Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756876AbYHNILH (ORCPT ); Thu, 14 Aug 2008 04:11:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752471AbYHNIKw (ORCPT ); Thu, 14 Aug 2008 04:10:52 -0400 Received: from yw-out-2324.google.com ([74.125.46.28]:47015 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752315AbYHNIKv (ORCPT ); Thu, 14 Aug 2008 04:10:51 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=knRjwWYpM7EIUxiTSKXnZargIA9jncNgw3TC6IsyoAu4rdYkDggW2W5NNdIdR3NFvQ hjAzGyE8AZzXTco55vkuwLMI/PGAJSWigPpIKcCxlTL8fVkUu/ZixC+QChThK8PAWg9x J/Lu17TaW3NhPkm7hz8ds1bs2VvyN0+WPYNeQ= Subject: Re: Timer unstability on when using C2 and deeper sleep states (Dell Latitude XT) From: Milan Plzik To: Robert Hancock Cc: Andi Kleen , linux-kernel@vger.kernel.org, tglx@linutronix.de In-Reply-To: <48A3BED6.3070207@shaw.ca> References: <48A3BED6.3070207@shaw.ca> Content-Type: text/plain Date: Thu, 14 Aug 2008 10:10:42 +0200 Message-Id: <1218701442.4285.15.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2255 Lines: 45 On St, 2008-08-13 at 23:12 -0600, Robert Hancock wrote: > Milan Plzik wrote: > > On St, 2008-08-13 at 22:17 +0200, Andi Kleen wrote: > >> Milan Plzik writes: > >> > >>> I apologize for replying on my own mail (and also for top-posting, but > >>> this information is global update, not exactly fitting any of topics > >>> mentioned below). > >>> > >>> After playing for a longer while I found out that the system ends > >>> sometimes in state where, in order to do anything useful, I need to > >>> press keys on keyboard. > >> This usually means it is using the wrong timer in a deeper idle state. > >> Some idle states cannot be woken up by e.g. the APIC timer and then > >> you get that effect: you only make progress when you wake up the > >> CPU in some other way like pressing a key. Then on wake up the > >> timers get processed. > >> > >> This is usually a bug in the kernel timer selection. It should be chosing > >> a timer that always wakes up from the deepest idle state used. > > > > Last days I also considered this option; I tried all possible timers (hpet, tsc, acpi_pm), but their behavior is the same. 'jiffies' timer works correctly, but that one doesn't seem to put CPU to deeper sleeps, so we can't deduce any information from that. > > > > I've seen some workaround in drivers/acpi/processor_idle.c, which seems to check the ARCH_APICTIMER_STOPS_ON_C3 macro, but it's enabled at compilation time, so the code is used by kernel... . > > That changes the clock interpolation source, but it doesn't change the > timer interrupt source though, which is quite possibly what you're > losing. Have you tried nolapictimer kernel option (or nolapic, which is > the bigger hammer)? I tried both on 2.6.26 kernel; nolapic_timer resulted in a bit (from my view) more sane results in powertop, but the freezes remained. With nolapic system seemed to run fine, but it also disabled SMP support. Maybe the issue is also SMP-related... Thank you, Milan -- 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/