From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753786AbXDDNcL (ORCPT ); Wed, 4 Apr 2007 09:32:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753803AbXDDNcL (ORCPT ); Wed, 4 Apr 2007 09:32:11 -0400 Received: from extu-mxob-2.symantec.com ([216.10.194.135]:57155 "EHLO extu-mxob-2.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753786AbXDDNcJ (ORCPT ); Wed, 4 Apr 2007 09:32:09 -0400 X-AuditID: d80ac287-976cabb000000c42-2d-4613a8d8ecdd Date: Wed, 4 Apr 2007 14:32:03 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@blonde.wat.veritas.com To: Andrea Arcangeli cc: Nick Piggin , Andrew Morton , Linus Torvalds , Linux Memory Management List , tee@sgi.com, holt@sgi.com, Linux Kernel Mailing List Subject: Re: [rfc] no ZERO_PAGE? In-Reply-To: <20070404130559.GD19587@v2.random> Message-ID: References: <20070329075805.GA6852@wotan.suse.de> <20070330024048.GG19407@wotan.suse.de> <20070404033726.GE18507@wotan.suse.de> <20070404102407.GA529@wotan.suse.de> <20070404130559.GD19587@v2.random> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 04 Apr 2007 13:32:08.0374 (UTC) FILETIME=[A47A8D60:01C776BD] X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 4 Apr 2007, Andrea Arcangeli wrote: > On Wed, Apr 04, 2007 at 01:45:06PM +0100, Hugh Dickins wrote: > > I'm confused. CONFIG_ZERO_PAGE off is where we'd like to end up: how > > would turning CONFIG_ZERO_PAGE on in -rc kernels help us to get there? > > He most certainly meant on by default. Okay, I thought it more diplomatic to label myself as the confused one ;) > > I think if we do this, we also need a zeropage counter in the vm stats > so that we'll get a measure of the waste and it'll be possible to > identify apps to optimize/fix. That's a little unfortunate, since we'd then have to lose the win from this change, that we issue a writable zeroed page (when VM_WRITE) in do_anonymous_page, even when it's a read fault, saving subsequent fault. Wouldn't we? Or am I confused ;? Hugh