[CentOS] smp falls back to up mode on quad core

Tue May 27 19:47:26 UTC 2008
John R Pierce <pierce at hogranch.com>

Julian Echave wrote:
> Hi,
> I'm running Centos 5.1 on an Intel Quad 2 Core with four Q6600 processors.
> Despite Centos 5 supporting multiple cores (SPM), it doesn't seem to 
> work for me:
> 1) a dmesg shows that only one processor is seen:
>      "SPM alternatives: switching to UP code", etc.
> 2) file /proc/cpuinfo shows only one processor
> 3) top with option 1 (to toggle between seeing all processors or an 
> average) shows only 1 processor.
> I've googled this, and other people have found this kind of trouble, 
> but I was not able to find any solutions.

it might help diagnose this if you paste the output of  'dmesg' at least 
up to that "SMP Alternatives" message and maybe a couple more lines 
after it...