On Friday, November 22, 2013 12:38:36 PM UTC-5, unruh wrote: > On 2013-11-22, [email protected] <[email protected]> wrote: > > > I have just written a PHC driver for NTP and tested it on this system: > > > Supermicro SYS-50150EHF-D525 which has a pair of Intel 82574L NICs which > > > have IEEE 1588 hardware-based timestamping. I'm using NTP dev 4.2.7p397 on > > Linux kernel 3.12 with linuxptp. One of the PHCs is sync'd via PTP to an > > FEI Zyfer Gsync GrandMaster, which is in turn synced via 5MHz to the USNO > > Master Clock #2. > > > > > > I'm running ptp4l to sync PHC1 to the GrandMaster. Then NTP is reading the > > refclocks PHC0, PHC1 and an NTP server on the LAN ptp2: > > > > > > ntpq -p > > > remote refid st t when poll reach delay offset > > jitter > > >============================================================================== > > > +PHC(0) .PTP. 0 l 15 16 377 0.000 0.000 > > 0.000 > > > *PHC(1) .PTP. 0 l 2 16 377 0.000 -0.001 > > 0.000 > > > +ptp2 .IRIG. 1 u 38 64 377 0.123 0.018 > > 0.007 > > > > > > After about 15 hours the loopstats shows a s.d. of +/- 0.579 microsec with > > peak-peak 2.52 microsec (3,073 points). Very superb. > > > > > > However, it took fully 75 minutes at start to converge. It took that long > > to remove 20ms of phase error. I have never seen such a slow convergence. > > Very smooth too. I have tested the NMEA/ATOM drivers on this system and > > the convergence was the normal few minutes. Any suggestions? Can email > > plots. > > > > David Mills has always stated that rate of convergence is not a problem > > he cares about at all. Stability of running is. ntpd is NOT designed to > > converge quickly. If you want faster convergence ( and better clock > > discipline although possibly slightly higher drift noise) use chrony. > > Certainly a SD of .5us is far better than any standard PC can get from > > an interrupt driven stratum 0 source due to > > interrupt latency fluctuations. I am surprized you can get such good > > results from a NIC based solution (even with hardware timestamping). > > > > > > > > Rich Schmidt > > > Time Service Dept > > > US Naval Observatory
Understood. Yes, just curious. Currently my loopstats looks like this: 56618 69198.256 0.000000157 -4.038 0.000000483 0.000045 4 56618 69214.256 0.000000141 -4.038 0.000000482 0.000044 4 56618 69230.255 0.000000123 -4.038 0.000000482 0.000042 4 56618 69246.255 0.000000137 -4.038 0.000000481 0.000041 4 56618 69262.256 0.000000271 -4.038 0.000000481 0.000047 4 56618 69278.255 -0.000000120 -4.038 0.000000480 0.000045 4 56618 69294.255 0.000000063 -4.038 0.000000480 0.000043 4 56618 69310.255 -0.000000200 -4.038 0.000000479 0.000045 4 56618 69326.255 0.000000045 -4.038 0.000000479 0.000043 4 56618 69342.255 0.000000018 -4.038 0.000000479 0.000040 4 56618 69358.256 0.000000052 -4.038 0.000000479 0.000038 4 56618 69374.256 -0.000000409 -4.038 0.000000478 0.000048 4 56618 69390.256 -0.000000176 -4.038 0.000000478 0.000048 4 56618 69406.256 -0.000000826 -4.038 0.000000503 0.000083 4 56618 69422.256 -0.000000668 -4.038 0.000000500 0.000098 4 56618 69438.255 -0.000001028 -4.039 0.000000497 0.000126 4 56618 69454.256 -0.000000961 -4.039 0.000000494 0.000146 4 56618 69470.256 -0.000000898 -4.039 0.000000492 0.000156 4 56618 69486.255 -0.000000908 -4.039 0.000000490 0.000167 4 56618 69502.255 -0.000000916 -4.040 0.000000489 0.000173 4 56618 69518.256 -0.000000660 -4.040 0.000000487 0.000173 4 56618 69534.255 -0.000000817 -4.040 0.000000486 0.000176 4 56618 69550.255 -0.000000319 -4.040 0.000000488 0.000167 4 56618 69566.254 -0.000000368 -4.040 0.000000486 0.000159 4 56618 69582.255 -0.000000257 -4.040 0.000000485 0.000151 4 56618 69598.256 -0.000000152 -4.040 0.000000484 0.000142 4 56618 69614.255 -0.000000218 -4.040 0.000000483 0.000134 4 56618 69630.256 0.000000032 -4.040 0.000000482 0.000125 4 56618 69646.255 -0.000000193 -4.040 0.000000482 0.000118 4 56618 69662.255 -0.000000076 -4.040 0.000000481 0.000111 4 56618 69678.255 0.000000197 -4.040 0.000000481 0.000105 4 56618 69694.255 0.000000438 -4.040 0.000000480 0.000105 4 56618 69710.256 0.000000031 -4.040 0.000000480 0.000098 4 56618 69726.256 0.000000220 -4.040 0.000000479 0.000093 4 56618 69742.254 0.000000779 -4.040 0.000000490 0.000112 4 56618 69758.255 0.000000721 -4.040 0.000000488 0.000120 4 56618 69774.256 0.000000349 -4.040 0.000000487 0.000117 4 56618 69790.255 0.000000612 -4.039 0.000000486 0.000122 4 56618 69806.255 0.000000637 -4.039 0.000000485 0.000126 4 56618 69822.255 0.000000353 -4.039 0.000000484 0.000123 4 56618 69838.256 0.000000660 -4.039 0.000000483 0.000127 4 56618 69854.255 0.000000179 -4.039 0.000000483 0.000120 4 56618 69870.256 0.000000327 -4.039 0.000000482 0.000115 4 56618 69886.256 0.000000252 -4.039 0.000000481 0.000110 4 56618 69902.256 0.000000306 -4.039 0.000000481 0.000106 4 56618 69918.256 0.000000102 -4.039 0.000000480 0.000100 4 56618 69934.256 0.000000309 -4.039 0.000000480 0.000097 4 56618 69950.254 0.000000384 -4.039 0.000000479 0.000097 4 56618 69966.256 0.000000161 -4.039 0.000000479 0.000092 4 56618 69982.256 0.000000026 -4.039 0.000000479 0.000086 4 _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
