Hi, I am using Xen on a Quad Core Phenom with 8G of RAM. Everything is fine except the clock! [oh god :((] In Dom0 everything works just fine but in DomUs the clock (both system time and the realtime clock (IRQ8) drift. I can live with the system time drift (I just enforce NTP every 5 minutes) but all my applications in DomUs that depend on the realtime clock (IRQ8) are messed up. Do you guys have any idea what could be wrong here? p.s. All DomUs and Dom0 are running CentOS 5 on on a M3A mother board from Assus (64 bit CPU - X4). Cheers, _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
[Re-sending with correct source address.] On 2008-08-16 01:59, Ray Fadaie wrote:> I am using Xen on a Quad Core Phenom with 8G of RAM. Everything is fine > except the clock! [oh god :((] > In Dom0 everything works just fine but in DomUs the clock (both system > time and the realtime clock (IRQ8) drift. I can live with the system > time drift (I just enforce NTP every 5 minutes) but all my applications > in DomUs that depend on the realtime clock (IRQ8) are messed up. > Do you guys have any idea what could be wrong here? > > p.s. All DomUs and Dom0 are running CentOS 5 on on a M3A mother board > from Assus (64 bit CPU - X4).I don''t understand *why* this happens, but I''ve seen the same thing, as have many others (check Google). I think I''ve got it under control now. The following works for me: On dom0: - Set xen.independent_wallclock = 1 in /etc/sysctl.conf (corresponding to /proc/sys/xen/independent_wallclock) - Run ntpd. On PVM domUs: - Set xen.independent_wallclock = 1 in /etc/sysctl.conf - Run ntpd. On HVM domUs: - Disable acpi in xen config (acpi = 0). - Run ntpd. The clock sometimes still jumps a bit during a live migration, but ntpd slews it back afterward. -- Jefferson Ogata : Internetworker, Antibozo _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Did you look into setting your clocksource to jiffies, that seemed to help with my live migration issues. I struggled with time drift for months, I was running the same configuration you were (except I didn''t have any HVMs). Then I tried the following: Dom0: independent wallclock = 1 ntpd clocksource = jiffies DomU: independent wallclock = 0 clocksource = jiffies I''ve been monitoring my Dom0s and DomUs with Hyperic for a few months (specifically looking at ntp drift) and these settings produce the closest numbers to a "bare metal" machine in my environment. Cheers, --------------------------------------------------------------------- Eric Ross Linux Systems Administrator Argonne National Laboratory Computing and Information Systems Phone: 630.252.2600 --------------------------------------------------------------------- Jefferson Ogata wrote:> [Re-sending with correct source address.] > > On 2008-08-16 01:59, Ray Fadaie wrote: >> I am using Xen on a Quad Core Phenom with 8G of RAM. Everything is >> fine except the clock! [oh god :((] >> In Dom0 everything works just fine but in DomUs the clock (both system >> time and the realtime clock (IRQ8) drift. I can live with the system >> time drift (I just enforce NTP every 5 minutes) but all my >> applications in DomUs that depend on the realtime clock (IRQ8) are >> messed up. >> Do you guys have any idea what could be wrong here? >> >> p.s. All DomUs and Dom0 are running CentOS 5 on on a M3A mother board >> from Assus (64 bit CPU - X4). > > I don''t understand *why* this happens, but I''ve seen the same thing, as > have many others (check Google). > > I think I''ve got it under control now. The following works for me: > > On dom0: > - Set xen.independent_wallclock = 1 in /etc/sysctl.conf (corresponding > to /proc/sys/xen/independent_wallclock) > - Run ntpd. > > On PVM domUs: > - Set xen.independent_wallclock = 1 in /etc/sysctl.conf > - Run ntpd. > > On HVM domUs: > - Disable acpi in xen config (acpi = 0). > - Run ntpd. > > The clock sometimes still jumps a bit during a live migration, but ntpd > slews it back afterward. >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 2008-08-25 17:04, Eric Ross wrote:> Did you look into setting your clocksource to jiffies, that seemed to > help with my live migration issues.Explicitly setting clocksource to jiffies made things worse if anything. IIRC it was the default anyway in most cases.> I struggled with time drift for months, I was running the same > configuration you were (except I didn''t have any HVMs). Then I tried > the following: > > Dom0: > independent wallclock = 1 > ntpd > clocksource = jiffies > > DomU: > independent wallclock = 0 > clocksource = jiffies > > I''ve been monitoring my Dom0s and DomUs with Hyperic for a few months > (specifically looking at ntp drift) and these settings produce the > closest numbers to a "bare metal" machine in my environment.As I say, my problem is under control. independent_wallclock anywhere possible, acpi off on HVMs, ntpd everywhere. Only bummer is HVMs don''t shut down all the way without acpi. Top posting sucks.> Jefferson Ogata wrote: >> On 2008-08-16 01:59, Ray Fadaie wrote: >>> I am using Xen on a Quad Core Phenom with 8G of RAM. Everything is >>> fine except the clock! [oh god :((] >>> In Dom0 everything works just fine but in DomUs the clock (both system >>> time and the realtime clock (IRQ8) drift. I can live with the system >>> time drift (I just enforce NTP every 5 minutes) but all my >>> applications in DomUs that depend on the realtime clock (IRQ8) are >>> messed up. >>> Do you guys have any idea what could be wrong here? >>> >>> p.s. All DomUs and Dom0 are running CentOS 5 on on a M3A mother board >>> from Assus (64 bit CPU - X4). >> I don''t understand *why* this happens, but I''ve seen the same thing, as >> have many others (check Google). >> >> I think I''ve got it under control now. The following works for me: >> >> On dom0: >> - Set xen.independent_wallclock = 1 in /etc/sysctl.conf (corresponding >> to /proc/sys/xen/independent_wallclock) >> - Run ntpd. >> >> On PVM domUs: >> - Set xen.independent_wallclock = 1 in /etc/sysctl.conf >> - Run ntpd. >> >> On HVM domUs: >> - Disable acpi in xen config (acpi = 0). >> - Run ntpd. >> >> The clock sometimes still jumps a bit during a live migration, but ntpd >> slews it back afterward.-- Jefferson Ogata : Internetworker, Antibozo _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users