CISC372 Lecture Notes - Lecture 3: Fortran

• School: University of Delaware
• Department: Computer and Information Sciences
• Course: CISC372
• Professor: Stephen Siegel

Document Summary

All processes in the communicator must call it. In most cases, all must pass same values for. There is no requirement on the pointer values. The recvbuf argument is only used on root. No barrier is needed, not every process has to meet at a point. Blocks calling process until all processes in comm call mpi_comm. If one process in comm calls mpi_barrier(comm), all should. A timer is specified even though it is not. Message-passing, because timing parallel programs is important in performance debugging and because existing timers (both in. Posix 1003. 1-1988 and 1003. 4d 14. 1 and in fortran 90) are either inconvenient or do not provide adequate access to high-resolution timers. Returns a floating point number of seconds representing time that has elapsed since some time in the past. Use: take difference between 2 mpi_wtime calls to find elapsed time between calls. Time in the past is not specified, but is fixed for the life of the process.