From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754883AbYCZE7n (ORCPT ); Wed, 26 Mar 2008 00:59:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752014AbYCZE7c (ORCPT ); Wed, 26 Mar 2008 00:59:32 -0400 Received: from hera.kernel.org ([140.211.167.34]:34066 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751342AbYCZE7b convert rfc822-to-8bit (ORCPT ); Wed, 26 Mar 2008 00:59:31 -0400 From: Len Brown Organization: Intel Open Source Technology Center To: Venki Pallipadi Subject: Re: 100% C0 with 2.6.25-rc Date: Wed, 26 Mar 2008 00:58:41 -0400 User-Agent: KMail/1.9.9 Cc: Jan Willies , "Rafael J. Wysocki" , linux-acpi@vger.kernel.org, Ingo Molnar , LKML , Thomas Gleixner References: <47BD600F.9090502@willies.info> <20080229182432.GA28660@linux-os.sc.intel.com> In-Reply-To: <20080229182432.GA28660@linux-os.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200803260058.41503.lenb@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org applied. thanks, -len On Friday 29 February 2008, Venki Pallipadi wrote: > On Fri, Feb 22, 2008 at 09:03:55AM -0800, Pallipadi, Venkatesh wrote: > > > > > > >-----Original Message----- > > >From: Jan Willies [mailto:jan@willies.info] > > >Sent: Friday, February 22, 2008 7:56 AM > > >To: Rafael J. Wysocki > > >Cc: linux-acpi@vger.kernel.org; Ingo Molnar; LKML; Thomas > > >Gleixner; Pallipadi, Venkatesh > > >Subject: Re: 100% C0 with 2.6.25-rc > > > > > >Rafael J. Wysocki wrote: > > >> On Thursday, 21 of February 2008, Jan Willies wrote: > > >>> Since 2.6.25-rc1 I have a lot of wakeups/s (≈134191,4) and > > >spend 100% in C0. > > >>> It worked fine with 2.6.24 and commandline nolapic. Without > > >nolapic I had 80k > > >>> wakeups/s after some time, but not right from the start like now. > > >> > > >> We have a regression from 2.6.24, apparently interrupts-related. > > > > > >After a lot of bisecting I've found the bad commit: > > > > > >9b12e18cdc1553de62d931e73443c806347cd974 is first bad commit > > >commit 9b12e18cdc1553de62d931e73443c806347cd974 > > >Author: venkatesh.pallipadi@intel.com > > >Date: Thu Jan 31 17:35:05 2008 -0800 > > > > > > ACPI: cpuidle: Support C1 idle time accounting > > > > > > Show C1 idle time in /sysfs cpuidle interface. C1 idle time may not > > > be entirely accurate in all cases. It includes the time spent > > > in the interrupt handler after wakeup with "hlt" based C1. > > >But, it will > > > be accurate with "mwait" based C1. > > > > > > > > >Reverting the commit brings my laptop back to C2. > > > > > > > Thanks for the bisect info. I will look at the bad side effects that patch > > may be having and I should have a patch for you to test later today.... > > > > Jan replied later on this issue that he is not able to reproduce this problem > any more. Looking at the above, I could see a potential problem where > menu governor may get confused by the C-state residency time from poll > idle or C1 idle, where this timing info is not accurate. This inaccuracy is > due to interrupts being handled before we account for C-state exit. > > Patch below fixes this and is needed regardless of the issue pointed out by > Jan Willies here. But, I am suspecting that the patch will also fix the > problem reported by Jan. > > Do not mark TIME_VALID for CO poll state. > Mark C1 time as valid only with mwait (CSTATE_FFH) entry method. > > This makes governors use the timing information only when it is correct and > eliminates any wrong policy decisions that may result from invalid timing > information. > > Signed-off-by: Venkatesh Pallipadi > > Index: linux-2.6.git/drivers/acpi/processor_idle.c > =================================================================== > --- linux-2.6.git.orig/drivers/acpi/processor_idle.c 2008-02-15 02:18:14.000000000 -0800 > +++ linux-2.6.git/drivers/acpi/processor_idle.c 2008-02-26 07:02:30.000000000 -0800 > @@ -1686,7 +1686,9 @@ > switch (cx->type) { > case ACPI_STATE_C1: > state->flags |= CPUIDLE_FLAG_SHALLOW; > - state->flags |= CPUIDLE_FLAG_TIME_VALID; > + if (cx->entry_method == ACPI_CSTATE_FFH) > + state->flags |= CPUIDLE_FLAG_TIME_VALID; > + > state->enter = acpi_idle_enter_c1; > dev->safe_state = state; > break; > Index: linux-2.6.git/drivers/cpuidle/cpuidle.c > =================================================================== > --- linux-2.6.git.orig/drivers/cpuidle/cpuidle.c 2008-02-15 02:18:14.000000000 -0800 > +++ linux-2.6.git/drivers/cpuidle/cpuidle.c 2008-02-22 03:59:01.000000000 -0800 > @@ -224,7 +224,7 @@ > state->exit_latency = 0; > state->target_residency = 0; > state->power_usage = -1; > - state->flags = CPUIDLE_FLAG_POLL | CPUIDLE_FLAG_TIME_VALID; > + state->flags = CPUIDLE_FLAG_POLL; > state->enter = poll_idle; > } > #else > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >