Hi, I''m running Xen 3.0.4 on an AMD64 server and noticed a weird problem: The time in the guest is 2 minutes ahead of the host''s time. The dom0 is synchronized via NTP and the domU has independent_wallclock=0. Any idea what might cause this? Or is the only way to fix this to use independent_wallclock=1 and use NTP in the guest as well? Thanks. -- Fridtjof Busse _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
NUMA skew? --are you running multi-core> -----Original Message----- > From: xen-users-bounces@lists.xensource.com [mailto:xen-users- > bounces@lists.xensource.com] On Behalf Of Fridtjof Busse > Sent: Monday, February 26, 2007 9:21 AM > To: xen-users@lists.xensource.com > Subject: [Xen-users] Problem with timekeeping > > Hi, > > I''m running Xen 3.0.4 on an AMD64 server and noticed a weird problem: > The time in the guest is 2 minutes ahead of the host''s time. The dom0is> synchronized via NTP and the domU has independent_wallclock=0. > Any idea what might cause this? > Or is the only way to fix this to use independent_wallclock=1 and use > NTP in the guest as well? > Thanks. > > -- > Fridtjof Busse > > _______________________________________________ > 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
* "Donofrio, Lewis" <donofrio@umich.edu>:> NUMA skew?On a single-core CPU? -- Fridtjof Busse _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 26 Feb 2007 at 15:21, Fridtjof Busse wrote:> Hi, > > I''m running Xen 3.0.4 on an AMD64 server and noticed a weird problem: > The time in the guest is 2 minutes ahead of the host''s time. The dom0 is > synchronized via NTP and the domU has independent_wallclock=0. > Any idea what might cause this? > Or is the only way to fix this to use independent_wallclock=1 and use > NTP in the guest as well?Using independent clocks and NTP everywhere fixes the problem, but basically running NTP in Dom0 only and slaved clocks SHOULD work (but it doesn''t). At least with SLES10 x86_64 and a 4 CPU Opeteron. Ulrich _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Tue, Feb 27, 2007 at 08:22:52AM +0100, Ulrich Windl wrote:> On 26 Feb 2007 at 15:21, Fridtjof Busse wrote: > > I''m running Xen 3.0.4 on an AMD64 server and noticed a weird problem: > > The time in the guest is 2 minutes ahead of the host''s time. The dom0 is > > synchronized via NTP and the domU has independent_wallclock=0. > > Any idea what might cause this? > > Or is the only way to fix this to use independent_wallclock=1 and use > > NTP in the guest as well? > > Using independent clocks and NTP everywhere fixes the problem, but basically > running NTP in Dom0 only and slaved clocks SHOULD work (but it doesn''t). At least > with SLES10 x86_64 and a 4 CPU Opeteron.This matches my experience. I have never seen any explanation for this beyond "you have crap hardware" which I reject because I see it on every platform I run Xen, from home servers based on "gamer" motherboards, through supermicro cheap rackmounts, to HP and Dell servers. Running ntp everywhere is the only way I can keep the clocks synched. Cheers, Andy _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, You wrote:> The time in the guest is 2 minutes ahead of the host''s time. The dom0 is > synchronized via NTP and the domU has independent_wallclock=0. > Any idea what might cause this?Yes, adjtime() doesn''t affect the time that Xen is keeping (it is used to change the speed of the timer in order to slowly compensate for deltas). Either you disable adjtime or do it like me - I am running a cron script that forces the time adjustment by sending commands to chronyd. Kind regards, Alexander _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
* Andy Smith <andy@strugglers.net>:> > Using independent clocks and NTP everywhere fixes the problem, but > > basically running NTP in Dom0 only and slaved clocks SHOULD work > > (but it doesn''t). At least with SLES10 x86_64 and a 4 CPU Opeteron. > > This matches my experience. I have never seen any explanation for > this beyond "you have crap hardware" which I reject because I see it > on every platform I run Xen, from home servers based on "gamer" > motherboards, through supermicro cheap rackmounts, to HP and Dell > servers.Same here. From DL-servers to desktops => clock not synching.> Running ntp everywhere is the only way I can keep the clocks > synched.Annoying, but it works. -- Fridtjof Busse _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users