[Xen-users] drifting clock in domUs

[Jonas Meurer <jonas@xxxxxxxxxxxxxxx>]

Hello,

On a xenserver with several (39) domUs, we experience problems with the
system clock of the domUs. The clock seems to drift away several seconds
up to two minutes from the dom0 clock.

We do have set independent_wallclock=0. According to the docs (i.e.
http://wiki.xensource.com/xenwiki/InstallationNotes) that way domUs
should use the dom0 clock, but apparently that's not the case.

permitted_clock_jitter is set to 10000000.

did we miss anything, or is it still required to run an ntpd on the dom0?
and if this is the case, where do we find documentation about howto
setup both dom0 and domUs to use this ntpd for the system clock?

The dom0 runs the debian 2.6.26-1-xen-amd64 kernel with 3.2 xen utils:

# dpkg -l | grep xen
ii  libxenstore3.0                     3.2.1-2              Xenstore 
communications library for Xen
ii  linux-image-2.6.26-1-xen-amd64     2.6.26-12            Linux 2.6.26 image 
on AMD64, oldstyle Xen support
ii  linux-modules-2.6.26-1-xen-amd64   2.6.26-12            Linux 2.6.26 
modules on AMD64
ii  xen-hypervisor-3.2-1-amd64         3.2.1-2              The Xen Hypervisor 
on AMD64
ii  xen-utils-3.2-1                    3.2.1-2              XEN administrative 
tools
ii  xen-utils-common                   3.2.0-2              XEN administrative 
tools - common files
ii  xenstore-utils                     3.2.1-2              Xenstore utilities 
for Xen

# xm info
host                   : xen0
release                : 2.6.26-1-xen-amd64
version                : #1 SMP Mon Dec 15 20:07:26 UTC 2008
machine                : x86_64
nr_cpus                : 4
nr_nodes               : 1
cores_per_socket       : 2
threads_per_core       : 1
cpu_mhz                : 1995
hw_caps                : 
178bf3ff:ebd3fbff:00000000:00000010:00002001:00000000:0000001f
total_memory           : 32767
free_memory            : 3120
node_to_cpu            : node0:0-3
xen_major              : 3
xen_minor              : 2
xen_extra              : -1
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 
hvm-3.0-x86_32p hvm-3.0-x86_64 
xen_scheduler          : credit
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          : unavailable
cc_compiler            : gcc version 4.3.1 (Debian 4.3.1-2) 
cc_compile_by          : waldi
cc_compile_domain      : debian.org
cc_compile_date        : Sat Jun 28 09:32:18 UTC 2008
xend_config_format     : 4

greetings,
 jonas

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