On Monday 06 December 2010 15:03:13 Mathieu Gontier wrote:
> A small update.
> My colleague made a mistake and there is no arithmetic performance
> issue. Sorry for bothering you.
> Nevertheless, one can observed some differences between MPICH and
> OpenMPI from 25% to 100% depending on the options we are using into our
> software. Tests are lead on a single SGI node on 6 or 12 processes, and
> thus, I am focused on the sm option.
A few previous threads on sm performance have been related to what /tmp is.
OpenMPI relies on (or at least used to rely on) this being backed by page
cache (tmpfs, a local ext3 or similar). I'm not sure what the behaviour is in
the latest version but then again you didn't say which version you've tried.