From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 0764F6B0071 for ; Fri, 8 Oct 2010 06:06:36 -0400 (EDT) From: "Wu, Xia" Date: Fri, 8 Oct 2010 18:04:44 +0800 Subject: RE: [PATCH] bdi: use deferable timer for sync_supers task Message-ID: References: <20101008083514.GA12402@ywang-moblin2.bj.intel.com> <20101008092520.GB5426@lst.de> In-Reply-To: <20101008092520.GB5426@lst.de> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org To: Christoph Hellwig , Yong Wang Cc: Jens Axboe , Artem Bityutskiy , "Wu, Fengguang" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" List-ID: On Fri, Oct 08, 2010 at 04:35:14PM +0800, Yong Wang wrote: > > sync_supers task currently wakes up periodically for superblock > > writeback. This hurts power on battery driven devices. This patch > > turns this housekeeping timer into a deferable timer so that it > > does not fire when system is really idle. > How long can the timer be defereed? We can't simply stop writing > out data for a long time. I think the current timer value should be > the upper bound, but allowing to fire earlier to run during the > same wakeup cycle as others is fine. If the system is in sleep state, this timer can be deferred to the next wak= e-up interrupt. If the system is busy, this timer will fire at the scheduled time. -- 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/ . Don't email: email@kvack.org