message-chain-non-blocking

Message chain

See the earlier message chain exercise for the description of the message chain.

Message chain with non-blocking communication

1. Implement the program using non-blocking communication, i.e. MPI_Isend, MPI_Irecv, and MPI_Wait. Utilize MPI_PROC_NULL when treating the special cases of the first and the last task. You may start from scratch, or use the skeleton code or your solution from the earlier message chain exercise as a starting point.

2. The skeleton code prints out the time spent in communication. Investigate the timings with different numbers of MPI tasks (e.g. 2, 4, 8, 16, ...). Compare the results to the implementation with MPI_Sends and MPI_Recv's and pay attention especially to rank 0. Can you explain the behaviour?

3. Write a version that uses MPI_Waitall instead of MPI_Waits.

Message chain with persistent communication

1. Implement the program using persistent communication, i.e. MPI_Send_init, MPI_Recv_init, MPI_Start and MPI_Wait. You may start from scratch, or use the skeleton code or your solution from the earlier message chain exercise as a starting point.

2. Write a version that uses MPI_Startall and MPI_Waitall instead of MPI_Starts and MPI_Waits.