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From: Jan-Benedict Glaw <jbglaw@lug-owl.de>
To: linux-kernel@vger.kernel.org
Subject: Re: [2.6 patch] add a config option for -Os compilation
Date: Tue, 21 Oct 2003 10:22:26 +0200	[thread overview]
Message-ID: <20031021082225.GA20846@lug-owl.de> (raw)
In-Reply-To: <20031018102127.GE12423@fs.tum.de>

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On Sat, 2003-10-18 12:21:27 +0200, Adrian Bunk <bunk@fs.tum.de>
wrote in message <20031018102127.GE12423@fs.tum.de>:
> On Wed, Oct 15, 2003 at 04:52:05PM -0700, Andrew Morton wrote:
> > I really doubt it.  Kernel CPU footprint is dominated by dcache misses.  If
> > -Os reduces icache footprint it may even be a net win; people tend to
> > benchmark things in tight loops, which favours fast code over small code.
> 
> The main effect of -Os compared to -O2 (besides disabling some
> reordering of the code and prefetching) is the disabling of various
> alignments. I doubt that's a win on all CPUs.

I definively *like* to see -Os be configureable by user. It's *big* win
for a lowmem system. There, the actual "running speed" may be limited by
HDD swap speed, and having a smaller kernel means having more pages left
to luserspace...

MfG, JBG

-- 
   Jan-Benedict Glaw       jbglaw@lug-owl.de    . +49-172-7608481
   "Eine Freie Meinung in  einem Freien Kopf    | Gegen Zensur | Gegen Krieg
    fuer einen Freien Staat voll Freier Bürger" | im Internet! |   im Irak!
   ret = do_actions((curr | FREE_SPEECH) & ~(NEW_COPYRIGHT_LAW | DRM | TCPA));

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  parent reply	other threads:[~2003-10-21  8:22 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-10-15 22:50 [2.6 patch] add a config option for -Os compilation 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 [this message]
     [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
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     [not found]                 ` <Ioi6.7kG.11@gated-at.bofh.it>
     [not found]                   ` <IorM.7wQ.11@gated-at.bofh.it>
2003-10-19 16:55                     ` Ihar 'Philips' Filipau
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     [not found] ` <I2Ue.7PG.5@gated-at.bofh.it>
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     [not found]         ` <I2Ue.7PG.13@gated-at.bofh.it>
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     [not found]             ` <ImzK.4TR.25@gated-at.bofh.it>
     [not found]               ` <ImzK.4TR.23@gated-at.bofh.it>
     [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] <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>
     [not found]             ` <20031018174434.GJ12423@fs.tum.de.suse.lists.linux.kernel>
     [not found]               ` <20031018105733.380ea8d2.akpm@osdl.org.suse.lists.linux.kernel>
2003-10-18 19:19                 ` Andi Kleen
2003-10-19 13:56                   ` Ingo Oeser
2003-10-19 14:09                     ` Michael Buesch
2003-10-19 17:37                     ` Sam Ravnborg
     [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
  -- 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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