From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 99E7160021B for ; Sun, 27 Dec 2009 22:57:45 -0500 (EST) Received: from d23relay05.au.ibm.com (d23relay05.au.ibm.com [202.81.31.247]) by e23smtp08.au.ibm.com (8.14.3/8.13.1) with ESMTP id nBS3vgls009908 for ; Mon, 28 Dec 2009 14:57:42 +1100 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id nBS3rSWr1335306 for ; Mon, 28 Dec 2009 14:53:28 +1100 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id nBS3vfZ1018437 for ; Mon, 28 Dec 2009 14:57:41 +1100 Date: Mon, 28 Dec 2009 09:27:38 +0530 From: Balbir Singh Subject: Re: [PATCH -mmotm-2009-12-10-17-19] Prevent churning of zero page in LRU list. Message-ID: <20091228035738.GH3601@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20091228115315.76b1ecd0.minchan.kim@barrios-desktop> <4B38246C.3020209@redhat.com> <20091228035639.GG3601@balbir.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20091228035639.GG3601@balbir.in.ibm.com> Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: Minchan Kim , Andrew Morton , lkml , linux-mm , Hugh Dickins , KOSAKI Motohiro List-ID: * Balbir Singh [2009-12-28 09:26:39]: > * Rik van Riel [2009-12-27 22:22:20]: > > > On 12/27/2009 09:53 PM, Minchan Kim wrote: > > > > > >VM doesn't add zero page to LRU list. > > >It means zero page's churning in LRU list is pointless. > > > > > >As a matter of fact, zero page can't be promoted by mark_page_accessed > > >since it doesn't have PG_lru. > > > > > >This patch prevent unecessary mark_page_accessed call of zero page > > >alghouth caller want FOLL_TOUCH. > > > > > >Signed-off-by: Minchan Kim > > > > The code looks correct, but I wonder how frequently we run into > > the zero page in this code, vs. how much the added cost is of > > having this extra code in follow_page. > > > > What kind of problem were you running into that motivated you > > to write this patch? > > > > Frequent moving of zero page should ideally put it to the head of the > LRU list, leaving it untouched is likely to cause it to be scanned > often - no? Should this be moved to the unevictable list? > Sorry, I replied to wrong email, I should have been clearer that this question is for Minchan Kim. -- Balbir -- 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