linux-kernel - Re: -Os versus -O2

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Message-ID: <467F191C.9090506@gmail.com>
Date:	Mon, 25 Jun 2007 03:23:40 +0200
From:	Rene Herman <rene.herman@...il.com>
To:	Adrian Bunk <bunk@...sta.de>
CC:	Arjan van de Ven <arjan@...radead.org>,
	Benjamin LaHaise <bcrl@...ck.org>,
	Oleg Verych <olecom@...wer.upol.cz>, rae l <crquan@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: -Os versus -O2

On 06/25/2007 02:41 AM, Adrian Bunk wrote:

> The interesting questions are:
> Does -Os still sometimes generate faster code with gcc 4.2?
> If yes, why?

I would wager that the CPU type makes more of a difference than the compiler 
version. That is, I'd expect my Duron with it's "puny" 64K L1 to have a very 
different profile than it's Athlon brother with 256K L1. Not to mention CPUs 
with as little as 8K L1 (P1).

I can't quote numbers -- it's a bit hard to test those things anyway as it's 
a system-global effect and not su much that's easily isolated in a dedicated 
benchmark.

Rene.
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