[vfio-users] Power Management of vfio-redirected devices

[Blank Field]

First of all, AFAIR, all power events are logged into dmesg.
And also i've had a similiar behaviour when the guest has some kind of a
glitch and there is an interrupt storm happening. It can be observed via
guest windows task manager(system interrupts task takes a lot of cpu) or on
host by watching /proc/interrupts.
And the last idea i have is to observe lspci when everything's fine and
when the supposed low power mode happens.
On Nov 17, 2015 6:13 AM, "Eric Hattemer" <hattenator at gmail.com> wrote:

> So I have this weird issue where if I run my Windows guest for days in a
> row, without allowing it to blank the screen or suspend or hibernate, it
> runs at full performance.  If I suspend it and let Linux blank the screen,
> or let Windows blank the screen, or things of that nature, it tends to
> break forever.  That is, rebooting Windows or starting a fresh qemu process
> (that doesn't resume from hibernate) doesn't fix anything.  The symptom is
> that the VM functions at about 1/10th speed.  It takes 10x as long to boot.
> Dragging windows across the screen stutters.  The sound playing almost
> refuses to work.  Rebooting the host (Linux) makes everything work again
> until it has a chance to enter low power mode or whatever.  It's probably
> either the sound card or more likely the Nvidia 660 that's causing the
> problem, since those are both vfio-pci redirected.
>
> I fixed it once without rebooting by messing with all of:
>
> modprobe -r vfio-pci
> service acpid restart
> tuned-adm profile powersaving
> tuned-adm profile vm-host
> modprobe nouveau
> modprobe -r nouveau
> modprobe vfio-pci
>
> and maybe some rescanning/disabling/enabling or things in /sys/bus/pci...
>
> I'm really not sure how I did that and I haven't really been able to fix
> it without a reboot since.  The important thing to note about modprobing
> nouveau is that the sysfs node for the video card still had
> driver_override=vfio-pci.  Otherwise nouveau really does take it over and
> there doesn't seem to be a way to unload nouveau once it's attached to a
> card.
>
> I ran MSI afterburner in the guest to look at the GPU clocks and see if I
> could get it to re-activate them to full speed.  But it might not really be
> a clocking issue, since I see about the same graphs whether the issue is
> present or not.
>
> Maybe my hypothesis that this is GPU power-saving related is wrong, but
> everything seems to run full speed if I disable vfio and run with the spice
> graphics card.
>
> So I'm wondering what exactly would cause this and what I should do to
> avoid/fix it.  I'm not that familiar with low-power modes and how they're
> managed.  Is this something well-understood, or am I the only one having
> this problem?
>
> -Eric Hattemer
>
> _______________________________________________
> vfio-users mailing list
> vfio-users at redhat.com
> https://www.redhat.com/mailman/listinfo/vfio-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/vfio-users/attachments/20151117/e4d5776a/attachment.htm>