Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264163AbTICSH6 (ORCPT ); Wed, 3 Sep 2003 14:07:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264128AbTICSG7 (ORCPT ); Wed, 3 Sep 2003 14:06:59 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:11786 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S264115AbTICSF1 (ORCPT ); Wed, 3 Sep 2003 14:05:27 -0400 Date: Wed, 3 Sep 2003 19:05:19 +0100 From: Russell King To: Jamie Lokier Cc: Larry McVoy , "Paul J.Y. Lahaie" , linux-kernel@vger.kernel.org Subject: Re: x86, ARM, PARISC, PPC, MIPS and Sparc folks please run this Message-ID: <20030903190519.D24951@flint.arm.linux.org.uk> Mail-Followup-To: Jamie Lokier , Larry McVoy , "Paul J.Y. Lahaie" , linux-kernel@vger.kernel.org References: <20030901151710.A22682@flint.arm.linux.org.uk> <20030901165239.GB3556@mail.jlokier.co.uk> <20030901181148.C22682@flint.arm.linux.org.uk> <20030902053415.GA7619@mail.jlokier.co.uk> <20030902091553.A29984@flint.arm.linux.org.uk> <20030902115731.GA14354@mail.jlokier.co.uk> <20030902195222.D9345@flint.arm.linux.org.uk> <20030902235900.GA5769@work.bitmover.com> <20030903083118.A17670@flint.arm.linux.org.uk> <20030903074134.GB19920@mail.jlokier.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20030903074134.GB19920@mail.jlokier.co.uk>; from jamie@shareable.org on Wed, Sep 03, 2003 at 08:41:34AM +0100 X-Message-Flag: Your copy of Microsoft Outlook is vulnerable to viruses. See www.mutt.org for more details. Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1282 Lines: 32 On Wed, Sep 03, 2003 at 08:41:34AM +0100, Jamie Lokier wrote: > Russell King wrote: > > > > Multiple mappings of the same object rarely occur in my experience, so > > > > the resulting performance loss caused by working around the cache and > > > > writebuffer is something we can live with. > > > > > > Multiple *writable* mappings. Don't forget about libc et al. > > > > I mean in the same group of threads with the same struct mm, not the whole > > system. > > Larry means that it's perfectly normal for libc to map the same file > more than once: you have the code section and the data section. Code is read-only, data is read-write and is copy on write. Therefore its a different scenario. Practical tests indicate that the vast majority of applications do not trip the test. You're right in theory, but I don't particularly care about theory when its real life which matters. -- 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/