The new Hyper-Threading Pentium 4 is in essence a normal Pentium 4 and the Hyper-Threading feature is an added bonus if you are an avid multitasker or have applications that are multithreaded. It can be considered transparant for applications that cannot take any benefit from it. However as we already mentioned in the previous pages there could well be applications that perform worse with Hyper-Threading enabled.
Clearly, this article is by no means an exhaustive analysis of Hyper-Threading technology. A full and complete exploration of the subject isn't a 10-page document, it's a 1,000 page one, and that's precisely what we've attempted to convey. There are no easy answers here, and in fact, by slight manipulation of the variables, we could likely achieve any 'answer' we wanted with respect to the performance of Hyper-Threading. It's important to remember that when forming an opinion of the technology.
Fig 5. The rather large, and faily loud, copper core, skived heatsink that is supplied with the 3.06GHz Pentium 4.
In summary Hyper-Threading is a innovative new feature that helps to up the efficiency of the Pentium 4 processor and can boost the performance of the processor significantly. There's only one drawback that might put the brakes on the performance under some circumstances and that's that the shared resources inside the Hyper-Threading processor are not SMT aware. These shared resources are both the Hyper-Threading Pentium 4' strength and weakness as they up efficiency but could also lower performance.
There’s unfortunately no easy way around this with the current Hyper-Threading implementation. Maybe a future generation of SMT processors will have SMT aware shared resources and thus can better schedule execution among them. This would greatly attribute to the performance of a Hyper-Threading processor and be especially beneficial for the shared cache subsystem. Maybe that is a feature we'll see debut with Prescott, Intel's next generation processor architecture?
Sander Sassen & Dan Mepham.