From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 29 Jul 2002 14:31:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 29 Jul 2002 14:31:42 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:15114 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Mon, 29 Jul 2002 14:31:42 -0400 Message-ID: <3D458A58.FB15D5D0@zip.com.au> Date: Mon, 29 Jul 2002 11:32:56 -0700 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.4.19-pre8 i686) X-Accept-Language: en MIME-Version: 1.0 To: Russell King CC: Linux Kernel Subject: Re: [BK PATCH 2.5] Introduce 64-bit versions of PAGE_{CACHE_,}{MASK,ALIGN} References: <5.1.0.14.2.20020728193528.04336a80@pop.cus.cam.ac.uk> <3D448808.CF8D18BA@zip.com.au> <20020729102721.B23843@flint.arm.linux.org.uk> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Russell King wrote: > > On Sun, Jul 28, 2002 at 05:10:48PM -0700, Andrew Morton wrote: > > - Remove ->virtual, do page_address() via a hash. 4(ish) bytes saved. > > Hmmmmmmm. page_address() is already 5 loads (on ARM) if page->virtual > isn't used. I'm seriously considering changing page_address() to cover > the 3 cases more efficiently: Well, one would want to keep the WANT_PAGE_VIRTUAL thing anyway. btw, the usage of page_address() will quite possibly drop sharply soon anyway. There's the patch floating about which permits atomic kmaps to be held across copy_*_user. If that is adopted, things like the pagecache IO routines won't do page_address() any more. Said patch speeds up pagecache IO by between 0% and probably 30%. It's the mystery surrounding this variation which is holding things up. -