Re: Compression Plugin

[PFC <lists@boutiquenumerique.com>]

>>> An interesting idea:  select the algo and a range of compression
>>> levels per file,

	A simple check on wether it's an already compressed file (using file  
extension and magic number) should be quite easy to do and cheap.

	Now, intrigued by this lzo thingie, I ran a little benchmark on my emails  
; I have a huge mail spool and my mail client is always slow to launch...
	Seems that on this laptop LZO can compress about 40 MB/s and decompress  
about 200 (!) MB/s. On the mail spool, compression ratio was about 1/2 ;  
gzip was better, although 5-6 times slower. So considering the disk  
throughput is only 15 MB/s, this could make it twice as fast with CPU to  
spare. Yowza !

>>> but select the actual compression level at flush time
>>> based on some estimate of how loaded the system is.. :)
>>> Probably not worth it even though the amount of compression and the
>>> speed differ greatly from -1 to -9... I hope no one wastes their time
>>> on it until the more important things are done.. but perhaps a nice
>>> touch.
>>   Kinda makes it sound like in addition to the "repacker" that repacks
>> blocks in order and squeezes them, (which should allow for filesystem
>> size reduction), there'll be a compression repacker too that allows
>> you to repack files to a higher or lower compression level (anyone
>> remember the Compression Agent that came with DoubleSpace and the like
>> in Windows 9x?).
>
> AFAIR e2compr patch to ext2 (which enables compression on a ex2  
> filesystem) could use many packing methods, including gzip and bzip2  
> (!), with a range from 1 to 9...
>
> I certainly could imagine cases where compression level is more  
> important than speed.
>
>