From: "H. Peter Anvin" <hpa@zytor.com>
To: Borislav Petkov <bp@alien8.de>,
mingo@kernel.org, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, arjan@linux.intel.com,
jbeulich@suse.com, ling.ml@alipay.com, rostedt@goodmis.org,
akpm@linux-foundation.org, tglx@linutronix.de
Cc: linux-tip-commits@vger.kernel.org
Subject: Re: [tip:x86/asm] x86/defconfig: Turn on CONFIG_CC_OPTIMIZE_FOR_SIZE= y in the 64-bit defconfig
Date: Sat, 26 Jan 2013 07:18:26 -0800 [thread overview]
Message-ID: <8b0dfc4a-6f9c-498a-9844-4d99deb3052f@email.android.com> (raw)
In-Reply-To: <20130126125208.GC21395@pd.tnic>
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.
Borislav Petkov <bp@alien8.de> wrote:
>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@alipay.com>
>> Cc: Linus Torvalds <torvalds@linux-foundation.org>
>> Cc: Arjan van de Ven <arjan@linux.intel.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Jan Beulich <jbeulich@suse.com>
>> Cc: Steven Rostedt <rostedt@goodmis.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@mns.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.
--
Sent from my mobile phone. Please excuse brevity and lack of formatting.
next prev parent reply other threads:[~2013-01-26 15:20 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-25 14:11 [PATCH] [x86]: Compiler Option Os is better on latest x86 ling.ma.program
2013-01-26 12:25 ` [tip:x86/asm] x86/defconfig: Turn on CONFIG_CC_OPTIMIZE_FOR_SIZE= y in the 64-bit defconfig tip-bot for Ma Ling
2013-01-26 12:52 ` Borislav Petkov
2013-01-26 15:18 ` H. Peter Anvin [this message]
2013-01-26 15:42 ` Borislav Petkov
2013-01-26 19:43 ` Linus Torvalds
2013-01-26 21:02 ` Steven Rostedt
2013-01-26 21:04 ` H. Peter Anvin
2013-01-27 12:49 ` Ingo Molnar
2013-01-26 21:08 ` H. Peter Anvin
2013-01-28 17:15 ` [PATCH] [x86]: Compiler Option Os is better on latest x86 Valdis.Kletnieks
2013-01-29 8:12 ` Ingo Molnar
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