Re: cloning the kernel - why long time in "Resolving 313037 deltas"

From: Linus Torvalds <torvalds@osdl.org>
Date: Dec 18, 2006, 22:22 UTC
Message-ID: <Pine.LNX.4.64.0612181414200.3479@woody.osdl.org>
In-Reply-To: <86hcvs984c.fsf@blue.stonehenge.com>

On Mon, 18 Dec 2006, Randal L. Schwartz wrote:

Show 7 quoted lines

> 
> I have a single pack.
> 
> "Indexing" took about 30 seconds.
> "Resolving 313037 deltas" looks like it's going to take an hour.
> 
> So that *was* a local delay.

Ok, interesting. Two questions:

 - what does "top" say (is it CPU-bound? Is it perhaps blowing out your 
   disk cache? Is it swapping?)

 - do you have "oprofile" (or even just pgprof) to see where the *hell* 
   that time is spent, if it's actually CPU?

For me, it takes 25 seconds. Not an hour:

	[torvalds@woody linux]$ time git-index-pack -v -o /dev/null .git/objects/pack/*.pack
	Indexing 393507 objects.
	 100% (393507/393507) done
	Resolving 316071 deltas.
	 100% (316071/316071) done
	fatal: unable to create /dev/null: File exists
	
	real    0m24.619s
	user    0m22.569s
	sys     0m1.316s

(I admit that 25 seconds is already "too much", but it does actually end up exploding a lot of objects and doing quite a bit of work, so I guess it's fair).

And the process grew to 33MB in RSS at it's biggest, so it wasn't even using all that much memory (33MB isn't _tiny_, but considering that the pack in question is 155MB and has hundreds of thousands of objects, 33MB isn't really all that bad.

You're running this under OS X, aren't you? It's a pig of an OS, but "almost one hour" vs "25 seconds" is still unreasonable.