times(2) [redhat man page]

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 It is obsolete now.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)

times(3)						     Library Functions Manual							  times(3)

NAME

       times - Gets process and child process times

LIBRARY

       Standard C Library (libc.so, libc.a)

SYNOPSIS

       #include <sys/times.h>

       clock_t times(
	       struct tms *buffer);

       Programs  that  are being developed for conformance to the AT&T System V Interface Definition must specify two #include statements, as fol-
       lows:

       #include <sys/types.h> #include <sys/times.h>

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       times():  XPG4, XPG4-UNIX

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Points to type tms structure space where system time information is stored.

DESCRIPTION

       The times() function fills the type tms structure space pointed to by the buffer parameter with time-accounting information.  All time val-
       ues reported by this function are in hardware-dependent clock ticks.

       The  times  of a terminated child process are included in the tms_cutime and tms_cstime elements of the parent process when a wait function
       returns the process ID of that terminated child.

       The tms structure, which  is defined in the sys/times.h header file, contains the following members: User time. The CPU time charged  while
       executing  user	instructions  of  the calling process.	System time. The CPU time charged during system execution on behalf of the calling
       process.  User time, children. The sum of the tms_utime and the tms_cutime times of the child processes.  System time, children. The sum of
       the tms_stime and the tms_cstime times of the child processes.

       When a child process does not wait for its children, its child-process times are not included in its times.

       This information comes from the calling process and each of its terminated child processes for which a wait function has been executed.

RETURN VALUES

       Upon  successful completion, the times() function returns the elapsed real time since an arbitrary reference time in the past (for example,
       system start-up time). The reference time does not change from one invocation of times() within the process to another.	The elapsed  times
       are  in	units  of  1/CLK_TCK  seconds,	where CLK_TCK is processor dependent.  For application portability, the value of CLK_TCK should be
       queried using the sysconf() function (see sysconf(3)).

       The return value may overflow the possible range of type clock_t values. When the  times()  function  fails,  a	value  of  (clock_t)-1	is
       returned.

RELATED INFORMATION

       Commands: cc(1)

       Functions: exec(2), fork(2), getrusage(2), profil(2), stime(3), sysconf(3), time(3), wait(2)

       Standards: standards(5) delim off

																	  times(3)