getmicrouptime(9) [freebsd man page]

MICROUPTIME(9)						   BSD Kernel Developer's Manual					    MICROUPTIME(9)

NAME

     binuptime, getbinuptime, microuptime, getmicrouptime, nanouptime, getnanouptime, sbinuptime, getsbinuptime -- get the time elapsed since boot

SYNOPSIS

     #include <sys/time.h>

     void
     binuptime(struct bintime *bt);

     void
     getbinuptime(struct bintime *bt);

     void
     microuptime(struct timeval *tv);

     void
     getmicrouptime(struct timeval *tv);

     void
     nanouptime(struct timespec *ts);

     void
     getnanouptime(struct timespec *tsp);

     sbintime_t
     sbinuptime(void);

     sbintime_t
     getsbinuptime(void);

DESCRIPTION

     The binuptime() and getbinuptime() functions store the time elapsed since boot as a struct bintime at the address specified by bt.  The
     microuptime() and getmicrouptime() functions perform the same utility, but record the elapsed time as a struct timeval instead.  Similarly
     the nanouptime() and getnanouptime() functions store the elapsed time as a struct timespec.  The sbinuptime() and getsbinuptime() functions
     return the time elapsed since boot as a sbintime_t.

     The binuptime(), microuptime(), nanouptime(), and sbinuptime() functions always query the timecounter to return the current time as precisely
     as possible.  Whereas getbinuptime(), getmicrouptime(), getnanouptime(), and getsbinuptime() functions are abstractions which return a less
     precise, but faster to obtain, time.

     The intent of the getbinuptime(), getmicrouptime(), getnanouptime(), and getsbinuptime() functions is to enforce the user's preference for
     timer accuracy versus execution time.

SEE ALSO

     bintime(9), getbintime(9), getmicrotime(9), getnanotime(9), microtime(9), nanotime(9), tvtohz(9)

AUTHORS

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

BSD
								   July 25, 2013							       BSD

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

NAME

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

SYNOPSIS

     #include <sys/time.h>

     void
     bintime(struct bintime *bt);

     void
     getbintime(struct bintime *bt);

     void
     microtime(struct timeval *tv);

     void
     getmicrotime(struct timeval *tv);

     void
     nanotime(struct timespec *ts);

     void
     getnanotime(struct timespec *tsp);

DESCRIPTION

     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 perfor-
     mance 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).

SEE ALSO

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

CODE REFERENCES

     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.

AUTHORS

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

BUGS

     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.

BSD
								   June 8, 2010 							       BSD