Dear Friends, I am writing a matrix multiplication program with MPI. MPI_Bcast does not broadcast to all processes, in last iteration for block size greater than a specific size. I test it with both MPICH and OPENMPI.I have 12 processes which 7 of them are reached to MPI_Bcast but when master (rank 0) send only 6 of them receive the broadcast (exactly from rank 1 to 6) and rank 7 stays in waiting. Surprisingly this happen only in iteration 3999 from 4000 and in the rest of cases every thing is all right, also if I reduce the block size, which, will be sent, every thing will be done correctly.
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