[Zope3-dev] hyperthreading (was: Re: Nightly Zope 3 Binary Compiles for Windows)

[Derrick 'dman' Hudson]

On Sat, Apr 24, 2004 at 10:45:53PM +0100, Chris Withers wrote:
| Tim Peters wrote:
 
| >+ One of the --all ZEO tests often fails on my hyper-threaded
| >  Pentium box, but never fails anywhere else, and never fails
| >  if I disable hyper-threading in the BIOS.
| 
| What IS hyper threading?!

Hyperthreading is when a single physical CPU presents two logical CPUs
to the OS.  It's a cheap form of SMP.  The OS kernel's scheduler can
then schedule processes to both logical CPUs and the hardware
(physical CPU) does the actual context switching necessary.  IME
hyperthreading does yield better performance than plain old
uniprocessor operation because a CPU intensive operation doesn't hog
the entire CPU, only half of it.

-D

-- 
Micros~1 :
 For when quality, reliability
  and security just aren't
   that important!
 
www: http://dman13.dyndns.org/~dman/            jabber: dman at dman13.dyndns.org
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