On Wed, Jan 16, 2002 at 02:05:10PM -0500, [EMAIL PROTECTED] wrote:
> AIX already supports this sort of compression. Interestingly enough,
> they use LZ compression instead, probably for the following reasons:
<shameless plug>liblzf.plan9.de - fast, free, primitive, or somesuch</>
lzf should be patent-free, very small (code) and lends itself to very
efficient implementations. it far from gzip's compression ratio, but
vastly easier to use in kernel etc. and might come for free (Although I
guess not in the reiserfs code).
> something that does a reasonable job for "very short" runs.
> 'gzip < /dev/null | wc' says 20 characters of overhead - do LZ or other
> schemes do better?
Any scheme can be coded with at most one bit overhead - the 20 bytes
are file time, name and other info that only gzip encodes. tghe actual
overhead is a few bytes only.
> Also, think about the startup CPU cost for each
> tail on compression/decompression - is gzip optimal or are other things
> better?
gzip is suboptimal. lzf and variants don't even need to initialize their
hash table (although compression ratio is not deterministic in that case
;)
--
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---==---(_)__ __ ____ __ Marc Lehmann +--
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