Re: strange guest slowness after some time

[Tomasz Chmielewski <mangoo@wpkg.org>]

Avi Kivity wrote:
> Tomasz Chmielewski wrote:
>>> Maybe virtio is racy and a loaded host exposes the race.
>>
>> I see it happening with virtio on 2.6.29.x guests as well.
>>
>> So, what would you do if you saw it on your systems as well? ;)
>>
>> Add some debug routines into virtio_* modules?
>>
> 
> I'm no virtio expert.  Maybe I'd insert tracepoints to record interrupts 
> and kicks.

Accidentally, I made some "interesting" discovery.

This ~2 MB video shows a kvm-86 guest being rebooted and GRUB started:

http://syneticon.net/kvm/kvm-slowness.ogg


GRUB has its timeout set to 50 seconds, and is supposed to show it on 
the screen by decreasing the number of seconds shown, every second.

Here, GRUB decreases the second counter very fast by 2 seconds, then 
waits 2 seconds, then again decreases the number of sends by 2 seconds 
very fast, and so on.

Perhaps my wording does not describe it very well though, so just try to 
download the video and open it i.e. in mplayer.


Comments?


-- 
Tomasz Chmielewski
http://wpkg.org