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[Superseded by #117] cuda : share single-token activation quantization - #116
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Assisted-by: Codex
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Cross-quant and older-GPU follow-up for this PR. Measured official base Correctness and method: all 23 weight formats supported by the MMVQ switch passed at the medium size. Both projection outputs were byte-identical between baseline and candidate, including after changing the shared input. All 328 unprofiled executions passed CPU comparison; worst NMSE was Timed the complete At
All 23 medium-size formats
Shape sensitivity: the six tested small cases ( Actual dispatch: eleven separate node-level profiles cover nine representative formats, plus Q4_K with PDL off and graphs off. Every comparison shows Launch sensitivity: at the medium size, disabling PDL reduced savings for Q4_0/Q4_K/IQ3_XXS to 0.80%/0.27%/0.15%. Disabling graphs while retaining PDL gave 24.00%/23.63%/22.54%. PDL-off on Blackwell is a control, not older-GPU emulation. NVIDIA documents PDL from compute capability 9.0 onward, so the default 33% result must not be projected onto Turing/Ampere/Ada. Architecture assessment: Turing has separate FP32/INT32 resources; Ampere GA10x and Ada have FP32-only capacity plus shared FP32/INT32 capacity. RTX Blackwell increases throughput for many integer instructions, but not every instruction. The CUDA native instruction table distinguishes arithmetic, shifts, shuffles and conversions. Packed INT8 dots are different from tensor-core INT8/FP4 MMA; this PR retains the existing MMVQ kernels and adds no tensor-core arithmetic. The benefit mechanism is removal of a duplicate activation read, reduction, conversion, scratch write and launch. Counterarguments remain: different launch scheduling, faster quantization on another device, host matching overhead, or eviction of the shared activation by the first projection can offset savings. These are risks to measure, not observed older-GPU regressions. Native older-GPU testing is pending hardware availability. The inherited eligibility guard rejects capability Model/PR85 boundary: the prior stabilized Q4_0 model observation remains approximately +0.33% TG, with retained startup/serving variability. This sweep adds no all-quant model-level claim. #85 operates on quantized KV-cache staging in MMA FlashAttention; these quant names are projection weight formats. Combined PR85/PR116 performance remains untested. Raw commands, cached fixture/output hashes, all samples, profiles, harness sources and binary identities are retained locally under AI assistance: Codex conducted this follow-up and prepared this comment at the repository owner's explicit request under the maintained-fork policy. |
Superseded by PR #117, which includes single-token and small multi-token adjacent MMVQ activation reuse in one matcher/helper implementation, with fresh combined correctness, dispatch and performance validation.
This standalone draft is closed without merging. Its branch and historical evidence remain available; active review belongs on #117.
AI usage: YES. Codex implemented and validated this owner-authorized fork change, with independent GPT-6.1 Sol High source review. The owner retains review, maintenance and any upstream submission responsibility.