Timer ISR/0: Time went backwards

[Michal Ludvig <michal@logix.cz>]

Hi,

I'm running latest Xen from 3.0 HG repository (changeset 9762) on a 
laptop with VIA C7 CPU (i.e. x86 arch). Apart from the kernel the rest 
of the system is Kubuntu 6.06.

With Xen kernel I observe all different kinds of problems, all could be 
timer related. E.g. sometimes a pressed key on a keyboard is read 
multiple times, for example when I want to write "password" I may end up 
with "paaassword". Or from time to time in KDE either mouse or a keybord 
suddenly stops responding and I need to switch windows to make it 
running again (strange enough Alt-Tab always worked so far even when no 
other keys seemed to be accepted).

In dmesg I see suspicious messages like this:

Timer ISR/0: Time went backwards: delta=-58905320 delta_cpu=-54905320 
shadow=123279593111 off=13519708 processed=123352017015 
cpu_processed=123348017015
  0: 123348017015
Timer ISR/0: Time went backwards: delta=-49996903 delta_cpu=-45996903 
shadow=123279593111 off=22427259 processed=123352017015 
cpu_processed=123348017015
  0: 123348017015
[...]
psmouse.c: TouchPad at isa0060/serio4/input0 lost synchronization, 
throwing 2 bytes away.
psmouse.c: TouchPad at isa0060/serio4/input0 lost synchronization, 
throwing 3 bytes away.
psmouse.c: resync failed, issuing reconnect request
psmouse.c: TouchPad at isa0060/serio4/input0 lost synchronization, 
throwing 5 bytes away.

I tried recompiling the kernel with different timer and HZ settings, 
with and without REGPARM, but no luck so far.

Needless to say none of these problems exist when running original 
Ubuntu or vanilla non-Xen kernel (otherwise I wouldn't complain here ;-)

Any idea what can be wrong? I'm keen to run any tests or give you any 
other information you may need.

Thanks!

Michal