From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751862Ab1LJHdc (ORCPT ); Sat, 10 Dec 2011 02:33:32 -0500 Received: from mailout-de.gmx.net ([213.165.64.22]:35488 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751170Ab1LJHda (ORCPT ); Sat, 10 Dec 2011 02:33:30 -0500 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1/8V71cxwH8q5cMVtUgAPAGFSA9eINI6sd+SFtb+s En7245Bsa/+z7a Subject: Re: Too many poll_idle cpu calls in kernel 3.2 rc-series From: Mike Galbraith To: Deepthi Dharwar Cc: linux-kernel@vger.kernel.org, Nicolas Kalkhof , Linux PM mailing list In-Reply-To: <4ED4BCD5.3090308@linux.vnet.ibm.com> References: <492649473.3864850.1322512273580.JavaMail.fmail@mwmweb020> <20111128204412.GM24062@one.firstfloor.org> <4ED4BCD5.3090308@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Date: Sat, 10 Dec 2011 08:33:25 +0100 Message-ID: <1323502405.8213.39.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2011-11-29 at 16:37 +0530, Deepthi Dharwar wrote: > On 11/29/2011 02:14 AM, Andi Kleen wrote: > > > On Mon, Nov 28, 2011 at 09:31:13PM +0100, Nicolas Kalkhof wrote: > >> Andi, > >> > >> correct. The issue was introduced somewhere between 3.1 final and 3.2-rc1. I've tried to track down the bad commit but so far I haven't been successfull. The only workaround I found is to set the idle boot parameter to mwait and to disable CONFIG_INTEL_IDLE. Somehow the kernel seems to set idle to poll by default - no idea why :-(. I wonder if other mobile sandy bridge cpus are affected as well. > > > > There are only a few changesets affecting drivers/idle > > > > Can you try to git revert > > > > 46bcfad7a819bd17ac4e831b04405152d59784ab > > 4202735e8ab6ecfb0381631a0d0b58fefe0bd4e2 > > e978aa7d7d57d04eb5f88a7507c4fb98577def77 > > > > ? > > > > -Andi > > > Hi, > > I am guessing that for workaround just setting the idle boot parameter > to mwait should work. Have u tested this without disabling > CONFIG_INTEL_IDLE ? > > Also one thing to note from your logs is, cpu is not entering any of the > other C states except for POLL. Can you also check if your are enabling > only POLL for idle. I am able to enter deeper C-states on i5-2540M with > Intel_Idle enabled. Seems I accidentally found a way to reproduce, boot with nohz=off. Q6600 box can be booted nohz=off without ending up as if I'd booted idle=poll, but boxen using intel_idle() end up using poll_idle(). -Mike