linux-kernel - Re: Size of kernel modules

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Message-Id: <20070610171321.1fbf37d5.vsu@altlinux.ru>
Date:	Sun, 10 Jun 2007 17:13:21 +0400
From:	Sergey Vlasov <vsu@...linux.ru>
To:	Jan Engelhardt <jengelh@...putergmbh.de>
Cc:	Jon Masters <jonathan@...masters.org>,
	"Robert P. J. Day" <rpjday@...dspring.com>,
	Kyle McMartin <kyle@...onical.com>,
	Christoph Pleger <Christoph.Pleger@...uni-dortmund.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Size of kernel modules

On Sat, 9 Jun 2007 15:59:55 +0200 (CEST) Jan Engelhardt wrote:

> On Jun 9 2007 08:08, Jon Masters wrote:
> >
> >So I missed half of this conversation - you're saying that on a
> >CONFIG_DEBUG_KERNEL, you have such large .ko module files that depmod
> >segfaults? Can I get a core dump or any further information? :-)
>
> Just make sure your /lib/modules/<kernel> is like 300 megabytes or
> even more. Then depmod will clog up quite a lot memory already.
> (Taking a 256 mb ram machine for example, no swap or just very
> little.)

I have noticed such problems before - the depmod code just loads whole
module files into memory.  The situation is especially bad when
module-init-tools is configured with --enable-zlib - in this case memory
for all module files is allocated with malloc().  (Without --enable-zlib
depmod just mmaps all module files, which at least does not eat swap,
and probably does not bring unused pages into memory.)

I have made some patches to module-init-tools - unfortunately, they
probably don't apply to the current version (they were based on
v3.3-pre4):

git://git.altlinux.org/people/vsu/packages/module-init-tools.git
(release-module-data branch)

http://git.altlinux.org/people/vsu/packages/?p=module-init-tools.git;a=shortlog;h=release-module-data

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