Re: Decompression speed: zip vs lzo

From: Sam Vilain <sam@vilain.net>
Date: Jan 12, 2008, 03:06 UTC
Message-ID: <47882EC5.2080406@vilain.net>
In-Reply-To: <alpine.LFD.1.00.0801112125470.3054@xanadu.home>

Nicolas Pitre wrote:

> Sorry to rain on your parade, but to me 6-10% time saving is not a clear 
> win at all, given the equal increase in repository size.  This is simply 
> not worth it.

Agree.

> And a 50% time saving on an operation, such a git log, which takes less 
> than 2 seconds in absolute time, is not worth the repo size increase 
> either.

Disagree. Going as much as twice as fast for many history operations for 10% added space sounds like a clear win to me. We can easily agree to disagree though - making it a disabled by default config option allows the user to unroll their packs if they want.

> Going from 2 seconds down to one second doesn't make enough of 
> a user experience difference.

What do you mean? 1 second waiting is far better than 2 seconds waiting. And the mmap optimizations have not even begun yet - that could result in boosts from zero-copy, such as a lighter VM footprint.

> If git blame was to go from 10 seconds down to 4 then I'd say this is a 
> clear win.  But this is not the case.

This is an awesome boost!  Everything feels snappier already :)

maia:~/src/perl.clean$ time git-log | LANG=C wc
 288927  894027 8860916

real    0m0.839s
user    0m0.824s
sys     0m0.144s
maia:~/src/perl.clean$ cd ../perl.clean.loose/
maia:~/src/perl.clean.loose$ time git-log | LANG=C wc
 288927  894027 8860916

real 0m0.515s user 0m0.504s sys 0m0.136s

maia:~/src/perl.clean.loose$ du -sk .git/objects/pack/ 113484 .git/objects/pack/ maia:~/src/perl.clean.loose$ cd - /home/samv/src/perl.clean maia:~/src/perl.clean$ du -sk .git/objects/pack/ 107040 .git/objects/pack/ maia:~/src/perl.clean$

Want me to try this on kde.git?

Sam.