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Date: Thu, 20 Jun 2002 15:18:44 -0700 (PDT)
From: Linus Torvalds <torvalds@transmeta.com>
To: Martin Dalecki <dalecki@evision-ventures.com>
cc: Cort Dougan <cort@fsmlabs.com>,
       "Eric W. Biederman" <ebiederm@xmission.com>,
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       Rusty Russell <rusty@rustcorp.com.au>, Robert Love <rml@tech9.net>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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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