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HP-UX 11i Version 3: February 2007

Technical documentation

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gethrtime() — get high resolution time


#include <time.h>

hrtime_t gethrtime(void);


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.


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


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).


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 );

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