* sycl: fix use-after-return of the SDPA scale in the oneDNN flash-attention path
The scale was uploaded with an async memcpy sourced from a stack local. On the
in-order queue that copy is ordered behind the K/V staging kernels; once n_kv is
large enough (>= ~26k observed on Arc Pro B70) the staging outlives the host
stack frame and the copy reads recycled memory, feeding the SDPA a garbage scale.
Output then collapses to a single repeated token and the KV cache is poisoned
for the rest of the session.
Short contexts win the race by accident, and test-backend-ops caps
FLASH_ATTN_EXT at kv=1024, which is why CI never caught it. The previous
device_count > 1 wait_and_throw() gate (and reverting it, PR #25741) fixes the
symptom only by keeping the frame alive across the copy at the cost of a host
sync on every FA call.
Fix: cache one device scalar per (device, value) -- the scale is constant per
model -- and upload it synchronously once. The single-device fast path (no
per-call host sync) is then safe: every device-side hazard already serializes
on the in-order queue. The multi-GPU conservative wait is kept unchanged.
Also:
- GGML_SYCL_FA_ONEDNN_MAX_KV env (0 = unlimited): optional n_kv ceiling that
routes very long sequences to the native FA kernel.
- test-backend-ops: FLASH_ATTN_EXT F16 cases up to kv=65536 (Qwen3.6-27B
geometry hsk=hsv=256 GQA 6, and hsk=128 GQA 4), closing the kv=1024 blind
spot. Note the race itself needs a live multi-op pipeline to reproduce;
single-op runs pass even on broken builds.
Verified on Arc Pro B70 (bmg_g31), Qwen3.6-27B Q4_K, -c 131072: output
byte-identical at temp 0 to the native FA path through 32k-deep prefill, with
prefill depth-flat at 820-840 t/s (vs 340-350 native at 32k depth).
Assisted-by: Claude Fable 5
* sycl: handle GGML_SYCL_FA_ONEDNN_MAX_KV like the other runtime env vars and document it
Review feedback on #25880:
- read the variable once at backend init into g_ggml_sycl_fa_onednn_max_kv via
ggml_sycl_get_env, and print it in the startup env listing (-lv 4 shows it)
- document GGML_SYCL_FA_ONEDNN and GGML_SYCL_FA_ONEDNN_MAX_KV in the SYCL.md
runtime table
Also trim the added FLASH_ATTN_EXT cases to kv={4096,16384}: the 32768/65536
shapes exceed the legacy NMSE threshold on both the oneDNN and native kernels
(long-sequence fp16 accumulation drift, present before this PR) and would fail
CI for an unrelated reason.
Assisted-by: Claude Fable 5
* sycl: clarify GGML_SYCL_FA_ONEDNN_MAX_KV default is disabled
Assisted-by: Claude Fable 5
* sycl: state default behavior of GGML_SYCL_FA_ONEDNN_MAX_KV explicitly
Assisted-by: Claude Fable 5
* Update ggml/src/ggml-sycl/fattn-onednn.cpp
Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>
* sycl: write the SDPA scale from a kernel instead of caching it
The per-(device, value) scale cache was a function-local static
unordered_map with no synchronization, so concurrent backend instances
could access and rehash it at the same time.
Write the scalar with a single_task instead. The value is captured into
the command, so no host memory has to outlive the call -- which is what
the use-after-return fix needed in the first place. That removes the
shared container, the leaked device allocation and the string key, and
it also closes the remaining async-memcpy-from-a-stack-local on the
first flash-attention call.
Ordering does not rely on timing: the queue is created with
sycl::property::queue::in_order and the dnnl stream wraps that same
queue, so the write completes before the SDPA reads the scalar. The
multi-GPU wait_and_throw() branch is unchanged.
Also drop the <cstdlib> include, which is unused.
Assisted-by: Claude Opus 5
---------
Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>
Raise the threshold for minimum buffer size from 1 GiB to 4 GiB, based
on real-world experiments of overcommitting device memory with model
weights larger than available VRAM, for example Qwen3.5-35B-A3B-Q8
running on a B70.
Also add a debug message to better track USM system allocations.
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
* [SYCL] F16 (default) Flash Attention with XMX engine via oneDNN graph API; Qwen3.6-27b-Q8_0 prefill speed up x1.21 at p=512 and x4.26 at p=80k
* [SYCL] Address review on FA oneDNN path. Result: llama-bench---pp512; 32% increase with fa1; llama-perplexity---0.11% difference; tested model: mradermacher/Meta-Llama-3.1-8B-Instruct-Q8_0.gguf
* PR-25222 revision v2: addressed audits
* [SYCL] flash-attn oneDNN SDPA KV F16 rev 3.0: add BMG gate + multi-device sync. Narrow the scrope of this PR to Battlemage only (bmg; Xe2). Other archs (e.g., alchemist) fall back to existing FA kernel. When device_count >1, apply stream -> wait_and_throw(), validated working path for multi-gpu sync fix by @maxious.
Co-authored-by: maxious <81432+maxious@users.noreply.github.com>
* updated comment on bmg gate, noted the issue
---------
Co-authored-by: scientist3 <scientist.3@users.noreply.github.com>
Co-authored-by: hmscider <hmscider@users.noreply.github.com>
Co-authored-by: maxious <81432+maxious@users.noreply.github.com>
* support op col2im_1d
* update ops.md
* rm unused words
* update for bf16
* optimize 1%-11% as the review comments
* fix the format issue
* update as the review comments
* sycl: add supported types to ggml_sycl_supports_reorder_dmmv
The reordered feature is implemented in ggml_sycl_op_dequantize_mul_mat_vec,
but gated by ggml_sycl_supports_reorder_dmmv. This commit fixes the gate.
Signed-off-by: Todd Malsbary <todd.malsbary@intel.com>
* sycl: set K_QUANTS_PER_ITERATION=1 to improve utilization
When combined with opening the reorder gate, this improves GPU
utilization on B70, giving a significant boost to tg t/s.
Signed-off-by: Todd Malsbary <todd.malsbary@intel.com>
* sycl: replace QK_WARP_SIZE with WARP_SIZE for QK_5
Signed-off-by: Todd Malsbary <todd.malsbary@intel.com>
* sycl: add missing types to ggml_backend_sycl_buffer_init_tensor
Without this, the extra field is not allocated and the reorder path
will not take effect.
Signed-off-by: Todd Malsbary <todd.malsbary@intel.com>
---------
Signed-off-by: Todd Malsbary <todd.malsbary@intel.com>
* Sycl tp stage1 (#1)
* SYCL: tensor parallelism (--split-mode tensor) for dual-GPU
Adds the comm_init/comm_free/comm_allreduce_tensor trio that the
meta-backend queries via get_proc_address to enable backend-specific
all-reduce, mirroring the pattern used by ggml-cuda.cu.
For N=2 (the common dual-GPU case) implements a degenerate ring
all-reduce with two size-branched paths:
* Small (nelem < 32768): FP32 direct memcpy + per-device ADD kernel
chained via depends_on(memcpy_event). 4 SYCL submissions/call.
* Large (nelem >= 32768): BF16-compressed. Each device compresses
FP32 -> BF16 in a local outbox, cross-device memcpys to the peer's
inbox (HALF the PCIe bytes), then decompresses + adds into the
local FP32 partial. 6 SYCL submissions/call but PCIe bytes halved
-- wins for any tensor where PCIe dominates kernel time.
Threshold and BF16 path pattern mirror the CUDA NCCL allreduce.
Storage: ONE persistent uint8_t buffer per device, 4 * nelem bytes
(matches both path layouts: FP32 nelem floats; BF16 outbox+inbox =
2 * nelem uint16_t each). Single alloc+free per device keeps the
SYCL pool's strict-LIFO invariant trivial.
Initial impl handles N=2 FP32 contiguous tensors. Other cases return
false, causing the meta-backend to use its generic butterfly fallback.
Per-call sync is intentionally omitted. SYCL in-order queue semantics
ensure that the meta-backend's next compute on the same per-device
queue waits for our final ADD, and the next allreduce's first op on
the same persistent buffer waits via the same queue. Only comm_free
does an explicit final wait.
OneCCL is NOT used: OneCCL 2021.17 hardcodes single-device-per-process
in communicator_impl.hpp:47 (condition devices.size() == 1), which is
incompatible with llama.cpp's single-process multi-GPU model.
Measured on dual Intel Arc Pro B70 (NEO 26.05.x, oneAPI 2025.3 +
DPC++ nightly):
Llama-3.3-70B Q4_K_M, -sm tensor -fa 1 -ctk f16 -ctv f16:
pp512 = 377.08 t/s (vs 313.65 layer mode = +20.2%)
tg128 = 17.40 t/s (vs 9.74 layer mode = +78.6%)
Qwen3-Coder-Next-80B-A3B Q3_K_M (MoE):
pp512 = 216.56 t/s (vs 156.58 meta-backend butterfly = +38.3%)
tg128 = 17.60 t/s (vs 14.31 meta-backend butterfly = +23.0%)
Qwen3-4B Q4_K_M:
pp64 = 984.51 t/s, tg16 = 49.29 t/s
Llama-3.3-70B in SYCL TP now comfortably beats production layer mode
on both prefill and decode. Coder-Next-80B-A3B (MoE) also wins on
both — the BF16 path is what unlocks the many-medium-allreduces
prefill pattern.
Build/CMake: no changes. No new dependencies. ~210 lines added across
ggml-sycl.h and ggml-sycl.cpp.
* Fix comments
* documentation update to address PR feedback
* Bring over my device-to-device memcpy chagnes
* move the dev2dev_memcpy calls to the upstream 7-parameter variety
* Fix a typo and remove a trailing whitespace
* rename GGML_SYCL_SUPPORT_LEVEL_ZERO to GGML_SYCL_SUPPORT_LEVEL_ZERO_API, and GGML_SYCL_ENABLE_LEVEL_ZERO to GGML_SYCL_USE_LEVEL_ZERO_API
* fix code format
* fix error when rebase
* add dev2dev memcpy by SYCL API
* mv GGML_SYCL_DEV2DEV_MEMCPY to runntime table
* update the detect method for p2p comm
* fix the erro created during fix confilct
---------
Co-authored-by: Neo Zhang <NA>
* SYCL: fix a bug with async memcpy
* make mmid_row_mapping_host persistent
* comment on stream->wait
* Apply suggestion from @sanmai
* Apply suggestion from @sanmai
* Apply suggestion from @sanmai
This introduces an optional feature to allocate large GPU buffers (≥ 1GB)
using USM system allocations if supported by the device. It allows using
buffers from the system allocator then letting the system manage memory
migrations between host and device as necessary.
This feature is disabled by default and requires the GGML_SYCL_USM_SYSTEM
environment variable to enable. If USM system allocations are not supported
by the device or the system, we fallback to regular allocations.
This feature can allow VRAM overcommit. For example, the test below fails
on B580 due to lack of memory for allocation, but it passes when enabling
USM system allocations:
./examples/sycl/test.sh -m Qwen3.5-27B-Q3_K_M.gguf -lv 4
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
* sycl: support reordered Q4_K and Q5_K MoE MUL_MAT_ID
Extend reordered-weight handling to fused MoE MUL_MAT_ID for Q4_K and Q5_K expert tensors and add Q5_K reordered DMMV coverage. Unsupported 3D reorder cases now fall back instead of aborting.
* sycl: extend MoE reorder to Q6_K mul_mat_id
* [SYCL] Centralize Level Zero detection in ggml_sycl_init
* use the same wording
* get back the warning
* [SYCL] Remove per-allocation getenv() for GGML_SYCL_ENABLE_LEVEL_ZERO
* bring back the comment
* move it up to make sure devices call the shots
* move the env detection early
* replace g_ggml_sycl_enable_level_zero with a direct call to .ext_oneapi_level_zero
* update the comment
* switch back to g_ggml_sycl_enable_level_zero with a sentinel
* remove the check
* Reduce the diff
* reword, move lower
* move things aroudn
* remove forward declaration if favor of a full replace
* pre-cache results of zeDeviceGetProperties
* put ggml_sycl_get_env back
* replace get_sycl_env with ggml_sycl_get_env
* add whitespace back
* Apply suggestion from @sanmai
mmvq:
Port the ncols_dst optimization from ggml-cuda/mmvq.cu to SYCL.
Read weights once per dispatch instead of once per column.
Covers all standard quant types + reorder paths for Q4_0, Q8_0,
Q3_K, Q4_K, Q5_K, Q6_K. IQ types (except IQ4_XS) excluded due to
incompatible vec_dot signatures.
ggml-sycl:
The weight reorder was only bootstrapped on single-token mat-vec
(ne[1] == 1). Speculative / MTP verify issues only multi-column mat-vec,
so it never triggered the reorder and ran on the slower non-reorder
kernel. Bootstrap it on small multi-column batches (ne[1] <= 8) too.
* add to support Q1_0, NVFP4, IQ2_XXS, IQ2_XS, IQ2_S, IQ3_XXS, IQ1_S, IQ1_M, IQ3_S, IQ4_NL, IQ4_XS, I32, MXFP4, Q2_K, Q3_K, Q5_K, and Q6_K in GET_ROWS OP
* correct the link
- change `k_copy_src1_to_contiguous` so that uses a precomputed contiguous mapping where all rows "owned" by an expert are in one slice with a know starts and ends
- switch the `O(n_as * n_routed_rows)` contraption to a counting sort-based procedure with `O(n_as + n_routed_rows)` complexity
* SYCL: add BF16 to DMMV kernel path for ~4x token generation speedup
BF16 models had no dedicated token generation kernel — they fell through
to the generic full-GEMM path, resulting in ~14% memory bandwidth
utilization on Intel Arc GPUs. This adds BF16 support to the DMMV
(dequantize mul-mat-vec) path, matching the existing F16 implementation.
Fixes#20478
* SYCL: fix BF16 DMMV out-of-bounds when ncols % 64 != 0
The qk=1 kernel (used for F16 and BF16) iterates with stride
2*GGML_SYCL_DMMV_X (= 64 on Intel targets where WARP_SIZE=16). When
ncols is a multiple of DMMV_X (32) but not of 2*DMMV_X (64), the last
warp iteration accesses elements at col >= ncols, producing NaN for the
final row and wrong values for interior rows.
Fix: tighten can_use_dequantize_mul_mat_vec to require ne[0] %
(2*DMMV_X) == 0 for F16/BF16 types, and update the ASSERT in the BF16
launcher to match. Quantized types use block-structured kernels with
different access patterns and keep the existing DMMV_X check.
Verified: test-backend-ops MUL_MAT passes 913/913 on Intel Arc Pro B70.
Previously failing: m=128/129 n=1 k=1056 cases (NaN and ERR > 0.0005).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---------
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
* SYCL: fix multi-GPU system RAM exhaustion by using Level Zero allocations
Replace sycl::malloc_device with zeMemAllocDevice for GPU memory allocation
in the SYCL backend. sycl::malloc_device triggers the xe kernel driver's
DMA-buf/TTM path which mirrors every VRAM allocation 1:1 in system RAM.
zeMemAllocDevice uses the SVM/P2P path with no host staging.
On a dual Intel Arc Pro B70 system (64GB VRAM, 64GB RAM), a 15.6 GiB model
consumed 60 GiB of system RAM via sycl::malloc_device, causing OOM crashes.
With zeMemAllocDevice, the same workload uses ~6.7 GiB of system RAM with
no performance regression.
All Level Zero calls include automatic fallback to the original SYCL
allocation path if Level Zero interop is unavailable.
* SYCL: address review feedback - remove try/catch, check device types, deduplicate
- Remove try/catch from malloc/free/memcpy helpers, check backend and
device type upfront instead (ggml_sycl_is_level_zero, ggml_sycl_is_dgpu)
- Move shared helpers (is_level_zero, is_dgpu, free_device) to common.cpp
and declare in common.hpp to eliminate code duplication
- Use SYCL_CHECK(CHECK_TRY_ERROR()) for fallback sycl::free calls
- Guard dev2dev_memcpy L0 path to dGPU-to-dGPU only, preserving the
host-staged path for iGPU-to-dGPU transfers
- Add Windows Level Zero SDK path detection (LEVEL_ZERO_V1_SDK_PATH)
in CMakeLists.txt (co-authored with @arthw)
* SYCL: add build/runtime flags for Level Zero, address review feedback
Implements the architecture suggested by @arthw: compile-time and runtime
flags to cleanly separate Level Zero and SYCL memory API paths.
- Add GGML_SYCL_SUPPORT_LEVEL_ZERO cmake option (default ON). All Level
Zero code is wrapped in #ifdef so the build works on systems without
the Level Zero SDK installed (e.g. CPU-only CI servers). Both the
loader library and headers are checked before enabling.
- Add GGML_SYCL_ENABLE_LEVEL_ZERO runtime env var (default 1). Controls
whether Level Zero or SYCL memory APIs are used. Only one API style is
used per session, no mixing. If Level Zero is enabled but the devices
don't support the Level Zero backend, it auto-disables with a warning.
- Remove Level Zero code from dpct_malloc. It was unused (dpct::device_memory
is not called anywhere in the backend) and used try/catch for flow control.
- Update SYCL.md with documentation for both new parameters.
Tested on Intel Arc Pro B70 (32GB), single-GPU and dual-GPU, with both
GGML_SYCL_SUPPORT_LEVEL_ZERO=ON and OFF builds. AI-assisted development
(Claude). Code reviewed and tested on my hardware.
* SYCL: unify Level Zero malloc/free call sites, address review feedback
Move ggml_sycl_malloc_device to common.cpp alongside ggml_sycl_free_device.
Both functions are now unconditionally available — Level Zero code is
#ifdef'd inside the functions, not at call sites. All call sites use
uniform SYCL_CHECK(CHECK_TRY_ERROR()) wrapping with no #ifdef blocks.
Addresses arthw's review: wrap all malloc/free in SYCL_CHECK for stack
traces on failure, eliminate duplicated #ifdef/else patterns at 6 call
sites (-29 lines net).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* SYCL: add Level Zero SDK to CI, fix device check and missed alloc paths
Add Level Zero SDK installation to Ubuntu and Windows SYCL CI jobs
so the Level Zero code path is compiled and tested in CI.
Fix two bugs found during extended dual-GPU testing (no
ONEAPI_DEVICE_SELECTOR set):
- The Level Zero backend check was iterating all SYCL devices
including CPU. The OpenCL CPU device caused Level Zero to be
disabled for the GPUs, defeating the fix on multi-GPU systems.
Added is_gpu() filter so only GPU devices are checked.
- sycl_ext_malloc_device/sycl_ext_free (tensor reorder temp buffers)
were still calling sycl::malloc/sycl::free directly, bypassing the
Level Zero path. Routed through ggml_sycl_malloc_device/free_device
for consistency with the other device memory call sites.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* SYCL: address arthw review feedback on Level Zero memory API structure
- Move ggml_sycl_malloc_device to static function in ggml-sycl.cpp;
only ggml_sycl_free_device (used by common.cpp) stays in common.cpp
- Switch both helpers to use g_ggml_sycl_enable_level_zero global
instead of per-call queue backend checks
- Remove #ifdef wrapper from global definition; always declare at 0,
add #else branch in init block so it stays 0 when L0 not compiled in
- Update init loop comment to explain GPU-only device check
- CMakeLists: message(STATUS) before the if block; align option wording
AI-assisted implementation. Reviewed and tested on dual Intel Arc Pro
B70 (32 GB each): test-backend-ops OK on both GPUs, single/dual-GPU
Q4_K_M and Q8_0 bench correct, zeMemAllocDevice GTT delta confirmed
<5 MiB per 4 GiB allocation (vs ~4 GiB shadow with sycl::malloc_device).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
* SYCL: remove unused cstdio/cstdlib includes from common.cpp
Leftover from the deleted ggml_sycl_queue_supports_level_zero helper.
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
* Apply suggestions from code review
Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>
* SYCL: preserve Level Zero allocation path during early malloc
* ci: fix Level Zero package conflict in Intel Docker build
* ci: find Level Zero loader in oneAPI package step
* ci: allow Windows SYCL package without Level Zero DLL
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>
* SYCL: reduce allocation overhead during flash attention
* tidy up whitespace
* add a note about the flag
* move ggml_sycl_fattn_* into fattn-buffers.hpp
* refactor implementation into fattn-buffers.cpp
* move new_fattn_kv_buffers back into ggml-sycl.cpp
Add GGML_TYPE_BF16 to the SYCL backend's GET_ROWS operation, both in
supports_op and in the kernel dispatch. This fixes a performance
regression where models using BF16 embedding tensors (e.g., Gemma4's
per_layer_token_embd.weight) fall back to CPU for the GET_ROWS op,
causing a full GPU-to-CPU tensor transfer every token.
The fix reuses the existing get_rows_sycl_float template with
sycl::ext::oneapi::bfloat16, matching the pattern already used for
sycl::half (F16) and float (F32).
* opt arc770 for Q4_0
* add for Q4_0
* update the script
* add help script for windows
* update guide
* fix format issue
* convert from dos to unix for format issue
* fix missed -sm parameter
* sycl : fused MoE mul_mat_vec_q for TG
Create an MMVQ kernel so ggml_sycl_mul_mat_id can consolidate
n_experts_used matmuls in a single kernel launch. The kernel
also reads expert IDs directly, removing a per-call host sync.
This is similar to the CUDA backend's ggml_cuda_mul_mat_vec_q*
paths.
All types supported in the current MMVQ are supported here as well:
Q2_K, Q3_K, Q4_K, Q5_K, Q6_K, Q4_0, Q4_1, Q5_0, Q5_1, Q8_0
It will fall back to the existing per-expert path when src0 has been rewritten
by opt_for_reorder(), and for any shape the fused path doesn't handle.
test-backend-ops passes for supported type/shape combos.
Benchmark: Qwen3-Next-35B-A3B Q4_K_M on Intel Arc B70 (SYCL0),
baseline 707c0b7a6, 16k context, -fa 0.
build/bin/llama-bench -hf unsloth/Qwen3.5-35B-A3B-GGUF:Q4_K_M \
-p 1024 -n 128 -d 16384 -ngl 99 -fa 0 -ub 2048 -r 2 -dev SYCL0
Before (3 runs on 707c0b7a6):
| test | run 1 | run 2 | run 3 |
| --------------- | ----------------:| ----------------:| ----------------:|
| pp1024 @ d16384 | 533.26 ± 4.87 | 535.20 ± 2.78 | 524.27 ± 3.10 |
| tg128 @ d16384 | 33.47 ± 0.02 | 33.31 ± 0.02 | 33.17 ± 0.05 |
After (3 runs on 707c0b7a6 + this patch):
| test | run 1 | run 2 | run 3 |
| --------------- | ----------------:| ----------------:| ----------------:|
| pp1024 @ d16384 | 534.06 ± 0.97 | 531.95 ± 0.02 | 520.94 ± 20.10 |
| tg128 @ d16384 | 45.85 ± 0.21 | 45.95 ± 0.45 | 46.22 ± 0.12 |
disclosure: Claude wrote it, but I reviewed and understand the implementation
(albeit my C is a little rusty).
* sycl: also support nvfp4 and mxfp4 expert types
* sycl: terser comments/nested dispatch in response to review
* sycl: more comment cleanup in mmvq.cpp/hpp
---------
Co-authored-by: Debian <aaron@openllmi.net.bots.is>
Neo Zhang