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Subject: [OMPI users] Parallel I/O Usage
From: Manuel Holtgrewe (holtgrewe_at_[hidden])
Date: 2009-07-06 05:39:59


do I understand the MPI-2 Parallel I/O correctly (C++)?

After opening a file with MPI::File::Open, I can use Read_at on the
returned file object. I give offsets in bytes and I can perform random
access reads from any process at any point of the file without
violating correctness (although the performance might/should/will be
better using views):

MPI::File f = MPI::File::Open(MPI::COMM_WORLD, filename, MPI::MODE_RDONLY,
// ...
MPI::Offset pos_in_file = ...;
// ...
f.Read_at(pos_in_file, buffer, local_n + 1, MPI::INTEGER);
// ...

I have some problems with the program reading invalid data and want to
make sure I am actually using parallel I/O the right way.

-- Manuel Holtgrewe