From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934121AbXHNVjV (ORCPT ); Tue, 14 Aug 2007 17:39:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752567AbXHNVX7 (ORCPT ); Tue, 14 Aug 2007 17:23:59 -0400 Received: from one.firstfloor.org ([213.235.205.2]:55476 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757157AbXHNVX5 (ORCPT ); Tue, 14 Aug 2007 17:23:57 -0400 Date: Tue, 14 Aug 2007 23:23:55 +0200 From: Andi Kleen To: Christoph Lameter Cc: Andi Kleen , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c Message-ID: <20070814212355.GA23308@one.firstfloor.org> References: <20070814153021.446917377@sgi.com> <20070814153501.766137366@sgi.com> <20070814203329.GA22202@one.firstfloor.org> <20070814204454.GC22202@one.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 14, 2007 at 02:15:12PM -0700, Christoph Lameter wrote: > On Tue, 14 Aug 2007, Andi Kleen wrote: > > > > Hmmmm... The spinlock is its own flag. > > > > Yes, but it's not CPU local. Taking the spinlock from another CPU's > > interrupt handler is perfectly safe, just not from the local CPU. > > If you use the spinlock as flag you would need to lock out everybody. > > So every spinlock would have an array of chars sized to NR_CPUS and set > the flag when the lock is taken? I was more thinking of a single per cpu flag for all of page reclaim That keeps it also cache local. -Andi