[mvapich-discuss] Problem with multi-threaded performance

[Matthew Koop]

David,

Just to clarify -- at this point you are using TCP device from the
MVAPICH2 and comparing with MPICH2?

I suspect the different multithreading performance you are seeing is
related to different base MPICH2 versions. MVAPICH2 0.9.8 is currently
based on the MPICH2 1.0.3 release. The next release will be based off of
MPICH2 1.0.5 and will have the related changes for multithreading.

Matt

> I'm in the process of moving from MPICH2 to MVAPICH2 (in order to take
> advantage of IB).  My program runs on a cluster of multi-core/smp
> machines and runs multi-threaded on each of those machines. In MPICH2
> I'm getting acceptable multi-threaded performance, but the moment I
> compile/link with MVAPICH performance deteriorates drastically. I'm
> comparing here only performance over a tcp/ip 1Gbt network.  Looking at
> process usage it appears that all the threads are blocking on something
> and doing very little work in parallel.  I'm compiling with
> --enable-threads=multiple --with-pm=mpd --without-mpe
> --enable-error-checking=no --enable-g=dbg --enable-fast, and calling
> MPI::Init_thread(MPI_THREAD_MULTIPLE).  I'm compiling MPICH2 with
> exactly the same parameters and running exactly the same code on the
> same network. A simple nm on your libraries indicates you use
> pthread_mutex_lock a lot more than MPICH2, but of course that may not be
> relevant!  Please advise.
>
> David Minor
>
> Orbotech
>
>