[vfio-users] VM Randomly Becomes Choppy

[Ben J]

I've narrowed it down to a cpu issue, I was giving 6 cores (I only have 6)
to the VM and from looking at htop it seems to start lagging from major cpu
spikes. For a moment Skype spikes to 250% cpu usage when it launches which
would explain why it triggered the issue. Is there a steadfast rule for cpu
allocation to gaming VM's? So far 6 has been unstable, 3 has always been
choppy on boot, and 4 seems fairly stable but has still occasionally gotten
choppy. I'm currently testing 5 but I expect it will be worse than 4. I'm
also only currently running at 3.3GHz and could easily overclock to ~3.9 if
that would make a big difference. I find it difficult to believe that it's
not just an optimization issue though since I've never had any issues with
this cpu before.
On Feb 27, 2016 12:36 AM, "Ben J" <btpprograms at gmail.com> wrote:

> I've recently been having issues with my VM's framerate dropping at
> random. It generally boots up completely fine, but at seemingly random
> points it starts to stutter and doesn't stop until the VM is fully turned
> off and back on again. It started out being fairly rare, but now happens on
> almost every launch of the VM after a few minutes.
>
> My specs:
>
> Host OS: Arch Linux
>
> Guest OS: Windows 7
>
> Motherboard: Asus Rampage IV Extreme
>
> CPU: I7-3960X
>
> Graphics: 2X EVGA GTX 580's
>
> My Launch Script:
>
> killall synergys
>
> synergys
>
>
> QEMU_PA_SAMPLES=4096 QEMU_AUDIO_DRV=pa qemu-system-x86_64 -enable-kvm -m
> 4096 -mem-path /dev/hugepages -cpu host,kvm=off \
>
> -smp 6,sockets=1,cores=6,threads=1 \
>
> -bios /usr/share/qemu/bios.bin  -vga none \
>
> -device vfio-pci,host=02:00.0,multifunction=on,x-vga=on \
>
> -device vfio-pci,host=02:00.1 \
>
> -net nic,model=virtio,vlan=0,macaddr=DE:AD:BE:EF:D4:41 \
>
> -net tap,vlan=0,id=network0,ifname=tap0,script=no,downscript=no,vhost=on \
>
> -usb -usbdevice host:046d:c534 -usbdevice host:045e:028e \
>
> -soundhw hda \
>
> -boot menu=on \
>
> -drive file=/dev/sda1,format=raw,if=virtio,cache=none \
>
> -drive
> file=/mnt/LinuxStorage/ISOs/Windows/Drivers/virtio.iso,id=virtiocd,if=none,format=raw
> -device ide-cd,bus=ide.1,drive=virtiocd
>
>
> The issue seems to get triggered immediately whenever I launch a Skype or
> Discord call. It also seems to be more likely when I'm running a game
> within the VM (Tested with Rocket League and Rivals of Aether). It has also
> happened without either of those being open though. I'm really at a loss.
> I've tried disabling huge pages since I suspected that I might not have
> enough, but that showed no difference. Restarting the computer fixes it
> temporarily but it usually happens again shortly after I restart. The same
> thing happens when I suspend and wake up the computer. Has anyone
> experienced this issue before?
>
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