Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752352Ab0H1AKY (ORCPT ); Fri, 27 Aug 2010 20:10:24 -0400 Received: from smtp-out.google.com ([74.125.121.35]:26794 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751128Ab0H1AKW convert rfc822-to-8bit (ORCPT ); Fri, 27 Aug 2010 20:10:22 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=l8Nizix41uVR5cpKc1pRa0CsEB/06dmYKKFR0wbUrk+aMO+a09Xeboy1QIFEY7lPpV pkFocgVqDrvCZ3UzfqQA== MIME-Version: 1.0 In-Reply-To: <1282932708.1946.8.camel@work-vm> References: <1282932708.1946.8.camel@work-vm> Date: Fri, 27 Aug 2010 17:10:19 -0700 Message-ID: Subject: Re: System time drifts when processor idle. From: Venkatesh Pallipadi To: john stultz Cc: jean-philippe francois , Lin Ming , "H. Peter Anvin" , linux-acpi@vger.kernel.org, LKML , jslaby@suse.cz Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1433 Lines: 45 On Fri, Aug 27, 2010 at 11:11 AM, john stultz wrote: > On Fri, 2010-08-27 at 16:12 +0200, jean-philippe francois wrote: >> My Timekeeping bug is still present, here is an updated script and log. >> I am willing to make test, but I don't know what kind of debugging >> info is needed. >> >> cat /sys/devices/system/clocksource/clocksource0/available_clocksource >> hpet acpi_pm >> cat /sys/devices/system/clocksource/clocksource0/current_clocksource >> hpet > > Huh. hpet was not what I would have expected. > > > So first, two experiments: > > 1) Does booting with "clock=acpi_pm" cause the issue to disappear? > > 2) Does booting with "nohz=off" cause the issue to disappear? > > > Venkatesh: You have any experience with HPETs that halt in idle? > No. Haven't seen anything like this before with HPET. The jump was system | hardware(RTC) 15:48:43 | ven. 27 ao?t 2010 15:48:44 CEST -0.985908 secondes 15:49:04 | ven. 27 ao?t 2010 15:54:04 CEST -0.032800 secondes We lost ~300 seconds and from dmesg hpet0: 3 comparators, 64-bit 14.318180 MHz counter Which is close to 2^32 HPET ticks. So, looks like we have some 32 bit wraparound somewhere.. Thanks, Venki -- 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/