Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |  

This web mail archive is frozen.

This page is part of a frozen web archive of this mailing list.

You can still navigate around this archive, but know that no new mails have been added to it since July of 2016.

Click here to be taken to the new web archives of this list; it includes all the mails that are in this frozen archive plus all new mails that have been sent to the list since it was migrated to the new archives.

Subject: Re: [OMPI users] How "CUDA Init prior to MPI_Init" co-exists with unique GPU for each MPI process?
From: Matthieu Brucher (matthieu.brucher_at_[hidden])
Date: 2011-12-14 10:47:05


Hi,

Processes are not spawned by MPI_Init. They are spawned before by some
applications between your mpirun call and when your program starts. When it
does, you already have all MPI processes (you can check by adding a sleep
or something like that), but they are not synchronized and do not know each
other. This is what MPI_Init is used for.

Matthieu Brucher

2011/12/14 Dmitry N. Mikushin <maemarcus_at_[hidden]>

> Dear colleagues,
>
> For GPU Winter School powered by Moscow State University cluster
> "Lomonosov", the OpenMPI 1.7 was built to test and popularize CUDA
> capabilities of MPI. There is one strange warning I cannot understand:
> OpenMPI runtime suggests to initialize CUDA prior to MPI_Init. Sorry,
> but how could it be? I thought processes are spawned during MPI_Init,
> and such context will be created on the very first root process. Why
> do we need existing CUDA context before MPI_Init? I think there was no
> such error in previous versions.
>
> Thanks,
> - D.
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users
>

-- 
Information System Engineer, Ph.D.
Blog: http://matt.eifelle.com
LinkedIn: http://www.linkedin.com/in/matthieubrucher