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Before use the library must be initialized. The initialization
call must come after the call to initialize MPI:
...
MPI_Init(&argc,&argv);
AP_init(&argc,&argv);
AP_setparam(size,packed,maxreq_proc,maxreq); /* optional */
...
The call to AP_setparam() is optional to specify settings
that affect the library's behavior.
- size: Controls the library's memory block allocation size
which also determines package size. This is only a default; if the
user requests a single message buffer larger than this, enough memory
will be allocated for a block that can hold the message.
- packed: If nonzero, enables message packing. Messages are
automatically grouped into packages and their actual send may be
delayed. If this argument is zero, message packing is disabled.
Messages must still be allocated through the library but they are sent
individually. This can be useful for making comparisons.
- maxreq_proc: This sets a per-destination limit on the
number of MPI send requests that will be posted at one time. This can
help to prevent overflowing the capacity of some MPI implementations.
- maxreq: This sets an overall limit on the number of MPI
send requests that will be posted at one time. It takes precedence
over maxreq_proc. If maxreq is negative, no global
limit is set (it is effectively the number of processors multiplied
by maxreq_proc).
Different architectures and MPI implementations will achieve their
best performance with different settings.
Next: Sending and Receiving Messages
Up: AUTOPACK User Manual 1
Previous: Fortran Binding Issues
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Raymond Loy
2000-05-12