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For a period of time this will double the memory use for these arrays, so this will not change the order of magnitude of the memory requirements. If we are concerned about scalability, we should address this specifically.<br><br>Rich</font></p>
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<b>From</b>: mpi3-coll-bounces@lists.mpi-forum.org <mpi3-coll-bounces@lists.mpi-forum.org>
<br><b>To</b>: 'MPI-3 Collective Subgroup Discussions' <mpi3-coll@lists.mpi-forum.org>
<br><b>Sent</b>: Sat Aug 01 11:18:41 2009<br><b>Subject</b>: Re: [mpi3-coll] array parameters in nonblocking collectives
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<DIV dir=ltr align=left><SPAN class=078451615-01082009><FONT color=#0000ff
size=2 face=Arial>That means the MPI implementation would need to make a copy of
potentially large lists. Reference counting won't work here. And the user could
easily issue several nonblocking calls in a row. Ouch.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=078451615-01082009><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=078451615-01082009><FONT color=#0000ff
size=2 face=Arial>Rajeev</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=078451615-01082009><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B> mpi3-coll-bounces@lists.mpi-forum.org
[mailto:mpi3-coll-bounces@lists.mpi-forum.org] <B>On Behalf Of </B>Graham,
Richard L.<BR><B>Sent:</B> Saturday, August 01, 2009 9:57 AM<BR><B>To:</B>
'mpi3-coll@lists.mpi-forum.org'<BR><B>Subject:</B> Re: [mpi3-coll] array
parameters in nonblocking collectives<BR></FONT><BR></DIV>
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<P><FONT color=navy size=2 face=Arial>I would expect that the user arguments
shouild not be expected to be preserved in the user's arrays between posting
the collectives and completing them.<BR><BR>Rich</FONT></P>
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<FONT size=2 face=Tahoma><B>From</B>: mpi3-coll-bounces@lists.mpi-forum.org
<MPI3-COLL-BOUNCES@LISTS.MPI-FORUM.ORG><BR><B>To</B>: Torsten Hoefler
<HTOR@CS.INDIANA.EDU><BR><B>Cc</B>: MPI-3 Collective Subgroup Discussions
<MPI3-COLL@LISTS.MPI-FORUM.ORG><BR><B>Sent</B>: Sat Aug 01 09:56:50
2009<BR><B>Subject</B>: [mpi3-coll] array parameters in nonblocking
collectives <BR></FONT>
<P></P><BR><FONT size=2 face=sans-serif>Hi,</FONT> <BR><BR><FONT size=2
face=sans-serif>I have one question about the array parameters (sendcounts,
recvcounts, sdispls and rdispls) in nonblocking collectives such as
MPI_IALLTOALLV. Are callers allowed to modify/destroy those arrays upon the
return of the calls, or they must wait until after the MPI_WAIT call? I
could not find the correct behavior defined in the latest proposal
(nbc-proposal-rev-6.2.pdf) and do not remember having discussion on such.
</FONT><BR><FONT size=2 face=sans-serif>I think this issue is quite unique to
nonblocking collective communication calls since arrays in other MPI
nonblocking calls are arrays of MPI objects, for which the correct handling is
well defined. So it needs to be clarified. </FONT><BR><FONT size=2
face=sans-serif>Am I missing something?</FONT> <BR><BR><FONT size=2
face=sans-serif>Thanks</FONT> <BR><FONT size=2 face=sans-serif>Bin
Jia<BR>Communication Protocol Development<BR>Advanced Clustering Technology
Team, IBM STG<BR>Poughkeepsie, NY 12601<BR>Tel: 845-433-6301(T/L 293-)</FONT>
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