clock synchronization The value returned for MPI_WTIME_IS_GLOBAL is 1 if clocks MPI_WTIME_IS_GLOBAL at all processes in MPI_COMM_WORLD are synchronized, 0 otherwise. A collection of clocks is considered synchronized if explicit effort has been taken to synchronize them. The expectation is that the variation in time, as measured by calls to MPI_WTIME, will be less then one half the round-trip time for an MPI message of length zero. If time is measured at a process just before a send and at another process just after a matching receive, the second time should be always higher than the first one.
The attribute MPI_WTIME_IS_GLOBAL need not be present when MPI_WTIME_IS_GLOBAL the clocks are not synchronized (however, the attribute key MPI_WTIME_IS_GLOBAL is always valid). This attribute may be associated with communicators other then MPI_COMM_WORLD.
The attribute MPI_WTIME_IS_GLOBAL has the same value on all processes in the group of MPI_COMM_WORLD.
MPI_GET_PROCESSOR_NAME(name, resultlen) OUT name A unique specifier for the current physical node. OUT resultlen Length(in printable characters) of the result returned in nameMPI_Get_processor_name(char *name, int *resultlen)
MPI_GET_PROCESSOR_NAME( NAME, RESULTLEN, IERROR)CHARACTER*(*) NAME
This routine returns the name of the processor on which it was called at the moment of the call. The name is a character string for maximum flexibility. From this value it must be possible to identify a specific piece of hardware; possible values include ``processor 9 in rack 4 of mpp.cs.org'' and ``231'' (where 231 is the actual processor number in the running homogeneous system). The argument name must represent storage that is at least MPI_MAX_PROCESSOR_NAME characters long. MPI_MAX_PROCESSOR_NAME MPI_GET_PROCESSOR_NAME may write up to this many characters into name.
The number of characters actually written is returned in the output argument, resultlen.
The constant MPI_BSEND_OVERHEAD provides an upper bound on MPI_BSEND_OVERHEAD the fixed overhead per message buffered by a call to MPI_BSEND.