Boyd Stephen Smith Jr. wrote:
On Wednesday 31 January 2007 09:58, Alan McKinnon <[EMAIL PROTECTED]> wrote about 'Re: [gentoo-user] Symlinking /usr/portage/distfiles':
On Wednesday 31 January 2007, Bo Ørsted Andresen wrote:
Furthermore Pentium 4 is a joke (it performs horribly). A 2 GHz
(Dothan I presume) Pentium-M should be faster than a 2,8 GHz Pentium
4. My timing is for an 1,6 GHz (Banias) Pentium-M btw.
This sounds odd, but I'm not a cpu expert so can't really comment. Care
to elaborate on why the P4 performs so horribly?

The instruction pipeline is very long, the CPU <-> RAM bandwith is quite small, and the pipeline has to be emptied any time the branch predictor is wrong. While the pipeline fills, the CPU works but no results are visible.

Hz has never been a complete trump of other issues affecting CPU performance, but is always a factor to consider. (Among CPUs that are otherwise identical, higher Hz wins.)


Also Pentium-M has a lower latency L2 cache than P-4. With respect to pipeline lengths I was curious to see what they actually were: P-4 has 20 stages, P-M has.. err... < 20 stages (Intel won't say exactly!).

I found this an interesting read for those of you interested in this:

http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2342&p=1

Cheers

Mark
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