NAME

       pvm_advise() - Controls use of direct task-to-task routing.
       [In Version 3.2: Replaced by pvm_setopt]

SYNOPSIS

       C    int info = pvm_advise( int route )

       Fortran   call pvmfadvise( route, info )

PARAMETERS

       route   Integer advising PVM to set up direct task-to-task links.
                                                         route options
               PvmDontRoute        1    Don't allow direct links to this task
               PvmAllowDirect      2    Allow but don't request direct links
               PvmRouteDirect      3    Request direct links

       info    Integer returning error status.

DESCRIPTION

       The  routine pvm_advise advises PVM on whether or not to set up direct task-to-task links (using TCP) for
       all subsequent communication. Once a link is established it remains until the application finishes.  If a
       direct link can not be established because one of the two tasks has requested PvmDontRoute or because  no
       resources  are  available,  then  the  default  route through the PVM daemons is used.  pvm_advise can be
       called multiple times to selectively establish direct links, but is typically  set  only  once  near  the
       beginning  of  each  task.   PvmAllowDirect is the default advise setting.  This setting on task A allows
       other tasks to set up direct links to A.  Once a direct link is established between tasks both tasks will
       use it for sending messages.  pvm_advise returns the error status in info.   The  performance  of  direct
       task-to-task links can be up to a factor of two better than the default route. The draw back is a lack of
       scalability of the direct links.  Some versions of UNIX limit the number of links to no more than 30.

EXAMPLES

       C:
                           info = pvm_advise( PvmRouteDirect );

       Fortran:
                           CALL PVMFADVISE( PVMROUTEDIRECT, INFO )

ERRORS

       This error condition can be returned by pvm_advise

       PvmBadParam
              giving an invalid route value.

SEE ALSO

       pvm_setopt(3PVM)

                                                 30 August, 1993                                    ADVISE(3PVM)