Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757395AbYLaWSa (ORCPT ); Wed, 31 Dec 2008 17:18:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753172AbYLaWSV (ORCPT ); Wed, 31 Dec 2008 17:18:21 -0500 Received: from relay1.sgi.com ([192.48.179.29]:34117 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752756AbYLaWSV (ORCPT ); Wed, 31 Dec 2008 17:18:21 -0500 Message-ID: <495BEFA9.80804@sgi.com> Date: Wed, 31 Dec 2008 14:18:17 -0800 From: Mike Travis User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Ravikiran G Thirumalai CC: Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [patch] x86: Fix incorrect __read_mostly on _boot_cpu_pda References: <20081231214446.GA6856@localdomain> In-Reply-To: <20081231214446.GA6856@localdomain> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1211 Lines: 31 Ravikiran G Thirumalai wrote: > The pda rework (commit 3461b0af025251bbc6b3d56c821c6ac2de6f7209) > to remove static boot cpu pdas introduced a bug. _boot_cpu_pda is the > actual pda used by the boot cpu and is definitely not "__read_mostly" and > ended up polluting the read mostly section with writes. This bug caused > regression of about 8-10% on certain syscall intensive workloads. > > Signed-off-by: Ravikiran Thirumalai > > Index: linux-2.6/arch/x86/kernel/head64.c > =================================================================== > --- linux-2.6.orig/arch/x86/kernel/head64.c 2008-12-30 15:28:08.000000000 -0800 > +++ linux-2.6/arch/x86/kernel/head64.c 2008-12-31 10:36:21.000000000 -0800 > @@ -27,7 +27,7 @@ > #include > > /* boot cpu pda */ > -static struct x8664_pda _boot_cpu_pda __read_mostly; > +static struct x8664_pda _boot_cpu_pda; > > #ifdef CONFIG_SMP > /* Thanks for catching that! Mike -- 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/