From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751456AbWFPPbU (ORCPT ); Fri, 16 Jun 2006 11:31:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751455AbWFPPbU (ORCPT ); Fri, 16 Jun 2006 11:31:20 -0400 Received: from ecfrec.frec.bull.fr ([129.183.4.8]:45516 "EHLO ecfrec.frec.bull.fr") by vger.kernel.org with ESMTP id S1751453AbWFPPbT (ORCPT ); Fri, 16 Jun 2006 11:31:19 -0400 Message-ID: <4492CEC0.2080102@bull.net> Date: Fri, 16 Jun 2006 17:31:12 +0200 From: Zoltan Menyhart User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20040913 X-Accept-Language: en-us, en, fr, hu MIME-Version: 1.0 To: Andi Kleen Cc: Jes Sorensen , Tony Luck , discuss@x86-64.org, linux-kernel@vger.kernel.org, libc-alpha@sourceware.org, vojtech@suse.cz, linux-ia64@vger.kernel.org Subject: Re: FOR REVIEW: New x86-64 vsyscall vgetcpu() References: <200606140942.31150.ak@suse.de> <44929CE6.4@sgi.com> <4492A5E4.9050702@bull.net> <200606161656.40930.ak@suse.de> In-Reply-To: <200606161656.40930.ak@suse.de> X-MIMETrack: Itemize by SMTP Server on ECN002/FR/BULL(Release 5.0.12 |February 13, 2003) at 16/06/2006 17:35:06, Serialize by Router on ECN002/FR/BULL(Release 5.0.12 |February 13, 2003) at 16/06/2006 17:35:06, Serialize complete at 16/06/2006 17:35:06 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote: > That is not how user space TLS works. It usually has a base a register. Can you please give me a real life (simplified) example? > This means it cannot be cache colored (because you would need a static > offset) and you couldn't share task_structs on a page. I do not see the problem. Can you explain please? E.g. the scheduler pulls a task instead of the current one. The CPU will see "current->thread_info.cpu"-s of all the tasks at the same offset anyway. > Also you would make task_struct part of the userland ABI which > seems like a very very bad idea to me. It means we couldn't change > it anymore. We can make some wrapper, e.g.: user_per_cpu_var(name, offset) "vgetcpu()" would also be added to the ABI which we couldn't change easily either. Thanks, Zoltan