From: Dimitrios Apostolou <jimis@gmx.net>
To: Pavel Machek <pavel@ucw.cz>
Cc: Arjan van de Ven <arjan@infradead.org>,
Alex Chiang <achiang@hp.com>, Len Brown <lenb@kernel.org>,
Bjorn Helgaas <bjorn.helgaas@hp.com>,
Andrew Morton <akpm@linux-foundation.org>,
Yinghai Lu <yinghai@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: -O0 kernel Re: High cpu temperature with 2.6.32, bisection shows commit 69d258 (fwd)
Date: Fri, 15 Jan 2010 22:40:39 +0200 (EET) [thread overview]
Message-ID: <alpine.LNX.2.00.1001152227360.2311@localhost.localdomain> (raw)
In-Reply-To: <20100115195811.GB1345@ucw.cz>
On Fri, 15 Jan 2010, Pavel Machek wrote:
>
>> BTW, how can I remove that irritating -O2 flag? I 'm used to compiling
>> with -O0 my debug builds in userland, because compilation is *many times*
>> faster. I should be really useful for bisections.
>
> Actually, figuring out kernel flags for fastest kernel compilation
> would be nice. Nice for bisect, and nice for slow machines. Zaurus
> needs 4 hours to compile kernel, kohjinsha cca 1.5 hours.
>
> -O0 may not fly, as inlining is needed... some tests are
I did some research too and this has been discussed again. Regarding
inlining and -O0 I understand that theoretically it should work, but
practically it doesn't. Here is an explanatory message from Andi Kleen:
http://lists.openwall.net/linux-kernel/2008/09/09/399
> neccessary. Now that we support icc, gcc -O0 should be doable, too...
>
> ...ok, so I tried -O0.
>
> -O2 compilation took 1250seconds, -O0 took 1167seconds and failed.
>
> is there some fast compiler around that could be used?
Strange that -O0 was not faster. Compiling userland I'm sure I've seen
great speeds, and much less memory usage. Another compiler that is
infamous for its speed is TCC (Tiny C Compiler) but I haven't actually
used it, perhaps you want to try first. :-)
Dimitris
prev parent reply other threads:[~2010-01-15 20:37 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <alpine.LNX.2.00.1001071941470.1363@localhost.localdomain>
2010-01-08 17:15 ` Alex Chiang
2010-01-09 21:43 ` Arjan van de Ven
2010-01-09 23:55 ` Dimitrios Apostolou
2010-01-10 0:08 ` Arjan van de Ven
2010-01-10 0:32 ` Dimitrios Apostolou
2010-01-10 0:42 ` Arjan van de Ven
2010-01-10 1:05 ` Dimitrios Apostolou
2010-01-10 1:38 ` Arjan van de Ven
2010-01-13 0:07 ` Andrew Morton
2010-01-13 5:32 ` Arjan van de Ven
2010-02-10 20:51 ` Dimitrios Apostolou
2010-02-10 21:42 ` Dimitrios Apostolou
2010-02-11 4:56 ` Arjan van de Ven
2010-02-11 18:00 ` Dimitrios Apostolou
2010-02-11 21:58 ` Wojciech Ploskonka
2010-02-12 5:24 ` Arjan van de Ven
2010-02-12 21:05 ` Matthew Garrett
2010-02-18 20:27 ` Dimitrios Apostolou
2010-02-18 20:34 ` Rafael J. Wysocki
2010-02-22 16:43 ` Dimitrios Apostolou
2010-02-23 1:55 ` Arjan van de Ven
2010-02-12 5:23 ` Arjan van de Ven
2010-01-10 2:07 ` Ray Lee
2010-01-10 3:09 ` Robert Hancock
2010-01-10 4:15 ` Arjan van de Ven
2010-01-15 20:00 ` -O0 kernel " Pavel Machek
2010-01-15 20:40 ` Dimitrios Apostolou [this message]
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