[Mpi3-rma] Available size and number of shared memory windows with MPI_WIN_ALLOCATE_SHARED
rabenseifner at hlrs.de
Mon Jun 3 15:14:29 CDT 2013
Dear implementers of MPI-3.0 MPI_WIN_ALLOCATE_SHARED,
my question is not about the Interface, but on the implementations:
If a set of MPI processes within a shared memory node and Communicator
wants to allocate a shared memory window:
- Are there similar limits as if a set of threads wants to allocate
memory and use it as global Memory by all threads, i.e.,
is it possible to allocate most physical
memory with MPI_WIN_ALLOCATE_SHARED?
- Is there an additional restriction on the number of shared memory
- Is there an additional restriction if one process defines the
whole size as window size and all other processes within
the SMP node use size=0?
- Do you know other restrictions if I want to substitute
OpenMP (not OpenMPI!) by shared memory MPI programming,
i.e. hybrid MPI+MPI instead of hybrid MPI+OpenMP?
Is your answer generally valid for mpich and OpenMPI and must
I expect some additional restrictions on some vendor's MPIs?
It is about the real implementations, e.g. in mpich and OpenMPI,
but I expect that our MPI-3 RMA working group knows the answer.
Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de
High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
Nobelstr. 19, D-70550 Stuttgart, Germany . . . . (Office: Room 1.307)
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