From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758378AbXLOMli (ORCPT ); Sat, 15 Dec 2007 07:41:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751276AbXLOMlb (ORCPT ); Sat, 15 Dec 2007 07:41:31 -0500 Received: from one.firstfloor.org ([213.235.205.2]:57409 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752249AbXLOMla (ORCPT ); Sat, 15 Dec 2007 07:41:30 -0500 Date: Sat, 15 Dec 2007 13:41:47 +0100 From: Andi Kleen To: Chuck Ebbert Cc: Andi Kleen , Eduard-Gabriel Munteanu , LKML Subject: Re: [PATCH] Option to disable AMD C1E (allows dynticks to work) Message-ID: <20071215124147.GA26909@one.firstfloor.org> References: <20071214004442.5f9eba88@linux360.ro> <20071214143941.2c7dcfb4@linux360.ro> <20071214101720.GA10981@one.firstfloor.org> <47630521.4060505@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47630521.4060505@redhat.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 14, 2007 at 05:35:13PM -0500, Chuck Ebbert wrote: > On 12/14/2007 05:17 AM, Andi Kleen wrote: > >> so do whatever is necessary to enable dynticks. > > > > dynticks' main purpose is to save power, but C1e saves more power. > > Disabling C1e for dynticks would be a fairly useless default > > trade off. > > > > What about machines where the BIOS has disabled C1e on CPU 0 but > left it enabled on CPU 1 ?? It's a BIOS bug. We handle this and threat it like C1e always enabled. The right fix would be to enable it on both CPUs, but then that's not strictly needed for correct operation and I'm not sure it would be worth special fixup code in Linux. Probably not. -Andi