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PTHREAD_GETCPUCLOCKID(3) | Linux Programmer's Manual | PTHREAD_GETCPUCLOCKID(3) |
NAME¶
pthread_getcpuclockid - retrieve ID of a thread's CPU time clock
SYNOPSIS¶
#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¶
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¶
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.
2009-02-08 | Linux |