Commit Graph
3 Commits
Author SHA1 Message Date
Nick Farrell cc83d7b482 sycl: make --fit respect --fit-target better (#27629)
improve the --fit algorithm to take into account the actual peak
required VRAM for a given context size on a SYCL backend.

This includes both properly accounting for how much VRAM is required
when the allocated context is fully used (which makes the reported
context drop below what it did before, but stop it OOMing) as well
as preventing some overly-conservative calculations which meant too much
VRAM was being reserved.

Tested on a Arc b70 with unsloth's qwen3.8 (Q4_K_XL), able to get 262144 context,
fully usable, with q8_0 KV and MTP and 4k ubatch size using --fit-target 1
2026-08-29 05:00:09 -04:00
9d9a6d29f6 SYCL: add oneMKL GEMM flash attention for XMX-accelerated prompt proc… (#25025)
* SYCL: add oneMKL GEMM flash attention for XMX-accelerated prompt processing

* fattn-mkl: fix interleaved dst layout in normalize kernel

- Fix mkl_fa_normalize_head: use interleaved dst layout
  ((query * n_q_heads + head) * DV) matching TILE's
  flash_attn_combine_results. Previously used dense head-major
  layout which wrote head outputs to wrong addresses, corrupting
  attention for all models except Qwen3.6-27B (where GQA=6 heads
  were sparse enough to avoid visible overlap).

- Remove 7 redundant stream->wait() calls — SYCL in-order queue
  already serializes pure SYCL kernel dependencies. Retain only
  the 4 MKL GEMM ↔ SYCL handshake barriers (oneMKL GEMM uses its
  own internal queue that does not respect SYCL in-order).

- Remove unused dst_row_stride, diagnostic clutter, and dead
  K/V hex dump (fa_diag block in fattn-mkl.cpp).

- Add MKL_FA_DISABLE=1 env var for A/B testing.
- Add FA-DISP watchdog (MKL_FA_DEBUG=1) and FA-DIAG output
  fingerprint (MKL_FA_DIAG=1) in fattn.cpp.

Tested: Gemma-4-26B, Gemma-4-31B, Qwen3.6-27B, Qwen3.6-35B-A3B
Perf (B70/Battlemage, 32K, q8_0 KV):
  Gemma-4-26B:  1473 t/s MKL vs 746 TILE (1.97x)
  Qwen3.6-27B:   609 t/s MKL vs 330 TILE (1.85x)

Co-Authored-By: Claude Code on DeepSeek-v4-Pro

* Thank you for the review feedback: rename env vars, use GGML_LOG_INFO, document in SYCL.md

Completed the following:
- Rename MKL_FA_DISABLE → GGML_SYCL_ENABLE_MKL_FA (inverted: 0 to disable)
- Rename MKL_FA_DEBUG → GGML_SYCL_MKL_FA_DEBUG
- Rename MKL_FA_DIAG → GGML_SYCL_MKL_FA_DIAG
- Replace fprintf(stderr, ...) / fflush(stderr) with GGML_LOG_INFO() macro
- Document all three env vars in docs/backend/SYCL.md under Runtime
- Add comment explaining MKL FA activation trigger (flash-attn + quantized
  KV cache + batch-size >= 1024 + n_kv >= 1024)

Resolves review feedback from arthw.
Again, thank you!!!

Co-Authored-By: Claude Code on DeepSeek-v4-Pro

* Thank you for the review feedback round 2: use ggml_sycl_get_env, remove dup waits, gate perf macros

- Replace raw getenv() with ggml_sycl_get_env() in all 4 env-var checks
  (fattn.cpp: GGML_SYCL_ENABLE_MKL_FA, GGML_SYCL_MKL_FA_DEBUG,
   GGML_SYCL_MKL_FA_DIAG; fattn-mkl.cpp: GGML_SYCL_MKL_FA_DEBUG)
- Remove duplicated stream->wait() before ev.wait_and_throw() in GEMM
  KQ and GEMM VKQ — ev.wait_and_throw() already waits for completion
- Gate MKL_ACCUM macro behind do_print so timing accumulators are
  no-ops in normal operation
- Remove redundant MIT/Intel copyright header from fattn-mkl.cpp
- Remove unused #include <cfloat>
- Expand SYCL.md MKL FA docs with step-by-step activation trigger
  and example llama-cli command

Again, thank you!!!

Co-Authored-By: Claude Code on DeepSeek-v4-Pro

* fattn-mkl: enable MKL FA for all KV cache types

Remove the quantized-only restriction on MKL activation — the MKL
kernel converts any non-F16 K/V to F16 via to_fp16_sycl before GEMM,
so F16 (default), BF16, and F32 caches all benefit from XMX hardware
acceleration.  The type restriction was an unnecessary gate.

Before (F16/BF16 default cache + FA on at 32K prefill): ~356 t/s (TILE path)
After:  ~670 t/s (MKL path, matching quantized-cache baseline)

Minimal change: two conditions removed, one comment updated in fattn.cpp.
No kernel or conversion code changes — the dequant pipeline already
covers all types.

* fattn-mkl: rename mkl_disable -> mkl_enable for clarity

* fattn-mkl: refine MKL FA dispatch gates

Three changes:
1. Remove quantized-only restriction - MKL FA activates for all
   KV cache types (F16 default, BF16, F32, quantized).  The MKL
   kernel converts non-F16 K/V via to_fp16_sycl before GEMM.
2. Rename mkl_disable -> mkl_enable to match env var
   (GGML_SYCL_ENABLE_MKL_FA).
3. Replace batch-size threshold with Q->ne[1] >= 32 gate.
   Keeps TG (Q=1) and MTP drafts (Q=3-8) on VEC path where
   fused kernel beats MKL launch overhead.  Routes all
   multi-token prefill through XMX-accelerated GEMM.

Production data confirms Q patterns: 1-8 TG, 32-127 cache reuse,
128+ full reprocess.  At 32K F16/BF16 FA-on: 356 -> 670 t/s.

* ggml-sycl: fix F16 cache + MKL FA multi-turn corruption; add gate guards

Two changes:

1. Always copy F16 K/V to dense row-major buffers before MKL GEMM.
   Previously F16 was read in-place with raw tensor strides. During
   multi-turn conversations, the accumulated KV cache had different
   stride properties than a fresh prefill, producing corrupted outputs.
   Now dense F16 gets a fast memcpy; interleaved (Gemma) gets a strided
   copy kernel. This matches what the quantized paths already did through
   to_fp16_sycl.

2. Gate MKL FA on unsupported op params (max_bias, logit_softcap, batch
   dim mismatch) and pathological F16 strides (nb[1] not a multiple of
   ne[0]*2). These conditions would previously crash inside the MKL
   kernel. Pathological strides (test-only) and ALiBi/softcap fall
   through to TILE/VEC which handle them correctly.

The stride check uses modulo rather than equality, so both dense
(nb1 == ne0*2) and interleaved (nb1 == H * ne0*2) pass — all real
models use these layouts. Only test cases with overlapping rows
(nb1=32 or nb1=75 for ne0=40) are blocked.

Thanks to hmscider for the oneDNN FA PR (#25222) which surfaced the
same insight: always normalize inputs to contiguous F16 before GEMM.

Co-Authored-By: Claude Code using DeepSeek-V4-Pro <noreply@anthropic.com>

* fattn-mkl: fix quant+GQA KV strides, tighten MKL gate, add K>=1024 tests

Adding K>=1024 flash-attn test cases surfaced several MKL bugs:

- Quant K/V with a padded seq-view (real KV cache) used the wrong
  strides in the dequant path... only the true Gemma interleave
  layout should reconstruct strides. nb[2] vs ne[1]*nb[1]
- Gate was firing on shapes the kernel doesn't handle: head_dim < 64
  or not a multiple of 64, MHA, attention sinks, and
  bf16 decode... fell through to vec which no bf16 case.

Gate MKL to the validated envelope: gqa>=2, head_dim 64 through 512
(has to be a multiple of 64) with matching K/V head size, mask,
no sinks/alibi/softcap... everything else falls back to tile.
Covers Qwen Dense/MoE and Gemma4 Dense/MoE

Ran test-backend-ops -o FLASH_ATTN_EXT: 3641/3641 pass.
Perplexity unchanged... 6.7267 MKL vs 6.7290 stock using
Qwen 27b q5_k_xl

* Update ggml/src/ggml-sycl/fattn.cpp

Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>

* Update ggml/src/ggml-sycl/fattn.cpp

Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>

* Update ggml/src/ggml-sycl/fattn.cpp

Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>

* fattn-mkl: bound attention scratch so it doesn't grow with batch or context... also dropped the bf16 comment in fattn.cpp per arthw review.

* Update ggml/src/ggml-sycl/fattn-mkl.cpp

Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>

* Update ggml/src/ggml-sycl/fattn-mkl.cpp

Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>

* apply arthw suggestions: enum for dequant modes, macro for wg_size, env-var one-liners

---------

Co-authored-by: Claude Code using DeepSeek-V4-Pro <noreply@anthropic.com>
Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>
2026-07-31 10:43:16 +03:00
Neo Zhang 213c4a0b81 [SYCL] supprt Flash Attention for fp32/fp16/Q4/Q5/Q8 (#20190)
* support flash-attention for fp32/fp16/Q4/Q5/Q8

* rm warining

* update for JIT
2026-03-08 12:00:07 +08:00