From: Ted Ts'o <tytso@mit.edu>
Subject: Re: Filesystem benchmarks on reasonably fast hardware
Date: Tue, 26 Jul 2011 10:57:36 -0400
Message-ID: <20110726145736.GA7684@thunk.org>
References: <20110717160501.GA1437@logfs.org>
 <20110718120751.GH14869@thunk.org>
 <20110718124229.GG1437@logfs.org>
 <20110725151825.GI3469@thunk.org>
 <20110725182037.GE26160@logfs.org>
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Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org
To: =?iso-8859-1?Q?J=F6rn?= Engel <joern@logfs.org>
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In-Reply-To: <20110725182037.GE26160@logfs.org>
Sender: linux-ext4-owner@vger.kernel.org

On Mon, Jul 25, 2011 at 08:20:37PM +0200, J=F6rn Engel wrote:
> On Mon, 25 July 2011 11:18:25 -0400, Ted Ts'o wrote:
> >=20
> > Did you have a chance to do an ext4 lockstat run?

Hi J=F6rn,

Thanks for forwarding it to me.  It's the same problem as in XFS, the
excessive coverage of the i_mutex lock.  In ext4's case, it's in the
generic generic_file_aio_write() machinery where we need to do the
lock busting.  (XFS apparently doesn't use the generic routines, so
the fix that Dave did won't help ext3 and ext4.)

I don't have the time to look at it now, but I'll put it on my todo
list; or maybe someone with a bit more time can look into how we might
be able to use a similar approach in the generic file system code.

   	       	 	 	     	 	 - Ted
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