Message-ID: <45A0B63E.2020803@zytor.com>
Date: Sun, 07 Jan 2007 00:58:38 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Willy Tarreau <w@1wt.eu>
CC: Linus Torvalds <torvalds@osdl.org>, git@vger.kernel.org,
       nigel@nigel.suspend2.net, "J.H." <warthog9@kernel.org>,
       Randy Dunlap <randy.dunlap@oracle.com>, Andrew Morton <akpm@osdl.org>,
       Pavel Machek <pavel@ucw.cz>, kernel list <linux-kernel@vger.kernel.org>,
       webmaster@kernel.org
Subject: Re: How git affects kernel.org performance
References: <20061216094421.416a271e.randy.dunlap@oracle.com> <20061216095702.3e6f1d1f.akpm@osdl.org> <458434B0.4090506@oracle.com> <1166297434.26330.34.camel@localhost.localdomain> <1166304080.13548.8.camel@nigel.suspend2.net> <459152B1.9040106@zytor.com> <1168140954.2153.1.camel@nigel.suspend2.net> <45A08269.4050504@zytor.com> <45A083F2.5000000@zytor.com> <Pine.LNX.4.64.0701062130260.3661@woody.osdl.org> <20070107085526.GR24090@1wt.eu>
In-Reply-To: <20070107085526.GR24090@1wt.eu>
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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
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