Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754574AbZLBJzw (ORCPT ); Wed, 2 Dec 2009 04:55:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754027AbZLBJzv (ORCPT ); Wed, 2 Dec 2009 04:55:51 -0500 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:46664 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751605AbZLBJzt (ORCPT ); Wed, 2 Dec 2009 04:55:49 -0500 Date: Wed, 2 Dec 2009 15:25:48 +0530 From: Arun R Bharadwaj To: Peter Zijlstra , Benjamin Herrenschmidt , Ingo Molnar , Vaidyanathan Srinivasan , Dipankar Sarma , Balbir Singh , Venkatesh Pallipadi , Arun Bharadwaj Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org, linux-acpi@vger.kernel.org Subject: [v10 PATCH 1/9]: cpuidle: Design documentation patch Message-ID: <20091202095548.GB27251@linux.vnet.ibm.com> Reply-To: arun@linux.vnet.ibm.com References: <20091202095427.GA27251@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20091202095427.GA27251@linux.vnet.ibm.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2464 Lines: 58 * Arun R Bharadwaj [2009-12-02 15:24:27]: This patch adds a little information about the redesigned cpuidle infrastructure in Documentation/cpuidle/core.txt Signed-off-by: Arun R Bharadwaj --- Documentation/cpuidle/core.txt | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) Index: linux.trees.git/Documentation/cpuidle/core.txt =================================================================== --- linux.trees.git.orig/Documentation/cpuidle/core.txt +++ linux.trees.git/Documentation/cpuidle/core.txt @@ -21,3 +21,38 @@ which can be used to switch governors at is meant for developer testing only. In normal usage, kernel picks the best governor based on governor ratings. SEE ALSO: sysfs.txt in this directory. + +Design: + +Cpuidle allows for registration of multiple sets of idle routines. +The latest registered set is used by cpuidle governors as the current +active set to choose the right idle state. This set is managed as a +list and each time the newly registered set is added to the head of the +list and made the current active set. + +An example of how this would work on x86 is shown below. + +----------------- ----------------- +| | | | +| choose b/w | mwait is chosen | mwait | +| mwait, poll, |-------------------------------------> |(current active| +| default, c1e | register to cpuidle | set) | +| | with mwait as the idle routine | | +----------------- ----------------- + + +----------------- ----------------- +| | | c1, c2, c3 | +| ACPI | register to cpuidle | (current) | +| discovery |-------------------------------------> |---------------| +| | with c1, c2, c3 | mwait | +| | as set of idle routines | | +----------------- ----------------- + +With this mechanism, a module can register and unregister its set of +idle routines at run time in a clean manner. + +The main idle routine called inside cpu_idle() of every arch is defined in +driver/cpuidle/cpuidle.c which would in turn call the idle routine selected +by the governor. If the CONFIG_CPU_IDLE is disabled, the arch needs to +provide an alternate definition for cpuidle_idle_call(). -- 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/