Xen clock drift

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Hello All,

Consider a CentOS-5.1 Xen server (2.6.18-53.1.4.el5xen) hosting two domains running CentOS-5.1 (2.6.18-53.1.4.el5). One domain has a fairly accurate clock, the other domain has a clock that gains ungodly amounts of time, roughly one minute every two or three minutes. For a fix, one suggestion is to run this command in DomU:

echo 1 > /proc/sys/xen/independent_wallclock

This didn't change anything. As an experiment, I wrote a script to call ntpd -q, sleep 60, and repeat indefinitely. Here are a couple of snippets of output:

goodclock# ksh ./xenclockdrift ntpd: time slew +0.001211s
ntpd: time slew +0.001200s
ntpd: time slew +0.001855s
ntpd: time slew +0.001532s
ntpd: time slew +0.001603s
ntpd: time slew +0.001320s
ntpd: time slew +0.001931s

badclock# ksh ./xenclockdrift ntpd: time slew -0.000193s
ntpd: time set -57.356377s
ntpd: time slew +0.002352s
ntpd: time slew +0.003018s
ntpd: time set -57.417488s
ntpd: time slew +0.012089s
ntpd: time slew -0.000985s

These domains are fully virtualized and set up identically, except "badclock" is allocated two processors versus one processor for "goodclock". DomU's clock is running normally.

Anyone know what's going or know how to fix it?

Jack



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