[Beowulf] MPI Persistent Comm Question

Bill Rankin Bill.Rankin at sas.com
Mon Jun 28 12:05:12 EDT 2010


Uhmmm, what is "MPI_Free()"?

It does not appear to be part of the MPI2 standard.  MPI_Free_mem() is part of the standard, but is used in conjunction with MPI_Alloc_mem() and doesn't seem to refer to what you are describing here.

Is it a local procedure and if so, what does it do?

-bill




From: beowulf-bounces at beowulf.org [mailto:beowulf-bounces at beowulf.org] On Behalf Of amjad ali
Sent: Saturday, June 26, 2010 4:12 PM
To: Beowulf Mailing List
Subject: [Beowulf] MPI Persistent Comm Question

Hi all,

What is the be the best way of using MPI persistent communication in an iterative/repetative kind of code about calling MPI_Free(); Should we call MPI_Free() in every iteration or
only once when all the iterations/repetitions are performed?
Means which one is the best out of following two:

(1)
Call this subroutines 1000 times
=============================
             call MPI_RECV_Init()
             call MPI_Send_Init()
             call MPI_Startall()
             call MPI_Free()
=============================

(2)
Call this subroutines 1000 times
===========================
             call MPI_RECV_Init()
             call MPI_Send_Init()
             call MPI_Startall()
==========================
            call MPI_Free()  --------- call it only once at the end.


Thanks in advance.
best regards
AA




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