Re: puzzled re hyperthreaded performance

["Wiljan Derks" <Wiljan.Derks@zonnet.nl>]

I did some performance testing on hyperthreaded pentium 2.8 using windows 
XP.
My conclusion was amazing:
* Hyperhreading works: it is as if things are executed in parallel
* Typically when only one thead is active, it can almost do the same amount 
of work
   compared to the situation with hyperthreading disabled.
* When two threads are active, the total amount of work done is certainly 
not more
   then having one thread is active.
* With hypertreading disabled, there seems to be more total performace.
Thus basically hyperthreading can makes a system more responsive, but not 
faster in cpu performance.
So it is not like a multiprocessor system.
I think the hypertreading is more like multiplexing the cpu over different 
threads without the
cost of taskswitching but t does not give you additional CPU performance.
This effect can make measurements very confusing.

I whould like to know if anyone has a different experience.