ADJTIMEX
NAME SYNOPSIS DESCRIPTION RETURN VALUE ERRORS CONFORMING TO SEE ALSO
adjtimex - tune kernel clock
#include
__int adjtimex(struct timex
Linux uses David L. Mills' clock adjustment algorithm (see RFC 1305). The system call adjtimex reads and optionally sets adjustment parameters for this algorithm. It takes a pointer to a timex structure, updates kernel parameters from field values, and returns the same structure with current kernel values. This structure is declared as follows:
struct timex { int modes; /* mode selector / long offset; / time offset (usec) / long freq; / frequency offset (scaled ppm) / long maxerror; / maximum error (usec) / long esterror; / estimated error (usec) / int status; / clock command/status / long constant; / pll time constant / long precision; / clock precision (usec) (read only) / long tolerance; / clock frequency tolerance (ppm) (read only) / struct timeval time; / current time (read only) / long tick; / usecs between clock ticks */ };
The modes field determines which parameters, if any, to set. It may contain a bitwise-or combination of zero or more of the following bits:
Ordinary users are restricted to a zero value for mode. Only the superuser may set any parameters.
On success, adjtimex returns the clock state:
On failure, adjtimex returns -1 and sets errno.
EFAULT
buf does not point to writable memory.
EPERM
buf.mode is non-zero and the user is not super-user.
EINVAL
An attempt is made to set buf.offset to a value outside the range -131071 to +131071, or to set buf.status to a value other than those listed above, or to set buf.tick to a value outside the range 900000/HZ to 1100000/HZ, where HZ is the system timer interrupt frequency.
adjtimex is Linux specific and should not be used in programs intended to be portable. There is a similar but less general call adjtime in SVr4.
4 pages link to adjtimex(2):
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