Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262191AbUCQXhg (ORCPT ); Wed, 17 Mar 2004 18:37:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262198AbUCQXhg (ORCPT ); Wed, 17 Mar 2004 18:37:36 -0500 Received: from dp.samba.org ([66.70.73.150]:14769 "EHLO lists.samba.org") by vger.kernel.org with ESMTP id S262191AbUCQXhe (ORCPT ); Wed, 17 Mar 2004 18:37:34 -0500 Date: Thu, 18 Mar 2004 10:36:57 +1100 From: Anton Blanchard To: Robert Love Cc: Chris Friesen , Linux kernel , akpm@osdl.org Subject: Re: status of PREEMPT and SMP together? Message-ID: <20040317233657.GD28212@krispykreme> References: <4058C37F.8070409@nortelnetworks.com> <1079560828.1435.24.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1079560828.1435.24.camel@localhost> User-Agent: Mutt/1.5.5.1+cvs20040105i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1780 Lines: 50 > Hrm, I thought I sent Anton a patch to fix that. Sorry, I had planned to send it once Linus got over his deep freeze mode but forgot. Here it is. Now that the option is selectable I marked it BROKEN for the moment since we havent got around to doing the low level exception bits yet... Do you have a G5 yet? :) > The comment is out of date. Technically speaking, the potential > SMP+PREEMPT races exist on UP+PREEMPT, too. > > Running SMP+PREEMPT on a 4-way here :-) -- From: Robert Love arch/ppc64/Kconfig's entry for CONFIG_PREEMPT is missing the description after the "bool" statement, so the entry does not show up. Also, the help description mentions a restriction that is not [any longer] true. ===== arch/ppc64/Kconfig 1.50 vs edited ===== --- 1.50/arch/ppc64/Kconfig Sun Mar 7 18:05:28 2004 +++ edited/arch/ppc64/Kconfig Thu Mar 18 10:33:17 2004 @@ -174,14 +179,12 @@ depends on DISCONTIGMEM config PREEMPT - bool + bool "Preemptible Kernel" + depends on BROKEN help This option reduces the latency of the kernel when reacting to real-time or interactive events by allowing a low priority process to be preempted even if it is in kernel mode executing a system call. - Unfortunately the kernel code has some race conditions if both - CONFIG_SMP and CONFIG_PREEMPT are enabled, so this option is - currently disabled if you are building an SMP kernel. Say Y here if you are building a kernel for a desktop, embedded or real-time system. Say N if you are unsure. - 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/