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Subject: [OMPI users] MPI_Init() and MPI_Init_thread()
From: Yuanyuan ZHANG (zhang.yuanyuan_at_[hidden])
Date: 2010-03-03 02:33:00

Hi all,

I am a beginner of MPI and a little confused with
MPI_Init_thread() function:

If we use MPI_Init() or MPI_Init_thread(MPI_THREAD_SINGLE, provided)
to initialize MPI environment, when we use OpenMP
PARALLEL directive each process is forked to multiple
threads and when an MPI function is called, one thread
is used to execute the call. It seems that this
has same effect when we use MPI_Init_Thread(MPI_THREAD_FUNNELED,
provided). So what's the difference between MPI_Init() and
MPI_Init_thread(MPI_THREAD_FUNNELED, provided)?

Thanks in advance,