[ntp:questions] Re: Monitoring the leap second tonight

David L. Mills mills at udel.edu
Sun Jan 1 04:16:06 UTC 2006


Hans,

Looks like the kernelmongers have not read the white paper on the NTP 
project page www.eecis.udel.edu/~mills/leap.html. FreeBSD does that at 
step 191 in the trace. Apparently, Linux does this, too. While the 
kernel does step the clock backward, the clock reading routine should 
remember the last reading and not allow a backward adjustment, unless 
more than two seconds. The kernel code that left here does in fact 
provide that function, but it seems to have been lost in translation.

As for the leap itself, all the radios, FreeBSDs, Solariba, Ultrax and 
Alphae leaped (lept?) the leap correctly. Not so all the radios. The 
WWV, WWVB and GPS radios all danced the wiggle. The CDMA receiver with 
embedded Linux went bonkers; it took the leap 24 hours ago and stayed 
that way until after the leap tonight. I'm not sure what this means; the 
CDMA takes its cue from GPS and the CDMA receiver hands off to NTP. Phil 
Karn was watching his cellphone, but apparently couldn't see the time 
clearly. Can somebody with a CDMA cellphone report?

Trivia department. Listening to WWV I heard no 5-ms tick during the leap 
second itself. Before the timing generators were replaced some years 
ago, they dropped the station carriers during the second. Betcha that 
flickered the lights.

Dave

Hans Jørgen Jakobsen wrote:

> On 31 Dec 2005 21:37:40 GMT, Hans Jørgen Jakobsen wrote:
> 
>>On 31 Dec 2005 21:02:44 GMT, Markus Kuhn wrote:
>>
>>>If you have nothing better to do around midnight UTC tonight, then
>>>install
>>>
>>>  http://www.cl.cam.ac.uk/~mgk25/time/leap/timelog.c
>>>
>>>and run it with
>>>
>>>  ./timelog -w2005-12-31T23:59:00 -d180 >/tmp/leapsecond.log
>>>
>>>to record the last minute of this year and the first to of the next on
>>>any potentially interesting NTP machine that you can get hold of.
>>>
>>>This records the BSD API, the POSIX API, and on Pentium CPUs also the
>>>Pentium timestamp counter. Command-line options allow you specify start
>>>time and duration of the recording.
>>>
>>>This is meant to be portable POSIX code, but has only been tested under
>>>Linux so far.
>>>
>>
>>Some output on FreeBSD 5.2.1:
>>hjj at old:~/leap> cc -c timelog.c
>>hjj at old:~/leap> cc timelog.o -o timelog
>>hjj at old:~/leap> ./timelog -w2005-12-31T21:14:00 -d180
>>#             gettimeofday         gettimeofday        TSC
>>0         2005-12-31T21:19:53Z 1136063993.028117 000438e310cad428
>>1         2005-12-31T21:19:53Z 1136063993.344206 000438e31491a11c
>>2         2005-12-31T21:19:53Z 1136063993.657504 000438e3184fe68a
>>3         2005-12-31T21:19:53Z 1136063993.970516 000438e31c0d4c39
>>....
>>574       2005-12-31T21:24:00Z 1136064240.497074 000438ee9d853b12
>>575       2005-12-31T21:24:00Z 1136064240.810569 000438eea1441b48
>>576       2005-12-31T21:24:01Z 1136064241.124419 000438eea50410a7
>>hjj at old:~/leap> uname -a
>>FreeBSD old.xxxx.dk 5.2.1-RELEASE FreeBSD 5.2.1-RELEASE #0: Fri Jun 18 22:37:02 CEST 2004     hjj at old.tele.dk:/usr/src/sys/i386/compile/OLD  i386
>>hjj at old:~/leap>
>>
> Machine 1 FreeBSD 5.2.1  200MHz:
> 182       2005-12-31T23:59:57Z 1136073597.420321 00043aa350de46ec
> 183       2005-12-31T23:59:57Z 1136073597.731842 00043aa354971dbf
> 184       2005-12-31T23:59:58Z 1136073598.043459 00043aa358503f3a
> 185       2005-12-31T23:59:58Z 1136073598.354796 00043aa35c08846d
> 186       2005-12-31T23:59:58Z 1136073598.666899 00043aa35fc32214
> 187       2005-12-31T23:59:58Z 1136073598.978153 00043aa3637b2722
> 188       2005-12-31T23:59:59Z 1136073599.289804 00043aa367346276
> 189       2005-12-31T23:59:59Z 1136073599.601743 00043aa36aee7fc8
> 190       2005-12-31T23:59:59Z 1136073599.912980 00043aa36ea6776b
> 191       2005-12-31T23:59:59Z 1136073599.224605 00043aa3725f9e2e
> 192       2005-12-31T23:59:59Z 1136073599.536449 00043aa3761970e0
> 193       2005-12-31T23:59:59Z 1136073599.847850 00043aa379d1e96e
> 194       2006-01-01T00:00:00Z 1136073600.160102 00043aa37d8cfc73
> 195       2006-01-01T00:00:00Z 1136073600.471680 00043aa38145fdfd
> 196       2006-01-01T00:00:01Z 1136073601.082626 00043aa38892aa81
> 197       2006-01-01T00:00:01Z 1136073601.395280 00043aa38c4ef6bd
> 
> FreeBSD 5.4:
> CPU: Intel(R) Xeon(TM) CPU 3.06GHz (3052.95-MHz 686-class CPU):
> 3476      2005-12-31T23:59:58Z 1136073598.922226 00d0bca4121f786a
> 3477      2005-12-31T23:59:58Z 1136073598.938604 00d0bca4151a188a
> 3478      2005-12-31T23:59:58Z 1136073598.955860 00d0bca4183da9a6
> 3479      2005-12-31T23:59:58Z 1136073598.976134 00d0bca41bedb716
> 3480      2005-12-31T23:59:58Z 1136073598.990737 00d0bca41e95cdde
> 3481      2005-12-31T23:59:59Z 1136073599.006386 00d0bca4216e7aea
> 3482      2005-12-31T23:59:59Z 1136073599.021528 00d0bca4242f94ca
> ....
> 3536      2005-12-31T23:59:59Z 1136073599.920014 00d0bca4c79f9b8a
> 3537      2005-12-31T23:59:59Z 1136073599.938273 00d0bca4caf1e94a
> 3538      2005-12-31T23:59:59Z 1136073599.955145 00d0bca4ce032c52
> 3539      2005-12-31T23:59:59Z 1136073599.971307 00d0bca4d0f43c82
> 3540      2005-12-31T23:59:59Z 1136073599.987840 00d0bca4d3f622f2
> 3541      2006-01-01T00:00:00Z 1136073600.003608 00d0bca4d6d47402
> 3542      2005-12-31T23:59:59Z 1136073599.019442 00d0bca4d9b5c756
> 3543      2005-12-31T23:59:59Z 1136073599.034824 00d0bca4dc82166e
> 3544      2005-12-31T23:59:59Z 1136073599.049513 00d0bca4df2e1626
> ....
> 3587      2005-12-31T23:59:59Z 1136073599.845912 00d0bca5700c7d6e
> 3588      2005-12-31T23:59:59Z 1136073599.861382 00d0bca572dce48e
> 3589      2005-12-31T23:59:59Z 1136073599.882819 00d0bca576c3258a
> 3590      2005-12-31T23:59:59Z 1136073599.899977 00d0bca579e2229e
> 3591      2005-12-31T23:59:59Z 1136073599.923741 00d0bca57e34c53e
> 3592      2005-12-31T23:59:59Z 1136073599.943775 00d0bca581d9aaa2
> 3593      2005-12-31T23:59:59Z 1136073599.966108 00d0bca585e9ab8e
> 3594      2005-12-31T23:59:59Z 1136073599.983840 00d0bca58923419a
> 3595      2006-01-01T00:00:00Z 1136073600.001210 00d0bca58c4c401e
> 3596      2006-01-01T00:00:00Z 1136073600.018617 00d0bca58f76e35e
> 3597      2006-01-01T00:00:00Z 1136073600.035573 00d0bca5928c8676
> 3598      2006-01-01T00:00:00Z 1136073600.050934 00d0bca59557cc52
> 3599      2006-01-01T00:00:00Z 1136073600.067111 00d0bca598491af6
> 3600      2006-01-01T00:00:00Z 1136073600.081464 00d0bca59ae58236
> 3601      2006-01-01T00:00:00Z 1136073600.102734 00d0bca59ec403be
> 
> /hjj




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