Re: Funny error with git gc...

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: May 15, 2009, 19:16 UTC
Message-ID: <alpine.LFD.2.01.0905151212160.3343@localhost.localdomain>
In-Reply-To: <alpine.DEB.1.00.0905152105340.26154@pacific.mpi-cbg.de>

On Fri, 15 May 2009, Johannes Schindelin wrote:

Show 10 quoted lines

> > 
> > 	[core]
> > 		packedGitWindowSize = 16k
> > 		packedGitLimit = 1M
> > 
> > you should hopefully be able to repack (slowly) even with a low file 
> > descriptor limit, because of the total limit on the size.
> 
> I don't think so, because the window size has nothing to do with the 
> amount of open windows, right?

No, but the packedGitLimit does.

So the argument is that you can't fit all that many open windows in 1M.

> No, in this case, nothing was disabled.  auto-gc did not kick in, probably 
> due to funny Git usage in hg2git.

Ahh. Scripting.

> > Dscho? What are your pack-file statistics in this case?
> 
> Mostly around 50kB.

Can you give us an approximation for how many are under 16kB or so?

The 16kB cutoff is where it's usually just better to malloc+read (because even if you don't end up using all the 16kB, just a page-fault or two is already more expensive than just doing the memcpy implied in a 16k read() system call).

> But using malloc()+read() to avoid my use case sounds not 
> straight-forward; it is rather a work-around than a proper solution.

Well, it's a workaround that is correct for other reasons too. So it's likely worth doing.

The "proper solution" is likely to not avoid repacking. Scripted stuff that does that is buggy.

			Linus