Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261523AbTICHlj (ORCPT ); Wed, 3 Sep 2003 03:41:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261613AbTICHli (ORCPT ); Wed, 3 Sep 2003 03:41:38 -0400 Received: from mail.jlokier.co.uk ([81.29.64.88]:45451 "EHLO mail.jlokier.co.uk") by vger.kernel.org with ESMTP id S261523AbTICHlg (ORCPT ); Wed, 3 Sep 2003 03:41:36 -0400 Date: Wed, 3 Sep 2003 08:41:34 +0100 From: Jamie Lokier To: 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: <20030903074134.GB19920@mail.jlokier.co.uk> References: <20030901101224.GB1638@mail.jlokier.co.uk> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030903083118.A17670@flint.arm.linux.org.uk> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1029 Lines: 25 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. I don't know if ARM's ELF is like the x86, but on the x86 the final partial page of code or read-only data will be mapped twice, as the latter part of the page can contain writable data. This avoids wasting up to a page's worth of bytes in the ELF file. -- Jamie - 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/