From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752615Ab2A0Ddd (ORCPT ); Thu, 26 Jan 2012 22:33:33 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50732 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751540Ab2A0Ddc (ORCPT ); Thu, 26 Jan 2012 22:33:32 -0500 Message-ID: <4F221AFE.6070108@redhat.com> Date: Thu, 26 Jan 2012 22:33:18 -0500 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:9.0) Gecko/20111222 Thunderbird/9.0 MIME-Version: 1.0 To: Dan Magenheimer CC: Andrew Morton , Dave Hansen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Konrad Wilk , Seth Jennings , Nitin Gupta , Nebojsa Trpkovic , minchan@kernel.org, KAMEZAWA Hiroyuki , Chris Mason Subject: Re: [PATCH] mm: implement WasActive page flag (for improving cleancache) References: <4F218D36.2060308@linux.vnet.ibm.com> <9fcd06f5-360e-4542-9fbb-f8c7efb28cb6@default> <20120126163150.31a8688f.akpm@linux-foundation.org> <20120126171548.2c85dd44.akpm@linux-foundation.org> <7198bfb3-1e32-40d3-8601-d88aed7aabd8@default> In-Reply-To: <7198bfb3-1e32-40d3-8601-d88aed7aabd8@default> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/26/2012 09:43 PM, Dan Magenheimer wrote: > Maybe the Active page bit could be overloaded with some minor > rewriting? IOW, perhaps the Active bit could be ignored when > the page is moved to the inactive LRU? (Confusing I know, but I am > just brainstorming...) The PG_referenced bit is already overloaded. We keep the bit set when we move a page from the active to the inactive list, so a page that was previously active only needs to be referenced once to become active again. The LRU bits (PG_lru, PG_active, etc) are needed to figure out which LRU list the page is on. I don't think we can overload those... -- All rights reversed