To hyper-thread or not to hyper-thread

[Joerg Bergmann]

Am Montag, den 07.12.2009, 09:02 -0600 schrieb Aaron Konstam:
> I acquired another computer recently that has a Pentium(R) 4  D CPU Dual
> core that is capable of hyper-threading.
> 
> I was not satisfied with its performance so I looked carefully at its
> configuration and found that hyper-threading was disabled. A little more
> looking and I noticed that hyper-threading was disabled in the BIOS and
> could not be turned on. So what are my options if I want to enable
> hyper-threading and is it worth it?
> 
> One option I assume is to find another BIOS. Are there other options or
> if it is disabled in the BIOS it is disabled?
> 
> Another question is how much boost in performance should I expect from
> the dual core SMB functionality of the CPU?
> --

The problem of the Pentium 4 D: It is not really a dual core one.
Hyper-Threading means: There is one core with two execution paths, which
means some of the common CPU features, but not all, are present twice.
As I remember: Under some circumstances, there were some percent
performance boost. But mostly there was more a performace loss if one
enables hyperthreading on a P4. That may be the reason for having 
disabled the hyperthreading in the BIOS. Things may have changed with
more up-to-date INTEL hyperthreading CPUs...

Joerg