From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754819AbXKTWxA (ORCPT ); Tue, 20 Nov 2007 17:53:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751405AbXKTWwv (ORCPT ); Tue, 20 Nov 2007 17:52:51 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:39240 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751403AbXKTWwu (ORCPT ); Tue, 20 Nov 2007 17:52:50 -0500 Date: Tue, 20 Nov 2007 23:52:46 +0100 From: Ingo Molnar To: Thomas Gleixner Cc: Pavel Machek , kernel list Subject: Re: nohz and strange sleep latencies Message-ID: <20071120225246.GA24380@elte.hu> References: <20071119203152.GA1772@elf.ucw.cz> <20071119205555.GA28696@elte.hu> <20071119211142.GA1857@elf.ucw.cz> <20071120085704.GA19950@elte.hu> <20071120105458.GA1597@elf.ucw.cz> <20071120205454.GD10008@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.1.7-deb -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Thomas Gleixner wrote: > On Tue, 20 Nov 2007, Ingo Molnar wrote: > > > > * Pavel Machek wrote: > > > > > > and send us the output? (Enabling CONFIG_TIMER_STATS, > > > > CONFIG_SCHED_DEBUG and CONFIG_SCHEDSTATS would maximize the amount > > > > of information.) > > > > > > This was w/o hpet=disable . Do you want me to test with hpet=disable? > > > > no, this is fine. You've got a hpet clockevents driver and two lapic > > drivers: > > > > Clock Event Device: hpet > > set_next_event: hpet_legacy_next_event > > set_mode: hpet_legacy_set_mode > > event_handler: tick_handle_oneshot_broadcast > > > > Clock Event Device: lapic > > set_next_event: lapic_next_event > > set_mode: lapic_timer_setup > > event_handler: hrtimer_interrupt > > > > Clock Event Device: lapic > > set_next_event: lapic_next_event > > set_mode: lapic_timer_setup > > event_handler: hrtimer_interrupt > > > > to me this has the feeling of lapic breakage in C2 mode. Does it get any > > better if you boot with 'nolapic'? (but that might in turn turn off > > high-res timers and nohz in essence) Thomas, any ideas? > > Hmm, lapic is considered unstable in c2 by default. You have to tell > the kernel that you trust it in C2 on the command line. yeah, i was wondering about that too. ACPI enumerated them properly at a certain stage: ACPI: CPU0 (power states: C1[C1] C2[C2] C3[C3]) ACPI: CPU1 (power states: C1[C1] C2[C2] C3[C3]) but perhaps somehow we miss this fact and fail to turn off the lapic clockevents drivers? Ingo