Re: strange guest slowness after some time

[Tomasz Chmielewski <mangoo@wpkg.org>]

Tomasz Chmielewski schrieb:

> The host is running kvm-83.
> Affected guests are running 2.6.27.14 kernels and use virtio drivers.
> The problem happens only _sometimes_. Out of 9 guests I have running on 
> this host, I saw this problem only on 3 guests. I never saw this 
> happening on more than one guest at a time.
> All three have 512 MB memory assigned, other guests have less memory.

I upgraded ~2 days ago to kvm-84 and the same just happened for a guest with 256 MB memory.

Note how _time_ is different (similar timings are to other unaffected guests):

# ping -f -c 10000 <unaffected_guest>

10000 packets transmitted, 10000 received, 0% packet loss, time 12313ms
rtt min/avg/max/mdev = 0.432/1.164/96.163/1.934 ms, pipe 7, ipg/ewma 1.231/1.111 ms


# ping -f -c 10000 <affected_guest>

10000 packets transmitted, 10000 received, 0% packet loss, time 135625ms
rtt min/avg/max/mdev = 0.807/14.228/55.569/5.779 ms, pipe 4, ipg/ewma 13.563/8.601 ms


Running "dd if=/dev/vda of=/dev/null" on the affected guest reduces that a bit:

# ping -f -c 10000 <affected_guest>

10000 packets transmitted, 10000 received, 0% packet loss, time 50469ms
rtt min/avg/max/mdev = 0.616/4.881/54.357/3.847 ms, pipe 5, ipg/ewma 5.047/7.783 ms



Anyone? Is it a known bug?


-- 
Tomasz Chmielewski
http://wpkg.org