Re: Decompression speed: zip vs lzo

From: Sam Vilain <sam@vilain.net>
Date: Jan 11, 2008, 06:29 UTC
Message-ID: <47870CDF.4010606@vilain.net>
In-Reply-To: <alpine.LFD.1.00.0801101805540.3148@woody.linux-foundation.org>

Linus Torvalds wrote:

Show 18 quoted lines

> 
> On Fri, 11 Jan 2008, Sam Vilain wrote:
>> Without compression of deltas:
>>
>> wilber:~/src/perl-preview$ du -sk .git/objects/pack/
>> 86781 .git/objects/pack/
>>
>> With compression of deltas:
>>
>> wilber:~/src/perl-preview$ du -sk .git/objects/pack/
>> 72907 .git/objects/pack/
> 
> Ok, so non-compressed deltas are 20% bigger.
> 
> That may well be a perfectly acceptable trade-off if the end result is 
> then a lot faster. Has somebody done performance numbers? I may have 
> missed them.. The best test is probably something like "git blame" on a 
> file that takes an appreciable amount of time.

The difference seems only barely measurable;

wilber:~/src/perl-preview$ time git annotate sv.c >/dev/null

real 0m8.130s user 0m6.712s sys 0m1.412s

wilber:~/src/perl-preview-loose$ time git annotate sv.c >/dev/null

real 0m7.930s user 0m6.480s sys 0m1.408s

(each one is last of three runs - dual-core x86_64 @ 2.1GHz w/512KB cache)

sv.c has about 1500 revisions, though the oldest line is I also tried annotate and log on the YACC generated parser which only has about 165 revisions, with similar results - a very minor difference or no difference.

Sam