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.

Description:

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 running, which is the sum of the running time of its threads. For more information, see “Monitoring execution times” in the “Understanding the Microkernel's Concept of Time” chapter of the QNX Neutrino Programmer's Guide.

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