gethrtime man page on SmartOS

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       gethrtime, gethrvtime - get high resolution time

       #include <sys/time.h>

       hrtime_t gethrtime(void);

       hrtime_t gethrvtime(void);

       The gethrtime() function returns the current high-resolution real time.
       Time is expressed as nanoseconds since some arbitrary time in the past;
       it  is  not  correlated	in any way to the time of day, and thus is not
       subject to resetting or drifting by way	of  adjtime(2)	or  settimeof‐
       day(3C).	 The hi-res timer is ideally suited to performance measurement
       tasks, where cheap, accurate interval timing is required.

       The gethrvtime() function returns the current high-resolution LWP  vir‐
       tual time, expressed as total nanoseconds of execution time.

       The  gethrtime()	 and  gethrvtime()  functions both return an hrtime_t,
       which is a 64-bit (long long) signed integer.

       The following code fragment measures the average cost of getpid(2):

	 hrtime_t start, end;
	 int i, iters = 100;

	 start = gethrtime();
	 for (i = 0; i < iters; i++)
	 end = gethrtime();

	 printf("Avg getpid() time = %lld nsec\n", (end − start) / iters);

       See attributes(5) for descriptions of the following attributes:

       │MT-Level       │ MT-Safe	 │

       proc(1), adjtime(2), gettimeofday(3C), settimeofday(3C), attributes(5)

       Although the units of hi-res time are always  the  same	(nanoseconds),
       the actual resolution is hardware dependent.  Hi-res time is guaranteed
       to be monotonic (it won't go backward, it won't periodically wrap)  and
       linear  (it  won't  occasionally	 speed up or slow down for adjustment,
       like the time of day can), but not necessarily unique: two sufficiently
       proximate calls may return the same value.

				  Sep 7, 2004			 GETHRTIME(3C)

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