NAME
getrusage - get information about resource utilization

SYNOPSIS
#include <sys/time.h>
#include <sys/resource.h>

#define RUSAGE_SELF 0 /* calling process */
#define RUSAGE_CHILDREN -1 /* terminated child processes */

getrusage(who, rusage)
int who;
struct rusage *rusage;

DESCRIPTION
Getrusage returns information describing the resources utilized by
the current process, or all its terminated child processes. The
who parameter is one of RUSAGE_SELF or RUSAGE_CHILDREN. The buffer
to which rusage points will be filled in with the following
structure:

struct rusage {
struct timeval ru_utime; /* user time used */
struct timeval ru_stime; /* system time used */
int ru_maxrss;
int ru_ixrss; /* integral shared text memory size */
int ru_idrss; /* integral unshared data size */
int ru_isrss; /* integral unshared stack size */
int ru_minflt; /* page reclaims */
int ru_majflt; /* page faults */
int ru_nswap; /* swaps */
int ru_inblock; /* block input operations */
int ru_oublock; /* block output operations */
int ru_msgsnd; /* messages sent */
int ru_msgrcv; /* messages received */
int ru_nsignals; /* signals received */
int ru_nvcsw; /* voluntary context switches */
int ru_nivcsw; /* involuntary context switches */
};

The fields are interpreted as follows:

ru_utime the total amount of time spent executing in user
mode.

ru_stime the total amount of time spent in the system
executing on behalf of the process(es).

ru_maxrss the maximum resident set size utilized (in
kilobytes).

ru_ixrss an "integral" value indicating the amount of memory
used by the text segment that was also shared among
other processes. This value is expressed in units
of kilobytes * ticks-of-execution.

ru_idrss an integral value of the amount of unshared memory
residing in the data segment of a process (expressed
in units of kilobytes * ticks-of-execution).

ru_isrss an integral value of the amount of unshared memory
residing in the stack segment of a process
(expressed in units of kilobytes * ticks-of-
execution).

ru_minflt the number of page faults serviced without any I/O
activity; here I/O activity is avoided by
"reclaiming" a page frame from the list of pages
awaiting reallocation.

ru_majflt the number of page faults serviced that required I/O
activity.

ru_nswap the number of times a process was "swapped" out of
main memory.

ru_inblock the number of times the file system had to perform
input.

ru_oublock the number of times the file system had to perform
output.

ru_msgsnd the number of IPC messages sent.

ru_msgrcv the number of IPC messages received.

ru_nsignals the number of signals delivered.

ru_nvcsw the number of times a context switch resulted due to
a process voluntarily giving up the processor before
its time slice was completed (usually to await
availability of a resource).

ru_nivcsw the number of times a context switch resulted due to
a higher priority process becoming runnable or
because the current process exceeded its time slice.

NOTES
The numbers ru_inblock and ru_oublock account only for real I/O;
data supplied by the caching mechanism is charged only to the first
process to read or write the data.

ERRORS
The possible errors for getrusage are:

[EINVAL] The who parameter is not a valid value.

[EFAULT] The address specified by the rusage parameter is not
in a valid part of the process address space.