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

[Chris Worley]

On Thu, Apr 10, 2008 at 12:05 PM, Johann Lombardi <johann at sun.com> wrote:
> 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?

x86_64.

>
>
>  >  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?

This is the default from RedHat vs. the default from
downloads.lustre.org.  We didn't rebuild either from scratch.

Chris
>
>  Cheers,
>  Johann
>