Query: pthread_getcpuclockid
OS: plan9
Section: 3
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PTHREAD_GETCPUCLOCKID(3) Linux Programmer's Manual PTHREAD_GETCPUCLOCKID(3)NAMEpthread_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.DESCRIPTIONThe pthread_getcpuclockid() function returns the clock ID for the CPU time clock of the thread thread.RETURN VALUEOn success, this function returns 0; on error, it returns a nonzero error number.ERRORSENOENT Per-thread CPU time clocks are not supported by the system. ESRCH No thread with the ID thread could be found.VERSIONSThis function is available in glibc since version 2.2.ATTRIBUTESFor an explanation of the terms used in this section, see attributes(7). +------------------------+---------------+---------+ |Interface | Attribute | Value | +------------------------+---------------+---------+ |pthread_getcpuclockid() | Thread safety | MT-Safe | +------------------------+---------------+---------+CONFORMING TOPOSIX.1-2001, POSIX.1-2008.NOTESWhen 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.EXAMPLEThe program below creates a thread and then uses clock_gettime(2) to retrieve the total process CPU time, and the per-thread CPU time con- sumed 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 "); 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 ", 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 "); sleep(1); printf("Main thread consuming some CPU time... "); 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 ALSOclock_gettime(2), clock_settime(2), timer_create(2), clock_getcpuclockid(3), pthread_self(3), pthreads(7), time(7)COLOPHONThis page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. Linux 2017-09-15 PTHREAD_GETCPUCLOCKID(3)