Re: Strange network behaviour

Mike
2007-12-05T17:21:58Z

Avi Kivity schrieb:
> Mike wrote:
>> Sure,
>> here the ping results from the host to the guest atm of the peaks:
>> 64 bytes from postfix (195.24.77.173): icmp_seq=347 ttl=64 time=10.6 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=348 ttl=64 time=11.6 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=349 ttl=64 time=11.6 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=350 ttl=64 time=465 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=351 ttl=64 time=455 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=352 ttl=64 time=349 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=353 ttl=64 time=314 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=354 ttl=64 time=483 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=355 ttl=64 time=871 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=357 ttl=64 time=1889 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=358 ttl=64 time=1635 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=359 ttl=64 time=1973 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=360 ttl=64 time=1796 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=361 ttl=64 time=1961 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=362 ttl=64 time=2029 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=363 ttl=64 time=1994 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=364 ttl=64 time=1689 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=365 ttl=64 time=932 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=366 ttl=64 time=899 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=367 ttl=64 time=752 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=368 ttl=64 time=860 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=369 ttl=64 time=483 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=370 ttl=64 time=244 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=371 ttl=64 time=7.89 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=372 ttl=64 time=5.98 ms
>> 64 bytes from postfix (195.24.77.173): icmp_seq=373 ttl=64 time=6.31 ms
>>
>> The peaks started @ +/- 14:53:39 and ended @ +/- 14:53:59
>> You can download the trace file at:
>> http://www.eliteserver.biz/trace2.tar.gz
>>
>>
>>
>
> The traces show that the periods of latency correspond to floods of
> broadcast packets on the network
>
>> 10 29895 14:53:25
>> 9 29895 14:53:26
>> 9 29895 14:53:27
>> 9 29895 14:53:28
>> 16 29895 14:53:29
>> 19 29895 14:53:30
>> 19 29895 14:53:31
>> 14 29895 14:53:32
>> 13 29895 14:53:33
>> 12 29895 14:53:34
>> 205 29895 14:53:35
>> 203 29895 14:53:36
>> 276 29895 14:53:37
>> 234 29895 14:53:38
>> 234 29895 14:53:39
>> 243 29895 14:53:40
>> 234 29895 14:53:41
>> 259 29895 14:53:42
>> 228 29895 14:53:43
>> 325 29895 14:53:44
>> 242 29895 14:53:45
>> 271 29895 14:53:46
>> 251 29895 14:53:47
>> 227 29895 14:53:48
>> 178 29895 14:53:49
>> 166 29895 14:53:50
>> 271 29895 14:53:51
>> 244 29895 14:53:52
>> 287 29895 14:53:53
>> 196 29895 14:53:54
>> 215 29895 14:53:55
>> 83 29895 14:53:56
>> 65 29895 14:53:57
>> 10 29895 14:53:58
>> 9 29895 14:53:59
>> 10 29895 14:54:00
>> 14 29895 14:54:01
>> 14 29895 14:54:02
>> 12 29895 14:54:03
>> 13 29895 14:54:04
>> 16 29895 14:54:05
>
> The first column is the number of packets delivered at the time in the
> third column. The broadcast packets are clearly visible in the trace
> as having \xff in the first 6 bytes of the packet. The ping packet is
> getting queued behind the broadcasts and thus delayed.
>
> However, kvm is capable of much more than 200 packets/sec. I get
> about 6500 here with a flood ping. Can you try this on the host:
>
> ping -f -q guest-ip
>
> Hit ctrl-C after a second or two and send the output.
>
> You can also try running wireshark on the host to capture the
> broadcast packets. Maybe they cause some processing on the guest and
> slow it down.
>
9066 packets transmitted, 9055 received, 0% packet loss, time 1956ms
rtt min/avg/max/mdev = 0.078/0.171/16.659/0.181 ms, pipe 2, ipg/ewma
0.215/0.213 ms

The same time a tried a ping over the internet. No peaks.

I also tried over a longer time, no peaks.