Parallelization Directives

Parallelization directives explicitly request the compiler attempt to parallelize the DO loop that follows the directive. The syntax differs from general directives. Parallelization directives are only recognized when compilation options -parallel or -explicitpar are used. ( expanded f90 parallelization directives are described in Appendix C; details of Fortran parallelization can be found in the Fortran Programming Guide.)

Parallelization directives have the following syntax:

• The first character must be in column one.

• The first character can be any one of c, C, *, or !.

• The next four characters are $PAR, no blanks, either upper or lower case.

• Next follows the directive keyword and options, separated by blanks. The explicit parallelization directive keywords are:

  TASKCOMMON, DOALL, DOSERIAL, and DOSERIAL*

Each parallelization directive has its own set of optional qualifiers that follow the keyword.

Example: Specifying a loop with a shared variable:

C$PAR DOALL SHARED(yvalue)

See the Fortran Programming Guide for details about parallelization and these directives.