hardclock(9) - NetBSD Manual Pages

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


NAME

     hardclock -- real-time timer


SYNOPSIS

     void
     hardclock(struct clockframe *frame);


DESCRIPTION

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

     The hardclock() performs different tasks such as:

           ·   Run the current process's virtual and profile time (decrease
               the corresponding timers, if they are activated, and generate
               SIGVTALRM or SIGPROF, respectively).

           ·   Increment the time-of-day, taking care of any ntpd(8) or
               adjtime(2) induced changes and leap seconds, as well as any
               necessary compensations to keep in sync with PPS signals or
               external clocks, if support for this is in the kernel (see
               options(4)).

           ·   Schedule softclock interrupts if any callouts should be trig-
               gered (see callout(9)).


SEE ALSO

     adjtime(2), ntp_adjtime(2), signal(7), ntpd(8), callout(9), hz(9)

NetBSD 6.1.2                    March 25, 2010                    NetBSD 6.1.2