Originální popis anglicky:
times - get process times
Návod, kniha: Linux Programmer's Manual
#include <sys/times.h>
clock_t times(struct tms *buf);
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 particular,
times of grandchildren that the children did not wait for are never seen.
All times reported are in clock ticks.
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.
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 It is obsolete now.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 children.
Note that
clock(3) returns values of type clock_t that are not measured
in clock ticks but in CLOCKS_PER_SEC.
SVr4, SVID, POSIX, X/OPEN, BSD 4.3
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.
time(1),
getrusage(2),
wait(2),
clock(3),
sysconf(3)
