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MSTOHZ(9) |
Kernel Developer's Manual |
MSTOHZ(9) |
NAME
mstohz, hztoms — convert between milliseconds and system clock ticks
SYNOPSIS
#include <sys/param.h>
int
mstohz(int ms);
int
hztoms(int hz);
DESCRIPTION
The
mstohz() macro can be used to convert time in milliseconds to system clock ticks, as used by the
callout(9) facility, in an integer-overflow safe way. Conversely,
hztoms() converts system clock ticks to milliseconds.
These macros are defined in the <sys/param.h> header. Individual ports can have a processor-specific, more efficient version implemented in their <machine/param.h> header as a define.
RETURN VALUES
The return value is either the number of clock ticks or milliseconds for the specified value.
BUGS
Neither mstohz() nor hztoms() make use of expensive 64-bit integer arithmetic. The result from mstohz() will be rounded down to one second if the parameter is larger than 131072 milliseconds.
