[thirdparty/man-pages.git] / man2 / getrusage.2

.\" Copyright (c) 1992 Drew Eckhardt, March 28, 1992
.\" and Copyright (c) 2002 Michael Kerrisk
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.\" 2004-11-16 -- mtk: the getrlimit.2 page, which formerly included
.\" coverage of getrusage(2), has been split, so that the latter is
.\" now covered in its own getrusage.2.  For older details of change
.\" history, etc., see getrlimit.2
.\"
.\" Modified 2004-11-16, mtk, Noted that the nonconformance
.\"	when SIGCHLD is being ignored is fixed in 2.6.9.
.\" 2008-02-22, Sripathi Kodi <sripathik@in.ibm.com>: Document RUSAGE_THREAD
.\" 2008-05-25, mtk, clarify RUSAGE_CHILDREN + other clean-ups.
.\" 2010-05-24, Mark Hills <mark@pogo.org.uk>: Description of fields,
.\"     document ru_maxrss
.\" 2010-05-24, mtk, enhanced description of various fields
.\"
.TH GETRUSAGE 2 2017-09-15 "Linux" "Linux Programmer's Manual"
.SH NAME
getrusage \- get resource usage
.SH SYNOPSIS
.B #include <sys/time.h>
.br
.B #include <sys/resource.h>
.PP
.BI "int getrusage(int " who ", struct rusage *" usage );
.SH DESCRIPTION
.PP
.BR getrusage ()
returns resource usage measures for
.IR who ,
which can be one of the following:
.TP
.B RUSAGE_SELF
Return resource usage statistics for the calling process,
which is the sum of resources used by all threads in the process.
.TP
.B RUSAGE_CHILDREN
Return resource usage statistics for all children of the
calling process that have terminated and been waited for.
These statistics will include the resources used by grandchildren,
and further removed descendants,
if all of the intervening descendants waited on their terminated children.
.TP
.BR RUSAGE_THREAD " (since Linux 2.6.26)"
Return resource usage statistics for the calling thread.
The
.B _GNU_SOURCE
feature test macro must be defined (before including
.I any
header file)
in order to obtain the definition of this constant from
.IR <sys/resource.h> .
.PP
The resource usages are returned in the structure pointed to by
.IR usage ,
which has the following form:
.PP
.in +4n
.EX
struct rusage {
    struct timeval ru_utime; /* user CPU time used */
    struct timeval ru_stime; /* system CPU 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 (soft page faults) */
    long   ru_majflt;        /* page faults (hard page faults) */
    long   ru_nswap;         /* swaps */
    long   ru_inblock;       /* block input operations */
    long   ru_oublock;       /* block output operations */
    long   ru_msgsnd;        /* IPC messages sent */
    long   ru_msgrcv;        /* IPC messages received */
    long   ru_nsignals;      /* signals received */
    long   ru_nvcsw;         /* voluntary context switches */
    long   ru_nivcsw;        /* involuntary context switches */
};
.EE
.in
.PP
Not all fields are completed;
unmaintained fields are set to zero by the kernel.
(The unmaintained fields are provided for compatibility with other systems,
and because they may one day be supported on Linux.)
The fields are interpreted as follows:
.TP
.I ru_utime
This is the total amount of time spent executing in user mode,
expressed in a
.I timeval
structure (seconds plus microseconds).
.TP
.I ru_stime
This is the total amount of time spent executing in kernel mode,
expressed in a
.I timeval
structure (seconds plus microseconds).
.TP
.IR ru_maxrss " (since Linux 2.6.32)"
This is the maximum resident set size used (in kilobytes).
For
.BR RUSAGE_CHILDREN ,
this is the resident set size of the largest child, not the maximum
resident set size of the process tree.
.TP
.IR ru_ixrss " (unmaintained)"
This field is currently unused on Linux.
.\" On some systems,
.\" this is the integral of the text segment memory consumption,
.\" expressed in kilobyte-seconds.
.TP
.IR ru_idrss " (unmaintained)"
This field is currently unused on Linux.
.\" On some systems, this is the integral of the data segment memory consumption,
.\" expressed in kilobyte-seconds.
.TP
.IR ru_isrss " (unmaintained)"
This field is currently unused on Linux.
.\" On some systems, this is the integral of the stack memory consumption,
.\" expressed in kilobyte-seconds.
.TP
.I 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
.I ru_majflt
The number of page faults serviced that required I/O activity.
.TP
.IR ru_nswap  " (unmaintained)"
This field is currently unused on Linux.
.\" On some systems, this is the number of swaps out of physical memory.
.TP
.IR ru_inblock " (since Linux 2.6.22)"
The number of times the filesystem had to perform input.
.TP
.IR ru_oublock " (since Linux 2.6.22)"
The number of times the filesystem had to perform output.
.TP
.IR ru_msgsnd " (unmaintained)"
This field is currently unused on Linux.
.\" On FreeBSD 6.2, this appears to measure messages sent over sockets
.\" On some systems,
.\" this field records the number of messages sent over sockets.
.TP
.IR ru_msgrcv " (unmaintained)"
This field is currently unused on Linux.
.\" On FreeBSD 6.2, this appears to measure messages received over sockets
.\" On some systems,
.\" this field records the number of messages received over sockets.
.TP
.IR ru_nsignals " (unmaintained)"
This field is currently unused on Linux.
.\" On some systems, this field records the number of signals received.
.TP
.IR ru_nvcsw " (since Linux 2.6)"
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
.IR ru_nivcsw " (since Linux 2.6)"
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.
.PP
.SH RETURN VALUE
On success, zero is returned.
On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B EFAULT
.I usage
points outside the accessible address space.
.TP
.B EINVAL
.I who
is invalid.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lb lb lb
l l l.
Interface	Attribute	Value
T{
.BR getrusage ()
T}	Thread safety	MT-Safe
.TE
.sp 1
.SH CONFORMING TO
POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
POSIX.1 specifies
.BR getrusage (),
but specifies only the fields
.I ru_utime
and
.IR ru_stime .
.PP
.B RUSAGE_THREAD
is Linux-specific.
.SH NOTES
Resource usage metrics are preserved across an
.BR execve (2).
.PP
Including
.I <sys/time.h>
is not required these days, but increases portability.
(Indeed,
.I struct timeval
is defined in
.IR <sys/time.h> .)
.PP
In Linux kernel versions before 2.6.9, if the disposition of
.B SIGCHLD
is set to
.B SIG_IGN
then the resource usages of child processes
are automatically included in the value returned by
.BR RUSAGE_CHILDREN ,
although POSIX.1-2001 explicitly prohibits this.
This nonconformance is rectified in Linux 2.6.9 and later.
.\" See the description of getrusage() in XSH.
.\" A similar statement was also in SUSv2.
.PP
The structure definition shown at the start of this page
was taken from 4.3BSD Reno.
.PP
Ancient systems provided a
.BR vtimes ()
function with a similar purpose to
.BR getrusage ().
For backward compatibility, glibc also provides
.BR vtimes ().
All new applications should be written using
.BR getrusage ().
.PP
See also the description of
.IR /proc/[pid]/stat
in
.BR proc (5).
.SH SEE ALSO
.BR clock_gettime (2),
.BR getrlimit (2),
.BR times (2),
.BR wait (2),
.BR wait4 (2),
.BR clock (3)
Commit	Line	Data
	1	.\" Copyright (c) 1992 Drew Eckhardt, March 28, 1992
	2	.\" and Copyright (c) 2002 Michael Kerrisk
	3	.\"
	4	.\" %%%LICENSE_START(VERBATIM)
	5	.\" Permission is granted to make and distribute verbatim copies of this
	6	.\" manual provided the copyright notice and this permission notice are
	7	.\" preserved on all copies.
	8	.\"
	9	.\" Permission is granted to copy and distribute modified versions of this
	10	.\" manual under the conditions for verbatim copying, provided that the
	11	.\" entire resulting derived work is distributed under the terms of a
	12	.\" permission notice identical to this one.
	13	.\"
	14	.\" Since the Linux kernel and libraries are constantly changing, this
	15	.\" manual page may be incorrect or out-of-date. The author(s) assume no
	16	.\" responsibility for errors or omissions, or for damages resulting from
	17	.\" the use of the information contained herein. The author(s) may not
	18	.\" have taken the same level of care in the production of this manual,
	19	.\" which is licensed free of charge, as they might when working
	20	.\" professionally.
	21	.\"
	22	.\" Formatted or processed versions of this manual, if unaccompanied by
	23	.\" the source, must acknowledge the copyright and authors of this work.
	24	.\" %%%LICENSE_END
	25	.\"
	26	.\" 2004-11-16 -- mtk: the getrlimit.2 page, which formerly included
	27	.\" coverage of getrusage(2), has been split, so that the latter is
	28	.\" now covered in its own getrusage.2. For older details of change
	29	.\" history, etc., see getrlimit.2
	30	.\"
	31	.\" Modified 2004-11-16, mtk, Noted that the nonconformance
	32	.\" when SIGCHLD is being ignored is fixed in 2.6.9.
	33	.\" 2008-02-22, Sripathi Kodi <sripathik@in.ibm.com>: Document RUSAGE_THREAD
	34	.\" 2008-05-25, mtk, clarify RUSAGE_CHILDREN + other clean-ups.
	35	.\" 2010-05-24, Mark Hills <mark@pogo.org.uk>: Description of fields,
	36	.\" document ru_maxrss
	37	.\" 2010-05-24, mtk, enhanced description of various fields
	38	.\"
	39	.TH GETRUSAGE 2 2017-09-15 "Linux" "Linux Programmer's Manual"
	40	.SH NAME
	41	getrusage \- get resource usage
	42	.SH SYNOPSIS
	43	.B #include <sys/time.h>
	44	.br
	45	.B #include <sys/resource.h>
	46	.PP
	47	.BI "int getrusage(int " who ", struct rusage *" usage );
	48	.SH DESCRIPTION
	49	.PP
	50	.BR getrusage ()
	51	returns resource usage measures for
	52	.IR who ,
	53	which can be one of the following:
	54	.TP
	55	.B RUSAGE_SELF
	56	Return resource usage statistics for the calling process,
	57	which is the sum of resources used by all threads in the process.
	58	.TP
	59	.B RUSAGE_CHILDREN
	60	Return resource usage statistics for all children of the
	61	calling process that have terminated and been waited for.
	62	These statistics will include the resources used by grandchildren,
	63	and further removed descendants,
	64	if all of the intervening descendants waited on their terminated children.
	65	.TP
	66	.BR RUSAGE_THREAD " (since Linux 2.6.26)"
	67	Return resource usage statistics for the calling thread.
	68	The
	69	.B _GNU_SOURCE
	70	feature test macro must be defined (before including
	71	.I any
	72	header file)
	73	in order to obtain the definition of this constant from
	74	.IR <sys/resource.h> .
	75	.PP
	76	The resource usages are returned in the structure pointed to by
	77	.IR usage ,
	78	which has the following form:
	79	.PP
	80	.in +4n
	81	.EX
	82	struct rusage {
	83	struct timeval ru_utime; /* user CPU time used */
	84	struct timeval ru_stime; /* system CPU time used */
	85	long ru_maxrss; /* maximum resident set size */
	86	long ru_ixrss; /* integral shared memory size */
	87	long ru_idrss; /* integral unshared data size */
	88	long ru_isrss; /* integral unshared stack size */
	89	long ru_minflt; /* page reclaims (soft page faults) */
	90	long ru_majflt; /* page faults (hard page faults) */
	91	long ru_nswap; /* swaps */
	92	long ru_inblock; /* block input operations */
	93	long ru_oublock; /* block output operations */
	94	long ru_msgsnd; /* IPC messages sent */
	95	long ru_msgrcv; /* IPC messages received */
	96	long ru_nsignals; /* signals received */
	97	long ru_nvcsw; /* voluntary context switches */
	98	long ru_nivcsw; /* involuntary context switches */
	99	};
	100	.EE
	101	.in
	102	.PP
	103	Not all fields are completed;
	104	unmaintained fields are set to zero by the kernel.
	105	(The unmaintained fields are provided for compatibility with other systems,
	106	and because they may one day be supported on Linux.)
	107	The fields are interpreted as follows:
	108	.TP
	109	.I ru_utime
	110	This is the total amount of time spent executing in user mode,
	111	expressed in a
	112	.I timeval
	113	structure (seconds plus microseconds).
	114	.TP
	115	.I ru_stime
	116	This is the total amount of time spent executing in kernel mode,
	117	expressed in a
	118	.I timeval
	119	structure (seconds plus microseconds).
	120	.TP
	121	.IR ru_maxrss " (since Linux 2.6.32)"
	122	This is the maximum resident set size used (in kilobytes).
	123	For
	124	.BR RUSAGE_CHILDREN ,
	125	this is the resident set size of the largest child, not the maximum
	126	resident set size of the process tree.
	127	.TP
	128	.IR ru_ixrss " (unmaintained)"
	129	This field is currently unused on Linux.
	130	.\" On some systems,
	131	.\" this is the integral of the text segment memory consumption,
	132	.\" expressed in kilobyte-seconds.
	133	.TP
	134	.IR ru_idrss " (unmaintained)"
	135	This field is currently unused on Linux.
	136	.\" On some systems, this is the integral of the data segment memory consumption,
	137	.\" expressed in kilobyte-seconds.
	138	.TP
	139	.IR ru_isrss " (unmaintained)"
	140	This field is currently unused on Linux.
	141	.\" On some systems, this is the integral of the stack memory consumption,
	142	.\" expressed in kilobyte-seconds.
	143	.TP
	144	.I ru_minflt
	145	The number of page faults serviced without any I/O activity; here
	146	I/O activity is avoided by \(lqreclaiming\(rq a page frame from
	147	the list of pages awaiting reallocation.
	148	.TP
	149	.I ru_majflt
	150	The number of page faults serviced that required I/O activity.
	151	.TP
	152	.IR ru_nswap " (unmaintained)"
	153	This field is currently unused on Linux.
	154	.\" On some systems, this is the number of swaps out of physical memory.
	155	.TP
	156	.IR ru_inblock " (since Linux 2.6.22)"
	157	The number of times the filesystem had to perform input.
	158	.TP
	159	.IR ru_oublock " (since Linux 2.6.22)"
	160	The number of times the filesystem had to perform output.
	161	.TP
	162	.IR ru_msgsnd " (unmaintained)"
	163	This field is currently unused on Linux.
	164	.\" On FreeBSD 6.2, this appears to measure messages sent over sockets
	165	.\" On some systems,
	166	.\" this field records the number of messages sent over sockets.
	167	.TP
	168	.IR ru_msgrcv " (unmaintained)"
	169	This field is currently unused on Linux.
	170	.\" On FreeBSD 6.2, this appears to measure messages received over sockets
	171	.\" On some systems,
	172	.\" this field records the number of messages received over sockets.
	173	.TP
	174	.IR ru_nsignals " (unmaintained)"
	175	This field is currently unused on Linux.
	176	.\" On some systems, this field records the number of signals received.
	177	.TP
	178	.IR ru_nvcsw " (since Linux 2.6)"
	179	The number of times a context switch resulted due to a process
	180	voluntarily giving up the processor before its time slice was
	181	completed (usually to await availability of a resource).
	182	.TP
	183	.IR ru_nivcsw " (since Linux 2.6)"
	184	The number of times a context switch resulted due to a higher
	185	priority process becoming runnable or because the current process
	186	exceeded its time slice.
	187	.PP
	188	.SH RETURN VALUE
	189	On success, zero is returned.
	190	On error, \-1 is returned, and
	191	.I errno
	192	is set appropriately.
	193	.SH ERRORS
	194	.TP
	195	.B EFAULT
	196	.I usage
	197	points outside the accessible address space.
	198	.TP
	199	.B EINVAL
	200	.I who
	201	is invalid.
	202	.SH ATTRIBUTES
	203	For an explanation of the terms used in this section, see
	204	.BR attributes (7).
	205	.TS
	206	allbox;
	207	lb lb lb
	208	l l l.
	209	Interface Attribute Value
	210	T{
	211	.BR getrusage ()
	212	T} Thread safety MT-Safe
	213	.TE
	214	.sp 1
	215	.SH CONFORMING TO
	216	POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
	217	POSIX.1 specifies
	218	.BR getrusage (),
	219	but specifies only the fields
	220	.I ru_utime
	221	and
	222	.IR ru_stime .
	223	.PP
	224	.B RUSAGE_THREAD
	225	is Linux-specific.
	226	.SH NOTES
	227	Resource usage metrics are preserved across an
	228	.BR execve (2).
	229	.PP
	230	Including
	231	.I <sys/time.h>
	232	is not required these days, but increases portability.
	233	(Indeed,
	234	.I struct timeval
	235	is defined in
	236	.IR <sys/time.h> .)
	237	.PP
	238	In Linux kernel versions before 2.6.9, if the disposition of
	239	.B SIGCHLD
	240	is set to
	241	.B SIG_IGN
	242	then the resource usages of child processes
	243	are automatically included in the value returned by
	244	.BR RUSAGE_CHILDREN ,
	245	although POSIX.1-2001 explicitly prohibits this.
	246	This nonconformance is rectified in Linux 2.6.9 and later.
	247	.\" See the description of getrusage() in XSH.
	248	.\" A similar statement was also in SUSv2.
	249	.PP
	250	The structure definition shown at the start of this page
	251	was taken from 4.3BSD Reno.
	252	.PP
	253	Ancient systems provided a
	254	.BR vtimes ()
	255	function with a similar purpose to
	256	.BR getrusage ().
	257	For backward compatibility, glibc also provides
	258	.BR vtimes ().
	259	All new applications should be written using
	260	.BR getrusage ().
	261	.PP
	262	See also the description of
	263	.IR /proc/[pid]/stat
	264	in
	265	.BR proc (5).
	266	.SH SEE ALSO
	267	.BR clock_gettime (2),
	268	.BR getrlimit (2),
	269	.BR times (2),
	270	.BR wait (2),
	271	.BR wait4 (2),
	272	.BR clock (3)