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