Commit Graph
9 Commits
Author SHA1 Message Date
Ruben Ortlam 723c71064d vulkan: fix fp16 Flash Attention on Windows AMD RDNA2 and below (#19921) 2026-02-26 19:11:04 +01:00
Ruben Ortlam aa6f918c1c Vulkan Scalar Flash Attention Refactor (#19625)
* vulkan: allow using fp16 in scalar flash attention shader

* split rows inside of subgroups for faster synchronization

* use row_split when Br >= 4, change reductions to use shared memory if row_split == 1

* use f32 scalar FA if f16 is not supported by device

* fix amd workgroup size issue

* optimize masksh use

* add medium rows FA shader Br size

* fixes

* add padding to mask shmem buffer

* cache q values into registers for KQ

* fuse lf accumulation, pf and v accumulation into a loop

* stage K loads through shmem

* stage V loads through shmem

* only stage through shmem on Nvidia

* default to Bc 32

* also stage V through shmem when this is done for K

* dynamic subgroups for intel

* use vectorized stores

* use float_type for dequantize4 functions

* use smaller scalar rows size for smaller rows count

* relax flash attention split_k condition to allow non-gqa use

* use minimal subgroup size on Intel

* fix shmem support function

* fix rebase issues

* fixes

* Bc 4 for scalar FA is not a valid configuration

* Use wave32 on AMD RDNA for scalar FA

* add Intel shader core count lookup-table

* fix regressions

* device tuning

* tmpsh size fix

* fix editorconfig

* refactor fa tuning logic into a single place

* fix gqa opt logic

* fix block_rows with small n_rows

* amd tuning

* fix hsk=72/80 issue

* tuning

* allow condition skipping for column check

* use float16 for Of if available

* address feedback

* fix bad RDNA performance on head size <= 128 by limiting occupancy

* allow printing pipeline stats

* cleanup and fixes

* limit occupancy for GCN for small batch FA with large HSK

* disable f16 FA for GCN AMD GPUs on the proprietary driver
2026-02-24 08:35:48 +01:00
Jeff Bolz 1946e46f4c vulkan: For coopmat2 FA, use fp16 accumulators for the final result (#19376)
The cpu and cuda backends use fp16 for the VKQ accumulator type, this change
does the same for vulkan. This helps particularly with large head sizes which
are very register-limited.

I tried this for the coopmat1 path and it slowed down a bit. I didn't try for
scalar.

I applied the softmax bias that the cuda backend uses to avoid overflow,
although I was not able to reproduce the original bug without it.
2026-02-06 09:15:13 +01:00
Jeff Bolz f9bd518a6b vulkan: make FA mask/softcap enables spec constants (#19309)
* vulkan: make FA mask/softcap enables spec constants

* don't specialize for sinks

* bump timeout a little bit
2026-02-06 08:49:58 +01:00
Jeff Bolz 449ec2ab07 vulkan: Preprocess FA mask to detect all-neg-inf and all-zero. (#19281)
Write out a 2-bit code per block and avoid loading the mask when it
matches these two common cases.

Apply this optimization when the mask is relatively large (i.e. prompt
processing).
2026-02-05 09:26:38 -06:00
Ruben Ortlam f6b533d898 Vulkan Flash Attention Coopmat1 Refactor (#19075)
* vulkan: use coopmat for flash attention p*v matrix multiplication

* fix P loading issue

* fix barrier position

* remove reduction that is no longer needed

* move max thread reduction into loop

* remove osh padding

* add bounds checks and padding

* remove unused code

* fix shmem sizes, loop duration and accesses

* don't overwrite Qf, add new shared psh buffer instead

* add missing bounds checks

* use subgroup reductions

* optimize

* move bounds check, reduce barriers

* support other Bc values and other subgroup sizes

* remove D_split

* replace Of register array with shared memory Ofsh array

* parallelize HSV across the rowgroups

* go back to Of in registers, not shmem

* vectorize sfsh

* don't store entire K tile in shmem

* fixes

* load large k tiles to shmem on Nvidia

* adapt shared memory host check function to shader changes

* remove Bc 32 case

* remove unused variable

* fix missing mask reduction tmspsh barrier

* fix mask bounds check

* fix rowmax f16 under/overflow to inf

* fix flash_attn_cm2 BLOCK_SIZE preprocessor directives
2026-01-28 18:52:45 +01:00
Jeff Bolz 33f890e579 vulkan: support flash attention GQA/split_k with small batches (#18938) 2026-01-21 17:43:43 +01:00
Jeff Bolz 4258e0cfe7 vulkan: Support FA with K/V in F32 (#16543) 2025-10-14 15:53:37 +02:00
AclyandJeff Bolz e29acf74fe vulkan : incremental shader builds (#16341)
* vulkan (DRAFT): split shader generation by GLSL source file, to improve incremental build times

* support dep-files so shaders are recompiled if their included files change

* rename shader files which are used as "headers" to use .glsl extension
* move glslc extension detection shaders to separate folders
* the above is to prevent them from getting glob'd with the actual compute shaders that need to be compiled

* vulkan : only write embedded shader .hpp/.cpp when they change

* avoid recompiling ggml-vulkan.cpp when editing shaders
* pass single --source argument instead of --input-dir & --filter to shader gen
* check for source file match earlier

* fix hang in vulkan-shaders-gen when there are compilation errors

* early out did not decrement compile_count

* clean up

* fix glslc integer dot product test

* unconditionally write the embedded shader cpp output

* replace output filepath in generated dep-files to match output in CMakeLists

---------

Co-authored-by: Jeff Bolz <jbolz@nvidia.com>
2025-10-04 11:42:56 +02:00