pthread_getcpuclockid - retrieve ID of a thread’s CPU time clock


#include <pthread.h> #include <time.h>

int pthread_getcpuclockid(pthread_t thread, clockid_t *clock_id);

Compile and link with -pthread.


The pthread_getcpuclockid() function returns the clock ID for the CPU time clock of the thread thread.


On success, this function returns 0; on error, it returns a non-zero error number.


ENOENT Per-thread CPU time clocks are not supported by the system.
ESRCH No thread with the ID thread could be found.


This function is available in glibc since version 2.2.




When thread refers to the calling thread, this function returns an identifier that refers to the same clock manipulated by clock_gettime(2) and clock_settime(2) when given the clock ID CLOCK_THREAD_CPUTIME_ID.


The program below creates a thread and then uses clock_gettime(2) to retrieve the total process CPU time, and the per-thread CPU time consumed by the two threads. The following shell session shows an example run: $ ./a.out Main thread sleeping Sub-thread starting infinite loop Main thread consuming some CPU time... Process total CPU time: 1.368 Main thread CPU time: 0.376 Sub-thread CPU time: 0.992

Program source

/* Link with "-lrt" */

#include <time.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <pthread.h> #include <string.h> #include <errno.h>

#define handle_error(msg) \ do { perror(msg); exit(EXIT_FAILURE); } while (0)

#define handle_error_en(en, msg) \ do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)

static void * thread_start(void *arg) { printf("Sub-thread starting infinite loop\n"); for (;;) continue; }

static void pclock(char *msg, clockid_t cid) { struct timespec ts;

printf("%s", msg); if (clock_gettime(cid, &ts) == -1) handle_error("clock_gettime"); printf("%4ld.%03ld\n", ts.tv_sec, ts.tv_nsec / 1000000); }

int main(int argc, char *argv[]) { pthread_t thread; clockid_t cid; int j, s;

s = pthread_create(&thread, NULL, thread_start, NULL); if (s != 0) handle_error_en(s, "pthread_create");

printf("Main thread sleeping\n"); sleep(1);

printf("Main thread consuming some CPU time...\n"); for (j = 0; j < 2000000; j++) getppid();

pclock("Process total CPU time: ", CLOCK_PROCESS_CPUTIME_ID);

s = pthread_getcpuclockid(pthread_self(), &cid); if (s != 0) handle_error_en(s, "pthread_getcpuclockid"); pclock("Main thread CPU time: ", cid);

/* The preceding 4 lines of code could have been replaced by: pclock("Main thread CPU time: ", CLOCK_THREAD_CPUTIME_ID); */

s = pthread_getcpuclockid(thread, &cid); if (s != 0) handle_error_en(s, "pthread_getcpuclockid"); pclock("Sub-thread CPU time: ", cid);

exit(EXIT_SUCCESS); /* Terminates both threads */ }


clock_gettime(2), clock_settime(2), timer_create(2), clock_getcpuclockid(3), pthread_self(3), pthreads(7), time(7)


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