The
bintime() and
getbintime() functions store the system time as a
struct bintime at the addresses specified by
bt. The
microtime() and
getmicrotime() functions perform the same utility, but record the time as a
struct timeval instead. Similarly the
nanotime() and
getnanotime() functions store the time as a
struct timespec. The structures are described in
timeval(3).
The
bintime(),
microtime(), and
nanotime() functions always query the timecounter to return the current time as precisely as possible. Whereas
getbintime(),
getmicrotime(), and
getnanotime() functions are abstractions which return a less precise, but faster to obtain, time.
The intent of the
getbintime(),
getmicrotime(), and
getnanotime() functions is to enforce the user's preference for timer accuracy versus execution time. They should be used where a precision of 1/
HZ (e.g., 10 msec on a 100
HZ machine, see
hz(9)) is acceptable or where performance is priority.
The system realtime clock is guaranteed to be monotonically increasing at all times. As such, all calls to these functions are guaranteed to return a system time greater than or equal to the system time returned in any previous calls. Comparable functions exist to retrieve the time elapsed since boot; see
microuptime(9).