Re: git performance

From: Pete Harlan <pgit@pcharlan.com>
Date: Oct 24, 2008, 23:10 UTC
Message-ID: <490255D1.8060804@pcharlan.com>
In-Reply-To: <49017F8F.3000908@pcharlan.com>

Pete Harlan wrote:

Show 15 quoted lines

> Edward Ned Harvey wrote:
>>> Yes, it does stat all the files. How many files are you talking about,
>>> and what platform?  From a warm cache on Linux, the 23,000 files kernel
>>> repo takes about a tenth of a second to stat all files for me (and this
>> I'm talking about 40-50,000 files, on multi-user production linux,
>> which means the cache is never warm, except when I'm benchmarking.
>> Specifically RHEL 4 with the files on NFS mount.  Cold cache "svn
>> st" takes ~10 mins.  Warm cache 20-30 sec.  Surprisingly to me,
> 
> I did some tests with a repo with ~32k files, and git was slightly
> slower than svn with a cold cache (10.2s vs 8.4s), and around twice as
> fast with a warm cache (.5s vs 1s).
> 
> Git 1.6.0.2, svn 1.4.6. Cache made cold with
> "echo 1 >/proc/sys/vm/drop_caches".  Timings best of 5 runs.

After redoing this test with "echo 3 >/proc/sys/vm/drop_caches" (which also discards metadata, as pointed out by Linus), the cold-cache timings are:

	svn 12.65 seconds
	git 10.3  seconds

So no Earth-shattering difference, but now git is somewhat quicker than Subversion at everything I tested.

--Pete