From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id 8D2D46B00EE for ; Tue, 6 Sep 2011 10:23:27 -0400 (EDT) Subject: Re: [PATCH 11/18] block: add bdi flag to indicate risk of io queue underrun From: Peter Zijlstra Date: Tue, 06 Sep 2011 16:22:48 +0200 In-Reply-To: <20110904020916.070059502@intel.com> References: <20110904015305.367445271@intel.com> <20110904020916.070059502@intel.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Message-ID: <1315318968.14232.6.camel@twins> Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Wu Fengguang Cc: linux-fsdevel@vger.kernel.org, Tejun Heo , Jens Axboe , Li Shaohua , Andrew Morton , Jan Kara , Christoph Hellwig , Dave Chinner , Greg Thelen , Minchan Kim , Vivek Goyal , Andrea Righi , linux-mm , LKML On Sun, 2011-09-04 at 09:53 +0800, Wu Fengguang wrote: > +++ linux-next/mm/page-writeback.c 2011-08-31 14:40:58.000000000 +08= 00 > @@ -1067,6 +1067,9 @@ static void balance_dirty_pages(struct a > nr_dirty, bdi_thresh, bdi_dirty, > start_time); > =20 > + if (unlikely(!dirty_exceeded && bdi_async_underrun(bdi))) > + break; > + > dirty_ratelimit =3D bdi->dirty_ratelimit; > pos_ratio =3D bdi_position_ratio(bdi, dirty_thresh, > background_thresh, nr_dirt= y, So dirty_exceeded looks like: 1109 dirty_exceeded =3D (bdi_dirty > bdi_thresh) || 1110 (nr_dirty > dirty_thresh); Would it make sense to write it as: if (nr_dirty > dirty_thresh ||=20 (nr_dirty > freerun && bdi_dirty > bdi_thresh)) dirty_exceeded =3D 1; So that we don't actually throttle bdi thingies when we're still in the freerun area? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org