Re: [Xen-users] Network latencies are a multiple of four

["Todd Deshane" <deshantm@xxxxxxxxx>]

On Wed, May 7, 2008 at 7:56 AM, Jan Marquardt <jm@xxxxxxxxxxx> wrote:
> Hallo list,
>
>  I just have noticed that the latency of ping as well as traceroute are
> always, nearly multiples of four. e. g. a ping to ripe.net looks like this:
>

That's weird... Did you test on a non Xen kernel?

Also, could you use a better benchmark for example iperf (or netperf)
on both the Xen and non-Xen kernels to see if there is a difference in
overall performance?

Cheers,
Todd


>  PING ripe.net (193.0.19.25) 56(84) bytes of data.
>  64 bytes from aquila.ripe.net (193.0.19.25): icmp_seq=1 ttl=55 time=20.0 ms
>  64 bytes from aquila.ripe.net (193.0.19.25): icmp_seq=2 ttl=55 time=16.0 ms
>  64 bytes from aquila.ripe.net (193.0.19.25): icmp_seq=3 ttl=55 time=16.0 ms
>  64 bytes from aquila.ripe.net (193.0.19.25): icmp_seq=4 ttl=55 time=16.0 ms
>  64 bytes from aquila.ripe.net (193.0.19.25): icmp_seq=5 ttl=55 time=20.0 ms
>  64 bytes from aquila.ripe.net (193.0.19.25): icmp_seq=6 ttl=55 time=20.0 ms
>  64 bytes from aquila.ripe.net (193.0.19.25): icmp_seq=7 ttl=55 time=32.0 ms
>  64 bytes from aquila.ripe.net (193.0.19.25): icmp_seq=8 ttl=55 time=16.0 ms
>  64 bytes from aquila.ripe.net (193.0.19.25): icmp_seq=9 ttl=55 time=28.0 ms
>  64 bytes from aquila.ripe.net (193.0.19.25): icmp_seq=10 ttl=55 time=28.0
> ms
>
>  It looks the same in domU and dom0. My system has the following key data:
> Ubuntu 7.10, 64 Bit, kernel was shipped with distribution (2.6.22-14-xen).
>
>  Did anyone experience the same problem or can give me a hint to find the
> reason for this.
>
>  Thanks for your help in advance.
>
>  Regards,
>
>  Jan Marquardt
>
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