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@kushanam kushanam commented Oct 5, 2025

Optimized performance on Blackwell is achieved with these defaults:
--enable-flashinfer-allreduce-fusion
--attention-backend=trtllm_mla
--enable-flashinfer-trtllm-moe
This change sets those as the default behaviors.

Update server arguments to apply DSv3 default backends for attention, allreduce fusion, and MoE

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Summary of Changes

Hello @kushanam, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the performance of DeepSeek V3 models on NVIDIA Blackwell architecture by automatically configuring optimal backend settings. It introduces default activations for trtllm_mla attention, FlashInfer TRTLLM MoE, and FlashInfer AllReduce Fusion, ensuring that DeepSeek V3 leverages these performance-critical features out-of-the-box on compatible hardware for improved efficiency.

Highlights

  • DeepSeek V3 Optimization: Introduces default performance optimizations specifically for DeepSeek V3 models when running on NVIDIA Blackwell (SM100) GPUs.
  • Attention Backend: Sets the attention_backend to trtllm_mla by default for DeepSeek V3 on Blackwell, if it hasn't been explicitly configured otherwise.
  • FlashInfer TRTLLM MoE: Enables flashinfer_trtllm_moe by default for DeepSeek V3 models when operating on Blackwell architecture.
  • FlashInfer AllReduce Fusion: Activates flashinfer_allreduce_fusion by default for DeepSeek V3 on Blackwell, provided that enable_dp_attention is not already active.
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Code Review

This pull request adds default server arguments to optimize performance for DeepSeek V3 models on Blackwell GPUs. The changes correctly set the attention backend and enable FlashInfer all-reduce fusion. However, there is a critical issue with how FlashInfer TRTLLM MoE is enabled, as it uses a deprecated and non-existent attribute, which will cause a runtime error. My review includes a suggestion to fix this by using the current moe_runner_backend argument.

Comment on lines +789 to +793
if not self.enable_flashinfer_trtllm_moe:
self.enable_flashinfer_trtllm_moe = True
logger.info(
f"Enable FlashInfer TRTLLM MoE on sm100 for {model_arch}"
)
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critical

The code attempts to use self.enable_flashinfer_trtllm_moe, which is not an attribute of the ServerArgs class. This will cause an AttributeError at runtime.

Additionally, the --enable-flashinfer-trtllm-moe command-line argument is deprecated. The recommended way to enable this feature is by setting moe_runner_backend to 'flashinfer_trtllm'. The help message for the deprecated argument states: NOTE: --enable-flashinfer-trtllm-moe is deprecated. Please set --moe-runner-backend to 'flashinfer_trtllm' instead.

The suggested change fixes the error and uses the current recommended approach. It also checks if a user has already specified a moe_runner_backend to avoid overriding their choice, which is consistent with how attention_backend is handled.

if self.moe_runner_backend == "auto":
    self.moe_runner_backend = "flashinfer_trtllm"
    logger.info(
        f"Set moe_runner_backend to 'flashinfer_trtllm' on sm100 for {model_arch}"
    )

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