JeremyP's Blog

I saw an advert on the telly last night, from PC World. The advert was pushing their latest PC bargain which had a Pentium "P4 with HT technology" apparently. They seemed very pleased with themselves that they could offer HT technology at £899 or whatever.

So, hands up any non techy who knows what HT technology is. Keep your hand up if you have any idea at all how it might make your computer better.

As far as I can see, this "includes HT technology" line is cynical marketing speak to blind ordinary people with techno-babble. There was no attempt made to explain what hyper-threading is and why it is better or even that HT means hyper-threading.

Htper-threading means that your CPU is divided into two logical processors and can handle two threads of execution simultaneously. You might think that this makes it twice as fast, but that's not necessarily the case. For one thing, both logical CPUs have to share all of the chip's resources including, importantly, the cache. The cache works on the assumption that recently used memory locations are most likely to be the ones used next so these memory locations are copied into extra fast memory on the processor chip. If you have two threads running on that chip, this will compromise the efficiency of the cache unless those two threads are working on the same data. In some circumstances, hyper-threading will slow your computer down.

Don't believe the techno-babble of PC World. If you want a faster computer, concentrate on memory bus speed and disk IO and cache size - the power of the actual processor is less important than you might think.