Re: Git performance on OS X

On Sun, 20 Apr 2008, Pieter de Bie wrote:

The number of lstats are cut down by your patch: 428761 vs. 338091. Funnily
enough, there is no significant difference in run-time:

It may be that the problem with OS X is a sucky pathname cache mechanism.

The trivial patch cut down the number of stat() calls by a fair amount, 
but the calls that got removed were all of the "do two 'lstat()' calls on 
the exact same pathname consecutively" type.

Maybe OS X has some very limited pathname caching that catches that, or 
even if not, it just ends up being very nice in the D$, so it's not a big 
deal. And then the real suckiness happens only with bigger workloads.

It may also be that the bulk of the OS X cost isn't in lstat() at all, but 
in the VM. That was true for some other OS X load.

Command                                            Mean     Std
git status .                                       13.970  1.298
/Users/pieter/projects/External/git/git-status .   13.759  0.321

This is the WebKit archive, right?

For me, doing a "time git status ." on the WebKit thing I just cloned from 
git://git.webkit.org/WebKit.git is much faster: 1.264s (and it goes down 
by maybe 5-10% with my lstat-avoidance patch).

Is there any system-level profiler for OS X to get a clue where that cost 
is, in case it's not the lstat() at all?

			Linus