Since upgrading to the 2.6.18-348.1.1 kernel I am
seeing continuous kernel exceptions of this form

2013-04-03T04:02:13-05:00 [log in to unmask] kernel: Warning Timer 
ISR/1: T
ime went backwards: delta=-500760595 delta_cpu=67239405 
shadow=1879913420310320
off=249335587 processed=1879914170340430 cpu_processed=1879913602340430
2013-04-03T04:02:13-05:00 [log in to unmask] kernel: 0: 
1879914170340430
2013-04-03T04:02:13-05:00 [log in to unmask] kernel: 1: 
1879913602340430


The system still is operational but the continuous error messages
make it difficult to diagnose any other problems that may be happening.

This hardware dual AMD Opteron 6134, has been running SL5 with
Xen kernel ever since we bought it a year and a half ago and
this is the first time we have seen this error message.  the
error message happens both in Xen Dom0 and Xen DomU's.  We
have three such identical machines and they all have the error.
Our Intel-based hardware is not affected at all.

Googling shows that there have been error messages of this sort
that come and go ever since the Xen kernel was able to run on
AMD64 hardware, and even a bugzilla against the upstream 5.6, but
as yet no fix available.  Is anyone else seeing this error in
the current kernels?

Steve Timm

------------------------------------------------------------------
Steven C. Timm, Ph.D  (630) 840-8525
[log in to unmask]  http://home.fnal.gov/~timm/
Fermilab Computing Division, Scientific Computing Facilities,
Grid Facilities Department, FermiGrid Services Group, Group Leader.
Lead of FermiCloud project.