From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754068Ab1J1HCd (ORCPT ); Fri, 28 Oct 2011 03:02:33 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:49047 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752307Ab1J1HCc (ORCPT ); Fri, 28 Oct 2011 03:02:32 -0400 Message-ID: <1319785345.23224.75.camel@work-vm> Subject: Re: [PATCH] time: Improve documentation of timekeeeping_adjust() From: John Stultz To: Richard Cochran Cc: LKML , Chen Jie , Steven Rostedt , Thomas Gleixner Date: Fri, 28 Oct 2011 00:02:25 -0700 In-Reply-To: <20111028060534.GB1957@netboy.at.omicron.at> References: <1319764362-32367-1-git-send-email-john.stultz@linaro.org> <20111028060534.GB1957@netboy.at.omicron.at> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.0- Content-Transfer-Encoding: 7bit Mime-Version: 1.0 x-cbid: 11102807-1780-0000-0000-00000086E770 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2011-10-28 at 08:05 +0200, Richard Cochran wrote: > On Thu, Oct 27, 2011 at 06:12:42PM -0700, John Stultz wrote: > > diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c > > index a5846a8..de8737e 100644 > > --- a/kernel/time/timekeeping.c > > +++ b/kernel/time/timekeeping.c > > @@ -802,14 +802,44 @@ static void timekeeping_adjust(s64 offset) > > s64 error, interval = timekeeper.cycle_interval; > > int adj; > > > > + /* > > + * The point of this is to check if the error is greater then half > > + * an interval. > > + * > > + * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs. > > + * > > + * Note we subtract one in the shift, so that error is really error*2. > > + * This "saves" dividing(shifting) intererval twice, but keeps the > > + * (error > interval) comparision as still measuring if error is > > + * larger then half an interval. > > + * > > + * Note: It does not "save" on aggrivation when reading the code. > > ... or on "aggravation" either :) Sigh. I do need to start using an editor with built in spell checking. I'm so poor of a speller (and a typist) its really amazing its not worse. Thanks for catching that. -john