On Fri, Apr 27, 2018 at 03:24:48PM +0200, Miroslav Lichvar wrote: > I think that might be even worse than making inaccurate corrections > with zero frequency offset. If a TC and slave are (re)started at the > same time, the slave's initial correction may have a large error, > which will need to corrected later (when steps may already be > disabled). It will also disrupt the slave's frequency estimate if the > TC starts correcting the messages before the slave's estimation > interval ends.
So lets consider the magnitude of the error. On a switch based system on my desk, the residence time is about 2 milliseconds. (This is rather large because the timestamps come over MDIO). The frequency offset is typically about 30 ppm, and so the induced error is 60 nanoseconds. Using HW time stamping, such small offsets are corrected at the slave in a few seconds using small frequency adjustments. Thanks, Richard ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
