From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx143.postini.com [74.125.245.143]) by kanga.kvack.org (Postfix) with SMTP id 4BD3D6B005C for ; Mon, 30 Jan 2012 03:59:07 -0500 (EST) Received: from m1.gw.fujitsu.co.jp (unknown [10.0.50.71]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 8E81A3EE0BD for ; Mon, 30 Jan 2012 17:59:05 +0900 (JST) Received: from smail (m1 [127.0.0.1]) by outgoing.m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 772BB3266C1 for ; Mon, 30 Jan 2012 17:59:05 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (s1.gw.fujitsu.co.jp [10.0.50.91]) by m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 5EDDC206FC2 for ; Mon, 30 Jan 2012 17:59:05 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 4DAA91DB8040 for ; Mon, 30 Jan 2012 17:59:05 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.240.81.146]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 0736F1DB804C for ; Mon, 30 Jan 2012 17:59:05 +0900 (JST) Date: Mon, 30 Jan 2012 17:57:30 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH] mm: implement WasActive page flag (for improving cleancache) Message-Id: <20120130175730.de654d9c.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <22f6781b-9cc4-4857-b3e1-e2d9f595f64d@default> 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> <4F221AFE.6070108@redhat.com> <22f6781b-9cc4-4857-b3e1-e2d9f595f64d@default> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dan Magenheimer Cc: Rik van Riel , Andrew Morton , Dave Hansen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Konrad Wilk , Seth Jennings , Nitin Gupta , Nebojsa Trpkovic , minchan@kernel.org, Chris Mason On Thu, 26 Jan 2012 21:15:16 -0800 (PST) Dan Magenheimer wrote: > > From: Rik van Riel [mailto:riel@redhat.com] > > Subject: Re: [PATCH] mm: implement WasActive page flag (for improving cleancache) > > > > 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... > > I suspected that was true, but was just brainstorming. > Thanks for confirming. > > Are there any other page bits that are dont-care when > a page is on an LRU list? > > I'd also be interested in your/RedHat's opinion on the > 64-bit vs 32-bit market. Will RHEL7 even support 32-bit? > How about replacing PG_slab ? I think PageSlab(page) be implemented as #define SLABMAGIC (some value) #define PageSlab(page) (page->mapping == SLABMAGIC) or some... Thanks, -Kame -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org