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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 || _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.

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

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