[ROCm] Fix sparse MLA metadata missing num_decodes - #48722
fanxingran wants to merge 1 commit into
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Hi @tjtanaa @AndreasKaratzas — could you help take a look and add the
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| @@ -515,6 +515,23 @@ def __init__( | |||
| vllm_config=vllm_config, | |||
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| # Sparse MLA impls that only implement the top-k MQA path (e.g. the | |||
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Can we drop/minimize this comment?
| @@ -333,6 +335,18 @@ class ROCMAiterMLASparseMetadata(AttentionMetadata): | |||
| block_size: int = 1 | |||
| topk_tokens: int = 2048 | |||
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| # Decode/prefill split consumed by the shared MLA forward wrapper in | |||
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Please minimize the comments, else LGTM! Thanks for the fix |
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Thanks for the review! Good point — I've trimmed these down to 1–2 lines and applied the same cleanup to the other comments added in this PR |
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This pull request has merge conflicts that must be resolved before it can be |
Signed-off-by: fanxingran <xingran.fan@amd.com>
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Hi @ColinZ22 @tjtanaa — thanks for the heads-up, and no worries at all about the overlap; happy to see the fix land either way since we clearly hit the same bug independently. Since #48886 is already approved and covers a superset (the indexer wk per-channel dequant fix is a nice addition), I'm fine consolidating on this one. Before we close #48722, one thing I'd love to carry over: my PR ships a dedicated unit test (tests/kernels/attention/test_rocm_aiter_mla_sparse_metadata_sync.py, ~75 lines) that asserts the num_decodes / num_prefills / num_decode_tokens fields stay in sync with split_decodes_and_prefills for both decode-only and mixed decode+prefill batches. #48886 currently validates the metadata fix via gsm8k e2e only, so adding this test would guard against regressions at the unit level. Feel free to grab that test file/commit directly from #48722 into your branch. I'd also be glad to share my MTP / speculative-decoding verification (acceptance length ~4.5–5.0/6 on GLM-5.2-FP8 + sparse MLA + MTP, 115k/1k) as an extra data point, since that path isn't covered in the current test plan. Either way, thanks for the quick turnaround here! |
…t#48722 Co-authored-by: fanxingran <xingran.fan@amd.com> Signed-off-by: ColinZ22 <Colin.Zeng@amd.com>
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This pull request has merge conflicts that must be resolved before it can be |
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Purpose
After #47327 the MLA wrapper reads
num_decodes/num_prefills/num_decode_tokensfrom the attention metadata, but the ROCm AITER sparse-MLA metadata
(
ROCMAiterMLASparseMetadata) never carried these fields. On gfx950 this raisesAttributeError: 'ROCMAiterMLASparseMetadata' object has no attribute 'num_decodes'at runtime, so GLM-5.2 (FP8 / MXFP4, DeepSeek Sparse Attention) crashes on the first
forward pass on AMD MI355X.
This PR:
num_decodes/num_prefills/num_decode_tokens(plusprefill_max_seq_len/prefill) fields toROCMAiterMLASparseMetadatawithsafe defaults, and populates them in
build()viasplit_decodes_and_prefills.supports_dense_mha_prefillcapability flag onMLAAttentionImpl(default
True). The ROCm sparse impl sets it toFalse, and the MLA layer thendisables the dense-MHA prefill backend for such impls so it only dispatches the
implemented top-k MQA path (avoids calling the unimplemented
forward_mha).Test Plan
pytest tests/kernels/attention/test_rocm_aiter_mla_sparse_metadata_sync.py(new cases cover decode-only and mixed decode+prefill batches).
TP=4, kv-cache fp8, 115k input / 1k output; plus gsm8k 5-shot accuracy.
Test Result
AttributeError: ... has no attribute 'num_decodes'.split_decodes_and_prefills.(out ~71 tok/s, total ~8.1k tok/s, TTFT ~23.6s, TPOT p50 ~28.7ms @ CONC=4).
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