times.2 (2010 09)

times(2) times(2)

NAME

times - get process and child process times

SYNOPSIS

#include <sys/times.h>

clock_t times(struct tms *buffer);

DESCRIPTION

times() ﬁlls the structure pointed to by buffer with time-accounting information. The structure deﬁned

is as follows:

struct tms {

clock_t tms_utime; /* user time */

clock_t tms_stime; /* system time */"

clock_t tms_cutime; /* user time, children */

clock_t tms_cstime; /* system time, children */

};

This information comes from the calling process and each of its terminated child processes for which it

has executed a

wait(), wait3(),or

waitpid(). The times are in units of 1 / CLK_TCK seconds,

where

CLK_TCK is processor dependent. The value of CLK_TCK can be queried using the sysconf()

function (see sysconf (2)).

tms_utime is the CPU time used while executing instructions in the user space of the calling process.

tms_stime is the CPU time used by the system on behalf of the calling process.

tms_cutime is the sum of the tms_utimes and tms_cutimes of the child processes.

tms_cstime is the sum of the tms_stimes and tms_cstimes of the child processes.

RETURN VALUE

Upon successful completion,

times() returns the elapsed real time, in units of 1 / CLK_TCK of a second,

since an arbitrary point in the past (such as system start-up time). This point does not change from one

invocation of times() to another. If times() fails, (clock_t) −1 is returned and errno is set to indi-

cate the error.

Remarks

times() has a granularity of one tick. Processes which run less than one tick may not register any

value.

ERRORS

[EFAULT]

times() fails if buffer points to an illegal address. The reliable detection of this error is

implementation dependent.

WARNINGS

Not all CPU time expended by system processes on behalf of a user process is counted in the system CPU

time for that process.