NAME¶
pvm_bcast - Broadcasts the data in the active message buffer to a group of
processes.
SYNOPSIS¶
C int info = pvm_bcast( char *group, int msgtag )
Fortran call pvmfbcast( group, msgtag, info )
PARAMETERS¶
- group
- Character string group name of an existing group.
- msgtag
- Integer message tag supplied by the user. msgtag should be >= 0. It
allows the user's program to distinguish between different kinds of
messages .
info integer status code returned by the routine. Values less than
zero indicate an error.
DESCRIPTION¶
The routine
pvm_bcast broadcasts a message stored in the active send
buffer to all the members of
group. In PVM 3.2 and later the broadcast
message is not sent back to the sender. Any PVM task can call pvm_bcast(), it
need not be a member of the group. The content of the message can be
distinguished by
msgtag. If pvm_bcast is successful,
info will
be 0. If some error occurs then
info will be < 0.
pvm_bcast is asynchronous. Computation on the sending processor resumes as soon
as the message is safely on its way to the receiving processors. This is in
contrast to synchronous communication, during which computation on the sending
processor halts until a matching receive is executed by all the receiving
processors.
pvm_bcast first determines the tids of the group members by checking a group
data base. A multicast is performed to these tids. If the group is changed
during a broadcast the change will not be reflected in the broadcast.
Multicasting is not supported by most multiprocessor vendors. Typically their
native calls only support broadcasting to
all the user's processes on a
multiprocessor. Because of this omission, pvm_bcast may not be an efficient
communication method on some multiprocessors.
EXAMPLES¶
C:
info = pvm_initsend( PvmDataRaw );
info = pvm_pkint( array, 10, 1 );
msgtag = 5 ;
info = pvm_bcast( "worker", msgtag );
Fortran:
CALL PVMFINITSEND( PVMDEFAULT )
CALL PVMFPKFLOAT( DATA, 100, 1, INFO )
CALL PVMFBCAST( 'worker', 5, INFO )
ERRORS¶
These error conditions can be returned by
pvm_bcast
- PvmSysErr
- pvmd was not started or has crashed.
- PvmBadParam
- giving a negative msgtag.
- PvmNoGroup
- giving a non-existent group name.
SEE ALSO¶
pvm_joingroup(3PVM)