<table cellspacing='0' cellpadding='0' border='0' ><tr><td valign='top' style='font: inherit;'><P>no easy way with mpiexec, especially if you do mpiexec -n. But this should work</P>
<P> </P>
<P> </P>
<P>mpiexec numactl --physcpubind N0 <1 of your proc> :</P>
<P> numactl -- physcpubind N1 <2nd of oof proc> :</P>
<P> .<same for the rest></P>
<P> </P>
<P>add --membind if you want (and you definately want it for Opteron). </P>
<P> </P>
<P>tan</P>
<P><BR><BR>--- On <B>Tue, 7/22/08, Franco Catalano <I><franco.catalano@uniroma1.it></I></B> wrote:<BR></P>
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: rgb(16,16,255) 2px solid">From: Franco Catalano <franco.catalano@uniroma1.it><BR>Subject: [mpich-discuss] processor/memory affinity on quad core systems<BR>To: mpich-discuss@mcs.anl.gov<BR>Date: Tuesday, July 22, 2008, 2:28 AM<BR><BR><PRE>Hi,
Is it possible to ensure processor/memory affinity on mpi jobs launched
with mpiexec (or mpirun)?
I am using mpich2 1.0.7 with WRF on a 4 processor Opteron quad core (16
cores total) machine and I have observed a sensible (more than 20%)
variability of the time needed to compute a single time step. Taking a
look to the output of top, I have noticed that the system moves
processes over the 16 cores regardless of processor/memory affinity. So,
when processes are running on cores away from their memory, the time
needed for the time advancement is longer.
I know that, for example, OpenMPI provides a command line option for
mpiexec (or mpirun) to ensure the affinity binding:
--mca param mpi_paffinity_alone = 1
I have tried this with WRF and it works.
Is there a way to do this with mpich2?
Otherwise, I think that it would be very useful to include such
cabability into the next release.
Thank you for any suggestion.
Franco
--
____________________________________________________
Eng. Franco Catalano
Ph.D. Student
D.I.T.S.
Department of Hydraulics, Transportation and Roads.
Via Eudossiana 18, 00184 Rome
University of Rome "La Sapienza".
tel: +390644585218</PRE></BLOCKQUOTE></td></tr></table><br>