times - get process times
#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 It is obsolete now.
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)
Linux 2000-12-11 TIMES(2)
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