From mboxrd@z Thu Jan 1 00:00:00 1970 From: mike-Z92qn3yYq0hWk0Htik3J/w@public.gmane.org Subject: Processor C states and USB problem Date: Mon, 05 Jan 2004 09:41:34 +0100 Sender: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Message-ID: Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Errors-To: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-acpi@vger.kernel.org Recently I had problems with my network card and ACPI (see earlier posts for the problem and solution) so I thought I'd take a closer look at ACPI on this notebook (Acer Travelmate 800). Looking at the proc entries for the processor I saw the following. active state: C3 default state: C1 bus master activity: 80070020 states: C1: promotion[C2] demotion[--] latency[000] usage[00000010] C2: promotion[C3] demotion[C1] latency[001]usage[01077887] *C3: promotion[--] demotion[C2] latency[085] usage[00083507] This looked pretty normal to me, apart from the fact that the processor was spending a lot of time in C3 although the notebook was idle. Now I plugged in my USB mouse. cat /proc/acpi/processor/CPU0/power active state: C2 default state: C1 bus master activity: ffffffff <---- USB is active states: C1: promotion[C2] demotion[--] latency[000] usage[00000010] *C2: promotion[C3] demotion[C1] latency[001]usage[00871647] C3: promotion[--] demotion[C2] latency[085] usage[00077386] The processor never left the C2 state. After unplugging the mouse "bus master activity" showed normal values again. Now for my two questions: 1.) Is it normal for the notebook to spend so much time in C3, even if it is idle? 2.) Why is an USB device screwing up the bus master activity, resulting in the processor never leaving C2? /Michael ------------------------------------------------------- This SF.net email is sponsored by: IBM Linux Tutorials. Become an expert in LINUX or just sharpen your skills. Sign up for IBM's Free Linux Tutorials. Learn everything from the bash shell to sys admin. Click now! http://ads.osdn.com/?ad_id=1278&alloc_id=3371&op=click