HARDCLOCK(9) BSD 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:
o Run the current process's virtual and profile time (decrease the corresponding timers, if they are activated, and generate
SIGVTALRM or SIGPROF, respectively).
o Increment the time-of-day, taking care of any ntpd(8) or adjtime(2) induced changes and leap seconds, as well as any necessary com-
pensations to keep in sync with PPS signals or external clocks, if support for this is in the kernel (see options(4)).
o Schedule softclock interrupts if any callouts should be triggered (see callout(9)).
SEE ALSO
adjtime(2), ntp_adjtime(2), signal(7), ntpd(8), callout(9), hz(9)
BSD
March 25, 2010 BSD
