gethrtime.3c (2010 09)

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gethrtime(3C) gethrtime(3C)
NAME
gethrtime( ) - get high resolution time
SYNOPSIS
#include <time.h>
hrtime_t gethrtime(void);
DESCRIPTION
The gethrtime() 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.
hrtime_t is a signed 64-bit number.
RETURN VALUE
Upon successful completion,
gethrtime() 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
getgid():
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 );
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1