Re: Compression algorithm in cloop

From: Lei Yang
Date: Wed Aug 11 2004 - 13:06:45 EST



If I don't want to build a new compression library and port it to kernel, all I want to do is to try out the idea -- whether it could work on cloop, whether the compression ratio is acceptable, can I just change the cloop code? In other words, I just need a loopback block device with other compression scheme.

I know that adding the new algorithm support to kernel would be standard way to do this and would be helpful to more people, it's just that I don't have that time :(

Phillip Lougher wrote:
> Hello,
>
> I am trying to do some experiment on compression ratios with cloop. I
> know that currently cloop uses zlib. How can I change it to other
> algorithms?

Changing the algorithm from gzip is going to be probably unpopular.
Cloop uses the gzip deflate library inside the kernel shared by a
large number of other programs. To change the algorithm you'll have
to add more (private) decompression code to the kernel. This is a retrograde
step because the shared library was only introduced in 2.4.17 to avoid lots
of private copies of gzip.

> Where should I start from? Really a newbie to this,
> appreciate any comments and suggestions!!

There has been discussion on this list before about adding
bzip2 support to the kernel. Do a search on the list for this.

Regards

Phillip

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