From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH 2/2] i7300_idle driver v1.55 Date: Thu, 23 Oct 2008 14:26:45 +0200 Message-ID: <49006D85.1050709@linux.intel.com> References: <1d80ebdb81444701024ad9b9f026516561496a43.1223706853.git.len.brown@intel.com> <20081011083347.GA31918@elte.hu> <48FE07AE.4010203@linux.intel.com> <7E82351C108FA840AB1866AC776AEC4637CD27F3@orsmsx505.amr.corp.intel.com> <48FED3FA.6040703@linux.intel.com> <20081022234006.GB28775@linux-os.sc.intel.com> <48FFCF28.3070604@linux.intel.com> <7E82351C108FA840AB1866AC776AEC4637D389DB@orsmsx505.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com ([134.134.136.24]:45053 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752550AbYJWM0g (ORCPT ); Thu, 23 Oct 2008 08:26:36 -0400 In-Reply-To: <7E82351C108FA840AB1866AC776AEC4637D389DB@orsmsx505.amr.corp.intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Pallipadi, Venkatesh" Cc: Len Brown , Ingo Molnar , "linux-acpi@vger.kernel.org" , Linux Kernel Mailing List , "Henroid, Andrew D" , Linus Torvalds , Thomas Gleixner , "H. Peter Anvin" , "paulmck@us.ibm.com" > This should not matter as we can safely remove the module even when > one or more CPUs are idle. As long as one CPU is running, we are sure > that throttling is not in effect. And as long as we make sure no one > is executing the notifier that is going to be rmmoded, we should > be OK. Say one CPU comes out of the idle later, it wont see the notifier > in the notifier list anymore, because of RCU in atomic notifier > and things will work fine. I mean we are not rmmoding the routine > that enters the idle state. We are just rmmoding the routine that > Can get called before and after idle routine. That means there is a ordering dependency between the RCU idle state getting updated and your code running. That is what I meant with "very careful with idle". Even if it worked right now would seem fragile to me. -Andi