From owner-svn-src-all@FreeBSD.ORG Fri Mar 25 10:02:18 2011 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 90D3F1065674; Fri, 25 Mar 2011 10:02:18 +0000 (UTC) (envelope-from brde@optusnet.com.au) Received: from mail03.syd.optusnet.com.au (mail03.syd.optusnet.com.au [211.29.132.184]) by mx1.freebsd.org (Postfix) with ESMTP id 0E0DE8FC12; Fri, 25 Mar 2011 10:02:17 +0000 (UTC) Received: from c122-107-125-80.carlnfd1.nsw.optusnet.com.au (c122-107-125-80.carlnfd1.nsw.optusnet.com.au [122.107.125.80]) by mail03.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id p2PA23o7011734 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 25 Mar 2011 21:02:05 +1100 Date: Fri, 25 Mar 2011 21:02:03 +1100 (EST) From: Bruce Evans X-X-Sender: bde@besplex.bde.org To: Warner Losh In-Reply-To: <4D8BD180.1060600@bsdimp.com> Message-ID: <20110325203713.K956@besplex.bde.org> References: <201103161644.p2GGi8ug098283@svn.freebsd.org> <20110317200156.GB65858@server.vk2pj.dyndns.org> <201103171706.12993.jkim@FreeBSD.org> <201103230834.19151.jhb@freebsd.org> <4D8BD180.1060600@bsdimp.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: src-committers@freebsd.org, John Baldwin , Peter Jeremy , svn-src-all@freebsd.org, svn-src-head@freebsd.org, Jung-uk Kim Subject: Re: svn commit: r219700 - head/sys/x86/x86 X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 25 Mar 2011 10:02:18 -0000 On Thu, 24 Mar 2011, Warner Losh wrote: > On 03/23/2011 06:34, John Baldwin wrote: >> On Thursday, March 17, 2011 5:06:09 pm Jung-uk Kim wrote: >>> I really hate the idea of adjusting timecounter frequency from >>> userland. I guess "use ntpd(8)" is not a good answer for some >>> people. :-( >> Actually, that doesn't work well if your timecounter frequency is off by a >> lot. Having the timecounter frequency accurate improves the accuracy of >> things like ntpd and ptpd. > > ntpd requires that the time counter be within 128ppm of true. If the time > counter guess is off by more than that, you lose: ntpd won't work. Is ntpd really that broken? What does it do if the drift file has the correct compensation to within 128 ppm? I use an old version of ntpd in which I've observed a positive feedback loop when -x is used to prevent steps and the slew wants to be more than 128 ppm due to a transient. Bruce