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   clock_getcpuclockid    ( 3 )

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Имя (Name)

clock_getcpuclockid - obtain ID of a process CPU-time clock

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Синопсис (Synopsis)

#include <time.h>

       int clock_getcpuclockid(pid_t pid, clockid_t *clockid);

       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

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Описание (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 clockid.  If pid is zero, then the clock
       ID of the CPU-time clock of the calling process is returned.

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Возвращаемое значение (Return value)

On success, clock_getcpuclockid() returns 0; on error, it returns
       one of the positive error numbers listed in ERRORS.

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Ошибки (Error)

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.

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Версии (Versions)

The clock_getcpuclockid() function is available in glibc since
       version 2.2.

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Атрибуты (Attributes)

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

       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │Interface                             │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │clock_getcpuclockid()                 │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

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Стандарты (Conforming to)

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

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Примечание (Note)

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.

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Примеры (Examples)

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 <stdint.h>
       #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 %jd.%09ld seconds\n",
                   argv[1], (intmax_t) ts.tv_sec, ts.tv_nsec);
           exit(EXIT_SUCCESS);
       }

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Смотри также (See also)

clock_getres(2), timer_create(2), pthread_getcpuclockid(3),
       time(7)

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