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

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Message-ID: <20130126154256.GB16044@pd.tnic>
Date:	Sat, 26 Jan 2013 16:42:56 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	mingo@...nel.org, 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,
	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 07:18:26AM -0800, H. Peter Anvin wrote:
> On the CPUs Ling is testing on the downsides of -Os probably matter
>less, in particular since rep movsb works well.
>
> It is questionable as a generic default, though.
>
> The whole -Ok discussion came from that.

Hmm,

maybe this warrants some sort of a text addition to the config option
about when and where it is ok to select -Os. Also, is it so that
on those CPUs, -Os is always better or at least neutral so that it
doesn't cause any perf regressions when people enable it? I mean, I
see only netperf and volano runs in the commit message, maybe running
a comprehensive set of benchmarks would give us a much more detailed
picture...

Thanks.

-- 
Regards/Gruss,
    Boris.

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