From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tomasz Chmielewski <mangoo@wpkg.org>
Subject: Re: strange guest slowness after some time
Date: Thu, 19 Mar 2009 14:03:23 +0100
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	Avi Kivity <avi@redhat.com>
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Tomasz Chmielewski schrieb:

>> Note how _time_ is different (similar timings are to other unaffected 
>> guests):
> 
> This is also pretty interesting:
> 
> # ping -c 10 <unaffected guest>
> PING 192.168.4.4 (192.168.4.4) 56(84) bytes of data.
> 64 bytes from 192.168.4.4: icmp_seq=1 ttl=64 time=1.25 ms
> 64 bytes from 192.168.4.4: icmp_seq=2 ttl=64 time=1.58 ms

(...)

> --- 192.168.4.4 ping statistics ---
> 10 packets transmitted, 10 received, 0% packet loss, time 9091ms
> rtt min/avg/max/mdev = 1.031/2.059/3.894/1.045 ms
> 
> 
> 
> How probable it is so many pings returned with exactly 1000 ms?
> 
> # ping -c 10 <affected_guest>
> PING 192.168.4.5 (192.168.4.5) 56(84) bytes of data.
> 64 bytes from 192.168.4.5: icmp_seq=1 ttl=64 time=1009 ms
> 64 bytes from 192.168.4.5: icmp_seq=2 ttl=64 time=9.61 ms
> 64 bytes from 192.168.4.5: icmp_seq=3 ttl=64 time=1000 ms
> 64 bytes from 192.168.4.5: icmp_seq=4 ttl=64 time=1000 ms
 
(...)

Just same as above happened for me again.
This time, I equipped the guest in one virtio card and one e1000 card.

00:03.0 Ethernet controller: Qumranet, Inc. Device 1000
00:04.0 Ethernet controller: Intel Corporation 82540EM Gigabit Ethernet Controller (rev 03)

Pinging e1000 card on affected guest - replies are as fast:

# ping 10.1.1.1
PING 10.1.1.1 (10.1.1.1) 56(84) bytes of data.
64 bytes from 10.1.1.1: icmp_seq=1 ttl=64 time=5.86 ms
64 bytes from 10.1.1.1: icmp_seq=2 ttl=64 time=3.40 ms
64 bytes from 10.1.1.1: icmp_seq=3 ttl=64 time=0.791 ms

Pinging virtio on affected guest - slow:

# ping 192.168.113.83
PING 192.168.113.83 (192.168.113.83) 56(84) bytes of data.
64 bytes from 192.168.113.83: icmp_seq=1 ttl=64 time=21.6 ms
64 bytes from 192.168.113.83: icmp_seq=2 ttl=64 time=1000 ms
64 bytes from 192.168.113.83: icmp_seq=3 ttl=64 time=2.73 ms
64 bytes from 192.168.113.83: icmp_seq=4 ttl=64 time=243 ms


(this is same network, guests on the same host, so latencies are not caused by packets 
travelling around the globe).


-- 
Tomasz Chmielewski
http://wpkg.org