Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751149AbWIMWWi (ORCPT ); Wed, 13 Sep 2006 18:22:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751151AbWIMWWh (ORCPT ); Wed, 13 Sep 2006 18:22:37 -0400 Received: from gw.goop.org ([64.81.55.164]:55719 "EHLO mail.goop.org") by vger.kernel.org with ESMTP id S1751149AbWIMWWh (ORCPT ); Wed, 13 Sep 2006 18:22:37 -0400 Message-ID: <450884A1.2060905@goop.org> Date: Wed, 13 Sep 2006 15:22:25 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 1.5.0.5 (X11/20060907) MIME-Version: 1.0 To: Linus Torvalds CC: Ingo Molnar , Andi Kleen , "Eric W. Biederman" , Arjan van de Ven , Zachary Amsden , Linux Kernel Mailing List , Michael A Fetterman Subject: Re: Assignment of GDT entries References: <450854F3.20603@goop.org> <45087C78.20308@goop.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1271 Lines: 31 Linus Torvalds wrote: > So I'd not be surprised if movign the TLS segments around would break > something. > I don't think so. 32-bit code running on x86-64 has different TLS selectors, and everything seems to work there... > That said, numbers talk, bullshit walks. If the above just works a lot > better for all modern CPU's that all have 64-byte cachelines (because now > _everything_ is in that bigger cacheline), and if you can show that with > numbers, and nothing breaks in practice, then hey.. > My goal would be to do a minimal change which packs all the useful stuff together in a 64-byte line. Ideally it would just use two 32-byte lines, but I don't think that's as important. Caching effects are pretty hard to measure anyway, and with something as deeply x86-microarchitectural as this, I could imagine lots of other CPU cleverness which could obscure any simple measurement. But packing things into a line certainly can't hurt. I'll put something together, and see how it goes... J - 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/