[CPU] Fix NUMA/core binding for DP ranks (#32856)

test/registered/cpu/test_binding.py

@@ -1,10 +1,13 @@
+import os
 import re
 import unittest
+from unittest.mock import patch
 
 import torch
 
 kernel = torch.ops.sgl_kernel
 
+from sglang.srt.utils.numa_utils import init_threads_binding
 from sglang.test.ci.ci_register import register_cpu_ci
 from sglang.test.test_utils import CustomTestCase
 
@@ -26,5 +29,47 @@ class TestBinding(CustomTestCase):
         self.assertEqual(bindings, expected_cores)
 
 
+class TestInitThreadsBinding(unittest.TestCase):
+    """Tests for init_threads_binding: NUMA/core selection by global rank.
+
+    numa_index is the worker's global device id (gpu_id) across all DP
+    replicas; world_size is dp_size * tp_size * pp_size.
+    """
+
+    @patch(
+        "sglang.srt.utils.numa_utils.get_cpu_ids_by_node",
+        return_value=["0,1,2,3", "4,5,6,7", "8,9,10,11", "12,13,14,15"],
+    )
+    @patch.dict(os.environ, {"SGLANG_CPU_OMP_THREADS_BIND": "all"})
+    def test_dp_ranks_get_distinct_numa_nodes(self, _mock_nodes):
+        # dp_size=2, tp_size=2 -> world_size=4, numa_index 0..3 global rank.
+        results = [init_threads_binding(numa_index=i, world_size=4) for i in range(4)]
+        self.assertEqual(results, ["0,1,2,3", "4,5,6,7", "8,9,10,11", "12,13,14,15"])
+
+    @patch(
+        "sglang.srt.utils.numa_utils.get_cpu_ids_by_node",
+        return_value=["0,1,2,3", "4,5,6,7"],
+    )
+    @patch.dict(os.environ, {"SGLANG_CPU_OMP_THREADS_BIND": "0-1|4-5"})
+    def test_explicit_bind_list_indexed_by_numa_index(self, _mock_nodes):
+        self.assertEqual(init_threads_binding(numa_index=0, world_size=2), "0-1")
+        self.assertEqual(init_threads_binding(numa_index=1, world_size=2), "4-5")
+
+    @patch(
+        "sglang.srt.utils.numa_utils.get_cpu_ids_by_node",
+        return_value=["0,1", "2,3", "4,5"],
+    )
+    @patch.dict(os.environ, {"SGLANG_CPU_OMP_THREADS_BIND": "0-1|2-3|4-5"})
+    def test_router_worker_uses_global_numa_index(self, _mock_nodes):
+        # Router mode: each worker is an independent dp_size=1 server, so
+        # world_size is locally 1 even though the bind string has multiple
+        # groups. numa_index is still the global gpu_id and must be able to
+        # select any group, not just index 0.
+        self.assertEqual(
+            init_threads_binding(numa_index=2, world_size=1),
+            "4-5",
+        )
+
+
 if __name__ == "__main__":
     unittest.main()