Script to pin vcpus to physical cpus for QEMU by using QMP (based on https://patchwork.kernel.org/project/qemu-devel/patch/[email protected]/)

pin-vcpus-threads.py

import asyncio
from qemu.qmp import QMPClient
import argparse
from subprocess import call
import os

async def main():
    parser = argparse.ArgumentParser(description='Pin QEMU vCPUs to physical CPUs')
    parser.add_argument('-s', '--server', type=str, required=True, help='QMP server path or address:port')
    parser.add_argument('cpu', type=int, nargs='+', help='Physical CPUs IDs')
    args = parser.parse_args()

    qmp = QMPClient('my-vm-nickname')
    await qmp.connect(args.server)
    
    devnull = open(os.devnull, 'w')

    res = await qmp.execute('query-cpus-fast')
    for vcpu in res:
        vcpuid = vcpu['cpu-index']
        tid = vcpu['thread-id']
        cpuid = args.cpu[vcpuid % len(args.cpu)]
        print(f"Pin vCPU {vcpuid} (tid {tid}) to physical CPU {cpuid}") #.format(vcpuid, tid, cpuid))
        try:
            call(['taskset', '-pc', str(cpuid), str(tid)], stdout=devnull)
        except OSError:
            print(f"Failed to pin vCPU{vcpuid} to CPU{cpuid}") #.format(vcpuid, cpuid)
    
    await qmp.disconnect()

asyncio.run(main())