Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757723AbZCDS7o (ORCPT ); Wed, 4 Mar 2009 13:59:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757205AbZCDS73 (ORCPT ); Wed, 4 Mar 2009 13:59:29 -0500 Received: from e38.co.us.ibm.com ([32.97.110.159]:55434 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757179AbZCDS72 (ORCPT ); Wed, 4 Mar 2009 13:59:28 -0500 Subject: Re: Linux 2.6.29-rc6 From: John Stultz To: Jesper Krogh Cc: Thomas Gleixner , Linus Torvalds , Linux Kernel Mailing List , Len Brown In-Reply-To: <49AECA3B.5030503@krogh.cc> References: <49A6F39F.9040801@krogh.cc> <49A6FEE2.90700@krogh.cc> <1f1b08da0902261319k7a60d80xaafc1101facfd2d9@mail.gmail.com> <49A70B24.6090706@krogh.cc> <1235685269.6811.11.camel@localhost.localdomain> <1235687483.6811.26.camel@localhost.localdomain> <49A78C79.304@krogh.cc> <1235766936.7402.5.camel@localhost.localdomain> <49ABACA0.3090300@krogh.cc> <1236029277.7756.0.camel@localhost.localdomain> <49ACC853.8070205@krogh.cc> <1236110026.6068.18.camel@localhost> <49AD90E2.7050209@krogh.cc> <1236118969.6068.87.camel@localhost> <49AE9EA4.2080500@krogh.cc> <49AECA3B.5030503@krogh.cc> Content-Type: text/plain Date: Wed, 04 Mar 2009 10:57:55 -0800 Message-Id: <1236193075.3793.63.camel@jstultz-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.24.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2456 Lines: 58 On Wed, 2009-03-04 at 19:36 +0100, Jesper Krogh wrote: > Jesper Krogh wrote: > > john stultz wrote: > >> I guess something to test my idea above (that the drift is bad enough > >> that NTPd isn't making slew adjustments via adjtimex offset) is to > >> remove NTPd from the init.d startup. > >> > >> Then after rebooting (into 2.6.29), run the attached python script for > >> 10 minutes or so to get an idea of the ppm drift. Then repeat with > >> 2.6.26. > >> > >> To run: ./drift-test.py > >> > >> It will give some wild ppm numbers, but after a few minutes it should > >> settle down to the "natural drift" of the system. > > > > Ok. I removed ntpd from the system... heres is from "non-working > > Updated. I think I has NTPd running in the former "non-working" test. I > just tried to reproduce the numbers, and they look like this > (reproducible on 2.6.29-rc6). Yea, the last numbers did look odd :) > jk@quad12:~$ python drift-test.py 10.192.96.19 > 04 Mar 19:27:10 offset: -0.157696 drift: -693.0 ppm > 04 Mar 19:28:10 offset: -0.195134 drift: -625.098360656 ppm > 04 Mar 19:29:10 offset: -0.232579 drift: -624.595041322 ppm > 04 Mar 19:30:10 offset: -0.270021 drift: -624.408839779 ppm > 04 Mar 19:31:11 offset: -0.307461 drift: -621.727272727 ppm > 04 Mar 19:32:11 offset: -0.344903 drift: -622.185430464 ppm > 04 Mar 19:33:11 offset: -0.382345 drift: -622.491712707 ppm > 04 Mar 19:34:11 offset: -0.419794 drift: -622.727488152 ppm > 04 Mar 19:35:11 offset: -0.457239 drift: -622.89626556 ppm Yea, so from this and the settled ntpdc -c kerninfo data before, we can see that the drift is further out then the 500ppm NTP can handle. So with that at least confirmed, we can focus back on to the fast-pit tsc calibration code. Ingo, Thomas: I'm missing a bit of the context to that patch, other then just speeding up boot times, was there other rational for moving away from the ACPI PM timer based calibration? Could we maybe add a quick test that the pit reads actually take the assumed 2us max? Doing this maybe via the HPET/ACPI PM? thanks -john -- 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/