FreeBSD VM random high CPU/Disk IO

[Kris von Mach | Swishmail.com]

Hello,

Since upgrading from Proxmox 6.4 to 7.1 I have experienced issues with 
FreeBSD VM's. Please keep in mind that I had no issues on 6.4.

When the issue occurs, Proxmox summary shows excessively high CPU and 
Disk IO for the VM, network is normal. CPU shows at near 100% and Disk 
IO shows at 2.5GB/sec. The VM itself shows regular low cpu usage and 
keeps on spawning new processes and doesn't kill old ones, they keep on 
deinit. And load average goes from below 1 to over 200. Nothing is 
actually using any CPU, so this definitely seems like disk IO issue.

There are no errors logged anywhere, on proxmox host or freebsd vm.

This happens on both raw and qcow2 VM's. I have tried switching from 
default io_uring to native and threads, as well as combinations of no 
cache and writeback using VirtIO SCSI single.

On FreeBSD vm, I have also tried different time counters from HPET, 
TSC-low, to kvmclock.

And I've disabled balloon memory just in case.

I have also tried different CPU options from host, to actual host 
processor to kvm64. It is happening on both Intel and Amd hosts, so 
probably not related to CPU.

This happens randomly, usually during busier times. Sometimes it happens 
within few hours, sometimes it takes days to occur.

I have also tried pve-kernel-5.13.19-1-pve and pve-kernel-5.15.7-1-pve.

I believe this has something to do with the issue that was occurring on 
Linux VM's with IO errors. pve-qemu-kvm_6.1.0-3 doesn't seem to fix this 
issue on FreeBSD VMs.

Only way that I could resolve it is to reboot the VM.

Anything else I could try?

This definitely seems like a bug, as it was working fine under Proxmox 6.4.

__
Kris