Re: Compression algorithm in cloop

[Lei Yang <leiyang@nec-labs.com>]

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
>