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From: Richard Cochran <richardcochran@gmail.com>
To: Chad Reese <kreese@cavium.com>
Cc: Willem de Bruijn <willemb@google.com>,
	netdev@vger.kernel.org, David Miller <davem@davemloft.net>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Stephen Hemminger <stephen@networkplumber.org>,
	Chad Reese <kreese@caviumnetworks.com>,
	David Daney <david.daney@cavium.com>
Subject: Re: [PATCH net-next v2 1/8] net-timestamp: explicit SO_TIMESTAMPING ancillary data struct
Date: Tue, 8 Jul 2014 08:08:18 +0200	[thread overview]
Message-ID: <20140708060818.GC3977@localhost.localdomain> (raw)
In-Reply-To: <20140708054919.GA3977@localhost.localdomain>

On Tue, Jul 08, 2014 at 07:49:19AM +0200, Richard Cochran wrote:
> 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.

And you are using synchronous Ethernet, too, I suppose?

Thanks,
Richard

  reply	other threads:[~2014-07-08  6:08 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-03 19:39 net-timestamp: MSG_TSTAMP flags and bytestream support Willem de Bruijn
2014-07-03 19:39 ` [PATCH net-next v2 1/8] net-timestamp: explicit SO_TIMESTAMPING ancillary data struct Willem de Bruijn
2014-07-05 20:10   ` Richard Cochran
2014-07-18 15:54     ` Willem de Bruijn
2014-07-05 20:18   ` Richard Cochran
2014-07-07 15:34     ` Willem de Bruijn
2014-07-07 18:47       ` Richard Cochran
2014-07-07 19:14         ` Willem de Bruijn
2014-07-07 19:44           ` Chad Reese
2014-07-07 20:11             ` Richard Cochran
2014-07-07 21:03               ` Chad Reese
2014-07-08  6:04                 ` Richard Cochran
2014-07-08  7:42                   ` Chad Reese
2014-07-08  9:41                     ` Richard Cochran
2014-07-10 15:36                       ` Willem de Bruijn
2014-07-07 20:18             ` Richard Cochran
2014-07-07 21:08               ` Chad Reese
2014-07-08  5:49                 ` Richard Cochran
2014-07-08  6:08                   ` Richard Cochran [this message]
2014-07-03 19:39 ` [PATCH net-next v2 2/8] net-timestamp: MSG_TSTAMP one-shot tx timestamps Willem de Bruijn
2014-07-03 19:39 ` [PATCH net-next v2 3/8] net-timestamp: tx timestamp without payload Willem de Bruijn
2014-07-03 19:39 ` [PATCH net-next v2 4/8] net-timestamp: TCP timestamping Willem de Bruijn
2014-07-03 19:39 ` [PATCH net-next v2 5/8] net-timestamp: ACK timestamp for bytestreams Willem de Bruijn
2014-07-03 19:39 ` [PATCH net-next v2 6/8] net-timestamp: ENQ timestamp on enqueue to traffic shaping layer Willem de Bruijn
2014-07-03 19:39 ` [PATCH net-next v2 7/8] net-timestamp: expand documentation Willem de Bruijn
2014-07-05 20:14   ` Richard Cochran
2014-07-07 15:40     ` Willem de Bruijn
2014-07-03 19:39 ` [PATCH net-next v2 8/8] net-timestamp: SOCK_RAW and PING timestamping Willem de Bruijn

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