[NVIDIA] FA3/FA4 Fix (#11606)

Co-authored-by: Baizhou Zhang <sobereddiezhang@gmail.com>

test/srt/run_suite.py

@@ -169,6 +169,7 @@ suites = {
         TestFile("test_disaggregation_pp.py", 140),
     ],
     "per-commit-4-gpu-b200": [
+        # TestFile("test_flash_attention_4.py"),
         # TestFile("test_gpt_oss_4gpu.py", 600),
         # TestFile("test_deepseek_v3_fp4_4gpu.py", 3600),
     ],

test/srt/test_flash_attention_4.py

@@ -0,0 +1,56 @@
+import unittest
+from types import SimpleNamespace
+
+from sglang.srt.environ import envs
+from sglang.srt.utils import get_device_sm, kill_process_tree
+from sglang.test.few_shot_gsm8k import run_eval as run_eval_few_shot_gsm8k
+from sglang.test.test_utils import (
+    DEFAULT_MODEL_NAME_FOR_TEST,
+    DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
+    DEFAULT_URL_FOR_TEST,
+    popen_launch_server,
+)
+
+
+@unittest.skipIf(get_device_sm() < 100, "Test requires CUDA SM 100 or higher")
+class TestFlashAttention4(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.model = DEFAULT_MODEL_NAME_FOR_TEST
+        cls.base_url = DEFAULT_URL_FOR_TEST
+        other_args = [
+            "--trust-remote-code",
+            "--mem-fraction-static",
+            "0.8",
+            "--prefill-attention-backend",
+            "fa4",
+        ]
+        cls.process = popen_launch_server(
+            cls.model,
+            cls.base_url,
+            timeout=DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
+            other_args=other_args,
+        )
+
+    @classmethod
+    def tearDownClass(cls):
+        kill_process_tree(cls.process.pid)
+
+    def test_gsm8k(self):
+        args = SimpleNamespace(
+            num_shots=4,
+            data_path=None,
+            num_questions=100,
+            max_new_tokens=512,
+            parallel=128,
+            host="http://127.0.0.1",
+            port=int(self.base_url.split(":")[-1]),
+        )
+        metrics = run_eval_few_shot_gsm8k(args)
+        print(metrics)
+
+        self.assertGreater(metrics["accuracy"], 0.65)
+
+
+if __name__ == "__main__":
+    unittest.main()