On Mon, 2017-04-03 at 15:52 +0200, Burkhard Ilsen wrote: > Hello, > Hi,
> I tested two-step peer_delay measurement with two peers with a high > nrate ratio. > I noticed that the first two measured delays are erronous because the > nrate is not known yet, and 1.0 is assumed. > The next raw delay measurements are correct but the two first errors > still affect the filtered_delay. > > I would like to discuss two issues regarding the function > port_peer_delay(). > > 1. > For the first measurement the nrate ratio cannot be calculated. > To avoid an erroneous measurement the calculation could be aborted if > the nrate is not valid, > e.g. by placing a "if(!p->nrate.ratio_valid) return;" between > port_nrate_calculate() and tsproc_update_delay(). > The drawback is that peer_delay is not available after the first > delay_response. > I prefer a later but correct measurement instead of an incorrect > value affecting the following filtered values as well. > I agree here, I definitely think we shouldn't calculate the values if the rate is not known. It's slightly slower at the start but erroneous values can impact the filtered values for some time. > 2. > For the second measurement the nrate ratio is calculated, after the > delay was calculated based on the old (invalid) nrate ratio. > The nrate ratio should be calculated before the delay, > e.g. by moving port_nrate_calculate() in front > of tsproc_set_clock_rate_ratio(). > Please tell me if there is a reason for the current sequence of > calculations. > I think we could change this but I'm not 100% sure of why the logic exists today. Thanks, Jake > Best regards, > Burkhard > ------------------------------------------------------------------- > ----------- > 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 ------------------------------------------------------------------------------ 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
