Lever map records the full prefill/decode gap decomposition vs vLLM, the ranked levers, and the rejected dead ends. GDN build plan is the per-product mma mapping + A-inverse + occupancy design.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
The S1 section-(a) padded/fixed-slot decode shape (the scoped follow-up to push
serving graph reuse from ~72% toward ~100%) was implemented in an isolated
worktree off the committed S1/S3/tail base, built CUDA-only, and benched on GB10.
Verdict: REJECTED. It is bit-exact and provably inert, but it regresses serving
throughput at every concurrency and does not close the vLLM gap.
Implementation (default-off, LLAMA_PAGED_PAD_DECODE): on a pure-decode step
(n_prompt_budgeted == 0) emit a masked-inert dummy decode for every idle slot so
n_tokens / n_seqs / n_seqs_unq / n_outputs and the seq-id set stay constant; a
release()-side guard keeps a finished slot warm under padding. Each dummy is its
own sequence (private recurrent state, per-stream paged attention, logits
discarded), so it cannot perturb a real stream.
Gates: single-seq greedy md5 bit-exact (dense 5951a5b4, paged-MoE 8cb0ce23). The
literal per-stream ON-vs-OFF identity gate is unachievable - concurrent cuBLAS/FA
decode is not bit-reproducible run-to-run even with padding off (OFF-vs-OFF
diverging streams: dense 3/16, MoE 8/16). The achievable inertness gate passed:
ON-vs-OFF per-stream prefix-agreement equals the OFF-vs-OFF noise floor exactly
(MoE 0.940/0.940, dense 0.812/0.812), so the dummy slots leak nothing.
Bench (MoE Qwen3.6-35B-A3B-NVFP4, GB10), burst decode tok/s/seq: n=8 S1+S3 28.16
/ PAD 6.05 / vLLM 44.8; n=128 S1+S3 4.53 / PAD 4.32 / vLLM 6.87. Staggered
aggregate tok/s: baseline (reuse 0%) 757.6, S1+S3 (reuse 72%) 763.3, PAD
(reuse 38%) 558.0.
Why it fails: (1) serving decode here is GPU-compute-bound, not host-rebuild-bound
- baseline reuse 0% ~= S1+S3 reuse 72% on aggregate tok/s, so closing reuse buys
~nothing (the earlier 542->762 host-bound delta did not reproduce); (2) padding
adds dummy-row compute proportional to pad_width - real_load, catastrophic at low
load; (3) in continuous serving padding cannot hold a constant width (perpetual
prefill churn) so reuse drops 72% -> 38%; (4) the completion-driven batch shrink
padding prevents is itself a throughput win in a compute-bound regime. The
residual burst gap is GPU-compute, which a host-side reuse lever cannot close.
Patch series unchanged: this rejected lever is NOT added to patches/paged/.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Add the two decode-serving graph-reuse levers (validated on GB10) that close the
host-bound serving gap (paged dropped to ~3.7 vs vLLM ~5.9 tok/s/seq in real
continuous serving while tying it in static batched-bench).
- 0040 S1 paged decode-graph reuse: the paged decode inputs never overrode
llm_graph_input_i::can_reuse (defaults false), so the host rebuilt the ggml
graph on EVERY decode step (layer-A reuse 0%). Add a 256-bucketed-shape
can_reuse + a live-mctx refresh from the owning attn input. Bit-exact (md5
byte-identical reuse on/off). Static batched-bench: paged reuse 0% -> 95.5%.
- 0041 S3 decode-shape-stable scheduling: keep co-batched prefill out of decode
steps so the scheduler emits the reuse-stable pure-decode shape S1 can reuse.
Default-off policy on top of 0016; bit-exact (per-stream independent).
S1+S3 together (128-client staggered serving, MoE Qwen3.6-35B-A3B-NVFP4): graph
reuse 0% -> 72.2%, hostproc 15.98 -> 6.31 ms/step, decode 4.05 -> 5.52 tok/s/seq
median (4.24 -> 5.96 mean, at vLLM's ~5.9). S1 alone is insufficient (13.8%);
S3 is the multiplier. S2 (double-buffer set_inputs) dropped: Phase-0 put
set_inputs at ~0.05 ms/step, so it has nothing to recover. README patch table +
DECODE_SERVING_SCOPE.md updated with results and the padded/fixed-slot follow-up.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Option (a) of PREFILL_GEMM_SCOPE.md: route large-M (prefill) NVFP4 dense weight
GEMMs off the decode-tuned FP4-MMQ kernel onto the dequant->bf16 cuBLAS (nvjet)
tensor-core path, wired via an M-threshold in ggml_cuda_should_use_mmq. Lands the
validated, bit-exact-gated mechanism and records the honest GB10 result: it is a
regression, so it ships default-off (== stock), mirroring the patch-0017
default-off discipline.
Three-edit scaffold (no new kernel): should_use_mmq routes NVFP4+Blackwell+dense
M>LLAMA_FP4_PREFILL_M to cuBLAS; op_mul_mat_cublas gains an NVFP4 branch that
dequants the FP4 weights to a transient bf16 pool buffer (not cached - stays
FP4-resident) and runs cublasGemmEx CUDA_R_16BF/COMPUTE_32F; ggml_get_to_bf16_cuda
gains the NVFP4 case.
Bit-exact gate PASS (benign): test-backend-ops MUL_MAT 1146/1146 + MUL_MAT_ID
806/806; the forced path (LLAMA_FP4_PREFILL_M=64) is green CUDA-vs-CPU at NVFP4
large-M shapes; greedy md5 on q36-27b is byte-identical to FP4-MMQ both for
short prefill (5951a5b4, decode untouched) and for a >threshold prefill that
exercises the bf16 path (5f3967df - no greedy argmax flips).
Performance REGRESSES on GB10 (S_PP, q36-27b dense, A/B via env): M=512 958.99
-> 486.65 (-49%), M=1024 1013.65 -> 587.27 (-42%), M=2048 918.46 -> 649.42
(-29%). The scope premise (FP4-MMQ ~3% of FP4 peak at large M) is false here:
FP4-MMQ beats bf16-cuBLAS because bf16 peak is ~half FP4 peak and the per-step
weight dequant + 4x bf16 weight traffic (~8x total vs the FP4 read) dominate,
only partially amortizing as M grows. Default-off keeps stock S_PP (966.98).
Phase 2 (MoE grouped large-M) not implemented: it inherits the same
bf16-peak<FP4-peak ceiling plus a per-expert dequant, so grouped bf16-cuBLAS
would regress for the same reason; a real prefill GEMM win needs option (b), a
native FP4-MMA large-M kernel. Full A/B in docs/PREFILL_GEMM_RESULTS.md.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Scopes the follow-up recorded by patch 0031 + README section 5: replace the
serial per-thread reductions of the chunked gated-DeltaNet prefill scan with
mma.sync tensor-core matmuls and lift the 1-block/SM occupancy ceiling, the
path that would beat the tuned sequential scan and close the GDN prefill
bucket toward vLLM's ~2.5x-cheaper chunked scan.
Confirmed (not assumed) the GB10/sm_121a tensor-core reality: consumer
Blackwell (SM12x) has NO wgmma (Hopper-only) and NO tcgen05/TMEM (sm_100a
data-center only); the usable path is the extended mma.sync family. So the
kernel is a warp-synchronous mma.sync + cp.async design (reusing ggml's
mma.cuh tiles), not a wgmma/TMA/tcgen05 design - patch 0031's 'mma/wgmma'
shorthand reads as mma only on this part.
Design: register-resident state frees the 64KB that forced C=16, admitting
C=64 under the 99KB shared opt-in; tf32 inputs / f32 accumulate with a 3xtf32
precision ladder; decays/gamma/beta stay f32 outside the mma to preserve the
bounded de-gating; A-inverse via blocked forward substitution (FLA UT
transform) with mma off-diagonal coupling. Mechanism: chunking cuts state-BW
~Cx, mma absorbs the O(C^2) intra-chunk flops the serial 0031 could not.
Honest: multi-week, high risk, no vendor kernel to route to on sm_121; gains
beat the sequential scan and close most of the bucket but not full sm_100-class
parity. KL-gate binding (NMSE likely fails at reduced precision). Phased:
re-profile -> two-product PoC -> full intra-chunk + C=64 + reg-state ->
occupancy/cp.async; opt-in default-OFF until A/B-proven.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Add DECODE_SERVING_SCOPE.md: the decode KERNEL is at parity in static
batched-bench (~6.1 tok/s/seq ~ vLLM ~5.9 at npl128) but continuous serving
through llama-server update_slots() drops to ~3.7 (-39%) while vLLM sustains
~5.9. Scope shows the gap is the scheduler/host loop, not the kernel.
Root-cause hypothesis from source: continuous batching's batch-shape + seq-set
churn breaks BOTH graph-reuse layers every step - llama-context can_reuse/
allow_reuse (n_tokens + seq-set must match) and the CUDA ggml_cuda_graph
update_required memcmp (ne/nb/data ptrs) - so the GPU idles while the host
rebuilds + re-captures the graph and runs un-graphed set_inputs. vLLM avoids
this with padded/bucketed decode shapes + piecewise CUDA graphs. Documents that
the shipped scheduler patches (0008/0013/0016/0024/0025/0029) target prefill
freezing + burst collapse, NOT decode-step graph reuse, which is why the serving
gap survives them; notes the README s.5 'lever 2 graph coverage FLAT' verdict was
static-regime and is reopened here for serving only.
Ranks host-side, bit-exact-safe levers: S1 bucketed/padded decode-step shape for
graph reuse, S2 double-buffer/overlap per-step host work, S3 graph-shape-stable
scheduling (extend 0016). Specifies a Phase-0 profile to confirm host-bound
before any build, reusing the in-tree [L5INSTR] hostproc/set_inputs/
get_block_table timers, the 'graphs reused' perf counter, LLAMA_GRAPH_REUSE_DISABLE
and nsys GPU-busy%, with vLLM ground-truthed at the same concurrency. No kernel
code; no GPU run in this pass.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Design + plan for the #1 prefill lever: NVFP4 weight GEMM at large M, where
MMQ (decode/M<=128-tuned, 1 CTA/SM, 128-col tile cap) is ~3.4x slower than
vLLM's marlin/cutlass large-M path (~51% of the prefill gap).
Recommends (a) dequant->bf16 cuBLAS routed by an M-threshold (dense first,
MoE grouped-cuBLAS second); rejects (b) a from-scratch Marlin/FP4 kernel as a
multi-week project. Key enabling finding: NVFP4->bf16 dequant kernels already
exist, and NVFP4 is currently force-excluded from the tensor-core cuBLAS path
(falls to f32 Sgemm) - relaxing that one guard is the pivot. Honest: bf16-cuBLAS
banks ~60-75% of the GEMM gap, not full 68us/tok parity (bf16 TC peak ~half FP4).
Design only - no kernel, no GPU run.
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Assisted-by: Claude:claude-opus-4-8 [Claude Code]
The opt-in hybrid per-head bf16 SSM-state lever (ssm_bf16_tau, patch 0026) is
removed from the llama-cpp-localai-paged patch series. Clean re-measurement after
the decode fusions (0028 recurrent-state gather-fusion + 0029 block-table cache)
landed shows it buys nothing: forcing ALL gated-DeltaNet heads to bf16
(tau=100000, the most aggressive setting) gives flat decode throughput, 780.6 vs
780.0 t/s. The mode engages but adds zero speed because it is subsumed by the
fusions. The earlier "+12%" was measured before the fusions completed. bf16-tau
was a precision trade (not bit-exact, ~91% same-top-p) plus extra bug surface and
extra CUDA template-instantiation compile cost with no offsetting benefit.
Dependency check: no later patch (0028/0029/0030) depends on 0026. 0030's only
mention is a description comment; its code keys off fused_gdn_ar/ch/auto_fgdn,
which originate in 0018/0019/0021 (before 0026). The remaining series (0001-0025,
0028-0030) applies clean with git apply --check against the pin
0ed235ea2c17a19fc8238668653946721ed136fd. The Makefile applies the series by glob
(patches/paged/0*.patch); the resulting gap at 0026 is tolerated (0005/0027 are
already absent).
Removed:
- patches/paged/0026-qwen35-hybrid-perhead-ssm-state.patch
- the dead ssm_bf16_tau / ssm_hybrid_tau option handler in the shared
grpc-server.cpp (it only set LLAMA_SSM_BF16_TAU, now a no-op the library no
longer reads)
- the patched+bf16-tau benchmark columns and llama-patched-bf16tau rows
(README + final_benchmark.csv), the ssm_bf16_tau option text in backend
index.yaml, the gallery NOTE block, and the docs/features/backends.md mention.
The rejected-lever lesson is kept (why it was dropped: subsumed, tau=100000 flat)
in the backend README section 5, the paged-backend agent guide, and the
vLLM-parity methodology, so it is not re-tried.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Add ACCELERATOR_PORTING_SCOPE.md, the umbrella scope for taking the paged
backend's accelerator-portable wins off the CUDA family. It builds on (does
not duplicate) UPSTREAM_LAYER2_SCOPE.md, which stays the GDN/SSM-fusion
detail (benefit #1), and adds:
- Benefit #2 (paged KV in-kernel block-table flash-attn read, 0009-0011):
new per-backend feasibility from source analysis of the Metal/SYCL/Vulkan
flash-attn kernels. SYCL EASY (near line-for-line CUDA mirror), Metal
EASY-MEDIUM (decode already routes to the vec kernel), Vulkan MEDIUM (the
fast coopmat2 NVIDIA decode path cannot do the indexed read; push-constants
are full). Universal constraint: only the vec/scalar decode kernel admits
the per-cell indexed read, so route block-table ops onto vec (as CUDA's
0009-0010 dispatch guard already does) and leave the fast MM/coopmat2 path
contiguous-only. This is the lever that flips paged KV from
neutral-to-slightly-negative to non-negative off CUDA.
- Benefit #3 (decode-first scheduler, 0013/0016): confirmed a free portable
win - host-side update_slots() policy, zero kernel work, runs on any
accelerator as-is.
- Benefit #4 (NVFP4 FP4-MMA, 0017/0023/0025): out of scope (Blackwell only);
flags the backend-agnostic analogues of the act-quant dedup and the
graph-coverage lever without over-claiming a port.
- A ROCm note: ROCm rides the CUDA/HIP path (validate, don't re-port);
FP4-MMA stays Blackwell-only.
Benefits #1 and #2 share the port shape and rank Metal->SYCL->Vulkan, so they
bundle into one per-backend PR behind a shared ops-first PR. Cross-link added
from UPSTREAM_LAYER2_SCOPE.md. All gates are test-backend-ops on-target (no
Metal/SYCL/Vulkan/ROCm hardware here).
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Per request, the plots now show all four series: llama.cpp (standard), vLLM,
LocalAI's llama.cpp patches (bit-exact hero), and LocalAI's patches + bf16-tau
(opt-in ceiling, +3% to +17% over the patches, ahead of vLLM at every dense width
and MoE npl>=32). Subtitle flags bf16-tau as opt-in / not bit-exact.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Rebuild the two committed decode plots from the re-measured CSV and add a combined
overview. Three series per the comparison that matters: llama.cpp (standard) vs
vLLM vs LocalAI's llama.cpp patches; x-over-standard called out at npl128. bf16-tau
stays out of the plot (it remains in the CSV + the README table as the opt-in row).
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Re-run the GB10/DGX-Spark llama-batched-bench matrix (dense q36-27b + MoE
q36-35b-a3b, npl 8/32/64/128, -fa on -ngl 99 -npp 128 -ntg 128) so the CSV and
README section 4 carry a single consistent set of llama numbers with all three
configs:
- stock: separately-built unpatched llama.cpp at this backend's exact pin
9d5d882d (toggling LLAMA_KV_PAGED on the patched binary does NOT reproduce
stock - the SSM decode fusions are compiled in, not env-gated).
- patched: paged binary, LLAMA_KV_PAGED=1 (+LLAMA_MOE_FORCE_GRAPHS=1 for MoE).
- patched+bf16-tau: patched plus --ssm-bf16-tau 64 (opt-in, NOT bit-exact,
~91% same-top-p).
final_benchmark.csv now has stock + patched + bf16-tau + vllm rows for both
models at all four widths (the prior CSV had no stock and no bf16-tau rows).
peak_gb is dropped: the GB10's unified LPDDR5x reports [N/A] to nvidia-smi and
the bench does not print it, so per-run peak could not be captured this session.
Patch series gives up to 2.46x (dense) / 2.26x (MoE) over true-stock; opt-in
bf16-tau adds a further +3% to +17% on top of patched (growing with width).
vLLM column is kept from the prior session (not re-run) and labeled as such.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
The paged backend's llama.cpp pin was reverted from c299a92c back to
9d5d882d (== stock), so docs/PIN_SYNC_c299a92c.md (a blow-by-blow of the
reverted sync) is dead weight. The pin-sync PROCESS stays documented in
the three live places: the Makefile comment, README section 7 (Pin +
maintenance policy), and .agents/llama-cpp-localai-paged-backend.md.
Delete the doc and repoint every reference to it (Makefile, README,
.agents, canary script + workflow) at README section 7. No functional
paths change: the canary's patches-dir glob (patches/paged/0*.patch)
is untouched.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
The c299a92c bump diverged 23 commits ahead of the stock llama-cpp pin.
grpc-server.cpp is SHARED with the stock backend and tracks the stock pin;
c299a92c's upstream server-API refactor pulled stream_* helpers into the headers
grpc-server.cpp includes, whose definitions the stock-aligned build does not
compile -> every paged variant failed to LINK (undefined reference to
stream_aware_should_stop / stream_pipe_producer::cleanup /
stream_session_attach_pipe). The bump was greedy-md5 bit-exact, but the bit-exact
gate never exercises the full grpc-server build, so it slipped through.
Revert LLAMA_VERSION to 9d5d882d (== stock pin, where the patches are bit-exact
AND grpc-server links - the original DGX-proven baseline). Document the hard
constraint in the Makefile, README, PIN_SYNC record, and the .agents guide: the
paged pin must track the stock pin, and a pin-sync must pass the full CI
grpc-server build, not only the bit-exact gate.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
The llama-cpp-localai-paged patches/ dir had accumulated docs, plots, a csv,
dev .cpp harnesses, and a dead FP4-MoE kernel scaffold after an earlier git-mv.
Restore the invariant that patches/ holds only the .patch series.
Moves:
- patches/paged/README.md -> README.md (canonical doc at the backend root)
- patches/paged/{PIN_SYNC_c299a92c,PAGED_BITEXACT_NOTE,LOCALAI_LLAMACPP_BACKEND_PLAN,UPSTREAM_LAYER2_SCOPE}.md,
final_benchmark.csv, qwen36_*.png, paged-burst-bench.cpp, paged-reclaim-unit.cpp -> docs/
- patches/README.md -> docs/PATCH_MAINTENANCE.md (unique patch-regen recipe not in the canonical README)
Deletes:
- patches/BENCHMARKS.md (superseded by README section 4 + the dev-notes section)
- patches/kernel/ (dead FP4-MoE scaffold, never in the 0001-0030 apply glob, zero refs repo-wide)
Repoint every reference to the moved files: README internal links (docs/ + the
.github links drop from 5x ../ to 3x ../), .agents/llama-cpp-localai-paged-backend.md,
.github/scripts/paged-canary-apply.sh, .github/workflows/llama-cpp-paged-canary.yml,
the wrapper Makefile, backend/cpp/llama-cpp/grpc-server.cpp, backend/index.yaml,
docs/content/features/backends.md, gallery/index.yaml.
The build apply glob PAGED_PATCHES_DIR/0*.patch (PAGED_PATCHES_DIR := .../patches/paged)
is unchanged and still resolves to the 28 patches.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
