From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Cochran Subject: Re: [PATCH net-next v2 1/8] net-timestamp: explicit SO_TIMESTAMPING ancillary data struct Date: Tue, 8 Jul 2014 07:49:19 +0200 Message-ID: <20140708054919.GA3977@localhost.localdomain> References: <1404416380-3545-1-git-send-email-willemb@google.com> <1404416380-3545-2-git-send-email-willemb@google.com> <20140705201851.GE3869@localhost.localdomain> <20140707184700.GA1610@localhost.localdomain> <53BAF8AC.6010907@cavium.com> <20140707201817.GA10683@localhost.localdomain> <53BB0C69.6000304@cavium.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Willem de Bruijn , netdev@vger.kernel.org, David Miller , Eric Dumazet , Stephen Hemminger , Chad Reese , David Daney To: Chad Reese Return-path: Received: from mail-wi0-f171.google.com ([209.85.212.171]:48308 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751566AbaGHFtn (ORCPT ); Tue, 8 Jul 2014 01:49:43 -0400 Received: by mail-wi0-f171.google.com with SMTP id n15so300503wiw.16 for ; Mon, 07 Jul 2014 22:49:42 -0700 (PDT) Content-Disposition: inline In-Reply-To: <53BB0C69.6000304@cavium.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Jul 07, 2014 at 02:08:57PM -0700, Chad Reese wrote: > > No, it was 1ns. Who would go through all this effort if all you > wanted was 1us? Our requirement was within 20ns, but me managed to > get 1ns with a lab setup. We had to be careful that the scope probes > used in the measurement were the same length. Well, in a lab, carefully compensating for phy delays, etc, etc, achieving 1ns is one thing. As a general statement, telling the public, "our PTP hardware synchronizes to within one nanosecond", is quite another thing. Thanks, Richard