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flashinfer's trtllm_batch_decode_with_kv_cache_mla instantiates a fresh runner per call, so its internal counter-buffer cache never survives across decode steps and it torch.zeros() a new one every call by default. Own a persistent buffer in TRTLLMMLABackend and DeepseekSparseAttnBackend and pass it via multi_ctas_kv_counter_buffer= instead. DSA's trtllm sparse-indexer path flattens every token in a prefill/ extend/verify chunk into its own decode-shaped batch entry, so its batch dimension can exceed max_running_requests; grow the buffer on demand there instead of assuming a fixed bound.
b8zhong
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/rerun-test test_dsa_glm52_nvfp4_dp_mtp.py |
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July 17, 2026 23:11
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flashinfer's trtllm_batch_decode_with_kv_cache_mla instantiates a fresh runner per call, so its internal counter-buffer cache never survives across decode steps and it torch.zeros() a new one every call by default. Own a persistent buffer in TRTLLMMLABackend and DeepseekSparseAttnBackend and pass it via multi_ctas_kv_counter_buffer= instead. DSA's trtllm sparse-indexer path flattens every token in a prefill/ extend/verify chunk into its own decode-shaped batch entry, so its batch dimension can exceed max_running_requests; grow the buffer on demand there instead of assuming a fixed bound. Cherry-picked from #31607 (squashed from 0042fd9, 121c901, a84b529, ed135a8).
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Move #31927 |
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Jul 23, 2026
…buffer for DCP The persistent multi-CTAS KV counter buffer (sgl-project#31607) is sized by head count; under DCP the trtllm decode runs with dcp-widened heads, so pre-size it by num_q_heads * dcp_size and let the grow check use the per-call head count. token_capacity in metrics and the load inquirer now reports logical tokens (physical * dcp_size), matching the allocator's accounting. Fix by @b8zhong, thanks. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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flashinfer's trtllm_batch_decode_with_kv_cache_mla instantiates a fresh runner per call (even in cuda graph). Instead use the buffer by multi_ctas_kv_counter_buffer= instead.
For prefill, it will reshape to
(num_tokens, 1, num_heads, head_dim). So we also need to grow the workspace, in case some users set chunk prefill larger than 8k. It just grows the buffer once.note: trtllm ragged prefill deepseek doesn't have this bug. It's recently introduced in #31502 after flashinfer-ai/flashinfer#3949
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Latest PR Test (Base): ❌ Run #29622595001
Latest PR Test (Extra): ❌ Run #29622594907