clock_getcpuclockid(3p) [centos man page]

CLOCK_GETCPUCLOCKID(3P) 				     POSIX Programmer's Manual					   CLOCK_GETCPUCLOCKID(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       clock_getcpuclockid - access a process CPU-time clock (ADVANCED REALTIME)

SYNOPSIS

       #include <time.h>

       int clock_getcpuclockid(pid_t pid, clockid_t *clock_id);

DESCRIPTION

       The clock_getcpuclockid() function shall return the clock ID of the CPU-time clock  of  the  process  specified	by  pid.  If  the  process
       described by pid exists and the calling process has permission, the clock ID of this clock shall be returned in clock_id.

       If  pid	is  zero,  the	clock_getcpuclockid()  function shall return the clock ID of the CPU-time clock of the process making the call, in
       clock_id.

       The conditions under which one process has permission to obtain the CPU-time clock ID of other processes are implementation-defined.

RETURN VALUE

       Upon successful completion, clock_getcpuclockid() shall return zero; otherwise, an error number shall be returned to indicate the error.

ERRORS

       The clock_getcpuclockid() function shall fail if:

       EPERM  The requesting process does not have permission to access the CPU-time clock for the process.

       The clock_getcpuclockid() function may fail if:

       ESRCH  No process can be found corresponding to the process specified by pid.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The clock_getcpuclockid() function is part of the Process CPU-Time Clocks option and need not be provided on all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       clock_getres(), timer_create(), the Base Definitions volume of IEEE Std 1003.1-2001, <time.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003						   CLOCK_GETCPUCLOCKID(3P)

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 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_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 3.25 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								    2009-02-20						    CLOCK_GETCPUCLOCKID(3)