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: 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 -- Artfiles New Media GmbH | Spaldingstr. 160 b | 20097 Hamburg Tel: 040 - 32 02 72 90 | Fax: 040 - 32 02 72 95 E-Mail: support@artfiles.de | Web: http://www.artfiles.de Geschäftsführer Carsten Bals | Handelsregister Hamburg - HRB 81478 _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Todd Deshane
2008-May-07 15:02 UTC
Re: [Xen-users] Network latencies are a multiple of four
On Wed, May 7, 2008 at 7:56 AM, Jan Marquardt <jm@artfiles.de> 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 > > -- > Artfiles New Media GmbH | Spaldingstr. 160 b | 20097 Hamburg > Tel: 040 - 32 02 72 90 | Fax: 040 - 32 02 72 95 > E-Mail: support@artfiles.de | Web: http://www.artfiles.de > Geschäftsführer Carsten Bals | Handelsregister Hamburg - HRB 81478 > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Javier Guerra
2008-May-07 15:04 UTC
Re: [Xen-users] Network latencies are a multiple of four
On Wed, May 7, 2008 at 9:56 AM, Jan Marquardt <jm@artfiles.de> 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:sounds like something to do with a kernel HZ of 250 -- Javier _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users