Messages in this thread | | | Date | Thu, 20 Jun 2002 15:18:44 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: latest linus-2.5 BK broken |
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On Thu, 20 Jun 2002, Martin Dalecki wrote: > > Yes HT gives 12%. naive SMP gives 50% and good SMP (aka corssbar bus) > gives 70% for two CPU. All those numbers are well below the level > where more then 2-4 makes hardly any sense...
You don't _understand_.
If it's "free", you take that 70% for the second CPU, and the additional 20% for the next two.
Don't bother repeating yourself about Amdahls law. Realize what Moore's law says: things get cheaper over time. A _lot_ cheaper.
It's still a fact that people are willing to pay for performance. Even if they strictly don't "need" it (but who are you or I to say who "needs" performance?).
At which point it doesn't _matter_ if you only get 70% or 30% or 12% improvement. If it's within "cheap enough", people will buy it. In fact, once it gets "too cheap", people will buy something more expensive just because a cheap PC obviously isn't good enough. That's _reality_.
Your "efficiency" arguments have no basis in the real life of economics in a developing market. Only embedded people care about absolute cost and absolute efficiencies ("it's not worth it for us to go for a more powerful CPU, since we don't need it"). The rest of the world takes that 66MHz improvement (in a CPU that does multiple gigahertz) and is happy about it. Or takes the added 12%, and is happy about it.
Humans are not rational creatures. We're _rationalizing_ creatures, and we love rationalizing that big machine that just makes us feel better.
Linus
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