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MICROTIME(9)               Kernel Developer's Manual              MICROTIME(9)

     bintime, getbintime, microtime, getmicrotime, nanotime, getnanotime - get
     the current time

     #include <sys/time.h>

     bintime(struct bintime *bt);

     getbintime(struct bintime *bt);

     microtime(struct timeval *tv);

     getmicrotime(struct timeval *tv);

     nanotime(struct timespec *tsp);

     getnanotime(struct timespec *tsp);

     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 100HZ machine, see hz(9)) is acceptable or where performance is

     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).

     The implementation of the microtime() family of functions is in
     sys/kern/kern_tc.c as a part of the timecounter(9) framework.

     The implementation of the time counter sources used by the timecounter(9)
     is machine dependent, hence its location in the source code tree varies
     from architecture to architecture.

     settimeofday(2), bintime_add(9), inittodr(9), time_second(9), tvtohz(9)

     This manual page was written by Jeremy Cooper and
     Kelly Yancey <kbyanc@posi.net>.

     Despite the guarantee that the system realtime clock will always be
     monotonically increasing, it is always possible for the system clock to
     be manually reset by the system administrator to any date.

NetBSD 10.99                     May 13, 2013                     NetBSD 10.99