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 B39D5600815 for ; Tue, 27 Jul 2010 10:56:43 -0400 (EDT) Date: Tue, 27 Jul 2010 22:55:25 +0800 From: Wu Fengguang 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> Sender: owner-linux-mm@kvack.org 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 List-ID: 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, 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