RE: Hyperthreading or not? Dual-core experience?

From our testing here, hyperthreading ends up just slowing down your HPC program instead of making it faster.

HPC programs utilize 100% of the processor all of the time.  Since hyperthreading just divides the processor you have into 2 logical units, you would be putting 200% load on your system.  Hyperthreading works better in business/home computing applications where you have lots and lots of processes that are shortlived that run on the same CPU.

Unless you are using your OM cluster for web servicing or other non HPC use I'd suggest disabling hyperthreading.

-Evan T.

-----Original Message-----
From: openmosix-general-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org [mailto:openmosix-general-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org] On Behalf Of Jürgen Knödlseder
Sent: Friday, February 24, 2006 10:48 AM
To: openmosix-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: [openMosix-general] Hyperthreading or not? Dual-core experience?

Hi everybody,

I would like to hear your opinion about enabling or not-enabling
hyperthreading in an openMosix cluster. The openMosix-HOWTO
states that the performances increase with the current Linux
scheduler when hyperthreading is disabled. On the other side,
I read some comment on an Intel web site that hyperthreading
in combination with openMosix brings some benifits ...

Does anybody has some opinion/experience about this issue?
Has somebody done some benchmarks?

By the way: has anyone experience with dual-core processors and
openMosix? I suppose that this should be transparent to openMosix,
but it would be nice if someone could confirm that there is no
problem. And: is a single dual-core processor as fast as two single-core
processors?

Thanks for providing your feedback!

Best regards,
Jürgen

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