Set the cgroup in centos7 VM and select 4 cpus in this cgroup, make the stress task in this cgroup, but only one of them works

Question

I use the stress tool and set up a cgroup in RT-centos7 VM. I try to make the stress work in the cgroup with using all cpus selected, but only one of cpus works which makes me puzzled. The stress script is below:

#!/bin/bash

stress --cpu 3 --io 3 --vm 1

The executing code is:

nohup /home/wxh/scripts/stress_test.sh &

The cgroup command I have used is: The other configurations are all defaults.

echo 2-5 > cpuset.cpus
echo 0 >cpuset.mems
echo 2216 >> tasks
echo 2217 >> tasks
echo 2218 >> tasks
echo 2219 >> tasks
echo 2220 >> tasks
echo 2221 >> tasks
echo 2222 >> tasks

The numbers from 2116 to 2222 are pid related with the stress process. The VM kernel is: 4.19.265-rt117,centos7

The htop command shows that only the No.2(which the CPU ID is 3) CPU is working with full load and other 3 cpus don't work at all.

enter image description here

The VM configuration xml is below:

<domain type='kvm'>
    <name>centos7</name>
    <memory unit='GiB'>16</memory>
    <vcpu>6</vcpu>
    <os>
    <type arch='aarch64' machine='virt'>hvm</type>
    <loader readonly='yes' type='pflash'>/usr/share/AAVMF/AAVMF_CODE.fd</loader>
    <nvram>/var/lib/libvirt/qemu/nvram/centos7_VARS.fd</nvram>
    </os>
    <features>
    <acpi/>
    <gic version='3'/>
    </features>
    <cpu mode='host-passthrough'>
        <topology sockets='2' cores='3' threads='1'/>
    </cpu>
    <iothreads>1</iothreads>
    <clock offset='utc'/>
    <on_poweroff>destroy</on_poweroff>
    <on_reboot>restart</on_reboot>
    <on_crash>restart</on_crash>
    <devices>
    <emulator>/usr/libexec/qemu-kvm</emulator>
    <disk type='file' device='disk'>
        <driver name='qemu' type='qcow2' iothread="1"/>
        <source file='/home/xxx/v1_2th.qcow2'/>
        <target dev='vda' bus='virtio'/>
        <boot order='1'/>
    </disk>
    <disk type='file' device='cdrom'>
        <driver name='qemu' type='raw'/>
        <source file='/home/xxx/softwares/Minimal_2th.iso'/>
        <readonly/>
        <target dev='sdb' bus='scsi'/>
        <boot order='2'/>
    </disk>
    <interface type='network'>
        <source network='default'/>
    </interface>
    <console type='pty'/>
        <video>
           <model type='virtio'/>
        </video>
        <controller type='scsi' index='0' model='virtio-scsi'/>
    </devices>
    <seclabel type='dynamic' model='dac' relabel='yes'/>
    <vcpu placement='static' cpuset='64,65,66,67,68,69,70,71'>6</vcpu>
    <cputune>
        <vcpupin vcpu='0' cpuset='64'/>
        <vcpupin vcpu='1' cpuset='65'/>
        <vcpupin vcpu='2' cpuset='66'/>
        <vcpupin vcpu='3' cpuset='67'/>
        <vcpupin vcpu='4' cpuset='68'/>
        <vcpupin vcpu='5' cpuset='69'/>
        <emulatorpin cpuset='70'/>
        <iothreadpin iothread='1' cpuset='71'/>
    </cputune>
</domain>

I have checked the cpuset.effective_cpus and cpuset.cpu_exclusive,but I think that problem is not here. My goal is to make the stress process works on all the 4 cpus.Thanks.

Answer 1

I know what the problem is with me. The problem is that you can't use isolcpus=2-5 command and cgroup at the same time. My decision is to withdraw the isolcpus command.