[Feature] DCP: A2A + FlashInfer-MNNVL comm backends and q-replicate (Helix) (#21637)

Co-authored-by: Hao Phan <htphan@nvidia.com> Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com> Co-authored-by: kpham-sgl <khoa.pham@radixark.ai> Co-authored-by: Cursor <cursoragent@cursor.com> Co-authored-by: Baizhou Zhang <sobereddiezhang@gmail.com>
2026-07-24 00:21:53 -07:00
parent 39955d5314
commit 35e25f5356
13 changed files with 1276 additions and 18 deletions
@@ -0,0 +1,102 @@
+"""Unit tests for DCP (Decode Context Parallelism) server args configuration.
+
+Covers the ``--dcp-comm-backend`` field ({ag_rs, a2a, fi_a2a}) and its
+validation in ``ServerArgs._handle_dcp_validation``:
+  - a2a / fi_a2a require --dcp-size > 1
+  - fi_a2a requires a CUDA platform (the authoritative MNNVL fabric probe runs
+    later, at model-runner init)
+  - dcp>1 requires CUDA or HIP (base behavior from the merged DCP PR)
+
+Tests construct with safe defaults (dcp_size=1) then mutate the fields and call
+``_handle_dcp_validation`` directly, so construction never trips the platform
+gate; is_cuda / is_hip are patched per-test to pin the platform deterministically
+(these are CPU-CI tests, where the real is_cuda() is False).
+"""
+
+import dataclasses
+import unittest
+from unittest.mock import patch
+
+from sglang.srt.server_args import ServerArgs
+from sglang.test.ci.ci_register import register_cpu_ci
+from sglang.test.test_utils import CustomTestCase
+
+register_cpu_ci(est_time=5, suite="base-a-test-cpu")
+
+_mock_device = patch("sglang.srt.server_args.get_device", return_value="cuda")
+_mock_device.start()
+
+
+class TestDCPFieldDefaults(CustomTestCase):
+    """Verify DCP-related dataclass fields exist with correct defaults."""
+
+    def test_dcp_size_field_exists(self):
+        fields = {f.name for f in dataclasses.fields(ServerArgs)}
+        self.assertIn("dcp_size", fields)
+
+    def test_dcp_comm_backend_field_exists(self):
+        fields = {f.name for f in dataclasses.fields(ServerArgs)}
+        self.assertIn("dcp_comm_backend", fields)
+
+    def test_dcp_size_default(self):
+        self.assertEqual(ServerArgs.dcp_size, 1)
+
+    def test_dcp_comm_backend_default(self):
+        self.assertEqual(ServerArgs.dcp_comm_backend, "ag_rs")
+
+
+class TestDCPCommBackendValidation(CustomTestCase):
+    """Verify ``_handle_dcp_validation`` accepts/rejects the right combos."""
+
+    @staticmethod
+    def _make_args(dcp_size, dcp_comm_backend):
+        # Construct with safe defaults (dcp_size=1) so __post_init__ never trips
+        # the dcp>1 platform gate, then set the fields under test.
+        args = ServerArgs(model_path="dummy")
+        args.dcp_size = dcp_size
+        args.dcp_comm_backend = dcp_comm_backend
+        return args
+
+    def test_a2a_requires_dcp_size_gt_1(self):
+        args = self._make_args(dcp_size=1, dcp_comm_backend="a2a")
+        with self.assertRaises(ValueError):
+            args._handle_dcp_validation()
+
+    def test_fi_a2a_requires_dcp_size_gt_1(self):
+        args = self._make_args(dcp_size=1, dcp_comm_backend="fi_a2a")
+        with self.assertRaises(ValueError):
+            args._handle_dcp_validation()
+
+    @patch("sglang.srt.server_args.is_hip", return_value=False)
+    @patch("sglang.srt.server_args.is_cuda", return_value=True)
+    def test_a2a_with_dcp_size_2_on_cuda_passes(self, *_):
+        args = self._make_args(dcp_size=2, dcp_comm_backend="a2a")
+        args._handle_dcp_validation()  # no raise
+        self.assertEqual(args.dcp_comm_backend, "a2a")
+
+    @patch("sglang.srt.server_args.is_hip", return_value=False)
+    @patch("sglang.srt.server_args.is_cuda", return_value=True)
+    def test_fi_a2a_with_dcp_size_2_on_cuda_passes_server_args(self, *_):
+        # server_args accepts fi_a2a on CUDA; the MNNVL fabric probe is deferred
+        # to model-runner init (init_fi_a2a_workspace).
+        args = self._make_args(dcp_size=2, dcp_comm_backend="fi_a2a")
+        args._handle_dcp_validation()  # no raise
+        self.assertEqual(args.dcp_comm_backend, "fi_a2a")
+
+    @patch("sglang.srt.server_args.is_hip", return_value=False)
+    @patch("sglang.srt.server_args.is_cuda", return_value=False)
+    def test_fi_a2a_on_non_cuda_raises(self, *_):
+        args = self._make_args(dcp_size=2, dcp_comm_backend="fi_a2a")
+        with self.assertRaises(ValueError):
+            args._handle_dcp_validation()
+
+    @patch("sglang.srt.server_args.is_hip", return_value=False)
+    @patch("sglang.srt.server_args.is_cuda", return_value=True)
+    def test_ag_rs_with_dcp_size_8_on_cuda_passes(self, *_):
+        args = self._make_args(dcp_size=8, dcp_comm_backend="ag_rs")
+        args._handle_dcp_validation()  # no raise
+        self.assertEqual(args.dcp_size, 8)
+
+
+if __name__ == "__main__":
+    unittest.main()