CLOCK_GETCPUCLOCKID
CLOCK_GETCPUCLOCKID
NAMESYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
VERSIONS
ATTRIBUTES
CONFORMING TO
NOTES
EXAMPLE
SEE ALSO
COLOPHON
NAME
clock_getcpuclockid − obtain ID of a process CPU-time clock
SYNOPSIS
#include <time.h>
int clock_getcpuclockid(pid_t pid, clockid_t *clock_id);
Link with −lrt (only for glibc versions before 2.17).
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
clock_getcpuclockid():
_XOPEN_SOURCE >= 600 || _POSIX_C_SOURCE >= 200112L
DESCRIPTION
The clock_getcpuclockid() function obtains the ID of the CPU-time clock of the process whose ID is pid, and returns it in the location pointed to by clock_id. If pid is zero, then the clock ID of the CPU-time clock of the calling process is returned.
RETURN VALUE
On success, clock_getcpuclockid() returns 0; on error, it returns one of the positive error numbers listed in ERRORS.
ERRORS
|
ENOSYS |
The kernel does not support obtaining the per-process CPU-time clock of another process, and pid does not specify the calling process. | ||
|
EPERM |
The caller does not have permission to access the CPU-time clock of the process specified by pid. (Specified as an optional error 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.) | ||
|
ESRCH |
There is no process with the ID pid. |
VERSIONS
The clock_getcpuclockid() function is available in glibc since version 2.2.
ATTRIBUTES
Multithreading
(see pthreads(7))
The clock_getcpuclockid() function is
thread-safe.
CONFORMING TO
POSIX.1-2001.
NOTES
Calling clock_gettime(2) with the clock ID obtained by a call to clock_getcpuclockid() with a pid of 0, is the same as using the clock ID CLOCK_PROCESS_CPUTIME_ID.
EXAMPLE
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(2) to obtain the time on that clock. An example run is the following:
$ ./a.out
1 # Show CPU clock of init process
CPU-time clock for PID 1 is 2.213466748 seconds
Program
source
#define _XOPEN_SOURCE 600
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <time.h>
int
main(int argc, char *argv[])
{
clockid_t clockid;
struct timespec ts;
if (argc != 2)
{
fprintf(stderr, "%s <process−ID>\n",
argv[0]);
exit(EXIT_FAILURE);
}
if
(clock_getcpuclockid(atoi(argv[1]), &clockid) != 0) {
perror("clock_getcpuclockid");
exit(EXIT_FAILURE);
}
if
(clock_gettime(clockid, &ts) == −1) {
perror("clock_gettime");
exit(EXIT_FAILURE);
}
printf("CPU-time
clock for PID %s is %ld.%09ld seconds\n",
argv[1], (long) ts.tv_sec, (long) ts.tv_nsec);
exit(EXIT_SUCCESS);
}
SEE ALSO
clock_getres(2), timer_create(2), pthread_getcpuclockid(3), 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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