linux-kernel - Re: [PATCH] Compress kernel modules on installation

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Message-ID: <alpine.LSU.2.00.0812262210080.12031@fbirervta.pbzchgretzou.qr>
Date:	Fri, 26 Dec 2008 22:15:44 +0100 (CET)
From:	Jan Engelhardt <jengelh@...ozas.de>
To:	david@...g.hm
cc:	Roland <devzero@....de>, linux-kernel@...r.kernel.org,
	Sam Ravnborg <sam@...nborg.org>
Subject: Re: [PATCH] Compress kernel modules on installation


On Friday 2008-12-26 23:02, david@...g.hm wrote:
>> ( see
>> http://www.linuxjournal.com/files/linuxjournal.com/linuxjournal/articles/080/8051/8051f1.png
>> )
>
> this varies a lot on the particulars of the data being compressed.

see my other reply.

> however, I do need to ask what the sizes of the resulting files end up being
> (on my system the last kernel that used modules was 2.4.31, so I can't just
> look this up myself). in most cases disks are formatted with 4K blocks, so
> unless it shrinks across such a boundry it's not actually going to help much.

Hey, don't forget exotic filesystems that pack that together anyway.
And if I fired up du right, then...

$ find . -iname "*.gz" | xargs du -cs -B 4096 | grep total
7086    total
$ echo $[7086*4096]
29024256
$ echo $[29024256-24782942]
4241314

So that's like 4M going off for the block stuff. Given that
the compression actually saved about 50 MB, I think we
can live with the 4M - especially since they have been
there already one way or another.

> one other thing to consider would be some ability to load the
> module out of a tar or cpio bundle, that way you end up saving all
> the partial blocks from each module as well.

tarfs, it's somewhere around the corner on the fuse pages probably.
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