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HARDCLOCK(9) NetBSD Kernel Developer's Manual HARDCLOCK(9)
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Maintained for NetBSD
by Kimmo Suominen.
Based on man-cgi by Panagiotis Christias.
hardclock -- real-time timer
hardclock(struct clockframe *frame);
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
· Schedule softclock interrupts if any callouts should be trig-
gered (see callout(9)).
adjtime(2), ntp_adjtime(2), signal(7), ntpd(8), callout(9), hz(9)
NetBSD 8.1 March 25, 2010 NetBSD 8.1