clock(3c) [opensolaris man page]

clock(3C)						   Standard C Library Functions 						 clock(3C)

NAME

       clock - report CPU time used

SYNOPSIS

       #include <time.h>

       clock_t clock(void);

DESCRIPTION

       The clock() function returns the amount of CPU time (in microseconds) used since the first call to clock() in the calling process. The time
       reported is the sum of the user and system times of the calling process and its terminated child processes for which it	has  executed  the
       wait(3C) function, the pclose(3C) function, or the system(3C) function.

RETURN VALUES

       Dividing  the  value returned by clock() by the constant CLOCKS_PER_SEC, defined in the <time.h> header, will give the time in seconds.	If
       the process time used is not available or cannot be  represented, clock returns the value (clock_t) -1.

USAGE

       The value returned by clock() is defined in microseconds for compatibility with systems that have CPU clocks with much  higher  resolution.
       Because of this, the value returned will wrap around after accumulating only 2147 seconds of CPU time (about 36 minutes).

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       times(2), popen(3C), system(3C), wait(3C), attributes(5), standards(5)

SunOS 5.11							    24 Jul 2002 							 clock(3C)

TIMES(2)						     Linux Programmer's Manual							  TIMES(2)

NAME

       times - get process times

SYNOPSIS

       #include <sys/times.h>

       clock_t times(struct tms *buf);

DESCRIPTION

       The times() function stores the current process times in the struct tms that buf points to.  The struct tms is as defined in <sys/times.h>:

       struct tms {
	      clock_t tms_utime;  /* user time */
	      clock_t tms_stime;  /* system time */
	      clock_t tms_cutime; /* user time of children */
	      clock_t tms_cstime; /* system time of children */
       };

       The  tms_utime  field contains the CPU time spent executing instructions of the calling process.  The tms_stime field contains the CPU time
       spent in the system while executing tasks on behalf of the calling process.  The tms_cutime field contains the sum  of  the  tms_utime  and
       tms_cutime values for all waited-for terminated children.  The tms_cstime field contains the sum of the tms_stime and tms_cstime values for
       all waited-for terminated children.

       Times for terminated children (and their descendants) is added in at the moment wait(2) or waitpid(2) returns their process ID. In particu-
       lar, times of grandchildren that the children did not wait for are never seen.

       All times reported are in clock ticks.

RETURN VALUE

       The  function  times  returns the number of clock ticks that have elapsed since an arbitrary point in the past. For Linux this point is the
       moment the system was booted.  This return value may overflow the possible range of type clock_t.  On error, (clock_t) -1 is returned,  and
       errno is set appropriately.

NOTES

       The number of clock ticks per second can be obtained using
	      sysconf(_SC_CLK_TCK);
       In POSIX-1996 the symbol CLK_TCK (defined in <time.h>) is mentioned as obsolescent. It is obsolete now.

       On  Linux,  if  the  disposition  of  SIGCHLD  is  set  to  SIG_IGN then the times of terminated children are automatically included in the
       tms_cstime and tms_cutime fields, although POSIX 1003.1-2001 says that this should only happen if the calling process wait()s on its  chil-
       dren.

       Note that clock(3) returns values of type clock_t that are not measured in clock ticks but in CLOCKS_PER_SEC.

CONFORMING TO

       SVr4, SVID, POSIX, X/OPEN, BSD 4.3

HISTORICAL NOTES

       SVr1-3  returns	long and the struct members are of type time_t although they store clock ticks, not seconds since the epoch.  V7 used long
       for the struct members, because it had no type time_t yet.

       On older systems the number of clock ticks per second is given by the variable HZ.

SEE ALSO

       time(1), getrusage(2), wait(2), clock(3), sysconf(3)

Linux								    2002-06-14								  TIMES(2)