[vfio-users] cpu usage in guest != cpu usage in host, even with exclusive pinning

[Brandon Ganem]

I see this on my end, ubuntu 16.04 beta. Also using CPU pinning.
Sitting in windows 10 with a web browser is enough.


Linux 4.4.0-15-generic #31-Ubuntu SMP Fri Mar 18 19:08:31 UTC 2016 x86_64
x86_64 x86_64 GNU/Linux
qemu: https://launchpad.net/ubuntu/+source/qemu/1:2.5+dfsg-5ubuntu6

Thanks.


On Tue, Mar 22, 2016 at 6:56 AM, Okky Hendriansyah <okky.htf at gmail.com>
wrote:

> On Tue, Mar 22, 2016 at 12:12 AM, Jon Panozzo <jonp at lime-technology.com>
> wrote:
>
>> Can confirm 4.2.8 kernel doesn’t exhibit this behavior with the same QEMU
>> package and VM guest.  So taking the exact same software configuration to
>> the 4.2.8 kernel results in normal CPU usage, but with any 4.4.x kernel
>> variant I’ve tried thus far, I’ve seen the same 100% usage.
>>
>> It seems to apply when any media application is in use (3D, audio, or
>> video).  Just playing an MP3 for me caused the host to go to 100%.  And if
>> I leave shadowplay running, it stays at 100% as well.  Any application that
>> pulls on a VFIO passed-through device seems to cause this to occur for me.
>
>
> Finally someone else beside me that experienced this kind of behavior. At
> first I thought it was only on the demanding games. But when I also noticed
> that also whenever I play music on my audio player the host CPU went 100%
> on all cores. Although it didn't really affect the game performance, but
> seeing the CPU load like that made me step back for the time being to
> kernel 4.1.x
>
> Best regards,
> Okky Hendriansyah
>
>
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