ClockId(), ClockId

Get the CPU-time clock ID for a given process and thread

Synopsis:

#include <sys/neutrino.h>
#include <inttypes.h>

int ClockId( pid_t pid, 
             int tid ); 

int ClockId_r( pid_t pid, 
               int tid );

Arguments:

pid: The ID of the process that you want to get the clock ID for. If this argument is zero, the ID of the process making the call is assumed.
tid: The ID of the thread that you want to get the clock ID for, or 0 to get the clock ID for the process as a whole.

Library:

libc

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

Description:

The ClockId() and ClockId_r() kernel calls retrieve the clock ID of a process or thread CPU-time clock. These clocks represent the approximate amount of time the process or thread has spent running. See "Monitoring execution times" in the Tick, Tock: Understanding the Microkernel's Concept of Time chapter of the QNX Neutrino Programmer's Guide.

The ClockId() and ClockId_r() functions are identical except in the way they indicate errors. See the Returns section for details.

Note: Instead of using these kernel calls directly, consider calling clock_getcpuclockid() or pthread_getcpuclockid().

Blocking states:

These calls don't block.

Returns:

A clock ID for a process or thread CPU-time clock. If an error occurs:

ClockId() returns -1 and sets errno.
ClockId_r() returns the negative of a value from the Errors section and doesn't set errno.

Errors:

ESRCH: The pid and/or tid don't exist.

Examples:

Here's how you can determine how busy a system is:

id = ClockId(1, 1);
for( ;; ) {
    ClockTime(id, NULL, &start);
    sleep(1);
    ClockTime(id, NULL, &stop);
    printf("load = %f%%\n", (1000000000.0 - (stop-start)) / 10000000.0);
}

Classification:

QNX Neutrino

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

ClockId(), ClockId_r()