Hi Miroslav, > -----Original Message----- > From: Miroslav Lichvar [mailto:mlich...@redhat.com] > Sent: Friday, October 26, 2018 9:28 AM > To: netdev@vger.kernel.org > Cc: intel-wired-...@lists.osuosl.org; Richard Cochran > <richardcoch...@gmail.com>; > Keller, Jacob E <jacob.e.kel...@intel.com>; Miroslav Lichvar > <mlich...@redhat.com> > Subject: [RFC PATCH 0/4] More accurate PHC<->system clock synchronization > > This series adds support for a more accurate synchronization between a > PTP hardware clock and the system clock. > > The first patch adds an extended version of the PTP_SYS_OFFSET ioctl, > which returns three timestamps for each measurement. The idea is to > shorten the interval between the system timestamps to contain just the > reading of the lowest register of the PHC in order to reduce the error > in the measured offset and give a better bound on the maximum error. > > The other patches add support for the new ioctl to the e1000e, igb, > and ixgbe driver. Tests with few different NICs in different machines > (and PCIe slots) show that: > - with an I219 (e1000e) the measured delay improved from 2500 to 1300 ns > and the error in the measured offset, when compared to cross > timestamping, was reduced by a factor of 5 > - with an I210 (igb) the delay improved from 5100 to 1700 ns > - with an I350 (igb) the delay improved from 2300 to 750 ns > - with an X550 (ixgbe) the delay improved from 1950 to 650 ns >
That is some very significant improvements! Excellent find. > There is some duplication of code in the igb and ixgbe drivers, which I > don't like very much, but I thought it's better than extending and > wrapping the existing functions like in the e1000e driver. Also, mixing > SYSTIM and "system time" in the code will probably be confusing. > Yea... > I wasn't able to find a better name for the ioctl, the structures, and > the driver function. If anyone has suggestions, please let me know. > I don't have any good suggestions yet. I'll reply after reviewing if I think of any. Thanks, Jake
