From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: 2.6.25 regression: powertop says 120K wakeups/sec Date: Fri, 28 Mar 2008 12:01:53 -0700 Message-ID: <200803281201.54380.david-b@pacbell.net> References: <20080322202454.9D69DCC0EF@adsl-69-226-248-13.dsl.pltn13.pacbell.net> <20080322173500.7b8b6751.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from smtp116.sbc.mail.sp1.yahoo.com ([69.147.64.89]:28676 "HELO smtp116.sbc.mail.sp1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752173AbYC1TB5 (ORCPT ); Fri, 28 Mar 2008 15:01:57 -0400 In-Reply-To: <20080322173500.7b8b6751.akpm@linux-foundation.org> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Andrew Morton , venkatesh.pallipadi@intel.com Cc: linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , linux-acpi@vger.kernel.org On Saturday 22 March 2008, Andrew Morton wrote: > On Sat, 22 Mar 2008 13:24:54 -0700 David Brownell wrote: > > > I noticed this with 2.6.25-rc2 (if not before), and the problem > > is still there with 2.6.25-rc6-git (as of this AM). A 2.6.24 kernel I still had stashed away didn't act odd; the problem joined us before 2.6.25-rc1 was tagged. > > System is an Athlon64 single CPU laptop, and instead of reading a > > few dozen wakeups per second, it says a many tens of thousands... > > clearly wrong. In previous kernels it gave more plausible counts; > > unfortunately high because of various un-evolved desktop tools in > > this Ubuntu system (Feisty). > > > > Possibly more truthful, it says that the system never enters > > C1 or C2, and spends all its time in C0. Though if I look at > > /sys/devices/system/cpu/cpu0/cpuidle/state[01]/usage, that > > seems to tell a different story ... it's C0 that's never used. > > In previous kernels it reported time in both C0 and C2. ISTR > > some patch to avoid C2, which would explain part of this. > > > > Comments or fixes, anyone? > > This is likely to be an acpi regression, isn't it? > > A git-bisect would be nice, please. The git-bisect says the 120K wakeups/second comes from a patch which unfortunately can't be directly reverted, so I didn't verify that reverting it resolves that problem. I've not tried to do anything with the other C0/C1/C2 stuff. $ git bisect good bc71bec91f9875ef825d12104acf3bf4ca215fa4 is first bad commit commit bc71bec91f9875ef825d12104acf3bf4ca215fa4 Author: venkatesh.pallipadi@intel.com Date: Thu Jan 31 17:35:04 2008 -0800 ACPI: enable MWAIT for C1 idle Add MWAIT idle for C1 state instead of halt, on platforms that support C1 state with MWAIT. Renames cx->space_id to something more appropriate. Signed-off-by: Venkatesh Pallipadi Signed-off-by: Len Brown :040000 040000 88ebe48d024f7fb21237cd75dbc9c681c43252b1 8af87317facbd018b47e717ede6907d9a831f92c M drivers :040000 040000 ecd73d87c1b7b7004e06ffa3a2b3e7260c045543 934c38290353186cbaaaf27094d5c1712e548fcc M include $