I'm sorry. I mistake to send this mail.
Thanks,
Yosihiro Itou
besus <[log in to unmask]> wrote:
> Tim Prince <[log in to unmask]> wrote:
>
> > On Sunday 23 February 2003 04:41, Jeffrey B. Layton wrote:
> > > Tim Prince wrote:
> > > >In my experience,
> > > >'mpirun -np 2' on a single CPU P4 increases throughput by about 10% from
> > > > -np 1, but that gain doesn't hold up for scaling to a large cluster with
> > > > simple interconnects.
> > >
> > > Tim,
> > >
> > > My experience agrees with yours. When I ran the NASA Parallel
> > > Benchmarks on a Xeon cluster with even plain Fast Ethernet, it
> > > was always faster to turn off HT (we did it at the kernel level and
> > > at the BIOS level) These results are also supported by the following:
> > >
> > > http://computational-battery.org/Maskinvare/Hyperthreading.html
> > >
> > Apparently, those results were obtained with an early Xeon model with small
> > cache. Not that I dare to judge the issue, but results like this, where
> > simply turning on HT hurts performance, have sometimes been traced to errors
> > in the BIOS.
> >
> > > Jeff
> >
> > --
> > Tim Prince
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