Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932538AbVKWVdT (ORCPT ); Wed, 23 Nov 2005 16:33:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932539AbVKWVdS (ORCPT ); Wed, 23 Nov 2005 16:33:18 -0500 Received: from clock-tower.bc.nu ([81.2.110.250]:49793 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S932538AbVKWVdR (ORCPT ); Wed, 23 Nov 2005 16:33:17 -0500 Subject: Re: [patch] SMP alternatives From: Alan Cox To: Andi Kleen Cc: Linus Torvalds , "H. Peter Anvin" , Gerd Knorr , Dave Jones , Zachary Amsden , Pavel Machek , Andrew Morton , Linux Kernel Mailing List , Zwane Mwaikambo , Pratap Subrahmanyam , Christopher Li , "Eric W. Biederman" , Ingo Molnar In-Reply-To: <20051123211353.GR20775@brahms.suse.de> References: <437B5A83.8090808@suse.de> <438359D7.7090308@suse.de> <1132764133.7268.51.camel@localhost.localdomain> <20051123163906.GF20775@brahms.suse.de> <1132766489.7268.71.camel@localhost.localdomain> <4384AECC.1030403@zytor.com> <1132782245.13095.4.camel@localhost.localdomain> <20051123211353.GR20775@brahms.suse.de> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Wed, 23 Nov 2005 22:05:40 +0000 Message-Id: <1132783540.13095.23.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 823 Lines: 19 On Mer, 2005-11-23 at 22:13 +0100, Andi Kleen wrote: > The idea was to turn LOCK on only if the process has any > shared writable mapping and num_online_cpus() > 0. That makes a lot of sense, and if we hit hardware that does funky stuff then the driver can set a 'vma needs lock' bit for the same effect. > Might be a bit costly to rewrite all the page tables for that case > just to change the PAT index. A bit is nicer for that. CPU insert/remove is performed how many times a second ? Or for that matter why not just reload the PAT register and keep the index the same ? - 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/