From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755657Ab0JHKbJ (ORCPT ); Fri, 8 Oct 2010 06:31:09 -0400 Received: from smtp.nokia.com ([147.243.1.47]:23928 "EHLO mgw-sa01.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752930Ab0JHKbH (ORCPT ); Fri, 8 Oct 2010 06:31:07 -0400 Subject: RE: [PATCH] bdi: use deferable timer for sync_supers task From: Artem Bityutskiy Reply-To: Artem.Bityutskiy@nokia.com To: "Wu, Xia" Cc: Christoph Hellwig , Yong Wang , Jens Axboe , "Wu, Fengguang" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" In-Reply-To: References: <20101008083514.GA12402@ywang-moblin2.bj.intel.com> <20101008092520.GB5426@lst.de> <1286532586.2095.55.camel@localhost> Content-Type: text/plain; charset="UTF-8" Organization: Nokia Date: Fri, 08 Oct 2010 13:28:07 +0300 Message-ID: <1286533687.2095.58.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 (2.30.3-1.fc13) Content-Transfer-Encoding: 8bit X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2010-10-08 at 18:27 +0800, Wu, Xia wrote: > > However, when the next wake-up interrupt happens is not defined. It can > > happen 1ms after, or 1 minute after, or 1 hour after. What Christoph > > says is that there should be some guarantee that sb writeout starts, > > say, within 5 to 10 seconds interval. Deferrable timers do not guarantee > > this. But take a look at the range hrtimers - they do exactly this. > > If the system is in sleep state, is there any data which should be written? May be yes, may be no. > Must > sb writeout start even there isn't any data? No. -- Best Regards, Artem Bityutskiy (Артём Битюцкий)