1ADVISE(3PVM)                    PVM Version 3.4                   ADVISE(3PVM)
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NAME

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

11       C    int info = pvm_advise( int route )
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13       Fortran   call pvmfadvise( route, info )
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PARAMETERS

17       route   Integer advising PVM to set up direct task-to-task links.
18                                        route options
19               PvmDontRoute        1    Don't allow direct links to this task
20               PvmAllowDirect      2    Allow but don't request direct links
21               PvmRouteDirect      3    Request direct links
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23       info    Integer returning error status.
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DESCRIPTION

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

45       C:
46                           info = pvm_advise( PvmRouteDirect );
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48       Fortran:
49                           CALL PVMFADVISE( PVMROUTEDIRECT, INFO )
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ERRORS

53       This error condition can be returned by pvm_advise
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55       PvmBadParam
56              giving an invalid route value.
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SEE ALSO

59       pvm_setopt(3PVM)
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63                                30 August, 1993                   ADVISE(3PVM)
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