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

Markus Kuhn n05W52+mgk25 at cl.cam.ac.uk
Sun Jan 1 00:24:17 UTC 2006


This is what the start of the leap second looked like under SuSE Linux 9.3
(kernel 2.6.11.4):

#             gettimeofday         gettimeofday            REALTIME            MONOTONIC             PROCESS               THREAD          TSC
6381      2005-12-31T23:59:59Z 1136073599.974488 1136073599.974491000    1340270.017237736       1776.279262510       1776.279262780 000e3f9bb62ed949
6382      2005-12-31T23:59:59Z 1136073599.983681 1136073599.983684000    1340270.026430736       1776.288451136       1776.288451409 000e3f9bb7d29b96
6383      2005-12-31T23:59:59Z 1136073599.992797 1136073599.992800000    1340270.035547736       1776.297562953       1776.297563193 000e3f9bb972dd85
6384      2005-12-31T23:59:59Z 1136073599.002817 1136073599.002821000    1340270.045567736       1776.307580061       1776.307580717 000e3f9bbb3c66b1
6385      2005-12-31T23:59:59Z 1136073599.011952 1136073599.011955000    1340270.054701736       1776.316708835       1776.316709098 000e3f9bbcdd7fc0
6386      2005-12-31T23:59:59Z 1136073599.021069 1136073599.021072000    1340270.063818736       1776.325821195       1776.325821536 000e3f9bbe7dc731
                                        ^^^

Both gettimeofday() and clock_gettime(REALTIME, ...) jump back by
one second at the start of the leap second, i.e. they run through
23:59:59 twice, messing up causality a little bit. On the other hand,
clock_gettime(MONOTONIC, ...) and the process clocks run through
just fine.

Good night,

Markus

-- 
Markus Kuhn, Computer Laboratory, University of Cambridge
http://www.cl.cam.ac.uk/~mgk25/ || CB3 0FD, Great Britain




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