From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail24c25.carrierzone.com (mail225c25.carrierzone.com [64.29.147.239]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 983803BA8E for ; Fri, 24 Nov 2017 04:20:24 -0500 (EST) X-POP-User: hmurray@megapathdsl.net Received: from ip-64-139-1-69.sjc.megapath.net (ip-64-139-1-69.sjc.megapath.net [64.139.1.69]) by mail24c25.carrierzone.com (8.14.9/8.13.1) with ESMTP id vAO9KM1l012349 for ; Fri, 24 Nov 2017 09:20:23 +0000 Received: from shuksan (localhost [127.0.0.1]) by ip-64-139-1-69.sjc.megapath.net (Postfix) with ESMTP id DC01D40605C; Fri, 24 Nov 2017 01:20:21 -0800 (PST) X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.3 To: Neil Davies cc: Hal Murray , bloat@lists.bufferbloat.net From: Hal Murray In-Reply-To: Message from Neil Davies of "Wed, 22 Nov 2017 10:31:36 GMT." <1CE2F13E-A918-4EC3-AAEF-3F92DA51C6E3@pnsol.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Fri, 24 Nov 2017 01:20:21 -0800 Message-Id: <20171124092021.DC01D40605C@ip-64-139-1-69.sjc.megapath.net> X-CSC: 0 X-CHA: v=2.2 cv=SPkybKnH c=1 sm=1 tr=0 a=OWgXOY7Tc8w5m7k7nGX6Zw==:117 a=OWgXOY7Tc8w5m7k7nGX6Zw==:17 a=kj9zAlcOel0A:10 a=sC3jslCIGhcA:10 a=W8nCjcToAAAA:8 a=jjW30NvNqbPCMMr_xKsA:9 a=CjuIK1q_8ugA:10 a=qwPC9J96l-VyD0zCd6W1:22 X-CTCH-RefID: str=0001.0A010201.5A17E458.0002, ss=1, re=0.000, recu=0.000, reip=0.000, cl=1, cld=1, fgs=0 X-CTCH-VOD: Unknown X-CTCH-Spam: Unknown X-CTCH-Score: 0.000 X-CTCH-Rules: X-CTCH-Flags: 0 X-CTCH-ScoreCust: 0.000 Subject: Re: [Bloat] Steam In Home Streaming on ath9k wifi X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 24 Nov 2017 09:20:25 -0000 neil.davies@pnsol.com said: > There are a few more issues - the relative drift between the two clocks > can be as high as 200ppm, though typically 50-75ppm is what we observe, but > this drift is monotonic. 200 ppm seems pretty high, but not off scale. If ntpd is running and not getting confused by long queuing delays, it should correct the drift to well under 1 ppm. If you turn on loopstats, you can graph it. If you are blasting the network and adding long queuing delays, ntpd can easily get confused. There is another quirk to keep in mind. The temperature coefficient of the crystal is ballpark of 1 ppm per C. Things can change significantly if an idle system starts flinging lots of bits around. > Also NTP can make changes at one (or both) ends - they show up as distinct > direction changes in the drift. I'm not sure what you mean by "direction change". I'd expect a graph of the time offset vs time to be linear and the slope would have a sharp change if ntpd changed it's "drift" correction and/or maybe a rounded bend as a system warmed up. ---------- Are you happy with whatever you are doing? Should we try to set things up so ntpd works well enough? How close would you like the times to be? ... -- These are my opinions. I hate spam.