49 lines
2.6 KiB
Markdown
49 lines
2.6 KiB
Markdown
# Attention Backend
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## Supporting matrix for different attention backends
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| **Backend** | **Page Size > 1** | **Spec Decoding** | **MLA** | **Sliding Window** | **MultiModal** |
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|--------------------------|-------------------|-------------------|---------|--------------------|----------------|
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| **FlashInfer** | ❌ | ✅ | ✅ | ✅ | ✅ |
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| **FA3** | ✅ | ✅ | ✅ | ✅ | ✅ |
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| **Triton** | ❌ | ✅ | ✅ | ✅ | ❌ |
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| **Torch Native** | ❌ | ❌ | ❌ | ❌ | ❌ |
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| **FlashMLA** | ✅ | ✅ | ✅ | ❌ | ❌ |
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Note: Every kernel backend is compatible with a page size > 1 by specifying an argument such as `--page-size 16`.
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This is because a page size of 16 can be converted to a page size of 1 in the kernel backend.
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The "❌" and "✅" symbols in the table above under "Page Size > 1" indicate whether the kernel actually operates with a page size greater than 1, rather than treating a page size of 16 as a page size of 1.
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## User guide
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#### Launch command for different attention backends.
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- FlashInfer (Default for Non-Hopper Machines, e.g., A100, A40)
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```bash
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python3 -m sglang.launch_server --model meta-llama/Meta-Llama-3.1-8B-Instruct --attention-backend flashinfer
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python3 -m sglang.launch_server --tp 8 --model deepseek-ai/DeepSeek-V3 --attention-backend flashinfer --trust-remote-code
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```
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- FlashAttention 3 (Default for Hopper Machines, e.g., H100, H200, H20)
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```bash
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python3 -m sglang.launch_server --model meta-llama/Meta-Llama-3.1-8B-Instruct --attention-backend fa3
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python3 -m sglang.launch_server --tp 8 --model deepseek-ai/DeepSeek-V3 --trust-remote-code --attention-backend fa3
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```
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- Triton
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```bash
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python3 -m sglang.launch_server --model meta-llama/Meta-Llama-3.1-8B-Instruct --attention-backend triton
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python3 -m sglang.launch_server --tp 8 --model deepseek-ai/DeepSeek-V3 --attention-backend triton --trust-remote-code
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```
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- Torch Native
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```bash
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python3 -m sglang.launch_server --model meta-llama/Meta-Llama-3.1-8B-Instruct --attention-backend torch_native
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```
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- FlashMLA
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```bash
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python3 -m sglang.launch_server --tp 8 --model deepseek-ai/DeepSeek-R1 --attention-backend flashmla --trust-remote-code
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python3 -m sglang.launch_server --tp 8 --model deepseek-ai/DeepSeek-R1 --attention-backend flashmla --kv-cache-dtype fp8_e4m3 --trust-remote-code
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```
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