pthread_getcpuclockid (3)
NAME
pthread_getcpuclockid - retrieve ID of a thread's CPU time clockSYNOPSIS
#include <pthread.h> #include <time.h> int pthread_getcpuclockid(pthread_t thread, clockid_t *clock_id); Compile and link with -pthread.
DESCRIPTION
The pthread_getcpuclockid() function returns the clock ID for the CPU time clock of the thread thread.RETURN VALUE
On success, this function returns 0; on error, it returns a nonzero error number.ERRORS
- ENOENT
- Per-thread CPU time clocks are not supported by the system.
- ESRCH
- No thread with the ID thread could be found.
VERSIONS
This function is available in glibc since version 2.2.CONFORMING TO
POSIX.1-2001.NOTES
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.EXAMPLE
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 Subthread starting infinite loop Main thread consuming some CPU time... Process total CPU time: 1.368 Main thread CPU time: 0.376 Subthread 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("Subthread 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("Subthread CPU time: 1 ", cid); exit(EXIT_SUCCESS); /* Terminates both threads */ }
SEE ALSO
clock_gettime(2), clock_settime(2), timer_create(2), clock_getcpuclockid(3), pthread_self(3), pthreads(7), time(7)COLOPHON
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