Max Power wrote:

FAQ : http://en.wikipedia.org/wiki/Hyperthreading

Hyper-threading, officially called Hyper-Threading Technology (HTT), is

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can support. According to Intel, the first implementation only used an additional 5% of the die area over the "normal" processor, yet yielded performance improvements of 15-30%.

Intel claims up to a 30% speed improvement compared against an otherwise identical, non-SMT Pentium 4. The performance improvement seen is very application dependent, however, and some programs actually slow down slightly when HTT is turned on. This is due to the replay system of the

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The future of Hyper-Threading is not bright. With Intel shifting its priority in processor design to energy efficiency and multi-core instead of single-core performance, Hyper-Threading seems to be a dead end. Hyper-Threading consumes about the same amount of power as an additional processor core, even though adding the technology only offers a fraction of the performance increase compared to adding another core to a processor.

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An interesting quote, thanks.

Rather interesting is the comment that the extra logic needed to add HT consumes so much power to then give only the (small) very application dependant performance boost seen.

The P4 very deep pipelines and HT sounds like an awful lot of design work just to chase high clock speeds!

(Note: clock speed alone does not equal performance.)

Regards,
Martin