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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | NOTES | EXAMPLES | SEE ALSO | COLOPHON |
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pthread_...puclockid(3) Library Functions Manual pthread_...puclockid(3)
pthread_getcpuclockid - retrieve ID of a thread's CPU time clock
POSIX threads library (libpthread, -lpthread)
#include <pthread.h>
#include <time.h>
int pthread_getcpuclockid(pthread_t thread, clockid_t *clockid);
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.
On success, this function returns 0; on error, it returns a
nonzero error number.
ENOENT Per-thread CPU time clocks are not supported by the
system.
ESRCH No thread with the ID thread could be found.
For an explanation of the terms used in this section, see
attributes(7).
┌─────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├─────────────────────────────────────┼───────────────┼─────────┤
│ pthread_getcpuclockid() │ Thread safety │ MT-Safe │
└─────────────────────────────────────┴───────────────┴─────────┘
POSIX.1-2008.
glibc 2.2. POSIX.1-2001.
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.
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 */
}
clock_gettime(2), clock_settime(2), timer_create(2),
clock_getcpuclockid(3), pthread_self(3), pthreads(7), time(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.9.1 2024-06-15 pthread_...puclockid(3)
Pages that refer to this page: clock_getres(2), clock_nanosleep(2), timer_create(2), clock_getcpuclockid(3), pthread_create(3), time(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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