Mark Cave-Ayland
2011-Jan-18 10:20 UTC
[Xen-devel] Slow dom0 with Xen 4.0 pv_ops kernel from Debian Squeeze
Hi everyone, We''re currently looking at upgrading some of our internal machines from Debian Lenny to Squeeze and so we''re currently testing the new Xen 4.0 pv_ops dom0 and domU kernel on one of our development servers. Information about these packages can be found at http://packages.debian.org/testing/kernel/linux-image-2.6.32-5-xen-amd64 and http://packages.debian.org/testing/kernel/xen-hypervisor-4.0-amd64 respectively. While the upgrade initially went without any problems, we are now starting to see some performance issues with the new kernel. After about 24 hours, the dom0 becomes noticeable sluggish and the domUs tend to go through frequent spikes of high network latency (between 2.5 - 4.0s in a ping test). In particular, one of the most noticeable symptoms we''re seeting is that the clock in the dom0 doesn''t seem to be working correctly, e.g. the following command: ptah:~# date; sleep 1s; date Mon Jan 17 19:11:17 GMT 2011 Mon Jan 17 19:11:18 GMT 2011 ...actually takes somewhere in the region of nearer 10s rather than 1s :( Since we are running a set of older Intel Xeons, we did find the reference in the Xen 4.0 pv_ops wiki related to hpet timer issues, and so we''ve already tried adding GRUB_CMDLINE_XEN="cpuidle=off" to /etc/default/grub and re-running update-grub but that doesn''t seem to have resolved the issue after a reboot. Can anyone help figure out exactly what is happening? We''re happy to provide the relevant diagnostic information if anyone can point us in the right direction. Many thanks, Mark. -- Mark Cave-Ayland - Senior Technical Architect PostgreSQL - PostGIS Sirius Corporation plc - control through freedom http://www.siriusit.co.uk t: +44 870 608 0063 Sirius Labs: http://www.siriusit.co.uk/labs _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel