{"id":6827,"date":"2022-12-20T19:33:42","date_gmt":"2022-12-20T22:33:42","guid":{"rendered":"http:\/\/lode.uno\/linux-man\/index.php\/2022\/12\/20\/clock_getcpuclockid-man3\/"},"modified":"2022-12-20T19:33:42","modified_gmt":"2022-12-20T22:33:42","slug":"clock_getcpuclockid-man3","status":"publish","type":"post","link":"https:\/\/lode.uno\/linux-man\/2022\/12\/20\/clock_getcpuclockid-man3\/","title":{"rendered":"CLOCK_GETCPUCLOCKID (man3)"},"content":{"rendered":"

CLOCK_GETCPUCLOCKID<\/h1>\n

NAME<\/a>
SYNOPSIS<\/a>
DESCRIPTION<\/a>
RETURN VALUE<\/a>
ERRORS<\/a>
VERSIONS<\/a>
ATTRIBUTES<\/a>
CONFORMING TO<\/a>
NOTES<\/a>
EXAMPLES<\/a>
SEE ALSO<\/a>
COLOPHON<\/a> <\/p>\n

\n

NAME <\/a> <\/h2>\n

clock_getcpuclockid \u2212 obtain ID of a process CPU-time clock<\/p>\n

SYNOPSIS <\/a> <\/h2>\n

#include <\/b><\/p>\n

int clock_getcpuclockid(pid_t<\/b> pid<\/i>, clockid_t *<\/b>clockid<\/i>);<\/b><\/p>\n

Link with \u2212lrt<\/i> (only for glibc versions before 2.17).<\/p>\n

Feature Test Macro Requirements for glibc (see feature_test_macros<\/b>(7)):<\/p>\n

clock_getcpuclockid<\/b>():<\/p>\n

_POSIX_C_SOURCE\u00a0>=\u00a0200112L<\/p>\n

DESCRIPTION <\/a> <\/h2>\n

The clock_getcpuclockid<\/b>() function obtains the ID of the CPU-time clock of the process whose ID is pid<\/i>, and returns it in the location pointed to by clockid<\/i>. If pid<\/i> is zero, then the clock ID of the CPU-time clock of the calling process is returned.<\/p>\n

RETURN VALUE <\/a> <\/h2>\n

On success, clock_getcpuclockid<\/b>() returns 0; on error, it returns one of the positive error numbers listed in ERRORS.<\/p>\n

ERRORS <\/a> <\/h2>\n\n\n\n\n
<\/td>\n\n

ENOSYS<\/b><\/p>\n<\/td>\n

<\/td>\n\n

The kernel does not support obtaining the per-process CPU-time clock of another process, and pid<\/i> does not specify the calling process.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

EPERM<\/b><\/p>\n<\/td>\n

<\/td>\n\n

The caller does not have permission to access the CPU-time clock of the process specified by pid<\/i>. (Specified in POSIX.1-2001; does not occur on Linux unless the kernel does not support obtaining the per-process CPU-time clock of another process.)<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

ESRCH<\/b><\/p>\n<\/td>\n

<\/td>\n\n

There is no process with the ID pid<\/i>.<\/p>\n<\/td>\n<\/tr>\n<\/table>\n

VERSIONS <\/a> <\/h2>\n

The clock_getcpuclockid<\/b>() function is available in glibc since version 2.2.<\/p>\n

ATTRIBUTES <\/a> <\/h2>\n

For an explanation of the terms used in this section, see attributes<\/b>(7).<\/p>\n

\"Image<\/p>\n

CONFORMING TO <\/a> <\/h2>\n

POSIX.1-2001, POSIX.1-2008.<\/p>\n

NOTES <\/a> <\/h2>\n

Calling clock_gettime<\/b>(2) with the clock ID obtained by a call to clock_getcpuclockid<\/b>() with a pid<\/i> of 0, is the same as using the clock ID CLOCK_PROCESS_CPUTIME_ID<\/b>.<\/p>\n

EXAMPLES <\/a> <\/h2>\n

The example program below obtains the CPU-time clock ID of the process whose ID is given on the command line, and then uses clock_gettime<\/b>(2) to obtain the time on that clock. An example run is the following:<\/p>\n

$ .\/a.out 1<\/b> # Show CPU clock of init process
CPU-time clock for PID 1 is 2.213466748 seconds<\/p>\n

Program source<\/b>
#define _XOPEN_SOURCE 600
#include
#include
#include
#include
#include <\/p>\n

int
main(int argc, char *argv[])
{
clockid_t clockid;
struct timespec ts;<\/p>\n

if (argc != 2) {
fprintf(stderr, “%s n”, argv[0]);
exit(EXIT_FAILURE);
}<\/p>\n

if (clock_getcpuclockid(atoi(argv[1]), &clockid) != 0) {
perror(“clock_getcpuclockid”);
exit(EXIT_FAILURE);
}<\/p>\n

if (clock_gettime(clockid, &ts) == \u22121) {
perror(“clock_gettime”);
exit(EXIT_FAILURE);
}<\/p>\n

printf(“CPU-time clock for PID %s is %jd.%09ld secondsn”,
argv[1], (intmax_t) ts.tv_sec, ts.tv_nsec);
exit(EXIT_SUCCESS);
}<\/p>\n

SEE ALSO <\/a> <\/h2>\n

clock_getres<\/b>(2), timer_create<\/b>(2), pthread_getcpuclockid<\/b>(3), time<\/b>(7)<\/p>\n

COLOPHON <\/a> <\/h2>\n

This page is part of release 5.10 of the Linux man-pages<\/i> 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\u2212pages\/.<\/p>\n

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