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 OS Programmer's Guide.
If pid is zero, the clock ID of the CPU-time clock of the process making 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:
| Safety: | |
|---|---|
| Cancellation point | No |
| Signal handler | Yes |
| Thread | Yes |