Re: Re: [ANNOUNCE] git-pasky-0.1

[Petr Baudis <pasky@ucw.cz>]

Dear diary, on Sun, Apr 10, 2005 at 07:45:12PM CEST, I got a letter
where Ingo Molnar <mingo@elte.hu> told me that...
> 
> * Willy Tarreau <willy@w.ods.org> wrote:
> 
> > > >   I will also need to do more testing on the linux kernel tree.
> > > > Committing patch-2.6.7 on 2.6.6 kernel and then diffing results in
> > > > 
> > > > 	$ time gitdiff.sh `parent-id` `tree-id` >p
> > > > 	real    5m37.434s
> > > > 	user    1m27.113s
> > > > 	sys     2m41.036s
> > > > 
> > > > which is pretty horrible, it seems to me. Any benchmarking help is of
> > > > course welcomed, as well as any other feedback.
> > > 
> > > it seems from the numbers that your system doesnt have enough RAM for 
> > > this and is getting IO-bound?
> > 
> > Not the only problem, without I/O, he will go down to 4m8s (u+s) which 
> > is still in the same order of magnitude.
> 
> probably not the only problem - but if we are lucky then his system was 
> just trashing within the kernel repository and then most of the overhead 
> is the _unnecessary_ IO that happened due to that (which causes CPU 
> overhead just as much). The dominant system time suggests so, to a 
> certain degree. Maybe this is wishful thinking.

It turns out to be the forks for doing all the cuts and such what is
bogging it down so awfully (doing diff-tree takes 0.48s ;-). I do about
15 forks per change, I guess, and for some reason cut takes a long of
time on its own.

I've rewritten the cuts with the use of bash arrays and other smart
stuff. I somehow don't feel comfortable using this and prefer the
old-fashioned ways, but it would be plain unusable without this.

Now I'm down to

	real    1m21.440s
	user    0m32.374s
	sys     0m42.200s

and I kinda doubt if it is possible to cut this much down. Almost no
disk activity, I have almost everything cached by now, apparently.

Anyway, you can git pull to get the optimized version.

Thanks for the help,

-- 
				Petr "Pasky" Baudis
Stuff: http://pasky.or.cz/
98% of the time I am right. Why worry about the other 3%.
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