Re: Recovering from repository corruption

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Jun 10, 2008, 23:00 UTC
Message-ID: <alpine.LFD.1.10.0806101554490.3101@woody.linux-foundation.org>
In-Reply-To: <alpine.LFD.1.10.0806101518590.3101@woody.linux-foundation.org>

On Tue, 10 Jun 2008, Linus Torvalds wrote:

Show 6 quoted lines

> 
> It's going to make big "git add" calls *much* slower, so I'm not very 
> happy about it (especially since we don't actually care that deeply about 
> the files really being there until much later, so doing something 
> asynchronous would be perfectly acceptable), but for you this is 
> definitely worth-while.

For me, on the whole kernel, on a pretty good system:

 - before:

	[torvalds@woody test-it-out]$ time git add .

	real    0m7.986s
	user    0m6.404s
	sys     0m1.456s

 - after:

	[torvalds@woody test-it-out]$ time ~/git/git-add .

	real    0m52.693s
	user    0m7.416s
	sys     0m2.516s

so it's definitely quite noticeable in that simplistic form.

A more interesting patch would use aio_fsync(), and then just wait for them at the end with aio_return(). Not that I love AIO, but this is definitely a case where it would make sense to do (of course, systems without AIO support would then fall back to regular fsync()).

I will have to think about this.

			Linus