[SOLVED] After backup, VM is consuming high CPU

[jeanmars]

Hi all,

I have a curious issue:
I have a VM that is almost idle and consuming < 2% CPU time under Proxmox console:

And after a successful backup (from VM-->backup or from the Datacenter automated backup job):

And this is not just temporary, it lasts like this.
On the VM itself, no CPU is used according to htop,but Proxmox hypervisor is eating up this CPU; running top on the nodeshows:

Looks like PID 1099495 (1st kvm command) is responsible for this.
This is only hapening on one of my VM (well I have 2 ).
Any idea?

Thanks,
Jean

 

[leesteken]

I think this is a known problem (with a fix in the works in the test-repository) but I cannot find the thread about it.

EDIT: Maybe this will help: https://forum.proxmox.com/threads/vms-hung-after-backup.137286/post-623867

 

[Dunuin]

Also make sure your PVE is up to date (you should not run the pve-qemu-kvm 8.1.2-5 package) and that you stop and start your VMs or reboot the PVE host after important updates so they use the latest QEMU version.

 

[jeanmars]

Hi all,

thanks for your response; I updated to the last version (pve-qemu-kvm 8.1.2-6) and restarted pve. Now after a backup CPU looks fine, no need to restart VM.
BTW "Disabling iothread on the VM's drives" did not help as another VM has 3 drives with this option set and it did not end-up with high CU after backup.

Thanks,
Jean

 

[leesteken]

BTW "Disabling iothread on the VM's drives" did not help as another VM has 3 drives with this option set and it did not end-up with high CU after backup.

It's the other way around: using IO thread is not enough to cause the issue but it was presented as enough to prevent the issue.