From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752175AbZEGGHw (ORCPT ); Thu, 7 May 2009 02:07:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751373AbZEGGHm (ORCPT ); Thu, 7 May 2009 02:07:42 -0400 Received: from science.horizon.com ([192.35.100.1]:19588 "HELO science.horizon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751242AbZEGGHl (ORCPT ); Thu, 7 May 2009 02:07:41 -0400 Date: 7 May 2009 02:07:41 -0400 Message-ID: <20090507060741.26571.qmail@science.horizon.com> From: "George Spelvin" To: johnstul@us.ibm.com, linux@horizon.com Subject: Re: [RFC][PATCH] Adjust SHIFT_PLL to improve NTP convergence. Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, ulrich.windl@rz.uni-regensburg.de, williams@redhat.com, zippel@linux-m68k.org In-Reply-To: <1241624640.9110.3.camel@jstultz-laptop> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Yea. The TSC calibration issue has been around for awhile. Although the > code has been tweaked recently, I'm not seeing that much improved > consistency from reboot to reboot. > > Its a hard trade off for folks who need very quick boot time, vs folks > that want very stable and accurate clocks across reboots. > > I'll be looking into the calibration code to see how much is needed to > bring the error rate down. The fast estimate is very good. Would it be possible to do a fine calibration in parallel with the rest of the boot sequence? Maybe until the first adjtimex call? Or is it essential that the numbers not change?