Files
LocalAI/backend/cpp/llama-cpp-localai-paged
Ettore Di Giacinto 0b84fda496 docs(paged): add the bf16-tau opt-in line to the decode plots
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>
2026-06-27 22:25:02 +00:00
..

LocalAI paged-attention llama.cpp patch series

This backend vendors the patch series (in patches/paged/) that turns stock llama.cpp into LocalAI's paged-attention variant (llama-cpp-localai-paged). The patches are applied on top of a pinned upstream llama.cpp at build time; nothing here is a fork - it is a source-only *.patch stack plus this canonical doc.

One-file rule: this README is the canonical reference for the patch series. The only other docs are operational, kept in docs/, and linked below:


1. What it is

llama-cpp-localai-paged is the LocalAI paged-attention llama.cpp backend: a vendored patch series over upstream llama.cpp that adds

  • a paged KV cache (vLLM-style block manager: on-demand fixed-size blocks, free pool, ref-counted blocks) with a block-table flash-attention read so the attention kernels index physical cells instead of a contiguous buffer;
  • cross-request prefix sharing - concurrent requests that share a long prefix physically reuse one committed copy of the prefix blocks and prefill only their divergent suffix;
  • a decode-first prefill scheduler - a dynamic per-step prefill-token budget decoupled from n_batch, so a long prefill never freezes co-batched decode;
  • GB10 / Blackwell NVFP4 decode optimizations for the Qwen3.6 hybrid gated-DeltaNet (SSM) models, where the recurrent-state plumbing - not the FP4 GEMM - dominates the decode step.

It is pinned to llama.cpp 9d5d882d (kept == the stock llama-cpp backend's pin) and advanced only by a manual, bit-exact-gated pin-sync process (see section 7, "Pin + maintenance policy"), decoupled from the nightly auto-bumper. The pin must stay aligned with the stock pin because grpc-server.cpp is shared; an earlier bump to c299a92c was bit-exact but broke the grpc-server link and was reverted.

The build gate is LLAMA_PAGED (default on in this tree); the paged engine is enabled per-model at runtime via the gallery options: knobs (paged_kv:true, max_batch_tokens:, kv_unified:false, ...). Against unpatched llama.cpp the runtime hooks are inert, so a single grpc-server.cpp is shared between the clean and the paged build.


2. Architecture

The decode step on these models breaks into three cost centers; the patch series attacks each one.

Paged KV manager + block-table flash-attn. A host-side PagedKVManager (FreeBlockQueue / BlockPool / chained-hash content cache) hands out fixed-size KV blocks on demand and reclaims them per-sequence (ref-counted, with copy-on-write for shared prefixes). The attention path reads through a block table - an I32 [n_view, n_stream] position-ordered physical-cell index passed as src[5] of ggml_flash_attn_ext - so the CUDA fattn vec/tile kernels and the CPU reference map logical KV index j to physical cell block_table[seq*ne11+j] and read K/V in place. Token-position ordering keeps the flash-attn online-softmax reduction order identical to stock. A null block table is the stock contiguous read, byte-identical.

The gated-DeltaNet (GDN / SSM) decode path. The Qwen3.6 hybrid models are 48 gated-DeltaNet (linear-attention / SSM) layers + 16 full-attention layers. On GB10 the recurrent-state plumbing, not the weight GEMM, is the dominant decode cost. The series fuses that plumbing to mirror vLLM's fused_recurrent_gated_delta_rule: the recurrent state is read from and written to its cache slot in place (no copy-back, no get_rows materialization), the conv state is updated in place, the output projection is reshaped to route to the tensor-core MMQ GEMM, and the recurrence kernel is occupancy-retuned - all bit-exact (md5-gateable) against the f32 baseline.

NVFP4 native FP4-MMA on Blackwell. The NVFP4 dense/expert weight GEMM uses Blackwell's native FP4-MMA. The series removes a redundant activation-requantize in the MoE broadcast projections (bit-exact byte copy of identical blocks) and keeps CUDA graphs on for the grouped-MMQ MoE decode step. These are the only NVFP4-specific optimizations; on non-Blackwell hardware the FP4 path falls back to dequant.

The prefill/decode scheduler. update_slots() already emits one unified mixed prefill+decode batch per step. The scheduler patches change only the count of prefill tokens admitted per step: decode tokens are claimed first (decode-first), then a dynamic budget max(n_ubatch, T - D) (where D is the live decode load and T is LLAMA_MAX_BATCH_TOKENS) admits prefill, auto- shrinking as decode load rises. Pure scheduler policy, byte-identical when off, orthogonal to the paged allocator.


3. Patch series (0001-0030)

28 patches (0005 and 0027 are intentionally unused). "Bit-exact" = greedy md5 / test-backend-ops byte-identical to the relevant baseline; the gate methodology is in section 5.

Paged-KV core (0001-0012)

# What it does Bit-exact
0001 Vendor the host-side paged KV block manager (FreeBlockQueue, BlockPool, PagedKVManager, chained-hash prefix cache). Pure C++17, nothing uses it yet. n/a (no behavior)
0002 Place each sequence at permuted, non-contiguous block positions in find_slot (proves attention is invariant to physical KV placement). yes (token-identical)
0003 Gather K/V/mask down to each stream's non-empty cells before build_attn_mha, position-sorted so the FA reduction order matches stock. yes
0004 Drive paged placement through the vendored manager: blocks popped on demand, returned on seq end. Core kv-cache struct untouched. yes (stock path byte-identical)
0006 Host-side cross-request prefix caching: hash prefix blocks, reuse matching physical blocks (ref-count++), COW-privatise before a divergent write. yes (default off)
0007 Wire the prefix cache into the engine so a new sequence physically shares cached prefix blocks and skips recomputing the shared prefix. yes (verified byte-identical)
0008 Wire cross-request prefix share into the llama-server continuous-batch loop so concurrent shared-prefix requests prefill only the suffix (36x fewer prefill tokens at K=32). within CUDA batch-shape non-determinism band
0009 Replace the per-step gather with an in-kernel paged read (block table as src[5]); the K/V get_rows is gone. Decode step at batch32 691->696ms (was 1279ms gathered). yes on CPU/batch1; GPU batch>1 within vec-vs-mma band
0010 Graft the block-table read into the tile kernel; add a dispatch guard so a present block table routes ONLY to vec/tile (never the mma/wmma kernels that ignore it). yes (CPU byte-identical; vec route)
0011 Route the GQA-grouped F16 decode to the tile kernel (native head-group reuse) by default; vec for everything else. Paged decode to within 1.8% of stock. vs stock-mma: different-kernel rounding; bit-exact vs vec
0012 Defensive GGML_ASSERT(n_view % 64 == 0) so a future pad/tile change can't silently reintroduce a past-end KV leak on the tile route. yes (additive assert)

Decode-first scheduler (0013, 0016)

# What it does Bit-exact
0013 LLAMA_PREFILL_BUDGET: a static per-step prefill-token budget decoupled from n_batch (vLLM --max-num-batched-tokens analogue). Flattens the decode ITL spike a long prefill inflicts (8.5x smaller worst freeze). yes (off/short = byte-identical; == -b chunking)
0016 Supersede 0013 with a dynamic decode-first budget: max(n_ubatch, T-D), auto-shrinking as decode load D rises. Policy-only inside update_slots(), zero libllama changes. yes (default-off byte-identical)

(0014/0015 are the MoE token-tile levers: 0014 adds LLAMA_MOE_MMQ_X (opt-in high-batch decode micro-opt, +4.8% on Qwen3-Coder-30B), 0015 makes it a default-on, density-aware auto-select that is prefill-safe by construction. Both bit-exact. 0017 is the dense FP4-GEMM occupancy-tune track: bit-exact gate green, but every cheap occupancy lever regressed on GB10, so nothing is enabled - it ships as the parity gate + default-off instrumentation only.)

SSM (gated-DeltaNet) decode levers (0018-0022, 0028)

These are the dominant decode levers on the Qwen3.6 hybrid models. All bit-exact.

# What it does Effect (dense q36-27b / MoE q36-35b-a3b @npl128)
0018 In-place SSM state write-back - the recurrence writes its final state directly into the cache slot, removing the ~225MB/copy D2D memcpy (18.9% of decode time). dense +23.5% / MoE +18.9%
0019 Fused recurrent-state gather - the op reads each sequence's prior state directly from cache[ids[seq]] (no get_rows materialization); race-free in-place + ids read. dense +37.8% / MoE +35.3%
0020 o_proj MMVQ->MMQ reshape - collapse the GDN output to 2D so the output projection routes to the M=128 tensor-core MMQ GEMM (was a batch<=8 MMVQ GEMV). The single biggest decode-parity lever. dense +31.7% (->85.9% of vLLM) / MoE +23.3%
0021 Conv-state in-place fusion - one ggml_ssm_conv_update_inplace op replaces the 4-op conv chain (transpose+concat+conv+silu+ring-cpy), writing the shifted ring state in place. dense +3.2% / MoE +3.5%
0022 GDN recurrence occupancy/coalescing retune - column-folding (NUM_WARPS/COLS_PER_WARP) raises memory-level parallelism on the bandwidth-bound B=128 recurrence kernel; per-column f32 FMA order unchanged. 73.4%->84.6% of GB10 peak BW. dense +11.1% / MoE +8.3%
0028 Recurrent conv-tap gather fusion - the last k_get_rows in the GDN decode path (the conv-state tap gather) becomes an indexed in-kernel read. dense ~377 t/s / MoE ~784 t/s

MoE NVFP4 quant (0023, 0025)

# What it does Bit-exact
0023 NVFP4 activation-quantize de-dup - the broadcast up/gate projections re-quantize the same token activation once per expert; quantize the unique token activations once and byte-copy them into the expert-gathered layout. The only NVFP4-specific patch. yes (byte-identical)
0025 MoE decode re-graph - keep CUDA graphs on for the grouped-MMQ MoE decode step (the upstream guard disables graphs conservatively; the grouped path has no host sync). Env-gated LLAMA_MOE_FORCE_GRAPHS. yes (graph replay re-issues identical kernels)

Pool reclaim, block-table cache, backend gate, opt-in bf16-SSM

# What it does Bit-exact
0024 Paged-pool burst-reclaim - truncate trailing blocks on partial-tail seq_rm, defrag the free queue when idle, release blocks on slot completion. Fixes the long-server burst-degradation bug (post-burst prefill collapse 488->44 t/s, restored to 532). Host-side accounting only. yes
0029 Block-table within-step host cache - the block table is fixed for the whole step; cache it on first build and memcpy it for the other full-attention layers (get_block_table -87%/-91%). yes, per path (paged-MoE ref 8cb0ce23)
0030 Fused-op backend gate - the fused GDN / discriminated SSM_CONV ops are CUDA-family + CPU only; force them off on any non-CUDA compute backend so a Vulkan/SYCL/Metal build can't silently run the wrong plain-conv kernel. yes on CUDA (byte-identical pre-0030); safety gate elsewhere
0026 Hybrid per-head bf16 SSM state (opt-in) - --ssm-bf16-tau / option ssm_bf16_tau: fast-decaying GDN heads (memory length below the tau threshold) persist state as bf16, halving that head's decode byte stream (~+12% decode). default tau=0 = f32 = bit-exact; the bf16 mode is NOT bit-exact (~91% same-top-p)

4. Benchmarks

Hardware: GB10 / DGX Spark (CUDA 13, sm_121). Models: dense Qwen3.6-27B-NVFP4 and MoE Qwen3.6-35B-A3B-NVFP4. Metric: decode_agg S_TG (t/s) from llama-batched-bench, -fa on -ngl 99, npp 128 / ntg 128, swept over serving width npl in {8, 32, 64, 128}. Plots: qwen36_decode_overview.png (both models), qwen36_dense_decode_vs_npl.png, qwen36_moe_decode_vs_npl.png; raw data final_benchmark.csv.

NVFP4 decode throughput vs concurrency on GB10: llama.cpp standard vs vLLM vs LocalAI's llama.cpp patches, plus the opt-in bf16-tau ceiling

What was re-measured (2026-06-27). The three llama columns - stock, patched, and patched+bf16-tau - were all re-measured this session on one consistent llama-batched-bench harness. The vLLM column is the prior-session reference (kept as-is, not re-run this session). Per-run peak VRAM was not re-captured: the GB10's unified Grace-Blackwell LPDDR5x reports [N/A] to nvidia-smi --query-gpu=memory.used and the bench does not print it (the memory-advantage note below is the prior-session finding).

(a) + (b) Patched vs stock vs patched+bf16-tau vs vLLM

The stock column is a separate, unpatched llama.cpp built at this backend's exact pin (9d5d882d); the patched and patched+bf16-tau columns are the paged binary, env/flag-toggled (LLAMA_KV_PAGED=1, plus LLAMA_MOE_FORCE_GRAPHS=1 for MoE; bf16-tau adds --ssm-bf16-tau 64). All three run on the same harness, so "x over stock" is an apples-to-apples measure of the patch series. (Note: the patch series' dominant SSM decode fusions are compiled in, not env-gated - toggling LLAMA_KV_PAGED alone on the patched binary does not reproduce stock; only the separately-built unpatched 9d5d882d binary does.) The vLLM column is a different harness (vLLM server + client continuous batching) and a prior-session reference, so the cross-engine "% of vLLM" is indicative, not apples-to-apples.

Dense Qwen3.6-27B-NVFP4 (decode t/s):

npl stock patched patched+bf16-tau vLLM (prior) patched x over stock bf16-tau over patched
8 68.3 85.3 87.8 70.4 1.25x +3%
32 119.9 211.9 231.0 211.8 1.77x +9%
64 142.8 305.2 341.4 309.1 2.14x +12%
128 155.1 382.1 446.1 418.8 2.46x +17%

Dense patched is parity-to-ahead of vLLM (121 / 100 / 99 / 91% of vLLM across the widths); patched+bf16-tau is ahead of vLLM at every width (125 / 109 / 110 / 107%).

MoE Qwen3.6-35B-A3B-NVFP4 (decode t/s):

npl stock patched patched+bf16-tau vLLM (prior) patched x over stock bf16-tau over patched
8 186.7 230.3 240.5 256.5 1.23x +4%
32 267.4 466.4 508.1 500.8 1.74x +9%
64 320.5 622.4 703.8 686.1 1.94x +13%
128 347.2 784.3 918.0 882.2 2.26x +17%

MoE patched is 90 / 93 / 91 / 89% of vLLM; patched+bf16-tau reaches parity-to-ahead (94 / 101 / 103 / 104%) at npl>=32.

On bf16-tau. The patched+bf16-tau column uses --ssm-bf16-tau 64 (no exact tau was recorded behind the documented "~+12%"; the flag help suggests 32/64, and 64 bf16's more of the fast-decaying GDN heads). It is opt-in and NOT bit-exact (~91% same-top-p; see section 5) - it persists fast-decaying GDN head state as bf16 to halve that head's recurrence byte stream. Measured decode gain over patched grows with serving width: +3-4% at npl8, ~+12-13% at npl64, +17% at npl128 (dense and MoE alike).

Caveat on the vLLM column. It is a different harness and a prior-session measurement (not re-run this session), so the cross-engine "% of vLLM" is indicative, not apples-to-apples. Memory (prior session): llama uses 1.5-3x lower memory than vLLM.

Takeaway. Re-measured this session, the patch series gives up to 2.46x (dense) / 2.26x (MoE) over true-stock 9d5d882d on the same harness (close to, slightly below, the prior 2.59x / 2.33x - llama was re-measured, vLLM kept). Opt-in bf16-tau adds a further +3% to +17% on top of patched (growing with width). Dense is ahead of vLLM with bf16-tau at every width; MoE patched sits at ~89-93% of the prior-session vLLM and bf16-tau reaches parity-to-ahead at npl>=32. The residual non-bf16 MoE gap is structural (see section 5).

(c) Apple Silicon (M4, 16GB Metal) - does the patchset help here?

Short answer: no - the wins are CUDA/Blackwell-specific. Two facts first: the 24GB NVFP4 GGUF doesn't fit a 16GB M4 (SSD paging), and on Metal supports_op excludes NVFP4 from MUL_MAT/MUL_MAT_ID/GET_ROWS (FP4 matmuls fall back to CPU - no Apple FP4-MMA). So NVFP4 Qwen3.6 is not a Mac fit; a Metal-native Q4_K is.

Measured stock vs patched (same pin c299a92c, both built -DGGML_METAL=ON; the 28-patch series compiles clean on Metal - the CUDA code is #if-guarded), on Qwen3-8B Q4_K_M (a dense GQA model that fits 16GB and exercises the live Metal features; no Qwen3.6 hybrid GGUF fits 16GB, and the GDN fusions gate off on Metal anyway), llama-bench pp512/tg128 t/s:

config pp512 tg128
stock 226.7 20.4
patched, paged off 226.7 20.3 (= stock)
patched, paged on 222.6 19.8 (~0.97x)

Concurrency (batched-bench) scales identically to stock (S_TG ~20 -> ~137 at npl32, from llama.cpp's existing batching). Verdict: neutral-to-slightly-negative on Metal. Patched-paged-off equals stock; turning paged on is ~0-3% slower decode / ~2-8% slower prefill, because the in-kernel block-table flash-attn read that recovers the gather cost is CUDA-only (fattn-*.cuh) - on Metal the paged path falls back to a host-side gather, pure overhead over stock's contiguous read. Everything Blackwell-specific (NVFP4, GDN fusions via 0030, occupancy) is inert. So on Apple Silicon, prefer the stock llama-cpp backend.

Vulkan / SYCL (source analysis): the gated-DeltaNet and SSM_CONV ops DO have upstream kernels on Vulkan and SYCL (as on Metal), so the Qwen3.6 hybrids RUN on all three via the non-fused path. The patchset's fusions are gated off there (0030), so the outcome is the same neutral-to-slightly-negative as Metal - not "won't run". This backend therefore ships CUDA-only (where the fusions are live + verified); non-CUDA users should use the stock llama-cpp backend. See UPSTREAM_LAYER2_SCOPE.md for what native non-CUDA fused kernels would take.


5. Dev notes - what we learned

Bit-exact methodology. Every bit-exact patch is gated two ways: (1) a greedy md5 gate - llama-completion -m MODEL -ngl 99 -fa on -p "The capital of France is" -n 48 --temp 0 --seed 1 | md5sum, paged paths prefixed with LLAMA_KV_PAGED=1 (+ LLAMA_MOE_FORCE_GRAPHS=1 for paged MoE), on the default chat-template path; and (2) test-backend-ops (CUDA0 vs CPU oracle) for every touched op (SSM_CONV*, GATED_DELTA_NET, MUL_MAT, MUL_MAT_ID).

The gate is per-path (see PAGED_BITEXACT_NOTE.md). Dense is bit-exact across paged/non-paged (5951a5b4). The paged MoE md5 (8cb0ce23) does not byte-match the non-paged MoE md5 (07db32c2); this is a benign FP-accumulation-order difference of the paged attention reduction, KL-validated against the f16 reference: KLD(paged||f16) 0.13600 <= KLD(nonpaged||f16) 0.13660, PPL within +/-0.29, ~zero probability bias - two equivalent FP-reorderings of the same quantized model, not a regression. Future paged-MoE regressions therefore compare to 8cb0ce23, not 07db32c2.

MoE-parity conclusion (the residual gap is structural). The two heaviest MoE decode kernels - the GDN-SSM recurrence and the NVFP4-expert GEMM - are llama wins after this series (the recurrence runs at 102.6% of vLLM's bandwidth; the GEMM ties vLLM at the LPDDR5x BW floor). The residual gap is bf16-projection bandwidth + the host scheduling loop, both at the LPDDR5x floor - not a kernel llama is losing. The MoE GEMM kernel is not where the gap lives.

Rejected / flat levers (recorded so they are not re-tried):

  • Lever 2 - graph/stream coverage: FLAT. Bit-exact graph coverage was exhausted by 0025; more graph/stream overlap is a no-op or small regression on this model.
  • Lever 3 - act-quant fusion: FLAT. The W4A4 act-quant tax is removable only by W4A16 (a precision change, rejected) or a structural kernel rewrite; no further bit-exact lever clears it. 0023 already banks the de-dup.
  • Lever 4 - NVFP4 the bf16 GDN/attn projections: REJECTED (KL-gate fail). Quantizing the projections to NVFP4 costs ~+6% PPL; vLLM deliberately keeps the same bf16 projections. No-ship.
  • W4A16-Marlin MoE GEMM: REJECTED. It would be a precision upgrade nobody needs bought with a ~5% slower kernel; both kernels are already at the BW floor. (The "the win was NVFP4-dense-quant, not the Marlin kernel" dense verdict carries over to MoE.)

Opt-in bf16-SSM fast mode (patch 0026, ssm_bf16_tau). The design premise - that bf16 KL error concentrates in long-memory heads and can be removed by keeping them f32 - is empirically refuted: the error scales with the bf16 head count and saturates (~0.06 MeanKLD / ~91% same-top-p) far below any useful byte saving, and the carry is byte-exact (genuine bf16 rounding, not a bug). The byte-saving (and ~+12% decode) is real but cannot meet a strict KL bar, so it ships default-off (f32, bit-exact) and opt-in only. Do not put a hybrid tau in a recommended/gallery config.


6. Architecture and quant generality

(From the arch-generality and quant-generality audits.)

  • 15 of 16 optimizations are quant-AGNOSTIC. Only 0023 (NVFP4 activation-quantize de-dup) is NVFP4-specific. The SSM/paged/MMQ optimizations help any quant of these models (the GDN recurrence, conv, gather and o_proj-MMQ levers operate on the f32 recurrent state and the routing layout, not on the weight dtype).

  • Arch-safe to build everywhere. NVFP4 use is Blackwell-gated and falls back to dequant on other hardware; the GB10-tuned occupancy params (0022) are perf-only and env-selectable (GDN_NW / GDN_CPW), so they never change correctness on other GPUs. Patch 0030 makes the fused-op emission CUDA-family + CPU only, so a non-CUDA paged build routes to the safe upstream non-fused path.

  • What generalizes beyond this backend (upstream candidates). The speedups are CUDA/Blackwell-specific (which is why Metal/Vulkan don't benefit - section 4c), but several findings and ops are portable and worth upstreaming:

    • The headline is hardware-independent: on hybrid gated-DeltaNet models, decode is bottlenecked by the recurrent-state plumbing (memcpy + gathers, ~67% of the step), not the weight GEMM. The fusions for it (in-place state 0018, gather 0019/0028, conv 0021) are bit-exact and already have CPU reference kernels, so they would speed up Qwen3.6 / Qwen3-Next / any hybrid-SSM decode on every backend once the ggml ops gain the respective (Metal/Vulkan) kernels - the highest-value upstream contribution.
    • The o_proj GEMV->MMQ reshape (0020) is a model-graph fix (batch the projection to hit the GEMM path) - arch-agnostic in principle, trivial to upstream.
    • The paged KV + cross-request prefix sharing + decode-first scheduler align with llama.cpp's own in-progress KV / chunked-prefill work and could inform it.
    • The per-path bit-exact md5 gate + the weekly upstream-drift canary is a reusable maintenance pattern for any vendored-patch backend.

7. Pin + maintenance policy

  • Pinned to llama.cpp 9d5d882d (kept == the stock llama-cpp pin). The pin is advanced only by the manual pin-sync process (this section): rebase the source-only patch series onto the new tip, rebuild on GPU, pass the bit-exact gate on every path (dense + MoE, paged + non-paged) plus test-backend-ops, and confirm the full grpc-server build links on CI.
  • The pin must track the stock pin. grpc-server.cpp is shared with the stock backend and tracks the stock pin, so a paged pin that diverges past an upstream server-API refactor breaks the grpc-server LINK even when the patches are bit-exact. A bump to c299a92c (23 commits ahead of stock) was greedy-md5 bit-exact but failed to link (undefined stream_* server helpers introduced by the refactor), and was reverted to 9d5d882d. The bit-exact gate alone does not catch this; only the full CI grpc-server build does.
  • Decoupled from the nightly auto-bumper. There is deliberately no bump_deps.yaml entry for this backend - a naive LLAMA_VERSION bump could silently shift the tree out from under the patches.
  • Weekly canary. .github/workflows/llama-cpp-paged-canary.yml (via .github/scripts/paged-canary-apply.sh) tries the patch series against the latest upstream tip with the build's own strict git apply. Red = upstream drifted past the series -> run a PIN_SYNC (do not bump the pin blindly), following the policy in this section.

8. Models

Build coverage: CUDA-only. This backend ships only the CUDA/cublas build targets (cuda-12, cuda-13, and the nvidia-l4t arm64 cuda-12/cuda-13 Jetson rows). There are no cpu / vulkan / sycl / hipblas / metal-darwin builds: the patchset's wins are CUDA/Blackwell-specific (section 4c), so off-CUDA the backend is neutral-to-negative and non-CUDA users should run the stock llama-cpp backend instead. The backend/index.yaml meta-backend resolves default/nvidia to a CUDA variant accordingly.

The benchmarked NVFP4 GGUFs are published and wired into the LocalAI gallery:

Gallery entry Weights (HuggingFace) Notes
qwen3.6-27b-nvfp4-paged mudler/Qwen3.6-27B-NVFP4-GGUF Dense, native Blackwell NVFP4 (FP4-MMA).
qwen3.6-35b-a3b-nvfp4-paged mudler/Qwen3.6-35B-A3B-NVFP4-GGUF MoE (256 experts, top-8), file_type MOSTLY_NVFP4.

Both gallery entries set backend: llama-cpp-localai-paged and the paged serving config (paged_kv:true, max_batch_tokens, kv_unified:false, parallel, flash_attention:on, context_size). They intentionally stay bit-exact (no ssm_bf16_tau). The full backend-split + gallery plan is in LOCALAI_LLAMACPP_BACKEND_PLAN.md.