From: Andi Kleen <ak@suse.de>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [2.6 patch] add a config option for -Os compilation
Date: 18 Oct 2003 21:19:32 +0200 [thread overview]
Message-ID: <p731xtapd4r.fsf@oldwotan.suse.de> (raw)
In-Reply-To: <20031018105733.380ea8d2.akpm@osdl.org.suse.lists.linux.kernel>
Andrew Morton <akpm@osdl.org> writes:
> And bear in mind that you can see significant changes in benchmark results
> between equivalent kernels even when the optimisation level is kept the
> same, due to aliasing and alignment luck.
It also depends on a lot on the compiler version. On 2.95
it was common wisdom that -Os is often fastest, but that changed
in later versions.
Best would be actually a mix of both - setting it case by case.
That's already done in specific cases, e.g. ACPI is always compiled
with -Os. This could be done for other files which are clearly
slow path too.
Profile feedback is unfortunately not an option because it is too
unpredictable and causes maintenance problems.
-Andi
next parent reply other threads:[~2003-10-18 19:19 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20031015225055.GS17986@fs.tum.de.suse.lists.linux.kernel>
[not found] ` <20031015161251.7de440ab.akpm@osdl.org.suse.lists.linux.kernel>
[not found] ` <20031015232440.GU17986@fs.tum.de.suse.lists.linux.kernel>
[not found] ` <20031015165205.0cc40606.akpm@osdl.org.suse.lists.linux.kernel>
[not found] ` <20031018102127.GE12423@fs.tum.de.suse.lists.linux.kernel>
[not found] ` <649730000.1066491920@[10.10.2.4].suse.lists.linux.kernel>
[not found] ` <20031018102402.3576af6c.akpm@osdl.org.suse.lists.linux.kernel>
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[not found] ` <20031018105733.380ea8d2.akpm@osdl.org.suse.lists.linux.kernel>
2003-10-18 19:19 ` Andi Kleen [this message]
2003-10-19 13:56 ` [2.6 patch] add a config option for -Os compilation Ingo Oeser
2003-10-19 14:09 ` Michael Buesch
2003-10-19 17:37 ` Sam Ravnborg
[not found] <Ip4B.8lT.23@gated-at.bofh.it>
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[not found] ` <Ip4B.8lT.21@gated-at.bofh.it>
2003-10-19 17:04 ` Ihar 'Philips' Filipau
[not found] <Ioi6.7kG.15@gated-at.bofh.it>
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[not found] ` <IorM.7wQ.11@gated-at.bofh.it>
2003-10-19 16:55 ` Ihar 'Philips' Filipau
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[not found] ` <InYQ.6OJ.21@gated-at.bofh.it>
2003-10-19 16:05 ` Ihar 'Philips' Filipau
2003-10-19 16:14 ` Wichert Akkerman
2003-10-19 16:31 ` Valdis.Kletnieks
2003-10-19 16:57 ` Maciej Zenczykowski
2003-10-19 18:00 ` Valdis.Kletnieks
[not found] <H2MN.3cm.7@gated-at.bofh.it>
[not found] ` <H366.3IC.9@gated-at.bofh.it>
[not found] ` <H3fO.3VO.13@gated-at.bofh.it>
[not found] ` <H3IO.4yt.9@gated-at.bofh.it>
[not found] ` <HWvz.5PI.9@gated-at.bofh.it>
[not found] ` <I1EP.5QO.1@gated-at.bofh.it>
2003-10-18 17:10 ` Ihar 'Philips' Filipau
[not found] ` <20031019113743.GO12423@fs.tum.de>
2003-10-19 14:15 ` Ihar 'Philips' Filipau
2003-10-19 15:40 ` Martin J. Bligh
2003-10-15 22:50 Adrian Bunk
2003-10-15 23:12 ` Andrew Morton
2003-10-15 23:24 ` Adrian Bunk
2003-10-15 23:52 ` Andrew Morton
2003-10-18 10:21 ` Adrian Bunk
2003-10-18 15:45 ` Martin J. Bligh
2003-10-18 17:24 ` Andrew Morton
2003-10-18 17:44 ` Adrian Bunk
2003-10-18 17:57 ` Andrew Morton
2003-10-19 15:43 ` Martin J. Bligh
2003-10-19 15:59 ` Adrian Bunk
2003-10-19 16:25 ` Arjan van de Ven
2003-10-19 18:32 ` Andrew Morton
2003-10-20 14:27 ` Martin J. Bligh
2003-10-21 8:22 ` Jan-Benedict Glaw
-- strict thread matches above, loose matches on Subject: below --
2003-09-14 12:16 Adrian Bunk
2003-09-14 12:33 ` Russell King
2003-09-14 13:21 ` Adrian Bunk
2003-09-14 14:52 ` Russell King
2003-09-25 14:38 ` Adrian Bunk
2003-09-25 18:11 ` Sam Ravnborg
2003-09-26 11:44 ` Russell King
2003-09-26 22:36 ` Adrian Bunk
2003-09-14 13:53 ` Wade
2003-09-14 14:57 ` Alan Cox
2003-09-15 15:15 ` Martin J. Bligh
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