<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">thank you very much. This paper and source codes help me alot.<br><br>--- On <b>Wed, 8/12/09, Rajeev Thakur <i><thakur@mcs.anl.gov></i></b> wrote:<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"><br>From: Rajeev Thakur <thakur@mcs.anl.gov><br>Subject: Re: [mpich-discuss] broadcast and reduce mechanism<br>To: mpich-discuss@mcs.anl.gov<br>Date: Wednesday, August 12, 2009, 8:59 AM<br><br><div class="plainMail">The code is in the src/mpi/coll directory. See bcast.c and reduce.c.<br><br>Rajeev <br><br>> -----Original Message-----<br>> From: <a ymailto="mailto:mpich-discuss-bounces@mcs.anl.gov" href="/mc/compose?to=mpich-discuss-bounces@mcs.anl.gov">mpich-discuss-bounces@mcs.anl.gov</a> <br>> [mailto:<a ymailto="mailto:mpich-discuss-bounces@mcs.anl.gov"
href="/mc/compose?to=mpich-discuss-bounces@mcs.anl.gov">mpich-discuss-bounces@mcs.anl.gov</a>] On Behalf Of Dave Goodell<br>> Sent: Wednesday, August 12, 2009 9:01 AM<br>> To: <a ymailto="mailto:mpich-discuss@mcs.anl.gov" href="/mc/compose?to=mpich-discuss@mcs.anl.gov">mpich-discuss@mcs.anl.gov</a><br>> Subject: Re: [mpich-discuss] broadcast and reduce mechanism<br>> <br>> You can find some information in this paper: <br>> <a href="http://www.mcs.anl.gov/~thakur/papers/mpi-coll.pdf" target="_blank">http://www.mcs.anl.gov/~thakur/papers/mpi-coll.pdf</a><br>> <br>> However since that was written there have been a few changes, some <br>> major and some minor. One difference is that we now perform those <br>> collective operations hierarchically on SMP systems (intranode, <br>> internode, then intranode again). Also, additional algorithms might <br>> have been selected and the cutoff
points are almost certainly <br>> different. So the best way to figure out what's going on in <br>> there is <br>> to read the code.<br>> <br>> As far as I know we don't use sequential communication to implement <br>> any of our collective operations.<br>> <br>> -Dave<br>> <br>> On Aug 11, 2009, at 9:34 PM, Gra zeus wrote:<br>> <br>> > Hello,<br>> ><br>> > Can any one comfirm or link me to documents that explain <br>> > communication mechanism of MPI_Bcast and MPI_Reduce?<br>> ><br>> > I searched in google and It said Bcast,Reduce can use tree <br>> algorithm <br>> > or sequential communication.<br>> > However, I can't find any specification that indicate <br>> communication <br>> > mechanism of MPI_Bcast and MPI_Reduce in MPICH2.<br>> ><br>> > thx,<br>> > gra<br>> ><br>> <br>>
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