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MPI 2.0 features supported
Thread-compliant library
To link with the thread-compliant library, use the -libmtmpi option
when compiling your application.
To create a communication thread for each process in your job (for
example, to overlap computation and communication), specify the ct
option in the MPI_MT_FLAGS environment variable. See
“MPI_MT_FLAGS” on page 44 for more information.
Alternatively, you may set the s[a][p]# option for the MPI_FLAGS
environment variable. For the thread-compliant library, setting
MPI_FLAGS=s[a][p]# has the same effect as setting
MPI_MT_FLAGS=ct when the value of # is greater than 0.
MPI_MT_FLAGS=ct takes priority over the default MPI_FLAGS=sp0
setting. Refer to “MPI_FLAGS” on page 37.
To set the level of thread support for your job, you can specify the
appropriate run time option in MPI_MT_FLAGS or modify your
application to use MPI_Init_thread instead of MPI_Init.
To modify your application, replace the call to MPI_Init with
MPI_Init_thread(int *argc, char *((*argv) []), int required, int
*provided));
where
required
Specifies the desired level of thread support.
provided
Specifies the provided level of thread support.
Table 16 shows the possible thread-initialization values for required and
the values returned by provided for the non thread-compliant library
(libmpi) and for the thread-compliant library (libmtmpi).
Appendix C
171