ADJFREQ(2) BSD System Calls Manual ADJFREQ(2)
adjfreq -- correct the rate of the system clock
adjfreq(const int64_t *freq, int64_t *oldfreq);
adjfreq() adjusts the rate in which time progresses if freq is non-null.
The unit of the rate of adjustment is nanoseconds per second, shifted
left 32 bits to allow for fractional values.
If oldfreq is non-null, the current value is returned.
Only the superuser may adjust the frequency.
Upon successful completion, the value 0 is returned; otherwise the
value -1 is returned and the global variable errno is set to indicate the
adjfreq() will fail if:
[EFAULT] Either of the arguments point outside the process's
allocated address space.
[EPERM] The freq argument is non-null and the process's effec-
tive user ID is not that of the superuser.
date(1), adjtime(2), gettimeofday(2), ntpd(8)
The adjfreq() function call first appeared in OpenBSD 4.0.
BSD December 10, 2014 BSD