[Lustre-discuss] 1.6.4.3 changes CPU mapping in RHEL., and 10x performance loss in one application

[Johann Lombardi]

Chris,

On Sat, Apr 05, 2008 at 06:11:32PM -0600, Chris Worley wrote:
> I was running RHEL's 2.6.9-67.0.4 kernel w/o Lustre patches, and the

What is the CPU architecture? x86_64 or IA64?

>  core to logical processor allocation was (as shown by /proc/cpuinfo):
> 
> 
>         =============      =============    Socket
> 
>         ====== ======       ======  ======    L2 cache domain
> 
>          0    4      1     5          2      6     3     7     logical processor
> 
> 
>  After installing the Lustre version of the kernel, the allocation is:
> 
>         =============      =============    Socket
> 
>         ======  ======      ======  ======    L2 cache domain
> 
>          0     1      2      3        4      5      6    7     logical processor

Hard to believe that one of our patches could cause this.
Have you compared the kernel config files?

Cheers,
Johann