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.