Re: [Monotone-devel] Re: zlib vs gzip

[Jack Lloyd]

On Tue, Oct 30, 2007 at 09:08:48AM +0100, Markus Schiltknecht wrote:
> Especially disk throughput is growing very slow compared to CPU-power 
> (i.e. compression-throughput). From that point of view I don't 
> necessarily think that compression slows down anything, rather quite the 
> opposite (given a desktop system with a single spindle, not a server 
> with a beefy disk subsystem).

Yes with that assumption I'd have to agree, but on anything else (eg,
4-way Opterons, old Unix machines with poor CPU and relatively
powerful I/O, etc) it probably hurts quite a bit. Even on my Core2
(with a RAID-1 setup, so each write has to hit all three disks), it is
faster (wall clock) to write 200 Mb to disk than it is to first
compress it with gzip and write the 30 Mb compressed result to disk.

> And then there's netsync, which certainly needs compression.

Over a WAN, perhaps. My experience with scp/sftp certainly is that
enabling compression over a 100 Mbit Ethernet reduced throughput
significantly.

-Jack