From mboxrd@z Thu Jan 1 00:00:00 1970 From: Niko Ehrenfeuchter Subject: Re: CPU - Power state (Cx) usage count not working Date: Mon, 23 Jan 2006 11:40:06 +0100 Message-ID: <1138012807.2948.9.camel@spitfire> References: <43D491A5.6010000@sbox.tugraz.at> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.126.187]:47861 "EHLO moutng.kundenserver.de") by vger.kernel.org with ESMTP id S932440AbWAWKkL (ORCPT ); Mon, 23 Jan 2006 05:40:11 -0500 In-Reply-To: <43D491A5.6010000@sbox.tugraz.at> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: linux-acpi@vger.kernel.org Hi Gerfried, On Mon, 2006-01-23 at 09:19 +0100, Gerfried Maier wrote: > Hi everybody! > > According to the ACPI4Linux doc > > cat /proc/acpi/processor/CPU0/power > > should look like > > active state: C2 > default state: C1 > bus master activity: 00004f00 > states: > C1: promotion[C2] demotion[--] latency[000] > usage[00033670] > *C2: promotion[C3] demotion[C1] latency[084] > usage[00357060] > C3: promotion[--] demotion[C2] latency[120] > usage[00000000] > > Unfortunaltely on my system (P4m 1800Mhz; 2.4.31 or .32) the usage count > shows always 00000000. Unloading several modules (eg usb-ohci) has no > effect. the counter normally shows the de facto usage, so I assume your system never uses C3 in the above situation. Unloading the usb-modules on a 2.4 kernel _might_ help, but it also might not suffice. If you have anything that causes busmaster activity, your system will never use C3. This could be a module (as said above, the usb-modules on 2.4 do so - that's fixed in the 2.6 series) as well as some process, e.g. sound output or some monitoring stuff (I remember gkrellm once preventing my system to enter C3). To check this, you could try to boot into single-user mode, unload all unnecessary modules and then recheck for C3 usage. Some time ago, I wrote a couple of lines considering the c-states with kernel 2.4 on the acpi-wiki. You can have a look there: http://acpi.sourceforge.net/wiki/index.php/WhyMyCxPowerStateIsNotUsed hth, Niko