AstrAI/csrc
ViperEkura 7ba43a7c6f perf: add split-K (FlashDecoding) to decode MMA kernel
Decode has only batch*kv_head independent tasks, so the grid was tiny (e.g. 16 blocks) leaving most SMs idle (ncu: 0.04 waves/SM, 11% DRAM).

- Partition KV across gridDim.z blocks emitting unnormalised (O, m, l) partials, reduced by a new combine kernel
- Choose split count to fill the device (~2 blocks/SM), capped by tile count and 32; fall back to single-pass direct-write when batch*kv_head already saturates the SMs
- Refactor decode dispatch into named helpers, de-duplicate scalar fallback

Result: now DRAM-bound at 63% (99->543 GB/s), 2.1-2.5x over torch SDPA in the low-parallelism regime, on par at high parallelism
2026-07-10 11:43:18 +08:00
..
kernels perf: add split-K (FlashDecoding) to decode MMA kernel 2026-07-10 11:43:18 +08:00
tests perf: reduce MMA kernel registers, switch to static smem 2026-07-10 00:39:47 +08:00
__init__.py feat: add optional CUDA kernel system (csrc/) + fused GQA decode attention 2026-07-06 12:09:58 +08:00
build.py perf: add fast-math and vectorization nvcc/cxx build flags 2026-07-07 22:28:32 +08:00