time_second(9) - NetBSD Manual Pages

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TIME_SECOND(9)         NetBSD Kernel Developer's Manual         TIME_SECOND(9)


NAME

     time_second, time_uptime, boottime -- system time variables


SYNOPSIS

     #include <sys/time.h>

     extern time_t time_second;
     extern time_t time_uptime;

     #include <sys/kernel.h>

     extern struct timeval boottime;


DESCRIPTION

     The time_second variable is the system's ``wall time'' clock.  It is set
     at boot by inittodr(9), and is updated periodically via timecounter(9)
     framework, and also updated by the settimeofday(2) system call.

     The time_uptime variable is a monotonically increasing system clock.  It
     is set at boot, and is updated periodically.  (It is not updated by
     settimeofday(2).)

     The boottime variable holds the system boot time.  It is set at system
     boot, and is updated when the system time is adjusted with
     settimeofday(2).  The variable may be read and written without special
     precautions.

     All of these variables contain times expressed in seconds and microsec-
     onds since midnight (0 hour), January 1, 1970.

     The bintime(9), getbintime(9), microtime(9), getmicrotime(9),
     nanotime(9), and getnanotime(9) functions can be used to get the current
     time more accurately and in an atomic manner.

     Similarly, the binuptime(9), getbinuptime(9), microuptime(9),
     getmicrouptime(9), nanouptime(9), and getnanouptime(9) functions can be
     used to get the time elapsed since boot more accurately and in an atomic
     manner.


SEE ALSO

     clock_settime(2), ntp_adjtime(2), timeval(3), hardclock(9), hz(9)

NetBSD 7.1_STABLE               March 13, 2008               NetBSD 7.1_STABLE