From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755743AbZIJOSD (ORCPT ); Thu, 10 Sep 2009 10:18:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755728AbZIJOSC (ORCPT ); Thu, 10 Sep 2009 10:18:02 -0400 Received: from mga14.intel.com ([143.182.124.37]:52045 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753319AbZIJOSA (ORCPT ); Thu, 10 Sep 2009 10:18:00 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,271,1249282800"; d="scan'208";a="186168914" Date: Thu, 10 Sep 2009 22:17:50 +0800 From: Wu Fengguang To: Jan Kara Cc: Andrew Morton , Jens Axboe , Dave Chinner , Chris Mason , Peter Zijlstra , Christoph Hellwig , Artem Bityutskiy , LKML , "linux-fsdevel@vger.kernel.org" Subject: Re: [RFC][PATCH 2/7] writeback: fix queue_io() ordering Message-ID: <20090910141750.GA11969@localhost> References: <20090909145141.293229693@intel.com> <20090909150600.451373732@intel.com> <20090909155330.GE7949@duck.suse.cz> <20090910012624.GA10957@localhost> <20090910141415.GK607@duck.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090910141415.GK607@duck.suse.cz> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 10, 2009 at 10:14:15PM +0800, Jan Kara wrote: > On Thu 10-09-09 09:26:24, Wu Fengguang wrote: > > On Wed, Sep 09, 2009 at 11:53:30PM +0800, Jan Kara wrote: > > > On Wed 09-09-09 22:51:43, Wu Fengguang wrote: > > > > This was not a bug, since b_io is empty for kupdate writeback. > > > > The next patch will do requeue_io() for non-kupdate writeback, > > > > so let's fix it. > > > But doesn't this patch also need your "anti-starvation" patch? > > > > Honza, can you show me that patch? > > > > > Looking into the code, we put inode to b_more_io when nr_to_write > > > drops to zero and this way we'd just start writing it again > > > in the next round... > > > > I'm confused. It's OK to start it in next round. Starvation can > > occur if we start it immediately in the next writeback_inodes() > > invocation. How can that happen with this patch? > Sorry, my fault. For kupdate, we splice the list only once s_io is empty > so that's not an issue. So the patch looks good. > Acked-by: Jan Kara Thank you :) Regards, Fengguang > > > > CC: Dave Chinner > > > > Cc: Martin Bligh > > > > Cc: Michael Rubin > > > > Cc: Peter Zijlstra > > > > Signed-off-by: Fengguang Wu > > > > --- > > > > fs/fs-writeback.c | 7 +++++-- > > > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > > > > > --- linux.orig/fs/fs-writeback.c 2009-09-09 21:41:14.000000000 +0800 > > > > +++ linux/fs/fs-writeback.c 2009-09-09 21:45:15.000000000 +0800 > > > > @@ -313,11 +313,14 @@ static void move_expired_inodes(struct l > > > > } > > > > > > > > /* > > > > - * Queue all expired dirty inodes for io, eldest first. > > > > + * Queue all expired dirty inodes for io, eldest first: > > > > + * (newly dirtied) => b_dirty inodes > > > > + * => b_more_io inodes > > > > + * => remaining inodes in b_io => (dequeue for sync) > > > > */ > > > > static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) > > > > { > > > > - list_splice_init(&wb->b_more_io, wb->b_io.prev); > > > > + list_splice_init(&wb->b_more_io, &wb->b_io); > > > > move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); > > > > } > > > > > > > > > > > > -- > > > > > > > -- > > > Jan Kara > > > SUSE Labs, CR > -- > Jan Kara > SUSE Labs, CR