4.2BSD/usr/man/man2/getrusage.2

.TH GETRUSAGE 2 "18 July 1983"
.UC 4
.SH NAME
getrusage \- get information about resource utilization
.SH SYNOPSIS
.nf
.ft B
#include <sys/time.h>
#include <sys/resource.h>
.PP
.ft B
.ta \w'#define 'u +\w'RUSAGE_CHILDREN  'u +\w'-1        'u
#define	RUSAGE_SELF	0	/* calling process */
#define	RUSAGE_CHILDREN	-1	/* terminated child processes */
.DT
.PP
.ft B
getrusage(who, rusage)
int who;
struct rusage *rusage;
.fi
.SH DESCRIPTION
.I Getrusage
returns information describing the resources utilized by the current
process, or all its terminated child processes.
The
.I who
parameter is one of RUSAGE_SELF and RUSAGE_CHILDREN.
If
.I rusage
is non-zero, the buffer it points to will be filled in with
the following structure:
.PP
.nf
.RS
.ta \w'struct  'u +\w'struct  'u +3u*\w'struct  'u
struct	rusage {
	struct timeval ru_utime;	/* user time used */
	struct timeval ru_stime;	/* system time used */
	int	ru_maxrss;
	int	ru_ixrss;	/* integral shared 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 */
};
.RE
.DT
.fi
.PP
The fields are interpreted as follows:
.TP 15
ru_utime
the total amount of time spent executing in user mode.
.TP 15
ru_stime
the total amount of time spent in the system executing on behalf
of the process(es).
.TP 15
ru_maxrss
the maximum resident set size utilized (in kilobytes).
.TP 15
ru_ixrss
an \*(lqintegral\*(rq value indicating the amount of memory used
which was also shared among other processes.  This value is expressed
in units of kilobytes * seconds-of-execution and is calculated by
summing the number of shared memory pages in use each time the internal
system clock ticks and then averaging over 1 second intervals.
.TP 15
ru_idrss
an integral value of the amount of unshared memory residing in the
data segment of a process (expressed in units of
kilobytes * seconds-of-execution).
.TP 15
ru_isrss
an integral value of the amount of unshared memory residing in the
stack segment of a process (expressed in units of
kilobytes * seconds-of-execution).
.TP 15
ru_minflt
the number of page faults serviced without any i/o activity; here
i/o activity is avoided by \*(lqreclaiming\*(rq a page frame from
the list of pages awaiting reallocation.
.TP 15
ru_majflt
the number of page faults serviced which required i/o activity.
.TP 15
ru_nswap
the number of times a process was \*(lqswapped\*(rq out of main
memory.
.TP 15
ru_inblock
the number of times the file system had to perform input.
.TP 15
ru_outblock
the number of times the file system had to perform output.
.TP 15
ru_msgsnd
the number of ipc messages sent.
.TP 15
ru_msgrcv
the number of ipc messages received.
.TP 15
ru_nsignals
the number of signals delivered.
.TP 15
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).
.TP 15
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.
.SH NOTES
The numbers 
.I ru_inblock
and 
.I ru_outblock
account only for real
i/o; data supplied by the cacheing mechanism is charged only
to the first process to read or write the data.
.SH SEE ALSO
gettimeofday(2), wait(2)
.SH BUGS
There is no way to obtain information about a child process
which has not yet terminated.