Unix/Linux Go Back    


Linux 2.6 - man page for clock_getcpuclockid (linux section 3)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)


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():
	   _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 3.55 of the Linux man-pages project.  A description of the
       project,    and	  information	 about	  reporting    bugs,	can    be    found     at
       http://www.kernel.org/doc/man-pages/.

Linux					    2013-07-04			   CLOCK_GETCPUCLOCKID(3)
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums


All times are GMT -4. The time now is 07:07 PM.