From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751359Ab1GFE16 (ORCPT ); Wed, 6 Jul 2011 00:27:58 -0400 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:39991 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750907Ab1GFE15 (ORCPT ); Wed, 6 Jul 2011 00:27:57 -0400 Date: Wed, 6 Jul 2011 09:57:44 +0530 From: Ankita Garg To: Valdis.Kletnieks@vt.edu Cc: linux-mm@kvack.org, svaidy@linux.vnet.ibm.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/5] mm,debug: VM framework to capture memory reference pattern Message-ID: <20110706042744.GA15861@in.ibm.com> Reply-To: Ankita Garg References: <1309854159-8277-1-git-send-email-ankita@in.ibm.com> <64797.1309908804@turing-police.cc.vt.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <64797.1309908804@turing-police.cc.vt.edu> 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 Hi, On Tue, Jul 05, 2011 at 07:33:24PM -0400, Valdis.Kletnieks@vt.edu wrote: > On Tue, 05 Jul 2011 13:52:34 +0530, Ankita Garg said: > > > by default) and scans through all pages of the specified tasks (including > > children/threads) running in the system. If the hardware reference bit in the > > page table is set, then the page is marked as accessed over the last sampling > > interval and the reference bit is cleared. > > Does that cause any issues for other code in the mm subsystem that was > expecting to use the reference bit for something useful? (Similarly, if other > code in mm turns that bit *off* for its own reasons, does your code still > produce useful results?) At this point, the VM code does not use the reference bit for any decision making, not even in the LRU. However, if the reference bit is used later on, then this change will interfere with that logic. -- Regards, Ankita Garg (ankita@in.ibm.com) Linux Technology Center IBM India Systems & Technology Labs, Bangalore, India