From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754042AbXKVSvX (ORCPT ); Thu, 22 Nov 2007 13:51:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752305AbXKVSvP (ORCPT ); Thu, 22 Nov 2007 13:51:15 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:35230 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752255AbXKVSvP (ORCPT ); Thu, 22 Nov 2007 13:51:15 -0500 Date: Thu, 22 Nov 2007 19:51:21 +0100 From: Pavel Machek To: Ingo Molnar Cc: Thomas Gleixner , kernel list Subject: Re: nohz and strange sleep latencies Message-ID: <20071122185121.GA1803@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! > > > 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 can confirm that setting max-cstate=1 helps. (Plus, problem gets _way_ more visible with stripped down config. With usb and irda off, time sleep .01 easily takes 2 seconds). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html