From: Sedat Dilek Subject: Re: jbd2: don't wake kjournald unnecessarily Date: Wed, 30 Jan 2013 11:29:02 +0100 Message-ID: References: <20130121140738.GI5588@quack.suse.cz> <20130121231130.GB12410@thunk.org> <20130122235041.GA7497@quack.suse.cz> <50FF3EEA.2030408@redhat.com> <20130123094421.GB9821@quack.suse.cz> <50FFFFC6.8070308@redhat.com> <20130123192911.GB21112@quack.suse.cz> <20130130052658.GE25006@thunk.org> <20130130100740.GA22091@quack.suse.cz> Reply-To: sedat.dilek@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: "Theodore Ts'o" , Eric Sandeen , Ext4 Developers List , mszeredi@suse.cz To: Jan Kara Return-path: Received: from mail-qc0-f178.google.com ([209.85.216.178]:40226 "EHLO mail-qc0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753147Ab3A3K3F (ORCPT ); Wed, 30 Jan 2013 05:29:05 -0500 Received: by mail-qc0-f178.google.com with SMTP id j34so650354qco.23 for ; Wed, 30 Jan 2013 02:29:03 -0800 (PST) In-Reply-To: <20130130100740.GA22091@quack.suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Jan 30, 2013 at 11:07 AM, Jan Kara wrote: > On Wed 30-01-13 00:26:58, Ted Tso wrote: >> On Wed, Jan 23, 2013 at 08:29:11PM +0100, Jan Kara wrote: >> > > old JBD: AIM7 jobs/min 97624.39; got 78193 jbd wakeups >> > > new JBD: AIM7 jobs/min 85929.43; got 6306999 jbd wakeups, 6264684 extra wakeups >> > Yeah, that's a lot. My guess would be *a lot* of processes are hanging in >> > start_this_handle() and waiting for transaction commit. Each of them calls >> > __log_start_commit() and things add up. Thanks for getting these numbers. >> >> Yeah, wow. That would imply that there are a huge number of processes >> that get hung up in start_this_handle(), and they are waking up the >> journal before the kjournald has a chance to set T_LOCKED (since then >> they would get blocked earlier in start_this_handle). >> >> Given that, I wonder if the following change would actually help or >> hurt things. Eric, would you be willing to ask your perf team to try >> testing out these patches? > Umm, I don't see anything. Forgot to attach them? > Here I catched the two patches: http://patchwork.ozlabs.org/patch/216768/ http://patchwork.ozlabs.org/patch/216767/ - Sedat - > Honza > -- > Jan Kara > SUSE Labs, CR