Mienai nous apporta ses lumieres en ce 2005-02-01 04:41:

> 
> That's not quite completely correct.  A P4 with hyperthreading is a single
> physical processor but two logical processors.  Logical and virtual are not
> to be confused.  Long story short while it's true the two logical
> processors do share some of their physical resources so it's not true SMP,
> it's fairly close in most aspects due to the way the pipeline is designed.
> It's more than emulation.  Overall it's a more efficient processor
> (assuming you have software that can utilize it).  So when windows is
> reporting that it's only using 50% of it resources that's mostly true and
> also why you can run other programs without lagging them or POV (POV keeps
> utilizing it's full logical processor while the other programs use
> resources from the other).
> 
> Actual benchmarks have shown that if you run 2 instances of POVRay on a
> hyperthreading machine (one instance on each logical processor, each
> rendering half your image) you will have the completed image in around half
> the time (assuming the two halfs take about the same time to render).
> 
> Try SMPov (I use it with my render farms and it works pretty good), it's
> fairly easy to set up and run.  The one downside to this sort of thing is
> when you're doing radiosity you can get seams where the images were put
> together and with photons I'd suggest saving a photon map and loading it to
> save on preprocessing time.
> 
> 
I've seen benchmarks results that point to a possible preformance *improvement* by
disabling 
hyperthreading.

Alain

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