Message-ID: <46503441.9050409@wpkg.org>
Date: Sun, 20 May 2007 13:42:57 +0200
From: Tomasz Chmielewski <mangoo@wpkg.org>
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Subject: Re: [RFC] LZO1X de/compression support
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Bill Rugolsky Jr. wrote:

>> I'm certainly missing something but what are the advantages of this
>> code (over current gzip etc.), and what will be using it?
> 
> Richard's patchset added it to the crypto library and wired it into
> the JFFS2 file system.  We recently started using LZO in a userland UDP
> proxy to do stateless per-packet payload compression over a WAN link.
> With ~1000 octet packets, our particular data stream sees 60% compression
> with zlib, and 50% compression with (mini-)LZO, but LZO runs at ~5.6x
> the speed of zlib.  IIRC, that translates into > 700Mbps on the input
> side on a 2GHZ Opteron, without any further tuning.
> 
> Once LZO is in the kernel, I'd like to see it wired into IPComp.
> Unfortunately, last I checked only the "deflate" algorithm had an
> assigned compression parameter index (CPI), so one will have to use a
> private index until an official one is assigned.

I also though of using LZO compression for some of the diskless nodes
which use iSCSI over 100 Mbit or slower.


Certainly, a fast de/compression algorithm in the kernel could bring
some new, innovative uses:

- there are talks about compressed filesystems (jffs2, reiser4, LogFS) -
why no one thought about a compressed tmpfs (should be way easier than a
compressed on-disk filesystem, as we don't have to care about data
recovery in event of a failure)?

- using compression for networking (like Bill mentioned)

- compressed caching

- compressed suspend-to-disk images (should suspend/restore faster this way)


-- 
Tomasz Chmielewski
http://wpkg.org


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