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add the fa4 mm backend and varlen func (#13539)

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Signed-off-by: vincentzed <207368749+vincentzed@users.noreply.github.com>
Co-authored-by: Brayden Zhong <b8zhong@uwaterloo.ca>
This commit is contained in:
Yi Zhong
2026-01-23 10:12:06 -05:00
committed by GitHub
parent 2fb328109f
commit 08fcda2f63
4 changed files with 58 additions and 5 deletions
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2
docs/advanced_features/attention_backend.md
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@@ -19,7 +19,7 @@ The support matrix is split into two parts: MHA (standard attention) and MLA (mu
|---------------------------------|-----------------------------|------------------|-----------------|-----------------|-----------------|--------------------|----------------|
| **FlashInfer** | ✅ | ✅ | ❌ | ✅ | ✅ | ✅ | ❌ |
| **FA3 (FlashAttention 3)** | ✅ | ✅ | ❌ | ✅ | ✅ | ✅ | ✅ |
| **FA4 (FlashAttention 4)** | 128 | ❌ | ✅ | ❌ | ❌ | ❌ | ❌ |
| **FA4 (FlashAttention 4)** | 128 | ❌ | ✅ | ❌ | ❌ | ❌ | ✅ |
| **Triton** | ❌ | ❌ | ✅ | ✅ | ✅ | ✅ | ✅ |
| **Torch Native (SDPA)** | ❌ | ✅ | ✅ | ❌ | ❌ | ❌ | ✅ |
| **FlexAttention (PyTorch)** | ❌ | ❌ | ✅ | ❌ | ❌ | ❌ | ❌ |

2
docs/advanced_features/server_arguments.md
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@@ -266,7 +266,7 @@ Please consult the documentation below and [server_args.py](https://github.com/s
| `--decode-attention-backend` | Choose the kernels for decode attention layers (have priority over --attention-backend). | `None` | `triton`, `torch_native`, `flex_attention`, `nsa`, `cutlass_mla`, `fa3`, `fa4`, `flashinfer`, `flashmla`, `trtllm_mla`, `trtllm_mha`, `dual_chunk_flash_attn`, `aiter`, `wave`, `intel_amx`, `ascend` |
| `--sampling-backend` | Choose the kernels for sampling layers. | `None` | `flashinfer`, `pytorch`, `ascend` |
| `--grammar-backend` | Choose the backend for grammar-guided decoding. | `None` | `xgrammar`, `outlines`, `llguidance`, `none` |
| `--mm-attention-backend` | Set multimodal attention backend. | `None` | `sdpa`, `fa3`, `triton_attn`, `ascend_attn`, `aiter_attn` |
| `--mm-attention-backend` | Set multimodal attention backend. | `None` | `sdpa`, `fa3`, `fa4`, `triton_attn`, `ascend_attn`, `aiter_attn` |
| `--nsa-prefill-backend` | Choose the NSA backend for the prefill stage (overrides `--attention-backend` when running DeepSeek NSA-style attention). | `flashmla_sparse` | `flashmla_sparse`, `flashmla_kv`, `flashmla_auto`, `fa3`, `tilelang`, `aiter` |
| `--nsa-decode-backend` | Choose the NSA backend for the decode stage when running DeepSeek NSA-style attention. Overrides `--attention-backend` for decoding. | `fa3` | `flashmla_sparse`, `flashmla_kv`, `fa3`, `tilelang`, `aiter` |
| `--fp8-gemm-backend` | Choose the runner backend for Blockwise FP8 GEMM operations. Options: 'auto' (default, auto-selects based on hardware), 'deep_gemm' (JIT-compiled; enabled by default on NVIDIA Hopper (SM90) and Blackwell (SM100) when DeepGEMM is installed), 'flashinfer_trtllm' (optimal for Blackwell and low-latency), 'cutlass' (optimal for Hopper/Blackwell GPUs and high-throughput), 'triton' (fallback, widely compatible), 'aiter' (ROCm only). **NOTE**: This replaces the deprecated environment variables SGLANG_ENABLE_FLASHINFER_FP8_GEMM and SGLANG_SUPPORT_CUTLASS_BLOCK_FP8. | `auto` | `auto`, `deep_gemm`, `flashinfer_trtllm`, `cutlass`, `triton`, `aiter` |