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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.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       clock_getcpuclockid(): _XOPEN_SOURCE >= 600

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 a positive error number.

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 sup-
              port 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.

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 3.22 of the Linux man-pages project.  A description of the project,  and  informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                             2009-02-20            CLOCK_GETCPUCLOCKID(3)