Commit Graph
5 Commits
Author SHA1 Message Date
Hongqiang WangandLi He 6f8895feec opencl: general flash attention decode performance optimizations (#25366)
* opencl: vec flash-attention decode kernels for f16/q8_0/q4_0 KV

* opencl: improve non FA KQ mv kernels

* opencl: tweaks for multiquery FA

* opencl: some tweaks for FA q1 kernels

* opencl: FA with DK=DV=512 for gemma-4

* opencl: various fixes

* opencl: cleanup

* opencl: fix FA decode crash for DK=512 (gemma-4)

The DK=512 decode-only program does not create the f32_f16 prefill
kernel, so the compiled check in ensure_fa_variant never hit and
supports_op gave inconsistent answers for the same op. block_n is also
unset for DK=512 decode; guard it to avoid an out-of-range read at
dispatch.

* opencl: run DK=512 FA decode on CPU

DK=512 decode is bandwidth-bound and faster on the CPU than the GPU,
increasingly so with depth. Decline it in supports_op; prefill stays on the GPU.

* opencl: compile MQ_GQA=8 FA kernels in a minimal program

The full program compiled with -D MQ_GQA=8 runs the Adreno compiler out
of memory at DK>=256. Only the vec_mq kernels are used from this
program, so compile it with FA_MQ_ONLY, which excludes everything else.
Also include the program name in the compile error log.

* opencl: remove stray token in flash_attn_f32_f16.cl

A stray "." broke the f32_f16 program build.

* opencl: split f16-KV FA decode finer (FD_KV_PER_SPLIT_F16)

The 2048 default under-fills the GPU on single-query f16-KV decode;
use 512 for f16 KV to get more splits. Quantized KV keeps 2048.

---------

Co-authored-by: Li He <lih@qti.qualcomm.com>
2026-07-06 19:57:52 -07:00
Hongqiang WangandLi He ebd048fc5e opencl: flash attention improvement (#25069)
* opencl: rework FA kernel for f16 and f32

* opencl: flash-attention prefill prepass kernels

- flash_attn_kv_pad_f16    pads the tail KV tile to a BLOCK_N multiple
- flash_attn_mask_pad_f16  pads the matching mask tile
- flash_attn_blk_f16       classifies each KV tile per query block as
                           fully masked / mixed / fully unmasked, so
                           the main kernel can skip fully-masked tiles
                           and the mask lookup for fully-unmasked ones

* opencl: FA kernels for q4_0 and q8_0

* opencl: `set_rows` for f32 to q8_0/q4_0

* opencl: dequant kernels for q4_0 and q8_0

* opencl: add FA tile tuning table with override

* opencl: wire host side for FA

* opencl: q4_0 MoE tensors are also SOA'ed

* opencl: cosmetic fix

* opencl: refactor, also clarify some code paths in comments

* opencl: fix inifity for `-cl-finite-math-only`

---------

Co-authored-by: Li He <lih@qti.qualcomm.com>
2026-06-27 15:36:06 -07:00
lhez d93f8439b0 opencl: fix FA for f32 (#16584) 2025-10-15 10:48:28 -07:00
rmatif 97669e4073 opencl: add attn sinks support for FA kernels (#15706) 2025-09-01 23:26:53 -07:00
rmatif 912ff8c119 OpenCL: add initial FA support (#14987)
* add F16/F16 fa support

* fix kernel init

* use mad instead of fma

* use inline function

* mark FA with sinks as unsupported for now

* add pragma unroll to loops
2025-08-16 01:05:55 -07:00