.\"	$OpenBSD: getrusage.2,v 1.14 2013/03/31 22:11:26 guenther Exp $
.\"
.\" Copyright (c) 1985, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)getrusage.2	8.1 (Berkeley) 6/4/93
.\"
.Dd $Mdocdate: March 31 2013 $
.Dt GETRUSAGE 2
.Os
.Sh NAME
.Nm getrusage
.Nd get information about resource utilization
.Sh SYNOPSIS
.Fd #include <sys/resource.h>
.Pp
.Fd #define RUSAGE_SELF		0
.Fd #define RUSAGE_CHILDREN	(-1)
.Ft int
.Fn getrusage "int who" "struct rusage *rusage"
.Sh DESCRIPTION
.Fn getrusage
returns information describing the resources utilized by the current
process, or all its terminated child processes.
The
.Fa who
parameter is either
.Dv RUSAGE_SELF
or
.Dv RUSAGE_CHILDREN .
The buffer to which
.Fa rusage
points will be filled in with
the following structure:
.Bd -literal
struct rusage {
        struct timeval ru_utime; /* user time used */
        struct timeval ru_stime; /* system time used */
        long ru_maxrss;          /* max resident set size */
        long ru_ixrss;           /* integral shared text 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 */
};
.Ed
.Pp
The fields are interpreted as follows:
.Bl -tag -width ru_minfltaa
.It Fa ru_utime
the total amount of time spent executing in user mode.
.It Fa ru_stime
the total amount of time spent in the system executing on behalf
of the process(es).
.It Fa ru_maxrss
the maximum resident set size utilized (in kilobytes).
.It Fa ru_ixrss
an \*(lqintegral\*(rq 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.
.It Fa 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).
.It Fa 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).
.It Fa 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.
.It Fa ru_majflt
the number of page faults serviced that required I/O activity.
.It Fa ru_nswap
the number of times a process was \*(lqswapped\*(rq out of main
memory.
.It Fa ru_inblock
the number of times the file system had to perform input.
.It Fa ru_oublock
the number of times the file system had to perform output.
.It Fa ru_msgsnd
the number of IPC messages sent.
.It Fa ru_msgrcv
the number of IPC messages received.
.It Fa ru_nsignals
the number of signals delivered.
.It Fa 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).
.It Fa 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.
.El
.Sh NOTES
The numbers
.Fa ru_inblock
and
.Fa 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.
.Sh RETURN VALUES
Upon success, a value of zero is returned.
Otherwise, \-1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn getrusage
will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa who
parameter is not a valid value.
.It Bq Er EFAULT
The address specified by the
.Fa rusage
parameter is not in a valid part of the process address space.
.El
.Sh SEE ALSO
.Xr clock_gettime 2 ,
.Xr gettimeofday 2 ,
.Xr wait 2
.Sh STANDARDS
The
.Fn getrusage
function conforms to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn getrusage
function call appeared in
.Bx 4.2 .
.Sh BUGS
There is no way to obtain information about a child process
that has not yet terminated.