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[ROCm][Perf] Avoid extra reshape kernel in Qwen GDN output norm - #47842
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This pull request has merge conflicts that must be resolved before it can be |
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Sorry for the noise here. I accidentally pushed a bad rebase/merge state while trying to sync this branch with main, which caused the huge diff and triggered the extra reviewers/labels. I’ve cleaned up the branch now, but unfortunately I can’t undo the notifications that were already sent 🙇 |
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Commit 0ae4b45 is missing Signed-off-by. Can you rebase with --signoff and push? |
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Would be good to add A/B perf and accuracy tests to this. |
A/B test results added in the description. |
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/ci run |
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✅ Triggered Buildkite CI #85995 for commit |
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Oh, does this still depend on an AITER bump, @mjkvaak-amd? I thought that this should be merged, but then I started thinking about that. |
The output projection flattened its per-head tensors to (N*H, D) to normalise, then reshaped back through (N, H, D) to reach the (N, H*D) out_proj consumes. Inductor materialised that round trip as its own pointwise kernel, one per GDN layer per forward. Every caller already passes (N, H, D), so normalise as-is and flatten once. forward_xpu and forward_cpu now share the existing _output_projection helper. That alone breaks the AITER RMSNorm+quant fusion for GDN models with an FP8 block-scaled out_proj. The pattern matches on op structure rather than rank, so it still matches from (N, H, D) and then hands a 3D tensor to a fused op that takes (M, D), failing compilation. Collapse the heads in the replacement instead. Where quant_fp8 is decomposed, the quant's group reshape back to (N, H, D) is additionally a no-op that the compiler drops, so that case needs its own pattern variant traced with the node removed. Cover both layouts and both quant_fp8 modes in the fusion test. Co-authored-by: Cursor <cursoragent@cursor.com> Signed-off-by: Mikko Tukiainen <Mikko.Tukiainen@amd.com>
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I found a bug in the fusion pass of RMSNorm with 3D layout + Changes:
The trace, serving sweep and GSM8K results in the description are unchanged and still describe this code @dllehr-amd apologies for invalidating the CI run on |
No AITER bump is needed. I marked this a draft, because I found a problem with RMSNorm and |
Guard the (N, H, D) GDN output-norm path against a flatten-to-2D regression, including a non-contiguous per-head z view, and lock the helper's (N, H*D) contract. Signed-off-by: Mikko Tukiainen <Mikko.Tukiainen@amd.com>
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@dllehr-amd : Regarding our discussion and your recommendation to check whether the suggested changes affect CUDA detrimentally. CUDA is affected, but nothing breaks.
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/ci run |
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✅ @mjkvaak-amd, CI is now available for this PR.
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❌ This PR is 561 commits behind upstream |
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/ci run |
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✅ Triggered Buildkite CI #90169 for commit |
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could you also test Qwen3-Next?
Tested
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The opaque AITER quant path preserves a BF16 intermediate before FP8 quantization, while the fused kernel normalizes and quantizes directly. Use a slightly wider tolerance for that mode to account for the expected rounding difference after the FP8 GEMM. Signed-off-by: Mikko Tukiainen <Mikko.Tukiainen@amd.com>
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/ci run |
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✅ Triggered Buildkite CI #90205 for commit |
Purpose
Removes an extra Inductor-generated reshape/copy kernel, by reworking Qwen GDN
_output_projectionmethod.RMSNormGatedlogic now directly produces the flattened[num_tokens, hidden]tensor consumed byout_projwhich allows Inductor to pick.Test Plan
Run existing RMSNormGated tests, performance benchmark and GSM8K accuracy tests
Test Result
Serving benchmark on
amd/Qwen3.8-2.4T-A95B-Quark-MXFP4, 8x MI355X, TP8, fixed input/output lengths (--random-range-ratio 0), one run per point, measured against a stock build of the same commit.The change removes a small number of kernel launches per GDN layer per step, so the serving-level effect is under 1% as expected; the kernel-level evidence is the decode trace above.
GSM8K, 5-shot, seed 4321,
batch_size=128:No accuracy regression.
I also validated manually with profiler traces on Qwen3.5-397B that the extra GDN output reshape/copy kernel is now removed.
Baseline:
After the proposed fix:
Co-authored by: Cursor
Essential Elements of an Effective PR Description Checklist
supported_models.mdandexamplesfor a new model.