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[Xen-users] Ping RTT is rounded on domu

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Ping RTT is rounded on domu
From: Ian Baber <ian@xxxxxxxxxxx>
Date: Thu, 04 Feb 2010 13:22:08 -0800
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I'm setting up a network monitoring program on a domu. domu and dom0 are running the debian 2.6.26-2-xen-686 kernel. All ping round trip times are an even integer number of milliseconds. I've seen other posts on the list about strange RTT times, but they seem to deal with large changes caused by domu/dom0 clock synchronization. I am already using the extra="clocksource=jiffies" option as described on the debian wiki (http://wiki.debian.org/Xen). This causes all systems on my lan to report a 0.00ms ping time. The rounding only occurs on the domu system, the dom0 can accurately measure ping rtt <1ms. I'm trying to use this system to diagnose intermittent VoIP problems I've had on our network, and accurate ping times on the lan as well as to our VoIP providers would be nice. At this point, I'm not even sure what to google next. If anyone has a fix or can at least point me in the right direction I'd be grateful.

Output from ping:


PING [host] (x.x.x.x) 56(84) bytes of data.
64 bytes from [host] (x.x.x.x): icmp_seq=1 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=2 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=3 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=4 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=5 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=6 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=7 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=8 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=9 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=10 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=11 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=12 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=13 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=14 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=15 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=16 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=17 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=18 ttl=48 time=48.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=19 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=20 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=21 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=22 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=23 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=24 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=25 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=26 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=27 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=28 ttl=48 time=72.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=29 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=30 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=31 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=32 ttl=48 time=60.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=33 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=34 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=35 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=36 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=37 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=38 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=39 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=40 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=41 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=42 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=43 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=44 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=45 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=46 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=47 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=48 ttl=48 time=60.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=49 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=50 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=51 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=52 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=53 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=54 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=55 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=56 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=57 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=58 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=59 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=60 ttl=48 time=56.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=61 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=62 ttl=48 time=52.0 ms
64 bytes from [host] (x.x.x.x): icmp_seq=63 ttl=48 time=52.0 ms
^C
--- [host] ping statistics ---
63 packets transmitted, 63 received, 0% packet loss, time 62248ms
rtt min/avg/max/mdev = 48.000/54.095/72.000/3.258 ms


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