[mpich-discuss] MPI_Recv: MPI + Pthreads

[Dmitri Chubarov]

Hello Olya, and all,

>
>  > Btw, the most common error people make while using threads (assuming all
>  > threads perform MPI calls) is to use MPI_Init() -- you should use
>  > MPI_Init_thread().
>  I will try that..... i am not sure what you mean, but i am using threads on
>  each MPI process, i.e. one MPI is an 8-pthread application.
>
multiple threads in an MPI process is what is often called "hybrid
parallelization". There are two good sets of slides from Rolf
Rabenseifner on the subject. The slides are some years old, and the
experiments do not cover the MPICH2 implementation, and they are on
using MPI + OpenMP, but since might be useful.

Here is the first set of slides
http://www.nsc.ru/cluster/A08_mpi_openmp_9.pdf
It has some sort of taxonomy of programming models on page 8. I
suppose your multiplication code leans to the right side where all
threads communicate with each other with MPI through the boundaries of
MPI processes.

The second set of slides is this one:
http://www.hlrs.de/organization/par/par_prog_ws/pdf/mpi_openmp_6.pdf

Best regards,
          Dima