From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262545AbVG2JDa (ORCPT ); Fri, 29 Jul 2005 05:03:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262523AbVG2JDZ (ORCPT ); Fri, 29 Jul 2005 05:03:25 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:46347 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S262540AbVG2JDJ (ORCPT ); Fri, 29 Jul 2005 05:03:09 -0400 Date: Fri, 29 Jul 2005 10:02:57 +0100 From: Russell King To: Ingo Molnar Cc: "Chen, Kenneth W" , Keith Owens , David.Mosberger@acm.org, Andrew Morton , linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org Subject: Re: Add prefetch switch stack hook in scheduler function Message-ID: <20050729100257.A10345@flint.arm.linux.org.uk> Mail-Followup-To: Ingo Molnar , "Chen, Kenneth W" , Keith Owens , David.Mosberger@acm.org, Andrew Morton , linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org References: <20050729070447.GA3032@elte.hu> <200507290722.j6T7Mig07477@unix-os.sc.intel.com> <20050729082826.GA6144@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20050729082826.GA6144@elte.hu>; from mingo@elte.hu on Fri, Jul 29, 2005 at 10:28:26AM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 29, 2005 at 10:28:26AM +0200, Ingo Molnar wrote: > @@ -2872,10 +2878,10 @@ go_idle: > /* > * Prefetch (at least) a cacheline below the current > * kernel stack (in expectation of any new task touching > - * the stack at least minimally), and a cacheline above > - * the stack: > + * the stack at least minimally), and at least a cacheline > + * above the stack: > */ > - prefetch_range(kernel_stack(next) - MIN_KERNEL_STACK_FOOTPRINT, > + prefetch_range(kernel_stack(next) - L1_CACHE_BYTES, > MIN_KERNEL_STACK_FOOTPRINT + L1_CACHE_BYTES); This needs to ensure that we don't prefetch outside the page of the kernel stack - otherwise we risk weird problems on architectures which support prefetching but not DMA cache coherency. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core