From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 31 Mar 2009 09:11:29 +0100 (BST) Received: from localhost.localdomain ([127.0.0.1]:55272 "EHLO h5.dl5rb.org.uk") by ftp.linux-mips.org with ESMTP id S20028983AbZCaIL1 (ORCPT ); Tue, 31 Mar 2009 09:11:27 +0100 Received: from h5.dl5rb.org.uk (localhost.localdomain [127.0.0.1]) by h5.dl5rb.org.uk (8.14.3/8.14.3) with ESMTP id n2V8BL5V018533; Tue, 31 Mar 2009 10:11:23 +0200 Received: (from ralf@localhost) by h5.dl5rb.org.uk (8.14.3/8.14.3/Submit) id n2V8BHX1018529; Tue, 31 Mar 2009 10:11:17 +0200 Date: Tue, 31 Mar 2009 10:11:13 +0200 From: Ralf Baechle To: =?utf-8?B?5p6X5bu65a6J?= , linux-mips@linux-mips.org Subject: Re: The impact to change page size to 16k for cache alias Message-ID: <20090331081113.GA17934@linux-mips.org> References: <9BDA961341E843F29C1C1ECDB54FD0CF@realtek.com.tw> <20090330082414.GA4797@adriano.hkcable.com.hk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090330082414.GA4797@adriano.hkcable.com.hk> User-Agent: Mutt/1.5.18 (2008-05-17) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 22194 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Mon, Mar 30, 2009 at 04:24:15PM +0800, Zhang Le wrote: > > Hi all, > > We are willing to use 16k page size to avoid cache alias problem. > > The Linux version we use is 2.6.12. If we just upgrade mm system to > > support 16k page size, what else problems will happen? > > There is already one thing we know that applications of ELF format > > applications should be transformed to be 16k alignment. > > Another one, we think, highly suspected to be problematic is that many > > drivers will be ok for 4k page size but fails for 16k. > > That is because 4k page size had been seemed to be natural for a very > > long long time. > > Any other problem that shall happen for 16k page size? > > Linux on Loongson 2E and 2F uses 16k page size to avoid cache alias problem, too. > However, I haven't encountered any problem on Linux kernel itself due to 16k page > size. > > Anyway, I am not 100% familiar with Loongson patches, so I am not sure whether > the page size problem is already been taken care of in the patch. If you are > interested to find out yourself, you can get the whole source here: > http://repo.or.cz/w/linux-2.6/linux-loongson.git I've got a report that Fulong is currently only working with 16k pages. So 4k is no longer the bullet proof choice for all cases :) Ralf