PetscGatherMessageLengths2#

Computes info about messages that a MPI rank will receive, including (from-id,length) pairs for each message. Same functionality as PetscGatherMessageLengths() except it takes TWO ilenths and output TWO olengths.

Synopsis#

#include "petscsys.h"  
PetscErrorCode PetscGatherMessageLengths2(MPI_Comm comm, PetscMPIInt nsends, PetscMPIInt nrecvs, const PetscMPIInt ilengths1[], const PetscMPIInt ilengths2[], PetscMPIInt **onodes, PetscMPIInt **olengths1, PetscMPIInt **olengths2)

Collective, No Fortran Support

Input Parameters#

comm - Communicator
nsends - number of messages that are to be sent.
nrecvs - number of messages being received
ilengths1 - first array of integers of length sizeof(comm)
ilengths2 - second array of integers of length sizeof(comm)

Output Parameters#

onodes - list of ranks from which messages are expected
olengths1 - first corresponding message lengths
olengths2 - second message lengths

Notes#

With this info, the correct MPIU_Irecv() can be posted with the correct from-id, with a buffer with the right amount of memory required.

The calling function should PetscFree() the memory in onodes and olengths

To determine nrecvs, one can use PetscGatherNumberOfMessages()

Level#

developer

Location#

src/sys/utils/mpimesg.c

Index of all Sys routines
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Index of all manual pages