Re: [lc-devel] linuxcompressed on a 2.4.x software RAID (md) enabled system ?

[Rodrigo S de C. <ro...@te...>]

Hi Olivier,=20

[Sorry for the delay]

On Sun, Nov 07, 2004 at 02:42:08AM +0100, Olivier Kaloudoff wrote:
> 	I'm really interested in linux compressed, as my current
> system is really slow when it comes to I/O access;
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> 	3x180Go IDE Disks, unfortunatelly they stand on
> two IDE channels.
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> 	Using "du -sk *" on a 110Go partition is slow and takes no more=20
> than 20% CPU. Launching the same command a second time is not faster,=20
> which makes me think that some caching or cache compression technique=20
> would be able to improve things.
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> 	I have 386Mo RAM, 1Go swap, no special tunning as of now.=20
> Unfortunatelly, running 2.4.27, I'm unable to find the=20
> /proc/sys/vm/buffermem file which would have allowed me to tune I/O=20
> buffers.
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> 	Do you think that compressed linux could improve performance in my=20
> case ? (I think that low ram is one of my problems, even if I don't have=
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> more than X running)

Depending on your workload, compressed cache may help you. It will use
memory for compressing pages from the page cache that as less recently
used. Given that the memory is used, only a small portion of your disk
data will be cached in it. It is very useful for "enlarging" your page
cache through compression, reducing the anonymous memory to be written
to the disk or the file pages that could be discarded and reread from
the disk. It is unlikely to be the solution for your "du", but it may
help you when using your system. I'd like to know what would be your
experience with it.

> 	I tried to apply the latest patch (for 2.4.18) to 2.4.27, but
> some work needs to be done, as little things seem to have changed in
> the code.  (about 7 rejects, not obvious to patch by hand)

I am going to check what are these rejects. If they are simple, I will
post a patch for you soon. :-)

Regards,
--=20
Rodrigo