From: Chad Reese <kreese@cavium.com>
To: Richard Cochran <richardcochran@gmail.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: Mon, 07 Jul 2014 14:08:57 -0700 [thread overview]
Message-ID: <53BB0C69.6000304@cavium.com> (raw)
In-Reply-To: <20140707201817.GA10683@localhost.localdomain>
On 07/07/2014 01:18 PM, Richard Cochran wrote:
> On Mon, Jul 07, 2014 at 12:44:44PM -0700, Chad Reese wrote:
>>
>> For Octeon, you can optionally use the hardware timestamp as the
>> system clock reference. Most people don't, but it is the only way to
>> get the system time to be accurate. 1588 can synchronize two Octeon
>> boards to less than 1ns for the hardware timer. The Linux software
>> timers is always farther off.
>
> Did you mean 1us ?
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.
Chad
--
Chad Reese <kreese@cavium.com>
Cavium Networks
Phone: 408 - 943 - 7183
Cell: 321 - 438 - 7753
next prev parent reply other threads:[~2014-07-07 21:09 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 [this message]
2014-07-08 5:49 ` Richard Cochran
2014-07-08 6:08 ` Richard Cochran
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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