CLOCK_GETCPUCLOCKID(3)					     Linux Programmer's Manual					    CLOCK_GETCPUCLOCKID(3)

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():
	   _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 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

       For an explanation of the terms used in this section, see attributes(7).

       +----------------------+---------------+---------+
       |Interface	      | Attribute     | Value	|
       +----------------------+---------------+---------+
       |clock_getcpuclockid() | Thread safety | MT-Safe |
       +----------------------+---------------+---------+
CONFORMING TO

       POSIX.1-2001, POSIX.1-2008.

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_get-
       time(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>
", 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
",
		   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 4.15 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 https://www.kernel.org/doc/man-pages/.

Linux								    2017-09-15						    CLOCK_GETCPUCLOCKID(3)