[no subject]

In our CFD (computational fluid dynamics) research, we've seen a wide
range of speed changes using HT.  Some are great, and others are
deplorable.  I think it mainly has to do with the APP and the data being
crunched.

Thanks

Jonathan Glass

On Wed, 2004-04-14 at 14:00, Steven A. DuChene wrote:
> I have been reading the responses in this thread so far but i have not as of
> yet actually heard anything about checking to see if a particular P4 processor
> is really Hyperthread capable. Not all P4 processors are created equal and
> some are not Hyperthread capable. Typically other than actually research the
> particular processor specs on the Intel web site the best way to tell is to
> see if there is an option in the motherboard BIOS to turn Hyperthreading on
> or off. Once it is turned on if you then run a SMP kernel you will actually
> see more than one processor being reported in /proc/cpuinfo
> 
> If you run an SMP kernel and still only see one processor in /proc/cpuinfo
> then either the Hyperthreading support is not turned on OR your processor
> is not Hyperthread capable.
> 
> Now, as to whether it is a good thing or a bad thing to turn on, it is all
> a question of the particular types of work loads the system sees. There are
> cases where Hyperthreading is not actually a help and in some cases it may
> actually be a performance degradation.
> 
> On Wed, Apr 14, 2004 at 10:40:40AM -0400, Dow Hurst wrote:
> > Yes, I run two minimizations simultaneously on my single P4 and until the 
> > second one starts the machine is very responsive.  It is truly like having a 
> > dual CPU from my user perspective.  Run times are doubled on the minimizations.
> > 
> > 25m37.821s   Single run
> > 
> > 49m54.143s
> > 44m10.795s   Dual runs (The second is the shorter due to different start 
> > times, so this is general datapoints)
> > 
> > 
> > These are GPCR receptor minimizations with delta 9 THC bound inside the 
> > receptor.  About ~2700 atoms in vacuum using molecular mechanics and a lot of 
> > torsional restraints applied.  Not a difficult calculation but is pure FPU on 
> > C and Fortran code.  But, my point is the machine was acting like a dual CPU 
> > machine in a very efficient manner.
> > Dow
> > 
> > 
> > Christopher Fowler wrote:
> > > How is the performance? Is there a real gain?
> > > 
> > > On Wed, 2004-04-14 at 10:03, Jonathan Glass wrote:
> > > 
> > >>On Wed, 2004-04-14 at 10:02, Mike Millson wrote:
> > >>
> > >>>I have a box with a P4 processor running Slackware 9.1. What do I need
> > >>>to do to enable hyperthreading support? Do I just have to compile a
> > >>>kernel with SMP support? Are there any other kernel options or config
> > >>>changes I need to make? Does anyone know of any good articles or howtos
> > >>>on configuring linux for hyperthreading?
> > >>>
> > >>>Thank you,
> > >>>Mike
> > >>>
-- 
Jonathan Glass
Systems Support Specialist II
Institute for Bioengineering & Bioscience
Georgia Institute of Technology
Email: jonathan.glass at ibb.gatech.edu
Office: 404-385-0127
Fax: 404-894-2291


</pre>
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<li><strong><a name="00498" href="msg00498.html">[ale] Hyperthreading</a></strong>
<ul><li><em>From:</em> jeffrey.b.layton at lmco.com (Jeff Layton)</li></ul></li>
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<li><strong><a name="00477" href="msg00477.html">[ale] Hyperthreading</a></strong>
<ul><li><em>From:</em> mmillson at meritonlinesystems.com (Mike Millson)</li></ul></li>
<li><strong><a name="00478" href="msg00478.html">[ale] Hyperthreading</a></strong>
<ul><li><em>From:</em> jonathan.glass at ibb.gatech.edu (Jonathan Glass)</li></ul></li>
<li><strong><a name="00480" href="msg00480.html">[ale] Hyperthreading</a></strong>
<ul><li><em>From:</em> cfowler at outpostsentinel.com (Christopher Fowler)</li></ul></li>
<li><strong><a name="00484" href="msg00484.html">[ale] Hyperthreading</a></strong>
<ul><li><em>From:</em> dhurst at kennesaw.edu (Dow Hurst)</li></ul></li>
<li><strong><a name="00495" href="msg00495.html">[ale] Hyperthreading</a></strong>
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