Man Page Of gethrtime

$ man gethrtime
Standard C Library Functions gethrtime(3C)
NAME
gethrtime, gethrvtime - get high resolution time
SYNOPSIS
#include
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 settimeofday(3C).
The hires 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. This function requires that micro state accounting be
enabled with the ptime utility (see proc(1)).
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 |
|_____________________________|_____________________________|
SunOS 5.8 Last change: 10 Apr 1997 1
Standard C Library Functions gethrtime(3C)
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 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.
SunOS 5.8 Last change: 10 Apr 1997 2