From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752011Ab3GDJcP (ORCPT ); Thu, 4 Jul 2013 05:32:15 -0400 Received: from cantor2.suse.de ([195.135.220.15]:39581 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750769Ab3GDJcO (ORCPT ); Thu, 4 Jul 2013 05:32:14 -0400 Date: Thu, 4 Jul 2013 10:32:11 +0100 From: Mel Gorman To: Peter Zijlstra Cc: Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML Subject: Re: [PATCH 12/13] mm: numa: Scan pages with elevated page_mapcount Message-ID: <20130704093211.GN1875@suse.de> References: <1372861300-9973-1-git-send-email-mgorman@suse.de> <1372861300-9973-13-git-send-email-mgorman@suse.de> <20130703184124.GD18898@dyad.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20130703184124.GD18898@dyad.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 03, 2013 at 08:41:24PM +0200, Peter Zijlstra wrote: > On Wed, Jul 03, 2013 at 03:21:39PM +0100, Mel Gorman wrote: > > > Note that the patch still leaves shared, file-backed in VM_EXEC vmas in > > place guessing that these are shared library pages. Migrating them are > > likely to be of major benefit as generally the expectation would be that > > these are read-shared between caches and that iTLB and iCache pressure is > > generally low. > > I'm failing to grasp.. we don't migrate them because migrating them would > likely be beneficial? > > Missing a negative somewhere? Yes. Note that the patch does not migrate shared, file-backed within vmas marked VM_EXEC as these are generally shared library pages. Migrating such pages is not beneficial as there is an expectation they are read-shared between caches and iTLB and iCache pressure is generally low. -- Mel Gorman SUSE Labs