Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964784AbVJDH7s (ORCPT ); Tue, 4 Oct 2005 03:59:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964786AbVJDH7s (ORCPT ); Tue, 4 Oct 2005 03:59:48 -0400 Received: from rrzmta2.rz.uni-regensburg.de ([132.199.1.17]:45449 "EHLO rrzmta2.rz.uni-regensburg.de") by vger.kernel.org with ESMTP id S964784AbVJDH7r (ORCPT ); Tue, 4 Oct 2005 03:59:47 -0400 From: "Ulrich Windl" Organization: Universitaet Regensburg, Klinikum To: Roman Zippel Date: Tue, 04 Oct 2005 09:58:54 +0200 MIME-Version: 1.0 Subject: Re: [RFC][PATCH 2/2] Reduced NTP rework (part 2) Cc: lkml , Thomas Gleixner , George Anzinger , Ulrich Windl Message-ID: <4342525D.31706.708950@Ulrich.Windl.rkdvmks1.ngate.uni-regensburg.de> In-reply-to: References: <1127419198.8195.10.camel@cog.beaverton.ibm.com> X-mailer: Pegasus Mail for Windows (4.30 public beta 1) Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Content-description: Mail message body X-Content-Conformance: HerringScan-0.26/Sophos-P=3.95.0+V=3.95+U=2.07.102+R=04 July 2005+T=108591@20051004.075630Z Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1500 Lines: 43 On 27 Sep 2005 at 18:37, Roman Zippel wrote: > Hi, > > On Thu, 22 Sep 2005, john stultz wrote: > > > + > > + /* calculate the total continuous ppm adjustment */ > > + total_sppm = time_freq; /* already shifted by SHIFT_USEC */ > > + total_sppm += offset_adj_ppm << SHIFT_USEC; > > + total_sppm += tick_adj_ppm << SHIFT_USEC; > > + total_sppm += singleshot_adj_ppm << SHIFT_USEC; > > } > > I'm not sure, why you still need this. > As I already said, I don't think you need to change the kernel NTP model. > This means in particular that the NTP time is still incremented in fixed > intervals (although it's not necessary to do it at HZ frequency). > I showed you how to do most of the calculation, so I'm a little confused, > why the above is still used. Hi all! As playing with "tick" is considered obsolete by the NTP people, frequency errors up to 500 PPM are corrected by the NTP kernel code. Thus, to provide continuous time, you might be interested in adjusting tick interpolation (i.e. _use_ the adjusted value whenever the clock is read). Ulrich > > In general I would prefer to see the introduction of the timesource > abstraction, which will first replace the arch callbacks do_gettimeofday/ > do_settimeofday. > > bye, Roman - 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/