From owner-freebsd-hackers@freebsd.org Thu Sep 24 13:07:52 2015 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id BDD22A07879; Thu, 24 Sep 2015 13:07:52 +0000 (UTC) (envelope-from joerg@britannica.bec.de) Received: from mo6-p00-ob.smtp.rzone.de (mo6-p00-ob.smtp.rzone.de [IPv6:2a01:238:20a:202:5300::6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.smtp.rzone.de", Issuer "TeleSec ServerPass DE-2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 3C5A41CF9; Thu, 24 Sep 2015 13:07:51 +0000 (UTC) (envelope-from joerg@britannica.bec.de) X-RZG-AUTH: :JiIXek6mfvEEUpFQdo7Fj1/zg48CFjWjQuEfXeSt/nWoxcg0dfabJPmkcf8ZVw== X-RZG-CLASS-ID: mo00 Received: from britannica.bec.de (ip-2-207-231-56.web.vodafone.de [2.207.231.56]) by smtp.strato.de (RZmta 37.12 DYNA|AUTH) with ESMTPSA id 603a87r8OD7mNcp (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (curve secp521r1 with 521 ECDH bits, eq. 15360 bits RSA)) (Client did not present a certificate); Thu, 24 Sep 2015 15:07:48 +0200 (CEST) Date: Thu, 24 Sep 2015 15:07:47 +0200 From: Joerg Sonnenberger To: freebsd-hackers@freebsd.org, hackers@freebsd.org Subject: Re: What IS the right NTP behaviour ? Message-ID: <20150924130747.GB10913@britannica.bec.de> Mail-Followup-To: freebsd-hackers@freebsd.org, hackers@freebsd.org References: <39337.1442999127@critter.freebsd.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <39337.1442999127@critter.freebsd.dk> User-Agent: Mutt/1.5.24 (2015-08-30) X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 24 Sep 2015 13:07:52 -0000 On Wed, Sep 23, 2015 at 09:05:27AM +0000, Poul-Henning Kamp wrote: > It is no surprise that people have different expectations of how > timekeeping should behave, and I'm trying to figure out > what Do What I Want is. > > I think I have identified three variations of "DWIW", which I have > named "eCommerce", "SCADA" and "Workstation" I think there is a class of network devices similar to SCADA, where the correct system time is a bonus, highly desirable, but still a bonus. Many entry class switches or routers often come without battery buffered RTC. For those, startup should not wait for NTP to become ready at all. Time drifts beyond a certain limit are better served by just stepping. The primary intention here is to have logfiles that can be correlated. Joerg