Re: The adjtime() system call

Andrew M. Bishop (amb@gedanken.demon.co.uk)
Wed, 16 Apr 1997 18:46:48 +0100

> I have used the adjtime() system call to correct the date/time of my
> Linux system and I notice that the time is only changed very slowly.
> Over a one hour period, the time changes only by about 2 seconds
> relative to a fixed reference.
>
> The adjtime system call has been carefully tuned to handle continues
> adjustment for use with a running ntpd. It wasn't really intended (at
> least not as currently coded) for what you were trying to do.

But surely the ntpd will use adjtimex() to handle the time adjustment,
to change the speed of the clock. Isn't adjtime() just an
old-fashioned system call to adjust the time, and thus separate from
the issues that are raised by the ntpd that can use adjtimex(). Not
everyone uses ntpd, but they may want to adjust the time by a finite
(non-trivial) amount. Putting limits in the kernel for one particular
application program (ntpd) to use is surely not the correct way to do
this. With adjtimex() it is possible to adjust the time faster than
with adjtime(), but adjtimex() is not portable to other systems.

-- 
Andrew.
----------------------------------------------------------------------
Andrew M. Bishop                             amb@gedanken.demon.co.uk
                                      http://www.gedanken.demon.co.uk/