Hi, In my program I have a loop of this form: loop { MPI_Send(small message) MPI_Isend(big message) } do_some_computation() MPI_Waitall The sends and isends all have the same target rank. Is there a risk that an MPI_Send forces a previously posted MPI_Isend to complete before it can complete itself (in which case I would loose the benefit of using non-blocking sends)? Thanks, Matthieu _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss