) -> None:
-        for conn_idx in self._graph.out_edge_indices(self._vertex_indices[source]):
-            if isinstance(self._graph.get_edge_data_by_index(conn_idx), RDMAConnection):
-                self._graph.remove_edge_from_index(conn_idx)
-        for sink, conn in new_connections:
-            self.add_connection(source, sink, conn)
-
-    def remove_connection(
-        self, source: NodeId, sink: NodeId, edge: SocketConnection | RDMAConnection
-    ) -> None:
-        if source not in self._vertex_indices or sink not in self._vertex_indices:
+    def remove_connection(self, connection: Connection) -> None:
+        if connection not in self._edge_id_to_rx_id_map:
             return
-        for conn_idx in self._graph.edge_indices_from_endpoints(
-            self._vertex_indices[source], self._vertex_indices[sink]
-        ):
-            if self._graph.get_edge_data_by_index(conn_idx) == edge:
-                self._graph.remove_edge_from_index(conn_idx)
+        rx_idx = self._edge_id_to_rx_id_map[connection]
+        self._graph.remove_edge_from_index(rx_idx)
+        del self._edge_id_to_rx_id_map[connection]
 
-    def get_cycles(self) -> list[list[NodeId]]:
+    def get_cycles(self) -> list[list[NodeInfo]]:
         cycle_idxs = rx.simple_cycles(self._graph)
-        cycles: list[list[NodeId]] = []
+        cycles: list[list[NodeInfo]] = []
         for cycle_idx in cycle_idxs:
             cycle = [self._graph[idx] for idx in cycle_idx]
             cycles.append(cycle)
 
         return cycles
 
-    def get_cycles_tb(self) -> list[list[NodeId]]:
+    def get_cycles_tb(self) -> list[list[NodeInfo]]:
         tb_edges = [
             (u, v, conn)
             for u, v, conn in self._graph.weighted_edge_list()
             if conn.is_thunderbolt()
         ]
 
-        tb_graph: rx.PyDiGraph[NodeId, SocketConnection] = rx.PyDiGraph()
+        tb_graph: rx.PyDiGraph[NodeInfo, Connection] = rx.PyDiGraph()
         tb_graph.add_nodes_from(self._graph.nodes())
 
         for u, v, conn in tb_edges:
-            if isinstance(conn, SocketConnection):
-                tb_graph.add_edge(u, v, conn)
+            tb_graph.add_edge(u, v, conn)
 
         cycle_idxs = rx.simple_cycles(tb_graph)
-        cycles: list[list[NodeId]] = []
+        cycles: list[list[NodeInfo]] = []
         for cycle_idx in cycle_idxs:
             cycle = [tb_graph[idx] for idx in cycle_idx]
             cycles.append(cycle)
 
         return cycles
 
-    def get_subgraph_from_nodes(self, node_ids: list[NodeId]) -> "Topology":
-        rx_idxs = [self._vertex_indices[idx] for idx in node_ids]
+    def get_subgraph_from_nodes(self, nodes: list[NodeInfo]) -> "Topology":
+        node_idxs = [node.node_id for node in nodes]
+        rx_idxs = [self._node_id_to_rx_id_map[idx] for idx in node_idxs]
         topology = Topology()
         for rx_idx in rx_idxs:
             topology.add_node(self._graph[rx_idx])
-        for source, sink, connection in self.list_connections():
-            if source in node_ids and sink in node_ids:
-                topology.add_connection(source, sink, connection)
+        for connection in self.list_connections():
+            if (
+                connection.local_node_id in node_idxs
+                and connection.send_back_node_id in node_idxs
+            ):
+                topology.add_connection(connection)
         return topology
 
-    def is_thunderbolt_cycle(self, cycle: list[NodeId]) -> bool:
-        node_idxs = [node for node in cycle]
-        rx_idxs = [self._vertex_indices[idx] for idx in node_idxs]
+    def is_thunderbolt_cycle(self, cycle: list[NodeInfo]) -> bool:
+        node_idxs = [node.node_id for node in cycle]
+        rx_idxs = [self._node_id_to_rx_id_map[idx] for idx in node_idxs]
         for rid in rx_idxs:
             for neighbor_rid in self._graph.neighbors(rid):
                 if neighbor_rid not in rx_idxs:

src/exo/shared/types/events.py

@@ -2,14 +2,14 @@ from datetime import datetime
 
 from pydantic import Field
 
-from exo.shared.topology import SocketConnection
+from exo.shared.topology import Connection, NodePerformanceProfile
 from exo.shared.types.chunks import GenerationChunk
 from exo.shared.types.common import CommandId, Id, NodeId, SessionId
+from exo.shared.types.profiling import MemoryPerformanceProfile
 from exo.shared.types.tasks import Task, TaskId, TaskStatus
 from exo.shared.types.worker.downloads import DownloadProgress
 from exo.shared.types.worker.instances import Instance, InstanceId
 from exo.shared.types.worker.runners import RunnerId, RunnerStatus
-from exo.utils.info_gatherer.info_gatherer import GatheredInfo
 from exo.utils.pydantic_ext import CamelCaseModel, TaggedModel
 
 
@@ -76,15 +76,25 @@ class RunnerDeleted(BaseEvent):
     runner_id: RunnerId
 
 
+# TODO
+class NodeCreated(BaseEvent):
+    node_id: NodeId
+
+
 class NodeTimedOut(BaseEvent):
     node_id: NodeId
 
 
-# TODO: bikeshed this naem
-class NodeGatheredInfo(BaseEvent):
+class NodePerformanceMeasured(BaseEvent):
     node_id: NodeId
     when: str  # this is a manually cast datetime overrode by the master when the event is indexed, rather than the local time on the device
-    info: GatheredInfo  # NB: this model is UNTAGGED!!! be warned for ser/de errors.
+    node_profile: NodePerformanceProfile
+
+
+class NodeMemoryMeasured(BaseEvent):
+    node_id: NodeId
+    when: str  # this is a manually cast datetime overrode by the master when the event is indexed, rather than the local time on the device
+    memory: MemoryPerformanceProfile
 
 
 class NodeDownloadProgress(BaseEvent):
@@ -97,15 +107,11 @@ class ChunkGenerated(BaseEvent):
 
 
 class TopologyEdgeCreated(BaseEvent):
-    source: NodeId
-    sink: NodeId
-    edge: SocketConnection
+    edge: Connection
 
 
 class TopologyEdgeDeleted(BaseEvent):
-    source: NodeId
-    sink: NodeId
-    edge: SocketConnection
+    edge: Connection
 
 
 Event = (
@@ -119,8 +125,10 @@ Event = (
     | InstanceDeleted
     | RunnerStatusUpdated
     | RunnerDeleted
+    | NodeCreated
     | NodeTimedOut
-    | NodeGatheredInfo
+    | NodePerformanceMeasured
+    | NodeMemoryMeasured
     | NodeDownloadProgress
     | ChunkGenerated
     | TopologyEdgeCreated

src/exo/shared/types/multiaddr.py

@@ -1,11 +1,10 @@
 import re
 from typing import ClassVar
 
-from pydantic import BaseModel, ConfigDict, computed_field, field_validator
+from pydantic import BaseModel, computed_field, field_validator
 
 
 class Multiaddr(BaseModel):
-    model_config = ConfigDict(frozen=True)
     address: str
 
     PATTERNS: ClassVar[list[str]] = [

src/exo/shared/types/profiling.py

@@ -1,14 +1,12 @@
-from collections.abc import Sequence
 from typing import Self
 
 import psutil
 
 from exo.shared.types.memory import Memory
-from exo.shared.types.thunderbolt import TBIdentifier
 from exo.utils.pydantic_ext import CamelCaseModel
 
 
-class MemoryUsage(CamelCaseModel):
+class MemoryPerformanceProfile(CamelCaseModel):
     ram_total: Memory
     ram_available: Memory
     swap_total: Memory
@@ -46,6 +44,7 @@ class SystemPerformanceProfile(CamelCaseModel):
     sys_power: float = 0.0
     pcpu_usage: float = 0.0
     ecpu_usage: float = 0.0
+    ane_power: float = 0.0
 
 
 class NetworkInterfaceInfo(CamelCaseModel):
@@ -54,16 +53,15 @@ class NetworkInterfaceInfo(CamelCaseModel):
 
 
 class NodePerformanceProfile(CamelCaseModel):
-    model_id: str = "Unknown"
-    chip_id: str = "Unknown"
-    friendly_name: str = "Unknown"
-    memory: MemoryUsage = MemoryUsage.from_bytes(
-        ram_total=0, ram_available=0, swap_total=0, swap_available=0
-    )
-    network_interfaces: Sequence[NetworkInterfaceInfo] = []
-    tb_interfaces: Sequence[TBIdentifier] = []
-    system: SystemPerformanceProfile = SystemPerformanceProfile()
+    model_id: str
+    chip_id: str
+    friendly_name: str
+    memory: MemoryPerformanceProfile
+    network_interfaces: list[NetworkInterfaceInfo] = []
+    system: SystemPerformanceProfile
 
 
 class ConnectionProfile(CamelCaseModel):
-    pass
+    throughput: float
+    latency: float
+    jitter: float

src/exo/shared/types/thunderbolt.py

@@ -1,64 +0,0 @@
-import anyio
-from pydantic import BaseModel, Field
-
-from exo.utils.pydantic_ext import CamelCaseModel
-
-
-class TBConnection(CamelCaseModel):
-    source_uuid: str
-    sink_uuid: str
-
-
-class TBIdentifier(CamelCaseModel):
-    rdma_interface: str
-    domain_uuid: str
-
-
-# Intentionally minimal, only collecting data we care about - there's a lot more
-
-
-class TBReceptacleTag(BaseModel, extra="ignore"):
-    receptacle_id_key: str
-
-
-class TBConnectivityItem(BaseModel, extra="ignore"):
-    domain_uuid_key: str | None
-
-
-class TBConnectivityData(BaseModel, extra="ignore"):
-    domain_uuid_key: str | None
-    device_name_key: str
-    items: list[TBConnectivityItem] | None = Field(None, alias="_items")
-    receptacle_1_tag: TBReceptacleTag
-
-    def ident(self, ifaces: dict[str, str]) -> TBIdentifier | None:
-        if self.domain_uuid_key is None:
-            return
-        tag = f"Thunderbolt {self.receptacle_1_tag.receptacle_id_key}"
-        iface = f"rdma_{ifaces[tag]}"
-        return TBIdentifier(rdma_interface=iface, domain_uuid=self.domain_uuid_key)
-
-    def conn(self) -> TBConnection | None:
-        if self.domain_uuid_key is None or self.items is None:
-            return
-
-        sink_key = next(
-            item.domain_uuid_key
-            for item in self.items
-            if item.domain_uuid_key is not None
-        )
-        return TBConnection(source_uuid=self.domain_uuid_key, sink_uuid=sink_key)
-
-
-class TBConnectivity(BaseModel):
-    SPThunderboltDataType: list[TBConnectivityData]
-
-    @classmethod
-    async def gather(cls) -> list[TBConnectivityData] | None:
-        proc = await anyio.run_process(
-            ["system_profiler", "SPThunderboltDataType", "-json"], check=False
-        )
-        if proc.returncode != 0:
-            return None
-        # Saving you from PascalCase while avoiding too much pydantic
-        return TBConnectivity.model_validate_json(proc.stdout).SPThunderboltDataType

src/exo/shared/types/topology.py

@@ -1,32 +1,37 @@
-from enum import Enum
-
-from loguru import logger
-
+from exo.shared.types.common import NodeId
 from exo.shared.types.multiaddr import Multiaddr
-from exo.utils.pydantic_ext import FrozenModel
+from exo.shared.types.profiling import ConnectionProfile, NodePerformanceProfile
+from exo.utils.pydantic_ext import CamelCaseModel
 
 
-class RDMAConnection(FrozenModel):
-    source_rdma_iface: str
-    sink_rdma_iface: str
+class NodeInfo(CamelCaseModel):
+    node_id: NodeId
+    node_profile: NodePerformanceProfile | None = None
+
+
+class Connection(CamelCaseModel):
+    local_node_id: NodeId
+    send_back_node_id: NodeId
+    send_back_multiaddr: Multiaddr
+    connection_profile: ConnectionProfile | None = None
+
+    def __hash__(self) -> int:
+        return hash(
+            (
+                self.local_node_id,
+                self.send_back_node_id,
+                self.send_back_multiaddr.address,
+            )
+        )
+
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, Connection):
+            raise ValueError("Cannot compare Connection with non-Connection")
+        return (
+            self.local_node_id == other.local_node_id
+            and self.send_back_node_id == other.send_back_node_id
+            and self.send_back_multiaddr == other.send_back_multiaddr
+        )
 
     def is_thunderbolt(self) -> bool:
-        logger.warning("duh")
-        return True
-
-
-# TODO
-class LinkType(str, Enum):
-    Thunderbolt = "Thunderbolt"
-    Ethernet = "Ethernet"
-    WiFi = "WiFi"
-
-
-class SocketConnection(FrozenModel):
-    sink_multiaddr: Multiaddr
-
-    def __hash__(self):
-        return hash(self.sink_multiaddr.ip_address)
-
-    def is_thunderbolt(self) -> bool:
-        return str(self.sink_multiaddr.ipv4_address).startswith("169.254")
+        return str(self.send_back_multiaddr.ipv4_address).startswith("169.254")

src/exo/shared/types/worker/instances.py

@@ -25,11 +25,12 @@ class BaseInstance(TaggedModel):
 
 
 class MlxRingInstance(BaseInstance):
-    hosts: list[Host]
+    hosts_by_node: dict[NodeId, list[Host]]
+    ephemeral_port: int
 
 
 class MlxJacclInstance(BaseInstance):
-    jaccl_devices: list[list[str | None]]
+    ibv_devices: list[list[str | None]]
     jaccl_coordinators: dict[NodeId, str]
 
 

src/exo/shared/types/worker/resource_monitor.py

@@ -0,0 +1,43 @@
+import asyncio
+from abc import ABC, abstractmethod
+from collections.abc import Coroutine
+from typing import Callable
+
+from exo.shared.types.profiling import (
+    MemoryPerformanceProfile,
+    SystemPerformanceProfile,
+)
+
+
+class ResourceCollector(ABC):
+    @abstractmethod
+    async def collect(self) -> SystemPerformanceProfile | MemoryPerformanceProfile: ...
+
+
+class SystemResourceCollector(ResourceCollector):
+    async def collect(self) -> SystemPerformanceProfile: ...
+
+
+class MemoryResourceCollector(ResourceCollector):
+    async def collect(self) -> MemoryPerformanceProfile: ...
+
+
+class ResourceMonitor:
+    data_collectors: list[ResourceCollector]
+    effect_handlers: set[
+        Callable[[SystemPerformanceProfile | MemoryPerformanceProfile], None]
+    ]
+
+    async def _collect(
+        self,
+    ) -> list[SystemPerformanceProfile | MemoryPerformanceProfile]:
+        tasks: list[
+            Coroutine[None, None, SystemPerformanceProfile | MemoryPerformanceProfile]
+        ] = [collector.collect() for collector in self.data_collectors]
+        return await asyncio.gather(*tasks)
+
+    async def collect(self) -> None:
+        profiles = await self._collect()
+        for profile in profiles:
+            for effect_handler in self.effect_handlers:
+                effect_handler(profile)

src/exo/utils/info_gatherer/info_gatherer.py

@@ -1,231 +0,0 @@
-import os
-import shutil
-import sys
-import tomllib
-from collections.abc import Sequence
-from dataclasses import dataclass, field
-from subprocess import CalledProcessError
-from typing import Self, cast
-
-import anyio
-from anyio import create_task_group, open_process
-from anyio.abc import TaskGroup
-from anyio.streams.buffered import BufferedByteReceiveStream
-from anyio.streams.text import TextReceiveStream
-from loguru import logger
-
-from exo.shared.constants import EXO_CONFIG_FILE
-from exo.shared.types.memory import Memory
-from exo.shared.types.profiling import (
-    MemoryUsage,
-    NetworkInterfaceInfo,
-)
-from exo.shared.types.thunderbolt import TBConnection, TBConnectivity, TBIdentifier
-from exo.utils.channels import Sender
-from exo.utils.pydantic_ext import TaggedModel
-
-from .macmon import MacmonMetrics
-from .system_info import get_friendly_name, get_model_and_chip, get_network_interfaces
-
-IS_DARWIN = sys.platform == "darwin"
-
-
-class StaticNodeInformation(TaggedModel):
-    """Node information that should NEVER change, to be gathered once at startup"""
-
-    model: str
-    chip: str
-
-    @classmethod
-    async def gather(cls) -> Self:
-        model, chip = await get_model_and_chip()
-        return cls(model=model, chip=chip)
-
-
-class NodeNetworkInterfaces(TaggedModel):
-    ifaces: Sequence[NetworkInterfaceInfo]
-
-
-class MacTBIdentifiers(TaggedModel):
-    idents: Sequence[TBIdentifier]
-
-
-class MacTBConnections(TaggedModel):
-    conns: Sequence[TBConnection]
-
-
-class NodeConfig(TaggedModel):
-    """Node configuration from EXO_CONFIG_FILE, reloaded from the file only at startup. Other changes should come in through the API and propagate from there"""
-
-    # TODO
-    @classmethod
-    async def gather(cls) -> Self | None:
-        cfg_file = anyio.Path(EXO_CONFIG_FILE)
-        await cfg_file.touch(exist_ok=True)
-        async with await cfg_file.open("rb") as f:
-            try:
-                contents = (await f.read()).decode("utf-8")
-                data = tomllib.loads(contents)
-                return cls.model_validate(data)
-            except (tomllib.TOMLDecodeError, UnicodeDecodeError):
-                logger.warning("Invalid config file, skipping...")
-                return None
-
-
-class MiscData(TaggedModel):
-    """Node information that may slowly change that doesn't fall into the other categories"""
-
-    friendly_name: str
-
-    @classmethod
-    async def gather(cls) -> Self:
-        return cls(friendly_name=await get_friendly_name())
-
-
-async def _gather_iface_map() -> dict[str, str] | None:
-    proc = await anyio.run_process(
-        ["networksetup", "-listallhardwareports"], check=False
-    )
-    if proc.returncode != 0:
-        return None
-
-    ports: dict[str, str] = {}
-    port = ""
-    for line in proc.stdout.decode("utf-8").split("\n"):
-        if line.startswith("Hardware Port:"):
-            port = line.split(": ")[1]
-        elif line.startswith("Device:"):
-            ports[port] = line.split(": ")[1]
-            port = ""
-    if "" in ports:
-        del ports[""]
-    return ports
-
-
-GatheredInfo = (
-    MacmonMetrics
-    | MemoryUsage
-    | NodeNetworkInterfaces
-    | MacTBIdentifiers
-    | MacTBConnections
-    | NodeConfig
-    | MiscData
-    | StaticNodeInformation
-)
-
-
-@dataclass
-class InfoGatherer:
-    info_sender: Sender[GatheredInfo]
-    interface_watcher_interval: float | None = 10
-    misc_poll_interval: float | None = 60
-    system_profiler_interval: float | None = 5 if IS_DARWIN else None
-    memory_poll_rate: float | None = None if IS_DARWIN else 1
-    macmon_interval: float | None = 1 if IS_DARWIN else None
-    _tg: TaskGroup = field(init=False, default_factory=create_task_group)
-
-    async def run(self):
-        async with self._tg as tg:
-            if (macmon_path := shutil.which("macmon")) is not None:
-                tg.start_soon(self._monitor_macmon, macmon_path)
-            if IS_DARWIN:
-                tg.start_soon(self._monitor_system_profiler)
-            tg.start_soon(self._watch_system_info)
-            tg.start_soon(self._monitor_memory_usage)
-            tg.start_soon(self._monitor_misc)
-
-            nc = await NodeConfig.gather()
-            if nc is not None:
-                await self.info_sender.send(nc)
-            sni = await StaticNodeInformation.gather()
-            await self.info_sender.send(sni)
-
-    def shutdown(self):
-        self._tg.cancel_scope.cancel()
-
-    async def _monitor_misc(self):
-        if self.misc_poll_interval is None:
-            return
-        prev = await MiscData.gather()
-        while True:
-            curr = await MiscData.gather()
-            if prev != curr:
-                prev = curr
-                await self.info_sender.send(curr)
-            await anyio.sleep(self.misc_poll_interval)
-
-    async def _monitor_system_profiler(self):
-        if self.system_profiler_interval is None:
-            return
-        iface_map = await _gather_iface_map()
-        if iface_map is None:
-            return
-
-        old_idents = []
-        while True:
-            data = await TBConnectivity.gather()
-            assert data is not None
-
-            idents = [it for i in data if (it := i.ident(iface_map)) is not None]
-            if idents != old_idents:
-                await self.info_sender.send(MacTBIdentifiers(idents=idents))
-            old_idents = idents
-
-            conns = [it for i in data if (it := i.conn()) is not None]
-            await self.info_sender.send(MacTBConnections(conns=conns))
-
-            await anyio.sleep(self.system_profiler_interval)
-
-    async def _monitor_memory_usage(self):
-        override_memory_env = os.getenv("OVERRIDE_MEMORY_MB")
-        override_memory: int | None = (
-            Memory.from_mb(int(override_memory_env)).in_bytes
-            if override_memory_env
-            else None
-        )
-        if self.memory_poll_rate is None:
-            return
-        while True:
-            await self.info_sender.send(
-                MemoryUsage.from_psutil(override_memory=override_memory)
-            )
-            await anyio.sleep(self.memory_poll_rate)
-
-    async def _watch_system_info(self):
-        if self.interface_watcher_interval is None:
-            return
-        old_nics = []
-        while True:
-            nics = get_network_interfaces()
-            if nics != old_nics:
-                old_nics = nics
-                await self.info_sender.send(NodeNetworkInterfaces(ifaces=nics))
-            await anyio.sleep(self.interface_watcher_interval)
-
-    async def _monitor_macmon(self, macmon_path: str):
-        if self.macmon_interval is None:
-            return
-        # macmon pipe --interval [interval in ms]
-        try:
-            async with await open_process(
-                [macmon_path, "pipe", "--interval", str(self.macmon_interval * 1000)]
-            ) as p:
-                if not p.stdout:
-                    logger.critical("MacMon closed stdout")
-                    return
-                async for text in TextReceiveStream(
-                    BufferedByteReceiveStream(p.stdout)
-                ):
-                    await self.info_sender.send(MacmonMetrics.from_raw_json(text))
-        except CalledProcessError as e:
-            stderr_msg = "no stderr"
-            stderr_output = cast(bytes | str | None, e.stderr)
-            if stderr_output is not None:
-                stderr_msg = (
-                    stderr_output.decode()
-                    if isinstance(stderr_output, bytes)
-                    else str(stderr_output)
-                )
-            logger.warning(
-                f"MacMon failed with return code {e.returncode}: {stderr_msg}"
-            )

src/exo/utils/info_gatherer/macmon.py

@@ -1,70 +0,0 @@
-from typing import Self
-
-from pydantic import BaseModel
-
-from exo.shared.types.profiling import MemoryUsage, SystemPerformanceProfile
-from exo.utils.pydantic_ext import TaggedModel
-
-
-class _TempMetrics(BaseModel, extra="ignore"):
-    """Temperature-related metrics returned by macmon."""
-
-    cpu_temp_avg: float
-    gpu_temp_avg: float
-
-
-class _MemoryMetrics(BaseModel, extra="ignore"):
-    """Memory-related metrics returned by macmon."""
-
-    ram_total: int
-    ram_usage: int
-    swap_total: int
-    swap_usage: int
-
-
-class RawMacmonMetrics(BaseModel, extra="ignore"):
-    """Complete set of metrics returned by macmon.
-
-    Unknown fields are ignored for forward-compatibility.
-    """
-
-    timestamp: str  # ignored
-    temp: _TempMetrics
-    memory: _MemoryMetrics
-    ecpu_usage: tuple[int, float]  # freq mhz, usage %
-    pcpu_usage: tuple[int, float]  # freq mhz, usage %
-    gpu_usage: tuple[int, float]  # freq mhz, usage %
-    all_power: float
-    ane_power: float
-    cpu_power: float
-    gpu_power: float
-    gpu_ram_power: float
-    ram_power: float
-    sys_power: float
-
-
-class MacmonMetrics(TaggedModel):
-    system_profile: SystemPerformanceProfile
-    memory: MemoryUsage
-
-    @classmethod
-    def from_raw(cls, raw: RawMacmonMetrics) -> Self:
-        return cls(
-            system_profile=SystemPerformanceProfile(
-                gpu_usage=raw.gpu_usage[1],
-                temp=raw.temp.gpu_temp_avg,
-                sys_power=raw.sys_power,
-                pcpu_usage=raw.pcpu_usage[1],
-                ecpu_usage=raw.ecpu_usage[1],
-            ),
-            memory=MemoryUsage.from_bytes(
-                ram_total=raw.memory.ram_total,
-                ram_available=(raw.memory.ram_total - raw.memory.ram_usage),
-                swap_total=raw.memory.swap_total,
-                swap_available=(raw.memory.swap_total - raw.memory.swap_usage),
-            ),
-        )
-
-    @classmethod
-    def from_raw_json(cls, json: str) -> Self:
-        return cls.from_raw(RawMacmonMetrics.model_validate_json(json))

src/exo/utils/info_gatherer/net_profile.py

@@ -1,56 +0,0 @@
-import socket
-from collections.abc import Mapping
-from ipaddress import ip_address
-
-from anyio import create_task_group, to_thread
-
-from exo.shared.topology import Topology
-from exo.shared.types.common import NodeId
-from exo.shared.types.profiling import NodePerformanceProfile
-
-
-# TODO: ref. api port
-async def check_reachability(
-    target_ip: str, target_node_id: NodeId, out: dict[NodeId, set[str]]
-) -> None:
-    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-    sock.settimeout(1)  # 1 second timeout
-    try:
-        result = await to_thread.run_sync(sock.connect_ex, (target_ip, 52415))
-    except socket.gaierror:
-        # seems to throw on ipv6 loopback. oh well
-        # logger.warning(f"invalid {target_ip=}")
-        return
-    finally:
-        sock.close()
-
-    if result == 0:
-        if target_node_id not in out:
-            out[target_node_id] = set()
-        out[target_node_id].add(target_ip)
-
-
-async def check_reachable(
-    our_node_id: NodeId,
-    topology: Topology,
-    profiles: Mapping[NodeId, NodePerformanceProfile],
-) -> Mapping[NodeId, set[str]]:
-    reachable: dict[NodeId, set[str]] = {}
-    our_profile = profiles.get(our_node_id, None)
-    if our_profile is None:
-        return {}
-    our_interfaces = our_profile.network_interfaces
-    async with create_task_group() as tg:
-        for node_id in topology.list_nodes():
-            if node_id not in profiles or node_id == our_node_id:
-                continue
-            for iface in profiles[node_id].network_interfaces:
-                if ip_address(iface.ip_address).is_loopback:
-                    # Definitely a loopback address
-                    continue
-                if iface in our_interfaces:
-                    # Skip duplicates with our own interfaces
-                    continue
-                tg.start_soon(check_reachability, iface.ip_address, node_id, reachable)
-
-    return reachable

src/exo/utils/pydantic_ext.py

@@ -19,20 +19,11 @@ class CamelCaseModel(BaseModel):
         alias_generator=to_camel,
         validate_by_name=True,
         extra="forbid",
+        # I want to reenable this ASAP, but it's causing an issue with TaskStatus
         strict=True,
     )
 
 
-class FrozenModel(BaseModel):
-    model_config = ConfigDict(
-        alias_generator=to_camel,
-        validate_by_name=True,
-        extra="forbid",
-        strict=True,
-        frozen=True,
-    )
-
-
 class TaggedModel(CamelCaseModel):
     @model_serializer(mode="wrap")
     def _serialize(self, handler: SerializerFunctionWrapHandler):

src/exo/utils/tests/testing_mp.py

@@ -28,8 +28,9 @@ def bar(send: MpSender[str]):
     send.close()
 
 
+# not async, just want the fail_after
 @pytest.mark.anyio
-async def test_channel_ipc():
+async def test_channel_setup():
     with fail_after(0.5):
         s, r = mp_channel[str]()
         p1 = mp.Process(target=foo, args=(r,))

src/exo/worker/engines/mlx/auto_parallel.py

@@ -22,6 +22,7 @@ from mlx_lm.models.qwen3_moe import Qwen3MoeSparseMoeBlock
 from exo.shared.types.worker.shards import (
     PipelineShardMetadata,
 )
+from exo.worker.runner.bootstrap import logger
 
 
 class _LayerCallable(Protocol):
@@ -170,6 +171,8 @@ def pipeline_auto_parallel(
 
     start_layer, end_layer = model_shard_meta.start_layer, model_shard_meta.end_layer
     device_rank, world_size = model_shard_meta.device_rank, model_shard_meta.world_size
+    logger.info(f"[RING3DBG] pipeline_auto_parallel: device_rank={device_rank} world_size={world_size}")
+    logger.info(f"[RING3DBG] layers: start={start_layer} end={end_layer} count={len(layers)}")
 
     layers = layers[start_layer:end_layer]
     layers[0] = PipelineFirstLayer(layers[0], device_rank, group=group)

src/exo/worker/engines/mlx/utils_mlx.py

@@ -101,16 +101,27 @@ def mlx_distributed_init(
     bound_instance: BoundInstance,
 ) -> mx.distributed.Group:
     """
-    Initialize the MLX distributed
+    Initialize the MLX distributed (runs in thread pool).
+
+    Either hosts or mlx_ibv_devices must be provided:
+    - hosts: traditional host-based connectivity using MLX_HOSTFILE
+    - mlx_ibv_devices: RDMA connectivity matrix using MLX_IBV_DEVICES
+    - mlx_ibv_coordinator: coordinator address (IP:PORT) for RDMA setup
+    - strict: if True, raise an error if the distributed backend is not available
     """
     rank = bound_instance.bound_shard.device_rank
     logger.info(f"Starting initialization for rank {rank}")
+    logger.info(f"[RING3DBG] mlx_distributed_init: bound_node_id={bound_instance.bound_node_id}")
+    logger.info(f"[RING3DBG] device_rank={rank}, world_size={bound_instance.bound_shard.world_size}")
 
     # TODO: singleton instances
     match bound_instance.instance:
-        case MlxRingInstance(hosts=hosts):
+        case MlxRingInstance(hosts_by_node=hosts_by_node, ephemeral_port=_):
             hostfile = f"./hosts_{rank}.json"
-            hosts_json = HostList.from_hosts(hosts).model_dump_json()
+            hosts_for_node = hosts_by_node[bound_instance.bound_node_id]
+            logger.info(f"[RING3DBG] hosts_by_node keys: {list(hosts_by_node.keys())}")
+            logger.info(f"[RING3DBG] hosts_for_node (len={len(hosts_for_node)}): {hosts_for_node}")
+            hosts_json = HostList.from_hosts(hosts_for_node).model_dump_json()
 
             with open(hostfile, "w") as f:
                 _ = f.write(hosts_json)
@@ -123,25 +134,26 @@ def mlx_distributed_init(
             group = mx.distributed.init(backend="ring", strict=True)
 
         case MlxJacclInstance(
-            jaccl_devices=jaccl_devices, jaccl_coordinators=jaccl_coordinators
+            ibv_devices=ibv_devices, jaccl_coordinators=jaccl_coordinators
         ):
             # Use RDMA connectivity matrix
             devices_file = f"./hosts_{rank}.json"
-            jaccl_devices_json = json.dumps(jaccl_devices)
+            ibv_devices_json = json.dumps(ibv_devices)
 
             with open(devices_file, "w") as f:
-                _ = f.write(jaccl_devices_json)
+                _ = f.write(ibv_devices_json)
 
             jaccl_coordinator = jaccl_coordinators[bound_instance.bound_node_id]
 
-            logger.info(f"rank {rank} MLX_JACCL_DEVICES: {jaccl_devices_json}")
+            logger.info(f"rank {rank} MLX_IBV_DEVICES: {ibv_devices_json}")
             logger.info(f"rank {rank} MLX_JACCL_COORDINATOR: {jaccl_coordinator}")
-            os.environ["MLX_JACCL_DEVICES"] = devices_file
+            os.environ["MLX_IBV_DEVICES"] = devices_file
             os.environ["MLX_RANK"] = str(rank)
             os.environ["MLX_JACCL_COORDINATOR"] = jaccl_coordinator
             group = mx.distributed.init(backend="jaccl", strict=True)
 
     logger.info(f"Rank {rank} mlx distributed initialization complete")
+    logger.info(f"[RING3DBG] ring init complete: group.rank()={group.rank()} group.size()={group.size()}")
 
     return group
 
@@ -222,6 +234,8 @@ def shard_and_load(
     tokenizer = get_tokenizer(model_path, shard_metadata)
 
     logger.info(f"Group size: {group.size()}, group rank: {group.rank()}")
+    logger.info(f"[RING3DBG] shard_and_load: expected device_rank={shard_metadata.device_rank} world_size={shard_metadata.world_size}")
+    logger.info(f"[RING3DBG] actual group.rank()={group.rank()} group.size()={group.size()}")
 
     match shard_metadata:
         case TensorShardMetadata():

src/exo/worker/main.py

@@ -16,13 +16,15 @@ from exo.shared.types.events import (
     ForwarderEvent,
     IndexedEvent,
     NodeDownloadProgress,
-    NodeGatheredInfo,
+    NodeMemoryMeasured,
+    NodePerformanceMeasured,
     TaskCreated,
     TaskStatusUpdated,
     TopologyEdgeCreated,
     TopologyEdgeDeleted,
 )
 from exo.shared.types.multiaddr import Multiaddr
+from exo.shared.types.profiling import MemoryPerformanceProfile, NodePerformanceProfile
 from exo.shared.types.state import State
 from exo.shared.types.tasks import (
     CreateRunner,
@@ -31,7 +33,7 @@ from exo.shared.types.tasks import (
     Task,
     TaskStatus,
 )
-from exo.shared.types.topology import SocketConnection
+from exo.shared.types.topology import Connection
 from exo.shared.types.worker.downloads import (
     DownloadCompleted,
     DownloadOngoing,
@@ -42,14 +44,14 @@ from exo.shared.types.worker.runners import RunnerId
 from exo.shared.types.worker.shards import ShardMetadata
 from exo.utils.channels import Receiver, Sender, channel
 from exo.utils.event_buffer import OrderedBuffer
-from exo.utils.info_gatherer.info_gatherer import GatheredInfo, InfoGatherer
-from exo.utils.info_gatherer.net_profile import check_reachable
 from exo.worker.download.download_utils import (
     map_repo_download_progress_to_download_progress_data,
 )
 from exo.worker.download.shard_downloader import RepoDownloadProgress, ShardDownloader
 from exo.worker.plan import plan
 from exo.worker.runner.runner_supervisor import RunnerSupervisor
+from exo.worker.utils import start_polling_memory_metrics, start_polling_node_metrics
+from exo.worker.utils.net_profile import check_reachable
 
 
 class Worker:
@@ -83,7 +85,7 @@ class Worker:
         self.state: State = State()
         self.download_status: dict[ShardMetadata, DownloadProgress] = {}
         self.runners: dict[RunnerId, RunnerSupervisor] = {}
-        self._tg: TaskGroup = create_task_group()
+        self._tg: TaskGroup | None = None
 
         self._nack_cancel_scope: CancelScope | None = None
         self._nack_attempts: int = 0
@@ -95,13 +97,37 @@ class Worker:
     async def run(self):
         logger.info("Starting Worker")
 
-        info_send, info_recv = channel[GatheredInfo]()
-        info_gatherer: InfoGatherer = InfoGatherer(info_send)
+        # TODO: CLEANUP HEADER
+        async def resource_monitor_callback(
+            node_performance_profile: NodePerformanceProfile,
+        ) -> None:
+            await self.event_sender.send(
+                NodePerformanceMeasured(
+                    node_id=self.node_id,
+                    node_profile=node_performance_profile,
+                    when=str(datetime.now(tz=timezone.utc)),
+                ),
+            )
 
-        async with self._tg as tg:
-            tg.start_soon(info_gatherer.run)
-            tg.start_soon(self._forward_info, info_recv)
+        async def memory_monitor_callback(
+            memory_profile: MemoryPerformanceProfile,
+        ) -> None:
+            await self.event_sender.send(
+                NodeMemoryMeasured(
+                    node_id=self.node_id,
+                    memory=memory_profile,
+                    when=str(datetime.now(tz=timezone.utc)),
+                )
+            )
+
+        # END CLEANUP
+
+        async with create_task_group() as tg:
+            self._tg = tg
             tg.start_soon(self.plan_step)
+            tg.start_soon(start_polling_node_metrics, resource_monitor_callback)
+
+            tg.start_soon(start_polling_memory_metrics, memory_monitor_callback)
             tg.start_soon(self._connection_message_event_writer)
             tg.start_soon(self._resend_out_for_delivery)
             tg.start_soon(self._event_applier)
@@ -114,17 +140,6 @@ class Worker:
         for runner in self.runners.values():
             runner.shutdown()
 
-    async def _forward_info(self, recv: Receiver[GatheredInfo]):
-        with recv as info_stream:
-            async for info in info_stream:
-                await self.event_sender.send(
-                    NodeGatheredInfo(
-                        node_id=self.node_id,
-                        when=str(datetime.now(tz=timezone.utc)),
-                        info=info,
-                    )
-                )
-
     async def _event_applier(self):
         with self.global_event_receiver as events:
             async for f_event in events:
@@ -144,6 +159,7 @@ class Worker:
                     self._nack_cancel_scope is None
                     or self._nack_cancel_scope.cancel_called
                 ):
+                    assert self._tg
                     # Request the next index.
                     self._tg.start_soon(
                         self._nack_request, self.state.last_event_applied_idx + 1
@@ -232,7 +248,8 @@ class Worker:
                     await self.runners[self._task_to_runner_id(task)].start_task(task)
 
     def shutdown(self):
-        self._tg.cancel_scope.cancel()
+        if self._tg:
+            self._tg.cancel_scope.cancel()
 
     def _task_to_runner_id(self, task: Task):
         instance = self.state.instances[task.instance_id]
@@ -249,24 +266,24 @@ class Worker:
         match msg.connection_type:
             case ConnectionMessageType.Connected:
                 return TopologyEdgeCreated(
-                    source=self.node_id,
-                    sink=msg.node_id,
-                    edge=SocketConnection(
-                        sink_multiaddr=Multiaddr(
+                    edge=Connection(
+                        local_node_id=self.node_id,
+                        send_back_node_id=msg.node_id,
+                        send_back_multiaddr=Multiaddr(
                             address=f"/ip4/{msg.remote_ipv4}/tcp/{msg.remote_tcp_port}"
                         ),
-                    ),
+                    )
                 )
 
             case ConnectionMessageType.Disconnected:
                 return TopologyEdgeDeleted(
-                    source=self.node_id,
-                    sink=msg.node_id,
-                    edge=SocketConnection(
-                        sink_multiaddr=Multiaddr(
+                    edge=Connection(
+                        local_node_id=self.node_id,
+                        send_back_node_id=msg.node_id,
+                        send_back_multiaddr=Multiaddr(
                             address=f"/ip4/{msg.remote_ipv4}/tcp/{msg.remote_tcp_port}"
                         ),
-                    ),
+                    )
                 )
 
     async def _nack_request(self, since_idx: int) -> None:
@@ -315,6 +332,7 @@ class Worker:
             event_sender=self.event_sender.clone(),
         )
         self.runners[task.bound_instance.bound_runner_id] = runner
+        assert self._tg
         self._tg.start_soon(runner.run)
         return runner
 
@@ -373,6 +391,7 @@ class Worker:
                 last_progress_time = current_time()
 
         self.shard_downloader.on_progress(download_progress_callback)
+        assert self._tg
         self._tg.start_soon(self.shard_downloader.ensure_shard, task.shard_metadata)
 
     async def _forward_events(self) -> None:
@@ -395,35 +414,33 @@ class Worker:
         while True:
             # TODO: EdgeDeleted
             edges = set(self.state.topology.list_connections())
-            conns = await check_reachable(
-                self.node_id, self.state.topology, self.state.node_profiles
-            )
+            conns = await check_reachable(self.state.topology, self.node_id)
             for nid in conns:
                 for ip in conns[nid]:
-                    edge = SocketConnection(
+                    if "127.0.0.1" in ip or "localhost" in ip:
+                        logger.warning(
+                            f"Loopback connection should not happen: {ip=} for {nid=}"
+                        )
+
+                    edge = Connection(
+                        local_node_id=self.node_id,
+                        send_back_node_id=nid,
                         # nonsense multiaddr
-                        sink_multiaddr=Multiaddr(address=f"/ip4/{ip}/tcp/52415")
+                        send_back_multiaddr=Multiaddr(address=f"/ip4/{ip}/tcp/52415")
                         if "." in ip
                         # nonsense multiaddr
                         else Multiaddr(address=f"/ip6/{ip}/tcp/52415"),
                     )
                     if edge not in edges:
                         logger.debug(f"ping discovered {edge=}")
-                        await self.event_sender.send(
-                            TopologyEdgeCreated(
-                                source=self.node_id, sink=nid, edge=edge
-                            )
-                        )
+                        await self.event_sender.send(TopologyEdgeCreated(edge=edge))
 
             for nid, conn in self.state.topology.out_edges(self.node_id):
-                if not isinstance(conn, SocketConnection):
-                    continue
-                if nid not in conns or conn.sink_multiaddr.ip_address not in conns.get(
-                    nid, set()
+                if (
+                    nid not in conns
+                    or conn.send_back_multiaddr.ip_address not in conns.get(nid, set())
                 ):
                     logger.debug(f"ping failed to discover {conn=}")
-                    await self.event_sender.send(
-                        TopologyEdgeDeleted(source=self.node_id, sink=nid, edge=conn)
-                    )
+                    await self.event_sender.send(TopologyEdgeDeleted(edge=conn))
 
             await anyio.sleep(10)

src/exo/worker/runner/bootstrap.py

@@ -22,7 +22,7 @@ def entrypoint(
 ) -> None:
     if (
         isinstance(bound_instance.instance, MlxJacclInstance)
-        and len(bound_instance.instance.jaccl_devices) >= 2
+        and len(bound_instance.instance.ibv_devices) >= 2
     ):
         os.environ["MLX_METAL_FAST_SYNCH"] = "1"
 

src/exo/worker/tests/unittests/conftest.py

@@ -67,5 +67,6 @@ def get_mlx_ring_instance(
         shard_assignments=get_shard_assignments(
             model_id, node_to_runner, runner_to_shard
         ),
-        hosts=[],
+        hosts_by_node={},
+        ephemeral_port=50000,
     )

src/exo/worker/tests/unittests/test_plan/test_warmup.py

@@ -21,134 +21,11 @@ from exo.worker.tests.unittests.conftest import (
 )
 
 
-def test_plan_starts_warmup_for_non_zero_rank_when_all_loaded_or_warming():
+def test_plan_starts_warmup_for_accepting_rank_when_all_loaded_or_warming():
     """
-    For non-zero device_rank shards, StartWarmup should be emitted when all
-    shards in the instance are Loaded/WarmingUp.
-    """
-    shard0 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=0, world_size=2)
-    shard1 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=1, world_size=2)
-    instance = get_mlx_ring_instance(
-        instance_id=INSTANCE_1_ID,
-        model_id=MODEL_A_ID,
-        node_to_runner={NODE_A: RUNNER_1_ID, NODE_B: RUNNER_2_ID},
-        runner_to_shard={RUNNER_1_ID: shard0, RUNNER_2_ID: shard1},
-    )
-
-    bound_instance = BoundInstance(
-        instance=instance, bound_runner_id=RUNNER_2_ID, bound_node_id=NODE_B
-    )
-    local_runner = FakeRunnerSupervisor(
-        bound_instance=bound_instance, status=RunnerLoaded()
-    )
-
-    runners = {RUNNER_2_ID: local_runner}
-    instances = {INSTANCE_1_ID: instance}
-    all_runners = {
-        RUNNER_1_ID: RunnerLoaded(),
-        RUNNER_2_ID: RunnerLoaded(),
-    }
-
-    result = plan_mod.plan(
-        node_id=NODE_B,
-        runners=runners,  # type: ignore
-        download_status={},
-        global_download_status={NODE_A: []},
-        instances=instances,
-        all_runners=all_runners,
-        tasks={},
-    )
-
-    assert isinstance(result, StartWarmup)
-    assert result.instance_id == INSTANCE_1_ID
-
-
-def test_plan_starts_warmup_for_rank_zero_after_others_warming():
-    """
-    For device_rank == 0, StartWarmup should only be emitted once all the
-    other runners in the instance are already warming up.
-    """
-    shard0 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=0, world_size=2)
-    shard1 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=1, world_size=2)
-    instance = get_mlx_ring_instance(
-        instance_id=INSTANCE_1_ID,
-        model_id=MODEL_A_ID,
-        node_to_runner={NODE_A: RUNNER_1_ID, NODE_B: RUNNER_2_ID},
-        runner_to_shard={RUNNER_1_ID: shard0, RUNNER_2_ID: shard1},
-    )
-
-    bound_instance = BoundInstance(
-        instance=instance, bound_runner_id=RUNNER_1_ID, bound_node_id=NODE_A
-    )
-    local_runner = FakeRunnerSupervisor(
-        bound_instance=bound_instance, status=RunnerLoaded()
-    )
-
-    runners = {RUNNER_1_ID: local_runner}
-    instances = {INSTANCE_1_ID: instance}
-    all_runners = {
-        RUNNER_1_ID: RunnerLoaded(),
-        RUNNER_2_ID: RunnerWarmingUp(),
-    }
-
-    result = plan_mod.plan(
-        node_id=NODE_A,
-        runners=runners,  # type: ignore
-        download_status={},
-        global_download_status={NODE_A: []},
-        instances=instances,
-        all_runners=all_runners,
-        tasks={},
-    )
-
-    assert isinstance(result, StartWarmup)
-    assert result.instance_id == INSTANCE_1_ID
-
-
-def test_plan_does_not_start_warmup_for_non_zero_rank_until_all_loaded_or_warming():
-    """
-    Non-zero rank should not start warmup while any shard is not Loaded/WarmingUp.
-    """
-    shard0 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=0, world_size=2)
-    shard1 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=1, world_size=2)
-    instance = get_mlx_ring_instance(
-        instance_id=INSTANCE_1_ID,
-        model_id=MODEL_A_ID,
-        node_to_runner={NODE_A: RUNNER_1_ID, NODE_B: RUNNER_2_ID},
-        runner_to_shard={RUNNER_1_ID: shard0, RUNNER_2_ID: shard1},
-    )
-
-    bound_instance = BoundInstance(
-        instance=instance, bound_runner_id=RUNNER_2_ID, bound_node_id=NODE_B
-    )
-    local_runner = FakeRunnerSupervisor(
-        bound_instance=bound_instance, status=RunnerLoaded()
-    )
-
-    runners = {RUNNER_2_ID: local_runner}
-    instances = {INSTANCE_1_ID: instance}
-    all_runners = {
-        RUNNER_1_ID: RunnerWaitingForModel(),
-        RUNNER_2_ID: RunnerLoaded(),
-    }
-
-    result = plan_mod.plan(
-        node_id=NODE_B,
-        runners=runners,  # type: ignore
-        download_status={},
-        global_download_status={NODE_A: [], NODE_B: []},
-        instances=instances,
-        all_runners=all_runners,
-        tasks={},
-    )
-
-    assert result is None
-
-
-def test_plan_does_not_start_warmup_for_rank_zero_until_others_warming():
-    """
-    Rank-zero shard should not start warmup until all non-zero ranks are
-    already WarmingUp.
+    For accepting ranks (device_rank != world_size - 1), StartWarmup should be
+    emitted when all shards in the instance are Loaded/WarmingUp.
+    In a 2-node setup, rank 0 is the accepting rank.
     """
     shard0 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=0, world_size=2)
     shard1 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=1, world_size=2)
@@ -159,6 +36,7 @@ def test_plan_does_not_start_warmup_for_rank_zero_until_others_warming():
         runner_to_shard={RUNNER_1_ID: shard0, RUNNER_2_ID: shard1},
     )
 
+    # Rank 0 is the accepting rank
     bound_instance = BoundInstance(
         instance=instance, bound_runner_id=RUNNER_1_ID, bound_node_id=NODE_A
     )
@@ -173,6 +51,93 @@ def test_plan_does_not_start_warmup_for_rank_zero_until_others_warming():
         RUNNER_2_ID: RunnerLoaded(),
     }
 
+    result = plan_mod.plan(
+        node_id=NODE_A,
+        runners=runners,  # type: ignore
+        download_status={},
+        global_download_status={NODE_A: []},
+        instances=instances,
+        all_runners=all_runners,
+        tasks={},
+    )
+
+    assert isinstance(result, StartWarmup)
+    assert result.instance_id == INSTANCE_1_ID
+
+
+def test_plan_starts_warmup_for_connecting_rank_after_others_warming():
+    """
+    For connecting rank (device_rank == world_size - 1), StartWarmup should
+    only be emitted once all the other runners are already warming up.
+    In a 2-node setup, rank 1 is the connecting rank.
+    """
+    shard0 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=0, world_size=2)
+    shard1 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=1, world_size=2)
+    instance = get_mlx_ring_instance(
+        instance_id=INSTANCE_1_ID,
+        model_id=MODEL_A_ID,
+        node_to_runner={NODE_A: RUNNER_1_ID, NODE_B: RUNNER_2_ID},
+        runner_to_shard={RUNNER_1_ID: shard0, RUNNER_2_ID: shard1},
+    )
+
+    # Rank 1 is the connecting rank
+    bound_instance = BoundInstance(
+        instance=instance, bound_runner_id=RUNNER_2_ID, bound_node_id=NODE_B
+    )
+    local_runner = FakeRunnerSupervisor(
+        bound_instance=bound_instance, status=RunnerLoaded()
+    )
+
+    runners = {RUNNER_2_ID: local_runner}
+    instances = {INSTANCE_1_ID: instance}
+    all_runners = {
+        RUNNER_1_ID: RunnerWarmingUp(),
+        RUNNER_2_ID: RunnerLoaded(),
+    }
+
+    result = plan_mod.plan(
+        node_id=NODE_B,
+        runners=runners,  # type: ignore
+        download_status={},
+        global_download_status={NODE_B: []},
+        instances=instances,
+        all_runners=all_runners,
+        tasks={},
+    )
+
+    assert isinstance(result, StartWarmup)
+    assert result.instance_id == INSTANCE_1_ID
+
+
+def test_plan_does_not_start_warmup_for_accepting_rank_until_all_loaded_or_warming():
+    """
+    Accepting rank should not start warmup while any shard is not Loaded/WarmingUp.
+    In a 2-node setup, rank 0 is the accepting rank.
+    """
+    shard0 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=0, world_size=2)
+    shard1 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=1, world_size=2)
+    instance = get_mlx_ring_instance(
+        instance_id=INSTANCE_1_ID,
+        model_id=MODEL_A_ID,
+        node_to_runner={NODE_A: RUNNER_1_ID, NODE_B: RUNNER_2_ID},
+        runner_to_shard={RUNNER_1_ID: shard0, RUNNER_2_ID: shard1},
+    )
+
+    # Rank 0 is the accepting rank
+    bound_instance = BoundInstance(
+        instance=instance, bound_runner_id=RUNNER_1_ID, bound_node_id=NODE_A
+    )
+    local_runner = FakeRunnerSupervisor(
+        bound_instance=bound_instance, status=RunnerLoaded()
+    )
+
+    runners = {RUNNER_1_ID: local_runner}
+    instances = {INSTANCE_1_ID: instance}
+    all_runners = {
+        RUNNER_1_ID: RunnerLoaded(),
+        RUNNER_2_ID: RunnerWaitingForModel(),
+    }
+
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
@@ -184,3 +149,46 @@ def test_plan_does_not_start_warmup_for_rank_zero_until_others_warming():
     )
 
     assert result is None
+
+
+def test_plan_does_not_start_warmup_for_connecting_rank_until_others_warming():
+    """
+    Connecting rank (device_rank == world_size - 1) should not start warmup
+    until all other ranks are already WarmingUp.
+    In a 2-node setup, rank 1 is the connecting rank.
+    """
+    shard0 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=0, world_size=2)
+    shard1 = get_pipeline_shard_metadata(MODEL_A_ID, device_rank=1, world_size=2)
+    instance = get_mlx_ring_instance(
+        instance_id=INSTANCE_1_ID,
+        model_id=MODEL_A_ID,
+        node_to_runner={NODE_A: RUNNER_1_ID, NODE_B: RUNNER_2_ID},
+        runner_to_shard={RUNNER_1_ID: shard0, RUNNER_2_ID: shard1},
+    )
+
+    # Rank 1 is the connecting rank
+    bound_instance = BoundInstance(
+        instance=instance, bound_runner_id=RUNNER_2_ID, bound_node_id=NODE_B
+    )
+    local_runner = FakeRunnerSupervisor(
+        bound_instance=bound_instance, status=RunnerLoaded()
+    )
+
+    runners = {RUNNER_2_ID: local_runner}
+    instances = {INSTANCE_1_ID: instance}
+    all_runners = {
+        RUNNER_1_ID: RunnerLoaded(),
+        RUNNER_2_ID: RunnerLoaded(),
+    }
+
+    result = plan_mod.plan(
+        node_id=NODE_B,
+        runners=runners,  # type: ignore
+        download_status={},
+        global_download_status={NODE_A: [], NODE_B: []},
+        instances=instances,
+        all_runners=all_runners,
+        tasks={},
+    )
+
+    assert result is None

src/exo/worker/utils/__init__.py

@@ -0,0 +1,6 @@
+from .profile import start_polling_memory_metrics, start_polling_node_metrics
+
+__all__ = [
+    "start_polling_node_metrics",
+    "start_polling_memory_metrics",
+]

src/exo/worker/utils/net_profile.py

@@ -0,0 +1,78 @@
+import http.client
+
+from anyio import create_task_group, to_thread
+from loguru import logger
+
+from exo.shared.topology import Topology
+from exo.shared.types.common import NodeId
+
+
+async def check_reachability(
+    target_ip: str,
+    expected_node_id: NodeId,
+    self_node_id: NodeId,
+    out: dict[NodeId, set[str]],
+) -> None:
+    """Check if a node is reachable at the given IP and verify its identity."""
+
+    def _fetch_remote_node_id() -> str | None:
+        connection = http.client.HTTPConnection(target_ip, 52415, timeout=1)
+        try:
+            connection.request("GET", "/node_id")
+            response = connection.getresponse()
+            if response.status != 200:
+                return None
+
+            body = response.read().decode("utf-8").strip()
+
+            # Strip quotes if present (JSON string response)
+            if body.startswith('"') and body.endswith('"') and len(body) >= 2:
+                body = body[1:-1]
+
+            return body or None
+        except OSError:
+            return None
+        finally:
+            connection.close()
+
+    remote_node_id_raw = await to_thread.run_sync(_fetch_remote_node_id)
+    if remote_node_id_raw is None:
+        return
+
+    remote_node_id = NodeId(remote_node_id_raw)
+    if remote_node_id == self_node_id:
+        # Connected to ourselves via loopback - skip
+        return
+
+    if remote_node_id != expected_node_id:
+        logger.warning(
+            f"Discovered node with unexpected node_id; "
+            f"ip={target_ip}, expected_node_id={expected_node_id}, "
+            f"remote_node_id={remote_node_id}"
+        )
+        return
+
+    if remote_node_id not in out:
+        out[remote_node_id] = set()
+    out[remote_node_id].add(target_ip)
+
+
+async def check_reachable(
+    topology: Topology, self_node_id: NodeId
+) -> dict[NodeId, set[str]]:
+    """Check which nodes are reachable and return their IPs."""
+    reachable: dict[NodeId, set[str]] = {}
+    async with create_task_group() as tg:
+        for node in topology.list_nodes():
+            if not node.node_profile:
+                continue
+            for iface in node.node_profile.network_interfaces:
+                tg.start_soon(
+                    check_reachability,
+                    iface.ip_address,
+                    node.node_id,
+                    self_node_id,
+                    reachable,
+                )
+
+    return reachable

src/exo/worker/utils/profile.py

@@ -0,0 +1,114 @@
+import asyncio
+import os
+import platform
+from typing import Any, Callable, Coroutine
+
+import anyio
+from loguru import logger
+
+from exo.shared.types.memory import Memory
+from exo.shared.types.profiling import (
+    MemoryPerformanceProfile,
+    NodePerformanceProfile,
+    SystemPerformanceProfile,
+)
+
+from .macmon import (
+    MacMonError,
+    Metrics,
+)
+from .macmon import (
+    get_metrics_async as macmon_get_metrics_async,
+)
+from .system_info import (
+    get_friendly_name,
+    get_model_and_chip,
+    get_network_interfaces,
+)
+
+
+async def get_metrics_async() -> Metrics | None:
+    """Return detailed Metrics on macOS or a minimal fallback elsewhere."""
+
+    if platform.system().lower() == "darwin":
+        return await macmon_get_metrics_async()
+
+
+def get_memory_profile() -> MemoryPerformanceProfile:
+    """Construct a MemoryPerformanceProfile using psutil"""
+    override_memory_env = os.getenv("OVERRIDE_MEMORY_MB")
+    override_memory: int | None = (
+        Memory.from_mb(int(override_memory_env)).in_bytes
+        if override_memory_env
+        else None
+    )
+
+    return MemoryPerformanceProfile.from_psutil(override_memory=override_memory)
+
+
+async def start_polling_memory_metrics(
+    callback: Callable[[MemoryPerformanceProfile], Coroutine[Any, Any, None]],
+    *,
+    poll_interval_s: float = 0.5,
+) -> None:
+    """Continuously poll and emit memory-only metrics at a faster cadence.
+
+    Parameters
+    - callback: coroutine called with a fresh MemoryPerformanceProfile each tick
+    - poll_interval_s: interval between polls
+    """
+    while True:
+        try:
+            mem = get_memory_profile()
+            await callback(mem)
+        except MacMonError as e:
+            logger.opt(exception=e).error("Memory Monitor encountered error")
+        finally:
+            await anyio.sleep(poll_interval_s)
+
+
+async def start_polling_node_metrics(
+    callback: Callable[[NodePerformanceProfile], Coroutine[Any, Any, None]],
+):
+    poll_interval_s = 1.0
+    while True:
+        try:
+            metrics = await get_metrics_async()
+            if metrics is None:
+                return
+
+            network_interfaces = get_network_interfaces()
+            # these awaits could be joined but realistically they should be cached
+            model_id, chip_id = await get_model_and_chip()
+            friendly_name = await get_friendly_name()
+
+            # do the memory profile last to get a fresh reading to not conflict with the other memory profiling loop
+            memory_profile = get_memory_profile()
+
+            await callback(
+                NodePerformanceProfile(
+                    model_id=model_id,
+                    chip_id=chip_id,
+                    friendly_name=friendly_name,
+                    network_interfaces=network_interfaces,
+                    memory=memory_profile,
+                    system=SystemPerformanceProfile(
+                        gpu_usage=metrics.gpu_usage[1],
+                        temp=metrics.temp.gpu_temp_avg,
+                        sys_power=metrics.sys_power,
+                        pcpu_usage=metrics.pcpu_usage[1],
+                        ecpu_usage=metrics.ecpu_usage[1],
+                        ane_power=metrics.ane_power,
+                    ),
+                )
+            )
+
+        except asyncio.TimeoutError:
+            logger.warning(
+                "[resource_monitor] Operation timed out after 30s, skipping this cycle."
+            )
+        except MacMonError as e:
+            logger.opt(exception=e).error("Resource Monitor encountered error")
+            return
+        finally:
+            await anyio.sleep(poll_interval_s)