[ale] Hyperthreading

[James P. Kinney III]

On Sun, 2004-08-15 at 22:51, James Sumners wrote:
> That is very odd. I have a box with dual 2.0Ghz HT processors and it can compile
> MySQL in four minutes and some change.

You have two physical processors. Some things do work OK with HT. Some
aspects of program compiling should while others should thrash the
cache. Test this by turning off the HT in the bios and recompile from a
fresh MySQL tarball and time it. Then reboot an turn the HT back on and
do it again and publish your results. 

Even better would be to add a third step of disabling one processor and
running just HT and get that timing data.

And while you're at it, turn of HT and do it all a fourth time just for
a baseline.

None of my dual CPU machines are even _close_ in capabilities so I can't
test anything like this with my rigs. (How does one compare a dual
Opteron 1.4 GHZ with a dual PIII 550 and a PIV 2.2GHz w/HT?)
> 
> On 15 Aug 2004 10:10:29 -0400
> "James P. Kinney III" <jkinney at localnetsolutions.com> wrote:
> 
> > On Sat, 2004-08-14 at 23:01, Christopher Fowler wrote:
> > > On the new machine I'm installing FC2 on it is a Intel PIV 3.0Ghz.  It
> > > supports Hyperthreading.  Should I disable it?  How do I use it?
> > 
> > A performance note: I have one P4 w/hyperthreading. There are so many
> > things it does slower with HT on than off that I finally turned it off.
> > 
> > The biggest slow-up was calculating the my digital signature on my
> > email. I would have to dig out the specs on my cpu  (it's an earlier
> > version) and do some hard timing tests, but a digital signature on a
> > short email would take 2-3 seconds with HT on and under 1 second with it
> > off. It may be a cache size issue that is causing the processor to
> > thrash.
-- 
James P. Kinney III          \Changing the mobile computing world/
CEO & Director of Engineering \          one Linux user         /
Local Net Solutions,LLC        \           at a time.          /
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GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics)
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