Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1945907AbXBUXMe (ORCPT ); Wed, 21 Feb 2007 18:12:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1945900AbXBUXMe (ORCPT ); Wed, 21 Feb 2007 18:12:34 -0500 Received: from www.osadl.org ([213.239.205.134]:56892 "EHLO mail.tglx.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1945907AbXBUXMe (ORCPT ); Wed, 21 Feb 2007 18:12:34 -0500 Subject: Re: NO_HZ: timer interrupt stuck [Re: Linux 2.6.21-rc1] From: Thomas Gleixner Reply-To: tglx@linutronix.de To: Luca Tettamanti Cc: linux-kernel@vger.kernel.org In-Reply-To: <20070221230409.GA1158@dreamland.darkstar.lan> References: <20070221230409.GA1158@dreamland.darkstar.lan> Content-Type: text/plain Date: Thu, 22 Feb 2007 00:17:39 +0100 Message-Id: <1172099859.25076.132.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1925 Lines: 44 On Thu, 2007-02-22 at 00:04 +0100, Luca Tettamanti wrote: > Hi Thomas, > I'm testing NO_HZ on my machines. On the laptop I see that the timer > interrupt counter is incremented (though slower than HZ). This machine > is running UP kernel. > > On my desktop I see this: > > CPU0 CPU1 > 0: 114 0 IO-APIC-edge timer > 1: 1624 10771 IO-APIC-edge i8042 > 6: 3 0 IO-APIC-edge floppy > 7: 0 0 IO-APIC-edge parport0 > 9: 0 0 IO-APIC-fasteoi acpi > 12: 40111 184047 IO-APIC-edge i8042 > 16: 75624 998858 IO-APIC-fasteoi radeon@pci:0000:01:00.0, uhci_hcd:usb1 > 17: 0 0 IO-APIC-fasteoi uhci_hcd:usb4 > 18: 711 5487 IO-APIC-fasteoi ide1, libata, ehci_hcd:usb7, uhci_hcd:usb3 > 19: 617 2254 IO-APIC-fasteoi libata, uhci_hcd:usb2 > 20: 0 0 IO-APIC-fasteoi ehci_hcd:usb6, uhci_hcd:usb5 > 21: 2483869 0 IO-APIC-fasteoi eth0 > 22: 2 0 IO-APIC-fasteoi ohci1394 > 218: 28872 360643 PCI-MSI-edge HDA Intel > 219: 32932 138196 PCI-MSI-edge libata > NMI: 0 0 > LOC: 2761191 2827539 > ERR: 0 > MIS: 0 > > Interrupt 0 is stuck at 114 (the number is consistent across reboots). I > don't experience any problem, time is running fine. Still it's strange > that the timer is doing nothing; maybe something other than the PIT is > used for time keeping? Yes, we switch away from PIT and use the local APIC timer. (LOC) tglx - 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/