Date: Thu, 31 Mar 2005 23:19:41 +0200
From: Adrian Bunk <bunk@stusta.de>
To: Roland Dreier <roland@topspin.com>
Cc: =?iso-8859-1?Q?J=F6rn?= Engel <joern@wohnheim.fh-wedel.de>,
       Yum Rayan <yum.rayan@gmail.com>, linux-kernel@vger.kernel.org,
       mvw@planets.elm.net
Subject: Re: Stack usage tasks
Message-ID: <20050331211941.GJ3185@stusta.de>
References: <df35dfeb05033023394170d6cc@mail.gmail.com> <20050331150548.GC19294@wohnheim.fh-wedel.de> <20050331203010.GF3185@stusta.de> <52ll83mtqd.fsf@topspin.com>
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On Thu, Mar 31, 2005 at 12:43:38PM -0800, Roland Dreier wrote:
>     > The task I'm suggesting was therefore:
>     > - remove the -fno-unit-at-a-time in arch/i386/Makefile in your private
>     >   kernel sources
>     > - use gcc 3.4
>     > - reduce the stack usages in call paths > 3kB
> 
> This is a good idea.  However, I might suggest using gcc 4.0 (you'll
> have to use a snapshot now, but the release should only be a few weeks
> away).  A patch went into gcc 4.0 that makes gcc more intelligent
> about sharing stack for variables that cannot be alive at the same
> time, and therefore it may be more feasible to make unit-at-a-time
> work for the i386 kernels.

That's one option.

J?rn, can you send a list of call paths with a stack usage > 3kB when 
compiling with gcc 3.4 and unit-at-a-time (or tell me how to generate 
these lists)?

If fixing a handful of places was sufficient, it was IMHO worth it for 
enabling unit-at-a-time with gcc 3.4 .

>  - R.

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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