I created a ticket for this: https://trac.mpich.org/projects/mpich/ticket/2332. Jeff On Mon, Mar 28, 2016 at 10:26 AM, Wei-keng Liao < [email protected]> wrote:
My test program can be compiled with command "mpicc get_count.c -o get_count" and run "mpiexec -n 4 get_count". For correct (expected) result, nothing will be printed on stdout. Otherwise, error messages will be printed.
My point is MPI_Get_count does not report correct result because MPI collective I/O call fails to initialize the MPI_Status object.
I found that OpenMPI and earlier version of MPICH (2-1.2.1) can run this test code correctly.
The test failed when I ran MPICH 3.1.4 and the current from GIT repo.
Wei-keng
On Mar 26, 2016, at 3:21 PM, יוסף אלון wrote:
בס"ד
becuse all the command confusion. which command should i put to run the above code?
2016-03-26 3:31 GMT+03:00 Wei-keng Liao <[email protected]>:
I notice an uninitialized MPI_Status object can make MPI_Get_count return a wrong result, when the data amount in the MPI operation is zero (although I only checked MPI-IO). Attached is a test program that uses MPI collective read where only root process has non-zero length data to read. The expected result from MPI_Get_count is 0 for all non-root process. To mimic an uninitialized MPI_Status object, I call memset to make the object non-zero.
Here is the code fragment.
if (rank == 0) len = 10; else len = 0;
MPI_File_read_all(fh, buf, len, MPI_BYTE, &status);
MPI_Get_count(&status, MPI_BYTE, &get_size);
For process rank > 0, get_size may not be 0.
Wei-keng
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-- בברכה, יוסף אלון 050-4916740 _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss
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