[gmx-users] hyperthreading

David van der Spoel spoel at xray.bmc.uu.se
Fri Jan 30 09:33:01 CET 2004

On Thu, 2004-01-29 at 19:31, Anton Feenstra wrote:
> IMHO, hyperthreading sounds like a dirty fix to a stupid problem that any
> decent operating system should be able to solve (and solve it better!).
yes and no,

since the P4 has such long pipelines, a stall due to, e.g., a cache miss
is expensive, if you have another process waiting for the CPU it can use
this stall time. Some benchmarks, like database/web server benchmarks do
show improved performance by 10-15%. Doesn't work for gromacs though.
However, Intel's plan is to put two chips on a chip, which will appear
to the OS as the same thing that is already here and now with
hyperthreading. Other vendors already have such chips AFAIK.
David van der Spoel, PhD, Assist. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://xray.bmc.uu.se/~spoel

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