From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Subject: Some Questions about C-States Date: Sun, 16 Dec 2012 18:35:29 +0100 Message-ID: <50CE0661.6070601@mueller.mn> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.mueller.mn ([85.93.18.63]:42200 "EHLO mail.mueller.mn" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751595Ab2LPRmv (ORCPT ); Sun, 16 Dec 2012 12:42:51 -0500 Received: from [10.20.0.117] (HSI-KBW-149-172-93-50.hsi13.kabel-badenwuerttemberg.de [149.172.93.50]) by mail.mueller.mn (Postfix) with ESMTPSA id 8DD8123305CA for ; Sun, 16 Dec 2012 18:35:29 +0100 (CET) Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: linux-acpi@vger.kernel.org Hi, I am a little confused about several things around ACPI and C-States. Maybe I misunderstood a few things and due to that I did not hit the right keywords in search engines and now I hope you can help me. First of all. I am running a old ASRock 760GM-GS3 with a AMD Athlon II X2 240 C3-Stepping (AM3) as a small homeserver, doing some virtualisation and vdr stuff on it. Most of the time the cpu is idle, so I started little time ago to reduce the power consumption. Today, it is using 42W idling. And I am just courious if I might get it lower. In the BIOS I've got a setting to enable C1E. Doing so, results in * [ 0.161189] process: System has AMD C1E enabled * [ 0.161202] process: Switch to broadcast mode on CPU1 * [ 0.161660] process: Switch to broadcast mode on CPU0 shown in dmesg. Followed by * [ 0.676465] ACPI: processor limited to max C-state 1 some lines below. When I disable C1E in the BIOS, none of the lines is shown up. Since C1 is not the same as C1E, it seems there is some limit. So, I tried to figure out if C1E is used, and which C-States are used overall. I read through many sites, some of them were stating that /proc/acpi is the place to take a look, others are telling /sys/power or /sys/devices/system/cpu/ is the right place to find information about C-States. Again others are telling me acpitool -c will show me C-States. For me, it shows only * # acpitool -c * CPU type : AMD Athlon(tm) II X2 240 Processor * Min/Max frequency : 800/2800 MHz * Current frequency : 800 MHz * Frequency governor : ondemand * Freq. scaling driver : acpi-cpufreq * Cache size : 800.000 KB * Bogomips : 5613.25 * Bogomips : 5613.25 * Function Show_CPU_Info : could not read directory /proc/\ acpi/processor/ * Make sure your kernel has ACPI processor support enabled. Tested with kernel version 3.7.0 and 3.2.12 and * [Deprecated] /proc/acpi/* switch in kernel config enabled. The modules are loaded, too. But the only file in /proc/acpi is called 'wakeup'. Can someone help me getting back on the track? What can I do to show up the used c-states? Cheers, Sebastian