Technical data

Advanced Features
101
Environment Variables: MP_SCHEDTYPE, CHUNK
These environment variables specify the type of scheduling to use on
DOACROSS loops that have their scheduling type set to RUNTIME. For
example, the following csh commands cause loops with the RUNTIME
scheduling type to be executed as interleaved loops with a chunk size of 4:
% setenv MP_SCHEDTYPE INTERLEAVE
% setenv CHUNK 4
The defaults are the same as on the DOACROSS directive; if neither
variable is set, SIMPLE scheduling is assumed. If MP_SCHEDTYPE is set,
but CHUNK is not set, a CHUNK of 1 is assumed. If CHUNK is set, but
MP_SCHEDTYPE is not, DYNAMIC scheduling is assumed.
Environment Variable: MP_PROFILE
By default, the multiprocessing routines use the fastest possible method of
doing their job. This can make it difficult to determine where the time is
being spent if the multiprocessing routines themselves seem to be a
bottleneck. By setting the environment variable MP_PROFILE, the
multiprocessing routines use a slightly slower method of synchronization,
where each step in the process is done in a separate subroutine with a long
descriptive name. Thus pixie or pc-sample profiling can get more complete
information regarding how much time is spent inside the multiprocessing
routines.
Note: Only set/unset is important. The value the variable is set to is
irrelevant (and typically is null).