From mboxrd@z Thu Jan 1 00:00:00 1970 From: Len Brown Subject: Re: [PATCH] ACPI: Fix the incorrect calculation about C-state idle time Date: Thu, 03 Jun 2010 01:42:34 -0400 (EDT) Message-ID: References: <1275447849-25761-1-git-send-email-yakui.zhao@intel.com> Mime-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-1450428054-1275543754=:4060" Return-path: Received: from vms173007pub.verizon.net ([206.46.173.7]:8998 "EHLO vms173007pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753046Ab0FCFmw (ORCPT ); Thu, 3 Jun 2010 01:42:52 -0400 Received: from localhost.localdomain ([unknown] [98.118.125.200]) by vms173007.mailsrvcs.net (Sun Java(tm) System Messaging Server 7u2-7.02 32bit (built Apr 16 2009)) with ESMTPA id <0L3F00GXCBUZHM10@vms173007.mailsrvcs.net> for linux-acpi@vger.kernel.org; Thu, 03 Jun 2010 00:42:41 -0500 (CDT) In-reply-to: Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Venkatesh Pallipadi Cc: yakui.zhao@intel.com, linux-acpi@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-1450428054-1275543754=:4060 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT thanks, Len Brown, Intel Open Source Technology Center On Wed, 2 Jun 2010, Venkatesh Pallipadi wrote: > On Tue, Jun 1, 2010 at 8:04 PM, 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. > > This was a bug from my recent patch here :-( > http://marc.info/?l=linux-acpi&m=127198016715509&w=2 > > Thanks for catching this.. > > Acked-by: Venkatesh Pallipadi Another question about that patch... regarding sched_clock_idle_wakeup_event(). Why do we call it for _simple and _bm, but not for _c1? Why do we bother calculating its sleep_ticks*PM_TIMER_TICK_NS argument, when that argument is never accessed? thanks, Len Brown, Intel Open Source Technology Center --8323328-1450428054-1275543754=:4060--