Lines Matching full:second
1 Leap Second Smearing with NTP
19 Whenever a leap second is to be handled ntpd either:
21 - passes the leap second announcement down to the OS kernel (if the OS
22 supports this) and the kernel handles the leap second automatically, or
24 - applies the leap second correction itself.
26 NTP servers also pass a leap second warning flag down to their clients via
28 approaching leap second, and can handle the leap second appropriately.
33 If a leap second is to be inserted then in most Unix-like systems the OS
34 kernel just steps the time back by 1 second at the beginning of the leap
35 second, so the last second of the UTC day is repeated and thus duplicate
39 system time is stepped back, e.g. due to a leap second insertion. Thus,
46 One good way to handle the leap second is to use ntp_gettime() instead of
49 if it is OK, if the current second is an in-progress leap second. But even
58 slewed by the client to compensate the leap second.
67 recently been implemented in ntpd. This means that to insert a leap second
69 sent to its clients, so that after some predefined interval the leap second
80 UTC before the leap second, up to the beginning of the smear interval, and
81 again corresponds to UTC after the insertion of the leap second has
87 have to (and even must not) care about the leap second anymore. Smearing is
89 leap second.
98 non-smearing NTP servers. The difference can be up to 1 second, depending
108 certain interval, which is what we call smearing the leap second.
117 available or was not enabled, ntpd didn't care about the leap second at all.
119 sudden 1 s offset after the leap second and normally would have stepped the
121 but "slews" the 1-second correction, which takes 33 minutes and 20 seconds
128 depended on the poll interval. The system time was off by 1 second for
132 midnight to insert a leap second, if kernel support was not used.
139 In 4.2.8 the leap second code was rewritten and some enhancements were
146 leap second without the time being stepped could have been to check the
161 works around kernel bugs due to the leap second.
165 the -x approach. The current leap second code in ntpd determines the point
166 in system time when the leap second is to be inserted, and given a
168 smearing, and the smearing is finished when the leap second ends, i.e. the
187 Using NTP's Leap Second Smearing
189 - Leap Second Smearing MUST NOT be used for public servers, e.g. servers
193 undefined client behavior. Instead, leap second smearing should only be
197 - Leap Second Smearing is NOT configured by default. The only way to get
213 - Smearing NTP servers DO NOT send a leap second warning flag to client time
214 requests. Since the leap second is applied gradually the clients don't even
215 notice there's a leap second being inserted, and thus there will be no log
216 message or similar related to the leap second be visible on the clients.
218 - Since clients don't (and must not) become aware of the leap second at all,
220 to use a leap second file. If they had a leap second file they would apply
221 the leap second twice: the smeared one from the server, plus another one
222 inserted by themselves due to the leap second file. As a result, the