Newsgroups: comp.parallel.mpi
From: Milind Bhandarkar <milind@cs.uiuc.edu>
Subject: Re: MPI messages ordered?
Organization: University of Illinois
Date: Fri, 26 Apr 1996 13:14:29 -0500
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Message-ID: <31811285.7C61@cs.uiuc.edu>

MARK NG wrote:
> 
> Hi to you all MPI experts,
> 
> I am a newbie in MPI but have this question: Does MPI guarantee the
> messages arrive in order? That is, if I have process 0 and 1 each
> send a message to process 2 but by some sync machanism, process 0
> does the send before process 1. So if I call MPI_Recv twice in process
> 2, is it sure going to receive the message from process 0 in the first
> MPI_Recv ?

No. MPI does not guarantee in-order delivery for messages from different
processors. The in-order delivery is guaranteed for different messages
between the same pair of processors.

milind

