From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754543AbZICGMa (ORCPT ); Thu, 3 Sep 2009 02:12:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754504AbZICGM3 (ORCPT ); Thu, 3 Sep 2009 02:12:29 -0400 Received: from mga11.intel.com ([192.55.52.93]:17662 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754503AbZICGM2 (ORCPT ); Thu, 3 Sep 2009 02:12:28 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,324,1249282800"; d="scan'208";a="723473115" Subject: Re: [PATCH 4/6] thermal: add sanity check for the passive attribute From: Zhang Rui To: Frans Pop Cc: Matthew Garrett , "linux-acpi@vger.kernel.org" , "linux-kernel@vger.kernel.org" In-Reply-To: <200908311230.32021.elendil@planet.nl> References: <1251303445-25317-1-git-send-email-elendil@planet.nl> <200908261848.29897.elendil@planet.nl> <1251707630.3483.181.camel@rzhang-dt> <200908311230.32021.elendil@planet.nl> Content-Type: text/plain; charset=utf-8 Date: Thu, 03 Sep 2009 14:10:05 +0800 Message-Id: <1251958205.3483.290.camel@rzhang-dt> Mime-Version: 1.0 X-Mailer: Evolution 2.22.1 (2.22.1-2.fc9) Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2009-08-31 at 18:30 +0800, Frans Pop wrote: > On Monday 31 August 2009, Zhang Rui wrote: > > On Thu, 2009-08-27 at 00:48 +0800, Frans Pop wrote: > > > On Wednesday 26 August 2009, Matthew Garrett wrote: > > > > On Wed, Aug 26, 2009 at 06:17:23PM +0200, Frans Pop wrote: > > > > > Values below 40000 milli-celsius (limit is somewhat arbitrary) > > > > > don't make sense and can cause the system to go into a thermal > > > > > heart attack: the actual temperature will always be lower and > > > > > thus the system will be throttled down to its lowest setting. > > > > > > > > Not keen on this - it's a pretty arbitrary cutoff, and there are > > > > some cases where someone might want this value. Policy belongs in > > > > userspace, and all that. > > > > > > What cases do you see? Testing? Or systems that might have to operate > > > at such a low temperature? I deliberately chose a value that's at a > > > level that's easy to reach. > > > > > > I agree it is arbitrary, but it will prevent major confusion when > > > someone like me echo's 95 directly in sysfs. > > > > this is a problem. > > how about something like: > > #define THERMAL_PASSIVE_WARNING_LEVEL 0x40000 > > Hmmm. 40000 hexadecimal? That seems a bit high ;-) > > > if (state < THERMAL_PASSIVE_WARNING_LEVEL) > > printk(KERN_WARNING PREFIX "Passive trip point too low, this may" > > "slow down your laptop because processors are throttled " > > "whenever the temperature is higher than %dC\n", state/1000); > > Disadvantage is that users are unlikely to actually see that message at > the time they set the value, especially if they're working in some xterm. > They'd have to check dmesg or log files. It also increases the .text size > of the module for an option that very few people are likely to use. > > > > Would 1000 (1 °C) perhaps be more acceptable as a limit? I doubt > > > there are valid use-cases for below 0 temps :-) > > I'd prefer this option. Do you see any downside to this? > I see many laptops with a passive trip point higher than 90C, so a passive trip point higher than 100C may be meaningful. I think we should use a higher value, say 2000? thanks, rui