[benchmarks]allow skip ready check for bench serve (#25420)

Signed-off-by: Lu Fang <fanglu@fb.com>
Signed-off-by: Lucia Fang <116399278+luccafong@users.noreply.github.com>
Co-authored-by: Lucia (Lu) Fang <fanglu@meta.com>

vllm/benchmarks/serve.py

@@ -531,18 +531,22 @@ async def benchmark(
         extra_body=extra_body,
     )
 
-    test_output = await wait_for_endpoint(
-        request_func,
-        test_input,
-        session,
-        timeout_seconds=ready_check_timeout_sec,
-    )
-    if not test_output.success:
-        raise ValueError(
-            "Initial test run failed - Please make sure benchmark arguments "
-            f"are correctly specified. Error: {test_output.error}")
+    if ready_check_timeout_sec > 0:
+        test_output = await wait_for_endpoint(
+            request_func,
+            test_input,
+            session,
+            timeout_seconds=ready_check_timeout_sec,
+        )
+        if not test_output.success:
+            raise ValueError(
+                "Initial test run failed - Please make sure benchmark "
+                "arguments are correctly specified. "
+                f"Error: {test_output.error}")
+        else:
+            print("Initial test run completed. Starting main benchmark run...")
     else:
-        print("Initial test run completed. Starting main benchmark run...")
+        print("Skipping endpoint ready check.")
 
     if lora_modules:
         # For each input request, choose a LoRA module at random.
@@ -1151,7 +1155,8 @@ def add_cli_args(parser: argparse.ArgumentParser):
         type=int,
         default=600,
         help="Maximum time to wait for the endpoint to become ready "
-        "in seconds (default: 600 seconds / 10 minutes).",
+        "in seconds (default: 600 seconds / 10 minutes). If set to 0, "
+        "the ready check will be skipped."
     )