From: peterm@tesla.EECS.Berkeley.EDU (Peter Mardahl) Newsgroups: comp.parallel.mpi Subject: Re: MPI using dual CPUs Date: 27 May 1999 17:12:47 -0700 Organization: UC Berkeley Message-Id: <7ikn1v$cnt$1@tesla.EECS.Berkeley.EDU> References: <374DD6A4.1528B5CA@ahpcc.unm.edu> Xref: ukc comp.parallel.mpi:5137 In article <374DD6A4.1528B5CA@ahpcc.unm.edu>, Brian Baltz wrote: >We have MPICH installed on several dual CPU systems running Redhat 5.2. >How do you know if both CPUs are being used? Are they both used by >default? I assume you're talking about 2 mpi processes on the same machine: what you'd like is for one process to sit on each CPU. An easy way to check is to run "top". This is top output on a dual-CPU RedHat machine which has both CPUs being used: ************ 4:58pm up 34 days, 22:51, 9 users, load average: 1.70, 1.26, 1.17 65 processes: 61 sleeping, 4 running, 0 zombie, 0 stopped CPU states: 173.2% user, 4.5% system, 77.4% nice, 0.0% idle Mem: 517500K av, 296052K used, 221448K free, 46964K shrd, 76400K buff Swap: 257032K av, 1588K used, 255444K free 124512K cached PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND 22794 peterm 1 0 5940 5940 2328 R 0 93.0 1.1 0:25 xoopic 1260 peggyjo 19 19 38232 37M 1320 R N 0 77.4 7.3 33147m xoopic.ionco 21519 wgqiu 0 0 17436 17M 7664 S 0 5.7 3.3 1:27 netscape-com ************ 2 CPUs are NOT used by default in RedHat 5.2. This isn't an MPI issue, but rather an issue with the default kernel shipped with RedHat: it does NOT have SMP enabled, so you will ONLY have 1 CPU to use. So you may need to rebuild the kernel with SMP enabled. This isn't that difficult. PeterM