[CPU] Remove speculative decoding stream overrides from CPUModelRunner#47162
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bigPYJ1151 merged 2 commits intoJul 1, 2026
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Remove 4 CPU-specific method overrides (_copy_draft_token_ids_to_cpu, _get_draft_token_ids_cpu, _copy_valid_sampled_token_count, _get_valid_sampled_token_count) that are no longer needed thanks to the monkey patches in shm.py. The GPU code path now works correctly on CPU with _StreamPlaceholder and _EventPlaceholder handling all CUDA stream/event operations as no-ops. Also adds `device` and `wait_stream` attributes to _StreamPlaceholder in both shm.py and _torch_cuda_wrapper to satisfy torch.cuda.stream() context manager requirements. Reduces maintenance burden — CPU backend automatically inherits future GPU speculative decoding improvements without manual overrides. Signed-off-by: jmamou <[email protected]>
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June 30, 2026 13:40
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vllm-project#47162) Signed-off-by: jmamou <[email protected]> Signed-off-by: mayuyuace <[email protected]>
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vllm-project#47162) Signed-off-by: jmamou <[email protected]> Signed-off-by: wang.yuqi <[email protected]>
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Summary
_copy_draft_token_ids_to_cpu,_get_draft_token_ids_cpu,_copy_valid_sampled_token_count,_get_valid_sampled_token_count) fromCPUModelRunnerthat are no longer needed thanks to the monkey patches invllm/v1/worker/cpu/shm.py_StreamPlaceholderand_EventPlaceholderdeviceandwait_streamattributes to_StreamPlaceholder(in bothshm.pyand_torch_cuda_wrapper) to satisfytorch.cuda.stream()context manager andstream.wait_stream()callsThis reduces maintenance burden and improves feature stability — the CPU backend now automatically inherits any future improvements to the GPU speculative decoding path without needing manual overrides.
Performance
No regression — TPOT is identical within noise (Xeon 8580, 120 cores, Llama-3.1-8B + Llama-3.2-1B draft, K=7):
Test plan
@bigPYJ1151