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<DIV dir=ltr align=left><SPAN class=062594315-18042008><FONT face=Arial
color=#0000ff size=2>Are your programs multithreaded or are they just
multiprocess MPI programs? If the latter, don't use the
--enable-threads=multiple option. Instead, use the Nemesis communication device
by configuring with --with-device=ch3:nemesis.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=062594315-18042008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=062594315-18042008><FONT face=Arial
color=#0000ff size=2>Rajeev</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=062594315-18042008></SPAN> </DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> owner-mpich-discuss@mcs.anl.gov
[mailto:owner-mpich-discuss@mcs.anl.gov] <B>On Behalf Of </B>David R
Anderson<BR><B>Sent:</B> Friday, April 18, 2008 9:10 AM<BR><B>To:</B>
mpich-discuss@mcs.anl.gov<BR><B>Subject:</B> [mpich-discuss] multi
threading<BR></FONT><BR></DIV>
<DIV></DIV><BR><FONT face=sans-serif size=2>I have mpich2 (1.0.6) installed on
a Dell poweredge compute server with Red Hat Linux installed. The server
is new and has 4-quad core processors. I have compiled mpich2 using the
--enable-threads=multiple option for configure. After compiling mpi
versions of several programs I find that I get good speedup results up to 8
processors, however, no benefit from 9-16. There is a small drop in
performance from 8-9 and then by 16 processors has caught back up to the same
speedup value as with 8.</FONT> <BR><BR><FONT face=sans-serif size=2>Is there
something else I need in the config options, or is dual threading the best
that I can get? I'd appreciate any advice.</FONT> <BR><FONT
face=sans-serif size=2><BR>Thanks in advance,</FONT> <BR><FONT face=sans-serif
size=2><BR>Dave</FONT> <BR><FONT face=sans-serif
size=2>---------------------------------------------------<BR>David R.
Anderson<BR>Principal Engineer<BR>D412, Radiation Analysis Section<BR>Phone:
(860)433-6584, FAX (860)433-3229<BR>E-mail:
danders3@gdeb.com<BR></BLOCKQUOTE></FONT></BODY></HTML>