From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx200.postini.com [74.125.245.200]) by kanga.kvack.org (Postfix) with SMTP id 677866B00A4 for ; Fri, 27 Jan 2012 00:15:17 -0500 (EST) MIME-Version: 1.0 Message-ID: <22f6781b-9cc4-4857-b3e1-e2d9f595f64d@default> Date: Thu, 26 Jan 2012 21:15:16 -0800 (PST) From: Dan Magenheimer 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> <4F221AFE.6070108@redhat.com> In-Reply-To: <4F221AFE.6070108@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel 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 > From: Rik van Riel [mailto:riel@redhat.com] > Subject: Re: [PATCH] mm: implement WasActive page flag (for improving cle= ancache) >=20 > On 01/26/2012 09:43 PM, Dan Magenheimer wrote: >=20 > > 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...) >=20 > 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. >=20 > 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? Dan -- 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