This bugzilla has Keywords: Regression.  

Since no regressions are allowed between releases, 
it is also being proposed as a blocker for this release.  

Please resolve ASAP.

Committed in 78.0.14.EL

Committed in 78.0.18.EL

Created attachment 340909 [details]
dmesg for kernel-largesmp-78.0.20.EL

Created attachment 340911 [details]
dmesg for kernel-largesmp-2.6.9-89.EL

This problem is also there for UP kernel.

[root@hp-dl580g5-01 ~]# grep -i nmi /var/log/dmesg
ACPI: LAPIC_NMI (acpi_id[0xff] dfl dfl lint[0x1])
activating NMI Watchdog ... done.
testing NMI watchdog ... CPU#0: NMI appears to be stuck (1)!
NMI watchdog: disabling NMI delivery on LINT0 for all CPUs
[root@hp-dl580g5-01 ~]# uname -ra
Linux hp-dl580g5-01.rhts.bos.redhat.com 2.6.9-78.0.20.EL #1 Thu Apr 16 13:37:56 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux

After a while, the following console messages have been displayed with the RHEL4.7.z kernel.

hp-dl580g5-01.rhts.bos.redhat.com login: warning: many lost ticks.
Your time source seems to be instable or some driver is hogging interupts
rip __do_softirq+0x4d/0xd0
Falling back to HPET

I'm trying to bisect what we miss in 4.7.z.

We need patch linux-2.6.9-nehalem-ex-support.patch from bz 491338, with this patch 4.7.z kernel works as desired.

Patch from BZ 491338 approved for 4.7.z. See Bug #497330

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2009-0459.html