[Suggestion] CPU Pinning in KVM and Docker and CPU Isolation

Hi,

I am currently using cpu isolation and pinning to lower stuttering in my vms. For now I'm using terminal and manual xml editing for that, I set `isolcpus=5-13,19-27` in grub and set cpu selection manually in the xml like the following:

  <vcpu placement='static'>8</vcpu>
  <cputune>
    <vcpupin vcpu='0' cpuset='5'/>
    <vcpupin vcpu='1' cpuset='19'/>
    <vcpupin vcpu='2' cpuset='6'/>
    <vcpupin vcpu='3' cpuset='20'/>
    <vcpupin vcpu='4' cpuset='7'/>
    <vcpupin vcpu='5' cpuset='21'/>
    <vcpupin vcpu='6' cpuset='8'/>
    <vcpupin vcpu='7' cpuset='22'/>
    <emulatorpin cpuset='1,15'/>
  </cputune>

I would like to see this possible in the gui directly if possible. Systemd can handle the cpu isolation instead of using the command line (example: https://www.reddit.com/r/VFIO/…cpu_pinning_explaination/).

Thanks.

Zitat von ryecoaaron

How did you envision entering that info in a GUI? It isn't really possible to make the web interface dynamic based on number of cpu cores. I am curious why you need this though. I have 20+ VMs running on an e5-2697v3 and don't have stuttering problems without this.

Either through the Change vCPU menu, you can list the thread siblings of each core (that can be listed through this command: cat /sys/devices/system/cpu/*/topology/thread_siblings_list | sort -nu) and in the VM creation page if the advanced section is enabled. It can be shown as a list with threads and check marks:

CPU0: Thread 0 [ ] - Thread 14 [ ]
CPU1: Thread 1 [ ] - Thread 15 [ ]
...
CPU12: Thread 12 [*] - Thread 26 [*]
CPU13: Thread 13 [*] - Thread 27 [*]

Isolating CPUs really helps with gaming performances in a VM, I have 2 nvidia GPUs each set for a different VM, if I do not isolate the cpus as before, the frametimes jump to the roof, by isolating the cores/threads, it removes any noise from other processes which leaves them exclusively for the vm (or docker) and leads to better performances.

For the docker section, it's just an option that you can add for select CPU threads (only works with non-isolated CPUs, meaning they're enabled and shared with the host). I do not have any real world use for it, but some people might need it, so I suggested it (ofc, you have the final word in that, you can also just set a "CPU Set" section where people enter their own thread counts like "1-3,6-8" or the like, it's per container/service basis).