tech-net archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: GSoC 2011 project proposal [packet timestamping]



On 03/28/11 19:52, Matt Thomas wrote:
On Mar 28, 2011, at 10:08 AM, Joerg Sonnenberger wrote:

On Mon, Mar 28, 2011 at 07:52:52PM +0400, Dmitry Cherkassov wrote:
     2. Design and implement SIOCSHTSTAMP ioctl support in one ore more
drivers;
What speaks against having the timestamping done as part of the normal
ifq operations?
I think timestamp should be a capability (like jumbogram).  If the
driver doesn't support it, it could be generically done in if_input
but with a small loss of accuracy.

Also, what happens on cpus/systems with out a highly accurate clock?
I agree with the notion that it should be a capability.
The PTP capable interfaces do the time stamping at PHY
level using a local counter of the interface and that
should be transparently supported.

For the ntpd interleave protocol Dave Mills called for
timestamping the start and the end of specific packets.
So this should be controllable/supportable too.
Also modern interfaces use interrupt moderation, thus
software only time stamping will not work too well with
these interfaces.

Frank


Home | Main Index | Thread Index | Old Index