PTHREAD_GETCPUCLOCKID
PTHREAD_GETCPUCLOCKID
NAMESYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
VERSIONS
ATTRIBUTES
CONFORMING TO
NOTES
EXAMPLE
SEE ALSO
COLOPHON
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
|
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.
ATTRIBUTES
Multithreading
(see pthreads(7))
The pthread_getcpuclockid() function is
thread-safe.
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 3.69 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 http://www.kernel.org/doc/man−pages/.
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