NAME
times —
process times
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/times.h>
clock_t
times(
struct tms
*tp);
DESCRIPTION
The
times() function returns the value of time in clock ticks
since 0 hours, 0 minutes, 0 seconds, January 1, 1970, Coordinated Universal
Time (UTC).
The number of clock ticks per second may be determined by calling
sysconf(3) with the
_SC_CLK_TCK
request. It is generally (but not always)
between 60 and 1024.
Note that at the common rate of 100 ticks per second on many
NetBSD ports, and with a 32-bit unsigned clock_t, this
value first wrapped in 1971.
The
times() call also fills in the structure pointed to by
tp with time-accounting information.
The
tms structure is defined as follows:
typedef struct {
clock_t tms_utime;
clock_t tms_stime;
clock_t tms_cutime;
clock_t tms_cstime;
}
The elements of this structure are defined as follows:
-
-
- tms_utime
- The CPU time charged for the execution of user
instructions.
-
-
- tms_stime
- The CPU time charged for execution by the system on behalf
of the process.
-
-
- tms_cutime
- The sum of the tms_utime s and
tms_cutime s of the child processes.
-
-
- tms_cstime
- The sum of the tms_stimes and
tms_cstimes of the child processes.
All times are measured in clock ticks, as defined above. Note that at 100 ticks
per second, and with a 32-bit unsigned clock_t, the values wrap after 497
days.
The times of a terminated child process are included in the
tms_cutime and
tms_cstime elements
of the parent when one of the
wait(2) functions returns the
process ID of the terminated child to the parent. If an error occurs,
times() returns the value ((clock_t)-1), and sets
errno to indicate the error.
ERRORS
The
times() function may fail and set the global variable
errno for any of the errors specified for the library
routines
getrusage(2) and
gettimeofday(2).
SEE ALSO
time(1),
getrusage(2),
gettimeofday(2),
wait(2),
sysconf(3)
STANDARDS
The
times() function conforms to
IEEE Std
1003.1-1990 (“POSIX.1”).