Obtain information about the numa topology of the system.

numa.py

import os
import re

def get_numa_nodes():
    """Return the numa topology of the system.
    
    Data is extracted from /sys/devices/system/cpu.
    The numa nodes on the system are the keys of the dictionary.
    Each value is a list of tuples which themselves represent physical cores.
    Each tuples contains the id of the threads belonging to the physical core.
    Without hyperthreading, each tuple contains one id, with hyperthreading each tuple contains two keys.

    Returns:
        dict: Topology of the numa nodes.
    """

    path = "/sys/devices/system/cpu"

    cpus = [d for d in os.listdir(path) if re.match("cpu\d+", d) is not None]

    nodes = {}

    for cpu in cpus:
        cpu_path = os.path.join(path, cpu)
        cpu_node = [s for s in os.listdir(cpu_path) if re.match("node\d+",s)][0]
        with open(os.path.join(cpu_path, "topology", "thread_siblings_list"), "r") as infile:
            threads = sorted(infile.read().strip().split(","))
        threads = tuple(threads)
        try:
            nodes[cpu_node].add(threads)
        except KeyError:
            nodes[cpu_node] = set()
            nodes[cpu_node].add(threads)

    for key in nodes:
        nodes[key] = sorted(nodes[key])

    return nodes

if __name__=="__main__":
    print(get_numa_nodes())