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From: Andi Kleen <andi@firstfloor.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>, Pekka Enberg <penberg@kernel.org>,
	Jesper Juhl <jj@chaosbits.net>,
	linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Daniel Lezcano <daniel.lezcano@free.fr>,
	Eric Paris <eparis@redhat.com>,
	Roman Zippel <zippel@linux-m68k.org>,
	linux-kbuild@vger.kernel.org,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: PATCH][RFC][resend] CC_OPTIMIZE_FOR_SIZE should default to N
Date: Wed, 23 Mar 2011 10:45:48 -0700	[thread overview]
Message-ID: <m21v1x91df.fsf@firstfloor.org> (raw)
In-Reply-To: <AANLkTikz+vJGFuysDXAdVb33q1q3L547dXNJa9NmeqeM@mail.gmail.com> (Linus Torvalds's message of "Tue, 22 Mar 2011 09:59:59 -0700")

Linus Torvalds <torvalds@linux-foundation.org> writes:

> On Tue, Mar 22, 2011 at 3:27 AM, Ingo Molnar <mingo@elte.hu> wrote:
>>
>> If that situation has changed - if GCC has regressed in this area then a commit
>> changing the default IMHO gains a lot of credibility if it is backed by careful
>> measurements using perf stat --repeat or similar tools.
>
> Also, please don't back up any numbers for the "-O2 is faster than
> -Os" case with some benchmark that is hot in the caches.

Haven't done it recently, but some time last year -O2 vs -Os
made a measurable difference in large OLTP benchmarks.

(-Os being worse of course -- friends don't let friends use -Os)

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only

  reply	other threads:[~2011-03-23 17:47 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-21 20:08 Jesper Juhl
2011-03-22  2:52 ` Steven Rostedt
2011-03-22  8:21 ` Pekka Enberg
2011-03-22  8:25   ` Jesper Juhl
2011-03-22 10:27   ` Ingo Molnar
2011-03-22 16:59     ` Linus Torvalds
2011-03-23 17:45       ` Andi Kleen [this message]
2011-03-23 21:14       ` Ingo Molnar

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