Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756397Ab0G0O4S (ORCPT ); Tue, 27 Jul 2010 10:56:18 -0400 Received: from mga09.intel.com ([134.134.136.24]:4163 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756054Ab0G0O4R (ORCPT ); Tue, 27 Jul 2010 10:56:17 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.55,269,1278313200"; d="scan'208";a="642124708" Date: Tue, 27 Jul 2010 22:55:25 +0800 From: Wu Fengguang To: Mel Gorman Cc: "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , Dave Chinner , Chris Mason , Nick Piggin , Rik van Riel , Johannes Weiner , Christoph Hellwig , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Andrew Morton , Andrea Arcangeli Subject: Re: [PATCH 8/8] vmscan: Kick flusher threads to clean pages when reclaim is encountering dirty pages Message-ID: <20100727145525.GA5184@localhost> References: <1279545090-19169-9-git-send-email-mel@csn.ul.ie> <20100726072832.GB13076@localhost> <20100726092616.GG5300@csn.ul.ie> <20100726112709.GB6284@localhost> <20100726125717.GS5300@csn.ul.ie> <20100726131008.GE11947@localhost> <20100727133513.GZ5300@csn.ul.ie> <20100727142412.GA4771@localhost> <20100727143423.GA5057@localhost> <20100727144026.GC5300@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100727144026.GC5300@csn.ul.ie> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1269 Lines: 32 On Tue, Jul 27, 2010 at 10:40:26PM +0800, Mel Gorman wrote: > On Tue, Jul 27, 2010 at 10:34:23PM +0800, Wu Fengguang wrote: > > > If you plan to keep wakeup_flusher_threads(), a simpler form may be > > > sufficient, eg. > > > > > > laptop_mode ? 0 : (nr_dirty * 16) > > > > This number is not sensitive because the writeback code may well round > > it up to some more IO efficient value (currently 4MB). AFAIK the > > nr_pages parameters passed by all existing flusher callers are some > > rule-of-thumb value, and far from being an exact number. > > > > I get that it's a rule of thumb but decided I would still pass in some value > related to nr_dirty that was bounded in some manner. > Currently, that bound is 4MB but maybe it should have been bound to > MAX_WRITEBACK_PAGES (which is 4MB for x86, but could be anything > depending on the base page size). I see your worry about much bigger page size making vmscan batch size > writeback batch size and it's a legitimate worry. Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/