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Subject: [OMPI devel] Progress of the asynchronous messages
From: vladimir marjanovic (mrdzy_at_[hidden])
Date: 2008-11-06 13:00:06


I am new user of Open MPI, I've used MPICH before. I've tried on the user list but they couldn't help me. There is performance bug with the following scenario: proc_B: MPI_Isend(...,proc_A,..,&request) do{ sleep(1); MPI_Test(..,&flag,&request); count++ }while(!flag); proc_A: MPI_Recv(...,proc_B); For message size 8MB, proc_B calls MPI_Test 88 times. It means that point to point communication costs 88 seconds. Btw, bandwidth isn't the problem (interconnection network: InfiniBand) Obviously, there is the problem with progress of the asynchronous messages. In order to overlap communication and computation I don't want to use MPI_Wait. Probably, the message is being decomposed into chucks and the size of chuck is probably defined by environment variable. How can I advance the message more aggressively or can I control size of chunk? Thank you very much Vladimir