From mboxrd@z Thu Jan 1 00:00:00 1970 From: ykzhao Subject: Re: [PATCH] ACPI: Fix the incorrect calculation about C-state idle time Date: Thu, 03 Jun 2010 09:06:54 +0800 Message-ID: <1275527214.3718.38.camel@localhost.localdomain> References: <1275447849-25761-1-git-send-email-yakui.zhao@intel.com> <20100602150659.GA5335@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com ([192.55.52.93]:28445 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757873Ab0FCBJy (ORCPT ); Wed, 2 Jun 2010 21:09:54 -0400 In-Reply-To: <20100602150659.GA5335@srcf.ucam.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Garrett Cc: "lenb@kernel.org" , "linux-acpi@vger.kernel.org" , Venkatesh Pallipadi On Wed, 2010-06-02 at 23:06 +0800, Matthew Garrett wrote: > On Wed, Jun 02, 2010 at 11:04:09AM +0800, yakui.zhao@intel.com wrote: > > From: Zhao Yakui > > > > The C-state idle time is not calculated correctly, which will return the wrong > > residency time in C-state. It will have the following effects: > > 1. The system can't choose the deeper C-state when it is idle next time. > > Of course the system power is increased. E.g. On one server machine about 40W > > idle power is increased. > > 2. The powertop shows that it will stay in C0 running state about 95% time > > although the system is idle at most time. > > What kind of system was this seen on? This can be seen on laptops. But maybe the idle power effect is not significant on laptops like that on server machine. I also test the power on one T400 laptop and test shows that about 0.3W idle power is increased. thanks. Yakui >