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)