From: Eric Sandeen Subject: Re: [PATCH RFC] jbd: don't wake kjournald unnecessarily Date: Wed, 19 Dec 2012 16:19:25 -0500 (EST) Message-ID: <83739F77-AB54-449D-B063-C6DCD3534D2B@redhat.com> 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> <20121219202734.GA18804@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: Jan Kara , Eric Sandeen , ext4 development To: "Theodore Ts'o" Return-path: Received: from mx3-phx2.redhat.com ([209.132.183.24]:45559 "EHLO mx3-phx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750907Ab2LSVUK convert rfc822-to-8bit (ORCPT ); Wed, 19 Dec 2012 16:20:10 -0500 In-Reply-To: <20121219202734.GA18804@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Dec 19, 2012, at 2:27 PM, "Theodore Ts'o" wrote: > 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. TBH I'm puzzled too, but that's what the perf guys tell me... Eric > - Ted