From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031151AbXDQUNB (ORCPT ); Tue, 17 Apr 2007 16:13:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1031197AbXDQUNB (ORCPT ); Tue, 17 Apr 2007 16:13:01 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:55941 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031189AbXDQUNA (ORCPT ); Tue, 17 Apr 2007 16:13:00 -0400 Subject: Re: Fw: [BUG 2.6.21-rc7] acpi_pm clocksource loses time on x86-64 From: john stultz To: mikpe@it.uu.se Cc: Ingo Molnar , Thomas Gleixner , Adrian Bunk , lkml , Andrew Morton In-Reply-To: <20070417100942.c990604b.akpm@linux-foundation.org> References: <20070417100942.c990604b.akpm@linux-foundation.org> Content-Type: text/plain Date: Tue, 17 Apr 2007 13:12:44 -0700 Message-Id: <1176840764.15198.136.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2007-04-17 at 10:09 -0700, Andrew Morton wrote: > I guess this counts as a regression. > > Begin forwarded message: > > Date: Tue, 17 Apr 2007 14:16:25 +0200 (MEST) > From: Mikael Pettersson > To: linux-kernel@vger.kernel.org > Subject: [BUG 2.6.21-rc7] acpi_pm clocksource loses time on x86-64 > > > The machine is an old Athlon64 laptop (Targa Visionary 811, > OEMd as the Arima W720-K8, also sold as the eMachines m6805) > with a VIA K8T800 chipset. ACPI is enabled. > > Up to kernel 2.6.20, time-keeping worked fine. In the > x86-64 kernel, the clock source is listed as "jiffies". > > With current 2.6.21-rc7, the x86-64 kernel selects > acpi_pm as its clock source. Unfortunately, with this > clock time drifts and it loses several minutes per hour. > > What's strange is that the i386 kernel on the same > machine (with similar .config) does not lose time > while using the acpi_pm clock source. Huh. Quite strange as its the same acpi_pm clocksource driver! The only difference I see right off is that verify_pmtmr_rate() isn't done on x86_64. Although I'd expect you'd see "PM-Timer running at invalid rate" w/ the i386 kernel if it made a difference. Could you send me the dmesg output for both the x86_64 and i386 kernels you tried? thanks -john