From: Theodore Ts'o <tytso@mit.edu>
Subject: Re: [PATCH RFC] jbd: don't wake kjournald unnecessarily
Date: Wed, 19 Dec 2012 15:27:34 -0500
Message-ID: <20121219202734.GA18804@thunk.org>
References: <50D0A1FD.7040203@redhat.com>
 <20121219012710.GF5987@quack.suse.cz>
 <20121219020526.GG5987@quack.suse.cz>
 <50D12FC3.6090209@redhat.com>
 <20121219081334.GB20163@quack.suse.cz>
 <20121219153725.GD7795@thunk.org>
 <20121219171401.GB28042@quack.suse.cz>
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Cc: Eric Sandeen <sandeen@redhat.com>,
	ext4 development <linux-ext4@vger.kernel.org>
To: Jan Kara <jack@suse.cz>
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In-Reply-To: <20121219171401.GB28042@quack.suse.cz>
Sender: linux-ext4-owner@vger.kernel.org

On Wed, Dec 19, 2012 at 06:14:01PM +0100, Jan Kara wrote:
>   I agree. Just I'm still somewhat puzzled by those two reports pointed to
> by Eric. In both cases stored tids were 0 and I cannot see how that happens
> (well how it could happen in a reasonably likely way).

I'm also really puzzled about how Eric's patch makes a 10% different
on the AIM7 benchmark; as you've pointed out, that will just cause an
extra wakeup of the jbd/jbd2 thread, which should then quickly check
and decide to go back to sleep.

					- Ted