Time

Keean Schupke k.schupke at imperial.ac.uk
Wed Jan 26 15:59:08 EST 2005


Marcin 'Qrczak' Kowalczyk wrote:

>But it does.
>
>Eventually, or sometimes immediately (I don't know how fast NTP
>clients react, or whether they are programmed for faster adjustment
>around a leap second).
>
>All syscalls give us an approximation of UTC or a time derived from UTC.
>
>  
>
If you don't run ntp (or you machine is not attached to the network) the 
timer
will count milliseconds without adjustment for leap-seconds. When the 
machine
is switched off, the hardware clock likewise does not account for 
leap-seconds.
When you switch on time is copied from the hardware clock. The system timer
(which counts time since switch on) will not be adjusted for 
leap-seconds surely,
as its perpose is to measure a time interval.

I guess I don't really know which timers NTP updates... but as some 
systems may
not run NTP it seems the system time cannot be assumed to have compensated
for leap-seconds. This seems worse than having things one way or the 
other...

    Keean


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