clock_getcpuclockid()

Return the clock ID of the CPU-time clock from a specified process

Synopsis:

#include <sys/types.h>
#include <time.h>
#include <errno.h>

int clock_getcpuclockid( pid_t pid,
                         clockid_t* clock_id );

Arguments:

pid: The process ID for the process whose clock ID you want to get.
clock_id: A pointer to a clockid_t object where the function can store the clock ID.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

The clock_getcpuclockid() function gets the clock ID of the CPU-time clock of the process specified by pid and stores it in the object pointed to by clock_id. The CPU-time clock represents the amount of time the process has spent actually running.

If pid is zero, the clock ID of the CPU-time clock of the process marking the call is returned in clock_id.

A process always has permission to obtain the CPU-time clock ID of another process.

Returns:

0: Success.
ESRCH: No process can be found corresponding to the specified pid.

Examples:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <errno.h>

int main( int argc, const char *argv[] )
{
    clockid_t clk_id;
    struct timespec tspec;
    int pid;

    /* Get the amount of time that the kernel has spent running. */

    pid = 1;

    if (clock_getcpuclockid( pid, &clk_id) == 0)
    {
        if (clock_gettime( clk_id, &tspec ) != 0)
        {
            perror ("clock_gettime():");
        }
        else
        {
            printf ("CPU time for pid %d is %d seconds, %ld nanoseconds.\n",
                    pid, tspec.tv_sec, tspec.tv_nsec);
        }
    }
    else
    {
        printf ("clock_getcpuclockid(): no process with ID %d.\n", pid);
    }

    return EXIT_SUCCESS;
}

Classification:

POSIX 1003.1 CPT

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes