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LocalAI/backend/cpp
Ettore Di Giacinto c0e0ed3865 docs(paged): synthesize decode-parity exploration - the o_proj MMVQ lever
Cross-check the adversarial validation against the profiler ground-truth and
finalize DECODE_PARITY_EXPLORE.md. The post-SSM 254->391 decode gap is one
llama-specific defect: the gated-DeltaNet output projection (ssm_out) runs as
an FP4 GEMV (mul_mat_vec_q, 132 ms/step = 26% of decode) at batch 128 instead
of a tensor-core MMQ GEMM. Mechanism confirmed at source: final_output is 3D
[6144,1,n_seqs] so src1->ne[1]=1 trips the MMVQ dispatch (<=8), with the 128
sequences in ne[2]. vLLM packs the same projection into a cutlass M=128 GEMM.

GDN recurrence is only +11%/call (not the lever); P2a optimized the wrong FP4
kernel (the 17% MMQ, not the 26% MMVQ); CUDA graphs, host loop, and DRAM bytes
are all ruled out. Decode parity is reachable in software (not a hardware
floor): identical bytes/floor, vLLM hits 62% util vs llama 40% on the same
GB10. Highest-value next step (~free, bit-exact): collapse final_output to 2D
before ssm_out so M=128 routes to MMQ. Ranked levers + cumulative ceilings
toward 391 documented.

Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
2026-06-25 09:06:50 +00:00
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