Newsgroups: comp.parallel.mpi
From: zxu@monalisa.usc.edu (Zhiwei Xu)
Subject: Re: Clarifications on Ready/Sync modes
Organization: University of Southern California, Los Angeles, CA
Date: 12 Aug 1995 17:02:05 -0700
Message-ID: <40jfdt$gql@monalisa.usc.edu>

rdaoud@magnus.acs.ohio-state.edu (Raja B Daoud) wrote:
>>Vivek Gupta <guptavi1@cps.msu.edu> wrote:
>>a) For the synchronous mode, can the send complete as soon as a matching
>>   receive is posted OR is it necessary that the matching receive should have
>>   "got/received some data" ? I believe the former is true since for a non-
>>   blocking sync-send can be matched by a non-blocking receive call.

>A sync. send can complete when a matching receive is posted and the
>the send buffer can be reused, whichever happens last.  It depends on
>how the implementation handles message buffering.

salo@mrjones.engr.sgi.com (Eric Salo) wrote:
>As I understand it, a synchronous send is allowed to return only after the
>following two things are true:
>
>        1) a matching receive has been posted
>        2) the send buffer may safely be modified

Are you guys sure about this? How about the non-blocking, synchronous send
MPI_Issend then?

"Synchronous" refers to whether the matching receive is posted, it does not
say anything about whether the send buffer maybe safely modified or not, which
is specified by blocking or non-blocking.

Can someone from MPI clarify on this?


