Messages in this thread | | | Date | Wed, 3 Nov 1999 14:55:13 +0100 | From | Jamie Lokier <> | Subject | Re: Unadjusted system time |
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Michael Schimek wrote: > For the new multimedia interfaces we need some global system clock for > timestamping and synchronization purposes. It has been argued the > time-of-day clock is inappropriate since not guaranteed to increase > monotonically.
A lot more applications than that break if the time is not monotonic or jumps forward. Emacs for example will get confused. So will mail transport agents (sendmail), and Netscape. Anything that has a pause or a peridic event handler.
Many window managers will also break. In some cases, you have to wait for the duration of the jump before getting control of your windows again.
One fix is to change all of those applications to use the UST where appropriate. But when is it appropriate and when is it not? A clock display program (including Emacs and xclock) ought to use both UST and gettimeofday: UST for the display update period, and gettimeofday to show the time itself.
A jump in the the system time breaks so many things that I'd argue you should simply not do it except perhaps at boot time. A gradual slew is reasonable, and there are programs like ntptime that can help you with that. Though they don't work either in many cases, like when you dial up once every few days and your system has drifted 15 minutes in the meantime.
-- Jamie
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