clock_getcpuclockid - Linux

Overview

clock_getcpuclockid retrieves the clock ID for a specific CPU or group of CPUs. It allows a process to obtain a handle to the CPU clock, enabling precise timing and synchronization tasks.

Syntax

#include <time.h>
int clock_getcpuclockid(pid_t pid, clockid_t *clock_id);

Options/Flags

• pid: The ID of the process for which the CPU clock ID is to be retrieved. If 0 is passed, the clock ID for the current process will be obtained.
• clock_id: A pointer to a variable that will receive the clock ID.

Examples

Example 1: Get CPU Clock ID for Current Process

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

int main() {
  clockid_t clock_id;
  if (clock_getcpuclockid(0, &clock_id) == 0) {
    printf("Current process CPU clock ID: %ld\n", clock_id);
  }
  return 0;
}

Example 2: Get CPU Clock ID for Specific Process

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

int main() {
  pid_t pid = 1234;
  clockid_t clock_id;
  if (clock_getcpuclockid(pid, &clock_id) == 0) {
    printf("Process %d CPU clock ID: %ld\n", pid, clock_id);
  }
  return 0;
}

Common Issues

• Invalid PID: If an invalid PID is passed, the function will fail and return -1.
• Invalid Clock ID: The function will return -1 if the clock ID specified in clock_id is invalid.

Integration

clock_getcpuclockid can be integrated with other Linux commands and tools for advanced timing and synchronization tasks. For example, it can be used with clock_gettime to obtain the current time from the CPU clock, or with clock_nanosleep to sleep for a specified interval of time.

Related Commands

• clock_getttime: Gets the current time from a specified clock.
• clock_nanosleep: Suspends the current process for a specified interval of time.
• clock_settime: Sets the current time of a specified clock.