linux-kernel - Re: [tip:x86/asm] x86/defconfig: Turn on CONFIG_CC_OPTIMIZE_FOR

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Message-ID: <20130126125208.GC21395@pd.tnic>
Date:	Sat, 26 Jan 2013 13:52:08 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	mingo@...nel.org, hpa@...or.com, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, arjan@...ux.intel.com,
	jbeulich@...e.com, ling.ml@...pay.com, rostedt@...dmis.org,
	akpm@...ux-foundation.org, tglx@...utronix.de
Cc:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/asm] x86/defconfig: Turn on
 CONFIG_CC_OPTIMIZE_FOR_SIZE= y in the 64-bit defconfig

On Sat, Jan 26, 2013 at 04:25:57AM -0800, tip-bot for Ma Ling wrote:
> During the same  time (269.410275674 seconds) IPC from Os is
> 0.37, O2 is 0.36, Os improved performance 2.7%.
> 
> Signed-off-by: Ma Ling <ling.ml@...pay.com>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Cc: Arjan van de Ven <arjan@...ux.intel.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Jan Beulich <jbeulich@...e.com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Link: http://lkml.kernel.org/r/1359123061-6139-1-git-send-email-ling.ma@alipay.com
> [ So, this is a bit symbolic as most people don't use the defconfig,
>   but the measurements are useful nevertheless so let's commit this
>   if there are no objections. ]

What about

commit 3a55fb0d9fe8e2f4594329edd58c5fd6f35a99dd
Author: Kirill Smelkov <kirr@....spb.ru>
Date:   Fri Nov 2 15:41:01 2012 +0400

    Tell the world we gave up on pushing CC_OPTIMIZE_FOR_SIZE

?

Reportedly, -Os generates suboptimal code in certain cases and we advise
against it with this patch.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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