From: H. Peter Anvin <hpa@zytor.com>
Date: Sun, 07 Jan 2007 08:58:38 GMT
Subject: Re: How git affects kernel.org performance
Message-ID: <45A0B63E.2020803@zytor.com>
In-Reply-To: <20070107085526.GR24090@1wt.eu>

Willy Tarreau wrote:
> 
> At work, we had the same problem on a file server with ext3. We use rsync
> to make backups to a local IDE disk, and we noticed that getdents() took
> about the same time as Peter reports (0.2 to 2 seconds), especially in
> maildir directories. We tried many things to fix it with no result,
> including enabling dirindexes. Finally, we made a full backup, and switched
> over to XFS and the problem totally disappeared. So it seems that the
> filesystem matters a lot here when there are lots of entries in a
> directory, and that ext3 is not suitable for usages with thousands
> of entries in directories with millions of files on disk. I'm not
> certain it would be that easy to try other filesystems on kernel.org
> though :-/
> 

Changing filesystems would mean about a week of downtime for a server. 
It's painful, but it's doable; however, if we get a traffic spike during 
that time it'll hurt like hell.

However, if there is credible reasons to believe XFS will help, I'd be 
inclined to try it out.

	-hpa