Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 29 Jul 2002 05:24:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 29 Jul 2002 05:24:02 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:25860 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id ; Mon, 29 Jul 2002 05:24:02 -0400 Date: Mon, 29 Jul 2002 10:27:21 +0100 From: Russell King To: Andrew Morton Cc: Linux Kernel Subject: Re: [BK PATCH 2.5] Introduce 64-bit versions of PAGE_{CACHE_,}{MASK,ALIGN} Message-ID: <20020729102721.B23843@flint.arm.linux.org.uk> References: <5.1.0.14.2.20020728193528.04336a80@pop.cus.cam.ac.uk> <3D448808.CF8D18BA@zip.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <3D448808.CF8D18BA@zip.com.au>; from akpm@zip.com.au on Sun, Jul 28, 2002 at 05:10:48PM -0700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 949 Lines: 22 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: 1. non-discontiguous case (should be around 2 loads + math) 2. discontiguous case (currently 5 loads + lots of math) 3. weirder setups where loading page->virtual is faster We currently ignore (1) completely, and just assume its the same as (2). -- Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/