[vfio-users] VM Randomly Becomes Choppy

[Ben J]

Neither the 4.1.X Kernel (Arch's linux-lts) or enabling MSI on all of my
passthrough devices in the guest seemed to help at all, although I did
notice that the kernel gets rid of the large cpu spike from Skype's
startup. I'm now trying to disable audio and use the hdmi audio from the
card to test with. So far it seems like disabling audio has stopped this
issue but I can't tell for sure without hearing if the audio is choppy or
not. If the audio was the issue maybe it's caused by my sample rate for
pulse? I'll reply again once I get hdmi audio working
On Feb 27, 2016 2:24 PM, "Okky Hendriansyah" <okky at nostratech.com> wrote:

> On February 28, 2016 at 02:00:54, ben j (btpprograms at gmail.com) wrote:
>
>> 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.
>>
>
> Hi Ben,
>
> My first thought is, have you tried enabling MSI on the guest? [1]
>
> What kernel is the host running? Although kernel 4.4.x should fix the
> utterly slow boot, my guest still suffer from it when I set the guest
> memory > 8 GB. Which when I set the host kernel back to 4.1.x, I never
> encountered this issue.
>
> Another issue that I noticed with kernel 4.4.x, is that the CPU usage when
> playing any sorts of audio, be it from games or even iTunes loads a very
> high CPU usage (around 70%), whilst quite low at kernel 4.1.x (around 30%).
>
> So if your kernel is at 4.4.x now, can you try using 4.1.x?
>
> [1]
> http://vfio.blogspot.com/2014/09/vfio-interrupts-and-how-to-coax-windows.html
>
> Best regards,
> Okky Hendriansyah
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/vfio-users/attachments/20160227/df4f59c2/attachment.htm>