[Ilugc] Re: 2.6 SMP kernel -- dual core opteron processor -- irqbalance(?) - only one CPU busy always

[Arun Khan]

On Tuesday 22 Jul 2008, Balu manyam wrote:
> anyone?

Perhaps, there is something quirky in the 2.6.9 kernel re: your CPU. 
Perhaps you can search other mailing lists for similar problem and 
possbily the fix.

> On Tue, Jul 22, 2008 at 12:27 AM, Balu manyam <balu.manyam at gmail.com> 
wrote:
> > hey gurus -- i have a HP server with 4*dual core AMD opteron
> > processors running 2.6.9-42  SMP kernel   -- one of my DBAs
> > complained of  poor performance while running an SQL query -- now
> > when  I check the 'mpstat -P ALL  5 '  o/p - I see that CPU 0 is
> > completely busy (idle 0%)  most of the time -- while the other CPUs
> > are close to 99% idle -- I did a cat /proc/interrupts  I see that
> > CPU0 is indeed having high values corresponding to ethernet devices
> > , other PCI devices , RAID controller  and the timer as well --- I
> > also checked that we are running irqbalance daemon and please note
> > that we are running the kernel with noapic option -- not sure if
> > that matters  at all
> >
> > any inputs you may render are higlhly appreciated

You have not mentioned the distro.  If it is RHEL or Novell/SuSE you can 
contact their tech support for help.  You can also investigate if AMD 
has any Linux support channel for systems using their CPU.

Do you have the luxury to boot the system using the latest kernel using 
a custom built kernel?   At a minimum, scan through the release notes 
of the subsequent kernel versions for fixes related to AMD chips.

-- 
Arun Khan