<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">Yes, in a very subtle way which has major impact on performance. I will try to decribe it a litle here:</DIV>
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<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">system has 32G, total image 35G. Load is a litle offbalance mathematically, 4X dual core, running 5 processes.</DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">4 processes are the same size, each runs on a CPU. the last process is very small, about10% of others, run</DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">on a core of one of the CPU. SO 1 CPU runs 2 procs: average (P1)one and light one (P2).</DIV>
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<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">All proc do first MPI comm in a fixed algorithmic point. The 'useful' image is about 29G at that point, and should</DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">fit into the physical memory. P2 get there in a heart beat, then others., followed by P1 which took another 60+ minutes</DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">to get there. If I combine P1 and P2 into 1 process, then I don;t no see this extra delay.</DIV>
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<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">tan</DIV>
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<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">----- Original Message ----<BR>From: Darius Buntinas <buntinas@mcs.anl.gov><BR>To: chong tan <chong_guan_tan@yahoo.com><BR>Cc: mpich-discuss@mcs.anl.gov<BR>Sent: Monday, December 17, 2007 8:02:17 AM<BR>Subject: Re: [MPICH] any way to ask nemesis to turn-off and turn of active polling ?<BR><BR><BR>No, there's no way to do that. Even MPI_Barrier will do active polling.<BR><BR>Are you having issues where an MPI process that is waiting in a blocking <BR>call is taking CPU time away from other processes?<BR><BR>-d<BR><BR>On 12/14/2007 04:53 PM, chong tan wrote:<BR>> My issue is like this :<BR>> <BR>> among all the processess, some will get to the point of first MPI <BR>> communication points faster than<BR>> than other. Is there a way that I tell nemesis to start without doing <BR>> active polling, and then turn<BR>> on active
polling with some function ?<BR>> <BR>> Or should I just use MPI_Barrier() on that ?<BR>> <BR>> thanks<BR>> tan<BR>> <BR>> <BR>> ------------------------------------------------------------------------<BR>> Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try <BR>> it now. <BR>> <<A href="http://us.rd.yahoo.com/evt=51733/*http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ" target=_blank>http://us.rd.yahoo.com/evt=51733/*http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ</A> <BR>> ><BR></DIV>
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