gethrtime(9f) [opensolaris man page]

gethrtime(9F)						   Kernel Functions for Drivers 					     gethrtime(9F)

NAME

       gethrtime - get high resolution time

SYNOPSIS

       #include <sys/time.h>

       hrtime_t gethrtime(void);

DESCRIPTION

       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 settime-
       ofday(3C). The hi-res timer is ideally suited to performance measurement tasks, where cheap, accurate interval timing is required.

RETURN VALUES

       gethrtime() always returns the current high-resolution real time. There are no error conditions.

CONTEXT

       There are no restrictions on the context from which gethrtime() can be called.

SEE ALSO

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

NOTES

       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 does not go backward, it does not periodically wrap) and linear (it does not occasionally speed up  or  slow  down  for
       adjustment, as the time of day can), but not necessarily unique: two sufficiently proximate calls might return the same value.

       The  time  base used for this function is the same as that for gethrtime(3C). Values returned by both of these functions can be interleaved
       for comparison purposes.

SunOS 5.11							     2 Oct 2007 						     gethrtime(9F)

gethrtime(3C)						   Standard C Library Functions 					     gethrtime(3C)

NAME

       gethrtime, gethrvtime - get high resolution time

SYNOPSIS

       #include <sys/time.h>

       hrtime_t gethrtime(void);

       hrtime_t gethrvtime(void);

DESCRIPTION

       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 settime-
       ofday(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 virtual 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.

EXAMPLES

       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++)
	       getpid();
       end = gethrtime();

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

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

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

NOTES

       Although  the  units of hi-res time are always the same (nanoseconds), the actual resolution is hardware dependent.  Hi-res time is guaran-
       teed 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 adjust-
       ment, like the time of day can), but not necessarily unique: two sufficiently proximate calls may return the same value.

SunOS 5.10							    7 Sep 2004							     gethrtime(3C)