gethrtime(3c) [hpux man page]

gethrtime(3C)															     gethrtime(3C)

NAME

       gethrtime() - get high resolution time

SYNOPSIS

DESCRIPTION

       The  function  returns the current high-resolution real time.  Time is expressed as nanoseconds since a certain time in the past.  This API
       uses a fast light weight system call to get the nanoseconds from a certain time.  It is not correlated in any way to the time of day.  This
       API is used for performance measurement tasks and is used for cheap and accurate interval timing.

       is a signed 64-bit number.

RETURN VALUE

       Upon successful completion, returns a number of nanoseconds.  Otherwise, a value of -1 is returned.

WARNINGS

       This  API  will	only  be available if the application is being compiled in -Ae mode (extended ANSI) because 64-bit integer numbers are not
       available in -Aa (ANSI) mode. Please refer to cc(1).

EXAMPLES

       The following code fragment measures the average cost of

	    hrtime_t begin, end;

	    int i, count = 1000;

	    begin = gethrtime();

	    for (i = 0; i < count; i++)

		    getgid();

	    end = gethrtime();

	    printf("Avg getgid() time = %lld nsec", (end - begin)/count );

																     gethrtime(3C)

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 5.11							    7 Sep 2004							     gethrtime(3C)