table of contents
| pthread_getcpuclockid(3) | Library Functions Manual | pthread_getcpuclockid(3) |
NAME¶
pthread_getcpuclockid - retrieve ID of a thread's CPU time clock
LIBRARY¶
POSIX threads library (libpthread, -lpthread)
SYNOPSIS¶
#include <pthread.h> #include <time.h>
int pthread_getcpuclockid(pthread_t thread, clockid_t *clockid);
DESCRIPTION¶
The pthread_getcpuclockid() function obtains the ID of the CPU-time clock of the thread whose ID is given in thread, and returns it in the location pointed to by clockid.
RETURN VALUE¶
On success, this function returns 0; on error, it returns a nonzero error number.
ERRORS¶
ATTRIBUTES¶
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| pthread_getcpuclockid () | Thread safety | MT-Safe |
STANDARDS¶
POSIX.1-2008.
HISTORY¶
glibc 2.2. 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.
EXAMPLES¶
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 <errno.h> #include <pthread.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <time.h> #include <unistd.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("%4jd.%03ld\n", (intmax_t) ts.tv_sec, ts.tv_nsec / 1000000); } int main(void) {
pthread_t thread;
clockid_t cid;
int 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 (unsigned int 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)
| 2024-06-15 | Linux man-pages (unreleased) |