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On Thu, Nov 11, 2004 at 05:11:59PM +0000, Ian Stokes-Rees wrote: > What advantage do you get by saying there is a second processor which > you only use for maintenance operataions? Couldn't you just run a > additional process on the one real processor? Well, first of all pbs_mom doesn't steal as much compute cpu cycles when HT is on, it's not a big difference but it's there. Secondly, some of our users do things like piping output through gzip while doing computations at the same time. They generally get somewhere around 102-103% cpu time used on their jobs on a physically single CPU. This is a good thing. Running atlas blas as a threaded libarary gives us 102% compared to the non threaded version on our Pentium(R) 4 CPU 2.80GHz for some larger codes. Every little piece of extra CPU gained is a plus. One does however have to be careful not to run things that steal alot of cache... > Sorry, I think that should have been PCI Express, which, I think, is not I suspected as much. -- Ake Sandgren, HPC2N, Umea University, S-90187 Umea, Sweden Internet: [log in to unmask] Phone: +46 90 7866134 Fax: +46 90 7866126 Mobile: +46 70 7716134 WWW: http://www.hpc2n.umu.se