[CPU] Bind threads and numa node for each TP rank (#6549)

Co-authored-by: srinarayan-srikanthan <srinarayan.srikanthan@intel.com>

python/sglang/srt/utils.py

@@ -40,6 +40,7 @@ import threading
 import time
 import traceback
 import warnings
+from collections import defaultdict
 from contextlib import contextmanager
 from enum import Enum
 from functools import lru_cache
@@ -2545,3 +2546,69 @@ def align(x: int, y: int) -> int:
 # COPIED FROM DeepGEMM
 def ceil_div(x: int, y: int) -> int:
     return (x + y - 1) // y
+
+
+def parse_lscpu_topology():
+    try:
+        # Get CPU topology: CPU,Core,Socket,Node
+        output = subprocess.check_output(
+            ["lscpu", "-p=CPU,Core,Socket,Node"], text=True
+        )
+    except Exception as e:
+        raise RuntimeError(f"Unexpected error running 'lscpu': {e}")
+
+    # Parse only data lines (skip comments)
+    cpu_info = []
+    for line in output.splitlines():
+        if not line.startswith("#"):
+            cpu, core, socket, node = map(int, line.strip().split(","))
+            cpu_info.append((cpu, core, socket, node))
+
+    # [(0,0,0,0),(1,1,0,0),...,(43,43,0,1),...,(256,0,0,0),...]
+    return cpu_info
+
+
+def get_physical_cpus_by_numa():
+    cpu_info = parse_lscpu_topology()
+
+    # Map NUMA node -> set of (core_id, socket) to avoid duplicates
+    # 0: {(0,0): 0, (1, 0): 1,...}
+    # ...
+    # 5: {(214,1): 214, (215,1): 215}
+    physical_by_node = defaultdict(dict)  # node -> core_id -> cpu_id
+
+    for cpu, core, socket, node in cpu_info:
+        key = (core, socket)
+        if key not in physical_by_node[node]:
+            physical_by_node[node][
+                key
+            ] = cpu  # pick first CPU seen for that physical core
+
+    # Retrieves CPUs that the current process is allowed to run on
+    cpus_allowed_list = psutil.Process().cpu_affinity()
+
+    # Convert to list of physical CPUs per node
+    # 0: [0,1,2,...,42]
+    # ...
+    # 2: [86,87,...,127]
+    # ...
+    # 5: [214,215,...,255]
+    node_to_cpus = {}
+    for node, core_to_cpu in physical_by_node.items():
+        cpus = sorted(core_to_cpu.values())
+        allowed_cpus = set(cpus).intersection(cpus_allowed_list)
+        node_to_cpus[node] = allowed_cpus
+
+    return node_to_cpus
+
+
+# Only physical cores are used. Logical cores are excluded.
+def get_cpu_ids_by_node():
+    node_to_cpus = get_physical_cpus_by_numa()
+    # Sort by NUMA node index
+    cpu_ids = [
+        ",".join(map(str, sorted(node_to_cpus[node]))) for node in sorted(node_to_cpus)
+    ]
+
+    # ['0,1,2,3', '4,5,6,7', '8,9,10,11', '12,13,14,15', '16,17,18,19', '20,21,22,23']
+    return cpu_ids