From mboxrd@z Thu Jan 1 00:00:00 1970 From: Octavian Purdila Subject: Re: [RFC] support for IEEE 1588 Date: Fri, 4 Jul 2008 03:42:36 +0300 Message-ID: <200807040342.36505.opurdila@ixiacom.com> References: <200807040147.11148.opurdila@ixiacom.com> <200807040240.04801.opurdila@ixiacom.com> <486D6B87.9030409@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , netdev@vger.kernel.org To: Rick Jones Return-path: Received: from ixia01.ro.gtsce.net ([212.146.94.66]:1504 "EHLO ixro-ex1.ixiacom.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754061AbYGDAoi (ORCPT ); Thu, 3 Jul 2008 20:44:38 -0400 In-Reply-To: <486D6B87.9030409@hp.com> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: On Friday 04 July 2008, Rick Jones wrote: > I've not had a good emily litella moment in at least a week, so I'll ask > - if the clock in the hardware generating the timestamp and the clock in > the host aren't synchronized in _some_ way, what benefit is there to > putting the hardware's timestamp in there? > We actually currently use them for delay/jitter calculation in conjunction with having the RX and TX port's source timestamping units running in sync. We can do that since both the RX and TX port (Linux based) will run in our hardware (chassis). I guess we could try to do a simple sync between the host clock and the hw clock by getting the initial delta between the two. But since the two clocks are not in sync, they will diverge in time. And since I do not know enough about the way in which tstamp is currently used, I'm not very confident that this will not break something... so, back to grepping :) Thanks, tavi