Hello list, in our code we use a very short front-end program to drive a larger set of codes that do our calculations. Right in the beginning of the front-end, we have an if() statement such that only the rank 0 front-end does something, and the other ranks go right away to an MPI_Barrier() statement, waiting for the rank 0 front-end to finish. The rank 0 front-end then goes ahead and does its thing by calling the other codes with MPI_Comm_spawn().
We noticed that the rank > 0 copies of the front-end consume a lot of CPU while they are waiting at the MPI_Barrier(). This is obviously not what we had intended. From previous discussion on this list I understand that the CPU consumption stems from the aggressive polling frequency of the MPI_Barrier() function. While I understand that there are a lot of situations where a high polling frequency in MPI_Barrier() is useful, the situation we are in is not one of them. Is our master and slave programming model such an unusual way of using MPI? nick
