mstohz(9) - NetBSD Manual Pages

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MSTOHZ(9)              NetBSD 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 millisec-
     onds.

     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.


SEE ALSO

     param(3), callout(9), tvtohz(9)


BUGS

     Neither mstohz() nor hztoms() make use of expensive 64-bit integer arith-
     metic.  The result from mstohz() will be rounded down to one second if
     the parameter is larger than 131072 milliseconds.

NetBSD 8.0                     October 20, 2011                     NetBSD 8.0