[Xen-users] ntpdate (dom0) causes user input problems

[Marcin Owsiany <marcin@xxxxxxxxxx>]

Hi,

I've been experiencing this for at least a few months, but only recently
found out what caused this.

The symptom is that when working in X on my laptop, suddenly keyboard
starts behaving as if I was typing over a high-latency link, with the
addition of some characters getting duplicated, unless I type very
slowly (less than 1 char/sec). After a few minutes (about 10) everything
goes back to normal.

Input works fine on text console, though.

Also, (the thing which pointed me at the system clock) tar tends to
complain (when unpacking) that "the timestamp is 0.00044 seconds in the
future". I don't remember the value exactly, but it was less than
1/100s.

I've found out that the start of this behavior coincides exactly with
the moment at which ntpdate -B is started from cron:
Aug 27 18:13:18 localhost ntpdate[7277]: adjust time server 66.92.68.11 offset 
-0.411010 sec

My private lame theory is that somehow, when running under Xen, despite
the "-B", ntpdate just sets the clock instead of slowing it down or
speeding it up. Or maybe there is a conflict with xen, which (I vaguely
remember) also adjusts the domains' clocks every now and then. And so
the tiny time warps disturb X's polling for keyboard/mouse.

Is it a known problem? How do I fix it?

I'm running Debian 2.6.17-2-xen-686 SMP (one CPU though), xen
3.0.2+hg9697-2.

Marcin
-- 
Marcin Owsiany <marcin@xxxxxxxxxx>              http://marcin.owsiany.pl/
GnuPG: 1024D/60F41216  FE67 DA2D 0ACA FC5E 3F75  D6F6 3A0D 8AA0 60F4 1216
 
"Every program in development at MIT expands until it can read mail."
                                                              -- Unknown

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