From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757239Ab1DLU1J (ORCPT ); Tue, 12 Apr 2011 16:27:09 -0400 Received: from a.ns.miles-group.at ([95.130.255.143]:48667 "EHLO radon.swed.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757149Ab1DLU1I (ORCPT ); Tue, 12 Apr 2011 16:27:08 -0400 From: Richard Weinberger To: Pekka Enberg Subject: Re: um: this_cpu_cmpxchg16b_emu Date: Tue, 12 Apr 2011 22:27:03 +0200 User-Agent: KMail/1.13.5 (Linux/2.6.25.20-0.7-pae; KDE/4.4.4; i686; ; ) Cc: Tejun Heo , Christoph Lameter , linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net, hpa@zytor.com References: <201104121609.56901.richard@nod.at> <20110412192014.GF16342@mtj.dyndns.org> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201104122227.03688.richard@nod.at> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Dienstag 12 April 2011, 21:22:47 schrieb Pekka Enberg: > On Tue, Apr 12, 2011 at 08:41:11PM +0200, Richard Weinberger wrote: > >> Am Dienstag 12 April 2011, 20:10:37 schrieb Christoph Lameter: > >> > On Tue, 12 Apr 2011, Richard Weinberger wrote: > >> > > This patch implements this_cpu_cmpxchg16b_emu() for UML. > >> > > >> > Is this really necessary? Just undefine CONFIG_CMPXCHG_LOCAL for UML > >> > and the asm code will not be used. > >> > >> UML includes arch/x86/Kconfig.cpu which defines CONFIG_CMPXCHG_LOCAL > >> automatically. Just disabling CONFIG_CMPXCHG_LOCAL for UML is IMHO not > >> very nice. When chpxchg is available also UML should use it... > > On Tue, Apr 12, 2011 at 10:20 PM, Tejun Heo wrote: > > Ugh... I'd really like to avoid things like this for UML. Is there > > any SLUB performance sensitive workload running on UML? I've never > > seen any UML in production environment. Wouldn't it be better to keep > > things simple? > > Yes, it would be. :-) Okay. Then let's keep it simple. :-) I'll disable CONFIG_CMPXCHG_LOCAL for UML. Has someone looked at my this_cpu_cmpxchg16b_emu() implementation, is it correct? Especially the call to C stuff. I've tested it, it works fine. Thanks, //richard