If I have HT enabled, does my processor go half the speed?I?

Question

I have Hyper Threading enabled on my Pentium 4 and I would like to know, since Hyper Threading creates two virtual cores, does each core run at half the speed? And what is the difference between using just one virtual core and the whole processor if HT is disabled?

Answer 1

No. There only is one core, but it pretends to be two. If you use all the CPU on one virtual processor you are utilizing most of the CPU. The purpose of Hyper Threading is to catch a few idle processor resources, resulting in a performance gain of a few percent. It takes advantage of SMP schedulers to get a bit more performance out of one core. There really isn't any different between using one virtual processor or the only processor when HT is disabled.