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Bug#517048: Clock problem with live migration



Package: linux-image-2.6.26-1-xen-amd64
Version: 2.6.26-13
Severity: important

When I migrate a domain from an host to another (which both run
the 2.6.26-1-xen-amd64 kernel), with the packaged xen 3.2.1-2,
the migrated domU have his time shifted by the timedelta of the
2 dom0 uptime.

# Demo :
xen-8:~# uname -a
Linux xen-8 2.6.26-1-xen-amd64 #1 SMP Sat Jan 10 20:39:26 UTC 2009 x86_64 GNU/Linux
xen-8:~# xm list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0   500     8     r-----   2559.1
flashstream-001                             86   250     2     -b----      6.9

xen-5:~# uptime
 12:36:53 up 12 days, 15 min,  1 user,  load average: 0.00, 0.00, 0.00
xen-5:~# xm list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0   500     8     r----- 448967.8
xen-5:~# uname -a
Linux xen-5 2.6.26-1-xen-amd64 #1 SMP Sat Jan 10 20:39:26 UTC 2009 x86_64 GNU/Linux

# Everyone is synced ...
xen-8:~# date
Tue Feb 24 12:37:17 CET 2009
xen-5:~# date
Tue Feb 24 12:37:18 CET 2009
flashstream-001:~# date
Tue Feb 24 12:37:19 CET 2009

# let's migrate the domU from xen-8 to xen-5
xen-8:/etc/xen# xm migrate flashstream-001 -l 10.20.0.5

On the domU :
flashstream-001:~# date
Tue Feb 24 12:41:35 CET 2009
# Migration is here
flashstream-001:~# date
Sat Mar  7 15:13:05 CET 2009

I don't encounter the bug when I use the 2.6.18-6-xen kernel from etch.
I tryed to do "echo 1 > /proc/sys/xen/independent_wallclock" everywhere it's
possible (in dom0 or domU), it don't change anything. Setting the clocksource
to jiffies in the domU fix the problem, but it have a resolution of 4ms which
sux :(. 


-- System Information:
Debian Release: 5.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.26-1-xen-amd64
Locale: LANG=fr_FR@euro, LC_CTYPE=fr_FR@euro (charmap=ISO-8859-15)



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