[Doc] Steps to add a new attention backend (#8155)

.github/workflows/pr-test.yml

@@ -56,7 +56,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        part: [0, 1, 2, 3, 4, 5, 6, 7, 8]
+        part: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -69,7 +69,7 @@ jobs:
         timeout-minutes: 30
         run: |
           cd test/srt
-          python3 run_suite.py --suite per-commit --auto-partition-id ${{ matrix.part }} --auto-partition-size 9
+          python3 run_suite.py --suite per-commit --auto-partition-id ${{ matrix.part }} --auto-partition-size 10
 
   unit-test-backend-2-gpu:
     if: (github.repository == 'sgl-project/sglang' || github.event_name == 'pull_request') &&

docs/backend/attention_backend.md

@@ -52,3 +52,31 @@ python3 -m sglang.launch_server --tp 8 --model deepseek-ai/DeepSeek-R1 --attenti
 ```bash
 python3 -m sglang.launch_server --model meta-llama/Meta-Llama-3.1-8B-Instruct --attention-backend ascend
 ```
+
+
+## Steps to add a new attention backend
+To add a new attention backend, you can learn from the existing backends
+(`python/sglang/srt/layers/attention/triton_backend.py`, `python/sglang/srt/layers/attention/flashattention_backend.py`)
+and follow the steps below.
+
+1. Run without cuda graph. Support the two forward functions
+    - forward_extend
+        - Will be used for prefill, prefill with KV cache, and target verification
+        - It will be called once per layer
+    - forward_decode
+        - Will be used for normal decode, and draft decode
+        - It will be called once per layer
+    - init_forward_metadata
+        - Initialize the class and common metadata shared by all layers
+        - Call the plan function for optimizations like split_kv
+        - It will be called once per forward
+2. Run with cuda graph. It has two phases (capture and replay) and you need to implement three functions
+    - init_cuda_graph_state
+        - It will be called once during life time
+        - Create all common shared buffers
+    - init_forward_metadata_capture_cuda_graph
+        - It will be called before capturing a cuda graph
+        - It is similar to init_forward_metadata but write the medatada to some pre-defined buffers
+    - init_forward_metadata_replay_cuda_graph
+        - It will be called before replaying a cuda graph
+        - This function is in the critical path and needs to be fast

python/sglang/srt/managers/io_struct.py

@@ -13,14 +13,14 @@
 # ==============================================================================
 """
 The definition of objects transferred between different
-processes (TokenizerManager, DetokenizerManager, Controller).
+processes (TokenizerManager, DetokenizerManager, Scheduler).
 """
 
 import copy
 import uuid
 from dataclasses import dataclass, field
 from enum import Enum
-from typing import TYPE_CHECKING, Any, Dict, List, Optional, Set, Union
+from typing import TYPE_CHECKING, Any, Dict, List, Optional, Union
 
 from sglang.srt.managers.schedule_batch import BaseFinishReason
 from sglang.srt.multimodal.mm_utils import has_valid_data
@@ -545,7 +545,7 @@ class EmbeddingReqInput:
     # The request id.
     rid: Optional[Union[List[str], str]] = None
     # Dummy sampling params for compatibility
-    sampling_params: Union[List[Dict], Dict] = None
+    sampling_params: Optional[Union[List[Dict], Dict]] = None
     # Dummy input embeds for compatibility
     input_embeds: Optional[Union[List[List[List[float]]], List[List[float]]]] = None
     # Whether to log metrics for this request (e.g. health_generate calls do not log metrics)
@@ -953,17 +953,6 @@ class ProfileReqType(Enum):
     STOP_PROFILE = 2
 
 
-class ExpertDistributionReq(Enum):
-    START_RECORD = 1
-    STOP_RECORD = 2
-    DUMP_RECORD = 3
-
-
-@dataclass
-class ExpertDistributionReqOutput:
-    pass
-
-
 @dataclass
 class ProfileReq:
     type: ProfileReqType
@@ -1013,6 +1002,17 @@ class HealthCheckOutput:
     pass
 
 
+class ExpertDistributionReq(Enum):
+    START_RECORD = 1
+    STOP_RECORD = 2
+    DUMP_RECORD = 3
+
+
+@dataclass
+class ExpertDistributionReqOutput:
+    pass
+
+
 @dataclass
 class Function:
     description: Optional[str] = None

test/srt/run_suite.py

@@ -155,11 +155,11 @@ suites = {
     "per-commit-2-gpu": [
         TestFile("models/lora/test_lora_tp.py", 116),
         TestFile("test_data_parallelism.py", 73),
-        TestFile("test_dp_attention.py", 137),
+        TestFile("test_dp_attention.py", 277),
         TestFile("test_mla_tp.py", 170),
         TestFile("test_patch_torch.py", 19),
         TestFile("test_update_weights_from_distributed.py", 103),
-        TestFile("test_release_memory_occupation.py", 44),
+        TestFile("test_release_memory_occupation.py", 127),
     ],
     "per-commit-2-gpu-amd": [
         TestFile("models/lora/test_lora_tp.py", 116),
@@ -170,7 +170,7 @@ suites = {
     ],
     "per-commit-4-gpu": [
         TestFile("test_local_attn.py", 250),
-        TestFile("test_pp_single_node.py", 150),
+        TestFile("test_pp_single_node.py", 372),
         TestFile("test_multi_instance_release_memory_occupation.py", 64),
     ],
     "per-commit-4-gpu-deepep": [
@@ -182,12 +182,12 @@ suites = {
     "per-commit-8-gpu": [
         # Disabled because it hangs on the CI.
         # TestFile("test_moe_ep.py", 181),
-        TestFile("test_disaggregation.py", 270),
+        TestFile("test_disaggregation.py", 499),
         TestFile("test_disaggregation_different_tp.py", 155),
-        TestFile("test_full_deepseek_v3.py", 463),
+        TestFile("test_full_deepseek_v3.py", 333),
     ],
     "per-commit-8-gpu-deepep": [
-        TestFile("test_deepep_large.py", 485),
+        TestFile("test_deepep_large.py", 338),
     ],
     "per-commit-8-gpu-amd": [
         TestFile("test_full_deepseek_v3.py", 250),
@@ -214,11 +214,11 @@ suites = {
         TestFile("test_nightly_gsm8k_eval_amd.py"),
     ],
     "vllm_dependency_test": [
-        TestFile("test_awq.py"),
+        TestFile("test_awq.py", 163),
-        TestFile("test_bnb.py"),
+        TestFile("test_bnb.py", 5),
-        TestFile("test_gguf.py", 78),
+        TestFile("test_gguf.py", 96),
-        TestFile("test_gptqmodel_dynamic.py", 72),
+        TestFile("test_gptqmodel_dynamic.py", 102),
-        TestFile("test_vllm_dependency.py"),
+        TestFile("test_vllm_dependency.py", 185),
     ],
 }