* cuda: enable topk-moe fusion for 288 experts
The topk-moe fusion only accepted power-of-2 expert counts (or the
special-cased 576), so models with 288 experts (e.g. Step-3.7-Flash)
fell back to the unfused per-layer routing chain: softmax/sigmoid,
argsort, get_rows, sum_rows, div, clamp, scale. At batch size 1 that
is ~330 extra tiny graph nodes per token.
288 is a multiple of the warp size, so the existing kernel already
handles it; this adds the missing template instantiation and accepts
288 in the eligibility check.
Measured on gfx1151 with Step-3.7-Flash IQ4_XS (llama-bench,
-b 4096 -ub 4096 -fa 1 -dio 1 -ctk q8_0 -ctv q8_0; machine idle,
before/after paired so pp4096 stays matched as a load control):
test | before | after
----------------+----------------+----------------
pp4096 | 460.99 ± 0.45 | 462.47 ± 0.34 (unchanged)
tg128 | 19.10 ± 0.04 | 19.56 ± 0.03 (+2.4%)
tg128 @ d30000 | 12.68 ± 0.04 | 12.69 ± 0.03 (unchanged)
Prompt processing is unaffected (the fusion only touches decode
routing). The decode gain is ~+2.4% at shallow context and fades with
depth: by 30k tokens each step is attention-bound over the KV cache,
so removing the fixed routing overhead is no longer visible.
Assisted-By: Claude Fable 5 <noreply@anthropic.com>
* Update tests/test-backend-ops.cpp
Co-authored-by: Oliver Simons <osimons@nvidia.com>
* Add comment for case 288 in topk-moe.cu
---------
Co-authored-by: Oliver Simons <osimons@nvidia.com>
* Adds initial PDL setup.
* Adds PDL barriers based on simple heuristic: place "sync" before first input pointer access, and "launch" after last write, e.g. to tensors like dst.
* Further optimization pass of the first half of kernels
* Optimized PDL barriers for the second batch of kernels
* Further refinements after rebase.
* Moves pdl logic to separate function, removes some whitespace
* Strips post-hoc PDL logic
* Adds stream capture PDL setup. Enrolls quantize_q8_1 to leverage pdl to
overlap execution with previous kernels
* Enrolls mul_mat_vec_q, rms_norm_f32 and k_bin_bcast (partly) into PDL
* Enrolls mmvf, rope, set-rows and topk kernels for gpt-oss into PDL
* Introduce ggml_cuda_kernel_launch, to abstract away cudaLaunchKernelEx,
to enable hip/musa compatibility
* Enrolls cpy_scalar_contiguous, k_get_rows_float and rms_norm_f32
* Enrolls flash_attn_combine_results
* Fix: Drops needless and broken check of CUDA arch for PDL. PDL either
works or is without effect.
* Enrolls flash-attention kernels to pdl
* Fix: inlines ggml_cuda_kernel_launch, and uses perfect forwarding for
kernels args. This fixes PDL.
* Perf: Enrolls k_bin_bcast variadic template invocation into PDL, via
and template alias and template expansion
* Enrolls all remaining kernels for qwen3-coder-next into PDL
* Remove all PDL LC calls to create a baseline
* Added LC according to internal guidance and tested kernel performance.
* Enrols missing qwen3-5 kernels passively into PDL.
* Kernel optimizations (LC signals) for qwen3.5
* Enrolls ssm-scan kernels into PDL
* Adds GGML_CUDA_PDL command line option to toggle PDL.
* Fix: Ada and lower compilation by guarding PDL calls correctly
* Cleanup: Removes commented out GGML_CUDA_PDL_LC
* Cleanup: Removes experimental comments
* Adds 90-virtual to build script so that Hopper GPUs can leverage PDL.
* Adds stricter checks to enable PDL, adds env-check to disable it, and removes now superfluous compile option to enable PDL.
* Fix: Correct PDL en/disablement based on device-side arch check. Host
side check is UB. Required moving from macros to inlined functions
* Fix: default-disable PDL. Enable by setting GGML_CUDA_ENABLE_PDL=1
* Enable PDL by default for Hopper+ devices
* Enrolls softcap_f32 and two flash_attn kernels into PDL.
* Improves flash attn PDL barrier placement
* Fix: Perf regression on ada; excludes ada and below from PDL launches
* Improves some sync barrier placements
* Drops superfluous constructor
* Adds #endif guard comments
* Reverts experimental change to top-k-moe.cu, which moved expensive allocations
in front of the PDL barrier. It did not have a meaningful impact.
* Exchanges GGML_CUDA_DISABLE_PDL with GGML_CUDA_PDL. IFF GGML_CUDA_PDL=0
PDL is disabled
* Revert "Drops superfluous constructor". Adds const to remaining
arguments
This reverts commit 12b1d250da0089ae02a9bb71bbb3fd6d70f6f2f1.
* Cleanup: Removes and fixes some comments and whitespace
* Clarifies comment of sync-barrier position
* Relocates and refactors PDL launch functions and accessories
* Adds error checking to the regular kernel launch path
* Drops "auto" in favor of "ggml_cuda_kernel_params"
* Adds "const" to ggml_cuda_kernel_launch_params
* [Whitespace] Adds final newline to common.cuh to make editorconfig CI job happy
* ggml-cuda: add mem check for fusion
* Replace NaNs with -FLT_MAX
* fix typo
Co-authored-by: Johannes Gäßler <johannesg@5d6.de>
---------
Co-authored-by: Johannes Gäßler <johannesg@5d6.de>
I updated test_topk_moe to more closely match llm_graph_context::build_moe_ffn
and added coverage for exp_probs_b and some other missing combinations. This
exposed a bug in both CUDA and Vulkan backends where they were assuming the
input to argsort and the input to get_rows are the same. I'd like to optimize
this graph in another change, but for now just get it functional.
CUDA also had a bug where it got n_experts from the wrong place, leading to
GGML_ASSERT failures in some of the new tests.
* CUDA: add a fused top-K MoE kernel
This kernel does the following:
1. softmax over the logits per token [n_experts, n_tokens]
2. argmax reduce over the top-k (n_experts_used) logits
3. write weights + ids to global memory
It is intended as fusion of softmax->top-k->get_rows pipeline for MoE models
* Refactor into ggml_cuda_should_use_topk_moe
* Review: Use better coalescing pattern, use WARP_SIZE, store logits into registers before
* Review: format + micro-optimizations
* Fix bug: fix tie breakers
* Add optional norm + clean-up code
* Use smem for final write
* Add bounds check
* Use better memory pattern for writeback
Aman Gupta