From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752916AbXKVKJS (ORCPT ); Thu, 22 Nov 2007 05:09:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751182AbXKVKJG (ORCPT ); Thu, 22 Nov 2007 05:09:06 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:54216 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750920AbXKVKJE (ORCPT ); Thu, 22 Nov 2007 05:09:04 -0500 Date: Thu, 22 Nov 2007 11:09:41 +0100 From: Pavel Machek To: Ingo Molnar Cc: Thomas Gleixner , kernel list Subject: Re: nohz and strange sleep latencies Message-ID: <20071122100941.GA1724@elf.ucw.cz> 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> <20071120225246.GA24380@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071120225246.GA24380@elte.hu> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > > > 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? I tried to add nolapic_timer manually, and that helped, but: checking TSC synchronization [CPU#0 -> CPU#1]: Measured 627605 cycles TSC warp between CPUs, turning off TSC clock. Marking TSC unstable due to: check_tsc_sync_source failed. Brought up 2 CPUs CPU0 attaching sched-domain: domain 0: span 3 groups: 1 2 CPU1 attaching sched-domain: domain 0: span 3 groups: 2 1 net_namespace: 64 bytes ... Bluetooth: HCI socket layer initialized ACPI: RTC can wake from S4 Time: hpet clocksource has been installed. Clockevents: could not switch to one-shot mode:<6>Clockevents: could not switch to one-shot mode: lapic is not functional. Could not switch to high resolution mode on CPU 1 lapic is not functional. Could not switch to high resolution mode on CPU 0 system 00:00: iomem range 0x0-0x9ffff could not be reserved ...and result is nohz is not functional :-(. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html