Date: Thu, 1 May 2003 22:14:25 -0700 (PDT)
From: Linus Torvalds <torvalds@transmeta.com>
To: "David S. Miller" <davem@redhat.com>
cc: linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] Faster generic_fls
In-Reply-To: <1051790452.8772.18.camel@rth.ninka.net>
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On 1 May 2003, David S. Miller wrote:
> 
> This actually is false.  GCC does not know what resources the
> instruction uses, therefore it cannot perform accurate instruction
> scheduling.

Yeah, and sadly the fact that gcc-3.2.x does better instruction scheduling 
has shown itself to not actually _matter_ that much. I'm quite impressed 
by the new scheduler, but gcc-2.x seems to still generate faster code on 
too many examples.

CPU's are getting smarter, not dumber. And that implies, for example, that 
instruction scheduling matters less and less. What matters on the P4, for 
example, seems to be the _choice_ of instructions, not the scheduling of 
them.

			Linus

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