Re: Strange network behaviour

[Mike <mike-kcIQ9yavhvsV/sYkb9DZNQ@public.gmane.org>]

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.

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