TVTOHZ(9) BSD Kernel Developer's Manual TVTOHZ(9)NAME
tvtohz_high, tvtohz_low — convert time interval to tick count
SYNOPSIS
#include <sys/time.h>
int
tvtohz_high(struct timeval *tv);
int
tvtohz_low(struct timeval *tv);
DESCRIPTION
The tvtohz_high() and tvtohz_low() functions accept a single argument tv
which specifies the time interval over which to calculate the number of
system ticks that would elapse.
RETURN VALUES
The tvtohz_high() function returns the integral number of system ticks
expected to elapse in the given interval. The return value is intended
to be used in a clock interrupt timed operation and guaranteed to meet or
exceed the requested time. The minimum return value is 1 tick and the
function will average the calculation up. If any value greater than 0
microseconds is supplied, a value of at least 2 will be returned to
ensure that a near-term clock interrupt does not cause the timeout to
occur (degenerately) early.
The tvtohz_low() function returns the uncompensated number of system
ticks for the specified amount of time. A return value of 0 is possible
if tv converts to less than 1 tick.
If the reprensentation overflows, both functions return INT_MAX.
FILES
sys/kern/kern_clock.c
SEE ALSOcallout(9), microtime(9), microuptime(9)HISTORY
The tvtohz function first appeared in FreeBSD 3.0. It was split into
tvtohz_high and tvtohz_low by Matt Dillon in DragonFly 1.0.
AUTHORS
This manual page was originally written by Kelly Yancey ⟨kbyanc@posi.net⟩
and later updated by Sascha Wildner.
BSD June 30, 2007 BSD
