Re: Monitoring the leap second tonight

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@old:~/leap> cc -c timelog.c
hjj@old:~/leap> cc timelog.o -o timelog
hjj@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@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@xxxxxxxxxxx:/usr/src/sys/i386/compile/OLD  i386
hjj@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 
.

Relevant Pages

  • Re: Bug: Status/Summary of slashdot leap-second crash on new years 2008-2009
    ... hence we regularly adjust the system. ... originates on Linux versus other, ... Leap seconds are an integral part of the NTP standard for the reasons ...
    (Linux-Kernel)
  • Re: ntp servers reporting leap second erroneously?
    ... The leap warning bit is exchanged in the NTP subnet exactly following announcement by NIST. ... The kernel will implement the leap at minute 1440 of that day. ... There has been a leap second scheduled for the end of this year, ...
    (comp.protocols.time.ntp)
  • Re: Lep seconds
    ... In the current development code when the kernel does not implement a leap function, the clock is stepped "near" the leap epoch. ... I certainly did not mean to disparage NTP time. ... run into problems is when a leap second occurs. ...
    (comp.protocols.time.ntp)
  • PPS on Linux status?
    ... The PPS part of the ntp documentation at one point refers to the PPSkit ... for Linux and at another point says "The FreeBSD, ... I understand that a full-scale PPS "system" in the kernel (and the PPS ...
    (comp.protocols.time.ntp)
  • Re: differences between kernel-tree and kernel-source and kernel image
    ... > will this install the kernel or try to patch an existing 2.6 kernel or ... affix-source - Driver source for the Affix Bluetooth protocol stack for Linux ... atlas-doc - Automatically Tuned Linear Algebra Software,documentation ...
    (Debian-User)