[MPICH] MPICH2 performance tuning and characterising

[Anthony Chan]

On Wed, 21 Mar 2007, stephen mulcahy wrote:

> Hi,
>
> Anthony Chan wrote:
> >
> > It seems everything is OK with your installation of MPICH2+MPE.
> > Another way to check if MPE logging is linked in is to do a grep on
> > the executable, "nm <your_executable> | grep -i MPE_Log".  If you
> > see a bunch of MPE_Log symbols listed, MPE logging library is linked
> > in.
> >
> > Does your app use MPI_THREAD_MULTIPLE support ?
>
> I don't have access to the system today but I got someone onsite to do
> those checks and they replied with the following
>
> "the nm command gave nothing back - symbol doesn't exist, and the
> MPI_THREAD_MULTIPLE text string does not appear in the ROMS source code
> tree - don't think it is multi threading."
>
> I'm confused as to why the log symbols don't exist - the compiler is
> clearly using the mpe=mpilog flag when running - perhaps it's missing
> from the linker step or I'm missing something else?

I was under the impression you are using the latest mpich2, 1.0.5pX, which
supports "-mpe=XXX" option in mpicc/mpif90.  Older mpich2, e.g. 1.0.2,
does not support the -mpe option.  If it is easier, you could add
"-llmpe -lmpe" in your Makefile during link step.

>
> As an aside - are there tools for measuring MPICH2 latency and bandwidth?

You could use mpptest from perftest or netpipe.

A.Chan