getrusage() returns current resource usages, for a who
of either
RUSAGE_SELF or
RUSAGE_CHILDREN. The former asks for resources used by the current process,
the latter for resources used by those of its children
that have terminated and have been waited for.
struct rusage {
struct timeval ru_utime; /* user time used */
struct timeval ru_stime; /* system time used */
long ru_maxrss; /* maximum resident set size */
long ru_ixrss; /* integral shared memory size */
long ru_idrss; /* integral unshared data size */
long ru_isrss; /* integral unshared stack size */
long ru_minflt; /* page reclaims */
long ru_majflt; /* page faults */
long ru_nswap; /* swaps */
long ru_inblock; /* block input operations */
long ru_oublock; /* block output operations */
long ru_msgsnd; /* messages sent */
long ru_msgrcv; /* messages received */
long ru_nsignals; /* signals received */
long ru_nvcsw; /* voluntary context switches */
long ru_nivcsw; /* involuntary context switches */
};
Including
<sys/time.h> is not required these days, but increases portability.
(Indeed,
struct timeval is defined in
<sys/time.h>.)
In Linux kernel versions before 2.6.9, if the disposition of
SIGCHLD is set to
SIG_IGN then the resource usages of child processes
are automatically included in the value returned by
RUSAGE_CHILDREN, although POSIX.1-2001 explicitly prohibits this.
This non-conformance is rectified in Linux 2.6.9 and later.
The above struct was taken from 4.3BSD Reno.
Not all fields are meaningful under Linux.
In linux 2.4 only the fields
ru_utime,
ru_stime,
ru_minflt, and
ru_majflt are maintained.
Since Linux 2.6,
ru_nvcsw and
ru_nivcsw are also maintained.
