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HARDCLOCK(9)             BSD Kernel Developer's Manual            HARDCLOCK(9)

NAME
     hardclock -- real-time system clock

SYNOPSIS
     #include <&lt;sys/systm.h>&gt;

     void
     hardclock(struct clockframe *frame);

DESCRIPTION
     hardclock() implements the real-time system clock, interrupting hz(9)
     times a second.  The argument frame is an opaque, machine dependent
     structure that encapsulates the previous machine state.

     hardclock() performs a variety of time related housekeeping tasks, such
     as

           o   If the current process has virtual or profiling interval
               timers, update the timers and deliver appropriate signals.

           o   If there is no separate statistics clock, execute statclock().

           o   Increment the time of day, implementing any adjustments
               requested by adjtime(2) or required as a result of running an
               NTP daemon or other configured external clock.

           o   Update the real-time timeout queue, calling softclock()
               directly if the current interrupt priority is low enough.

CODE REFERENCES
     hardclock() is implemented in the file sys/kern/kern_clock.c.

SEE ALSO
     adjtime(2), hz(9), microtime(9), spl(9), time(9), timeout(9)

BSD                              June 4, 2013                              BSD