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28.\"     @(#)getrusage.2	8.1 (Berkeley) 6/4/93
29.\" $FreeBSD: stable/10/lib/libc/sys/getrusage.2 208914 2010-06-08 16:48:59Z uqs $
30.\"
31.Dd May 1, 2010
32.Dt GETRUSAGE 2
33.Os
34.Sh NAME
35.Nm getrusage
36.Nd get information about resource utilization
37.Sh LIBRARY
38.Lb libc
39.Sh SYNOPSIS
40.In sys/types.h
41.In sys/time.h
42.In sys/resource.h
43.Fd "#define    RUSAGE_SELF      0"
44.Fd "#define    RUSAGE_CHILDREN -1"
45.Fd "#define    RUSAGE_THREAD   1"
46.Ft int
47.Fn getrusage "int who" "struct rusage *rusage"
48.Sh DESCRIPTION
49The
50.Fn getrusage
51system call
52returns information describing the resources utilized by the current
53thread, the current process, or all its terminated child processes.
54The
55.Fa who
56argument is either
57.Dv RUSAGE_THREAD ,
58.Dv RUSAGE_SELF ,
59or
60.Dv RUSAGE_CHILDREN .
61The buffer to which
62.Fa rusage
63points will be filled in with
64the following structure:
65.Bd -literal
66struct rusage {
67        struct timeval ru_utime; /* user time used */
68        struct timeval ru_stime; /* system time used */
69        long ru_maxrss;          /* max resident set size */
70        long ru_ixrss;           /* integral shared text memory size */
71        long ru_idrss;           /* integral unshared data size */
72        long ru_isrss;           /* integral unshared stack size */
73        long ru_minflt;          /* page reclaims */
74        long ru_majflt;          /* page faults */
75        long ru_nswap;           /* swaps */
76        long ru_inblock;         /* block input operations */
77        long ru_oublock;         /* block output operations */
78        long ru_msgsnd;          /* messages sent */
79        long ru_msgrcv;          /* messages received */
80        long ru_nsignals;        /* signals received */
81        long ru_nvcsw;           /* voluntary context switches */
82        long ru_nivcsw;          /* involuntary context switches */
83};
84.Ed
85.Pp
86The fields are interpreted as follows:
87.Bl -tag -width ru_minfltaa
88.It Fa ru_utime
89the total amount of time spent executing in user mode.
90.It Fa ru_stime
91the total amount of time spent in the system executing on behalf
92of the process(es).
93.It Fa ru_maxrss
94the maximum resident set size utilized (in kilobytes).
95.It Fa ru_ixrss
96an
97.Dq integral
98value indicating the amount of memory used
99by the text segment
100that was also shared among other processes.
101This value is expressed
102in units of kilobytes * ticks-of-execution.
103Ticks are statistics clock ticks.
104The statistics clock has a frequency of
105.Fn sysconf _SC_CLK_TCK
106ticks per second.
107.It Fa ru_idrss
108an integral value of the amount of unshared memory residing in the
109data segment of a process (expressed in units of
110kilobytes * ticks-of-execution).
111.It Fa ru_isrss
112an integral value of the amount of unshared memory residing in the
113stack segment of a process (expressed in units of
114kilobytes * ticks-of-execution).
115.It Fa ru_minflt
116the number of page faults serviced without any I/O activity; here
117I/O activity is avoided by
118.Dq reclaiming
119a page frame from
120the list of pages awaiting reallocation.
121.It Fa ru_majflt
122the number of page faults serviced that required I/O activity.
123.It Fa ru_nswap
124the number of times a process was
125.Dq swapped
126out of main
127memory.
128.It Fa ru_inblock
129the number of times the file system had to perform input.
130.It Fa ru_oublock
131the number of times the file system had to perform output.
132.It Fa ru_msgsnd
133the number of IPC messages sent.
134.It Fa ru_msgrcv
135the number of IPC messages received.
136.It Fa ru_nsignals
137the number of signals delivered.
138.It Fa ru_nvcsw
139the number of times a context switch resulted due to a process
140voluntarily giving up the processor before its time slice was
141completed (usually to await availability of a resource).
142.It Fa ru_nivcsw
143the number of times a context switch resulted due to a higher
144priority process becoming runnable or because the current process
145exceeded its time slice.
146.El
147.Sh NOTES
148The numbers
149.Fa ru_inblock
150and
151.Fa ru_oublock
152account only for real
153I/O; data supplied by the caching mechanism is charged only
154to the first process to read or write the data.
155.Sh RETURN VALUES
156.Rv -std getrusage
157.Sh ERRORS
158The
159.Fn getrusage
160system call will fail if:
161.Bl -tag -width Er
162.It Bq Er EINVAL
163The
164.Fa who
165argument is not a valid value.
166.It Bq Er EFAULT
167The address specified by the
168.Fa rusage
169argument is not in a valid part of the process address space.
170.El
171.Sh SEE ALSO
172.Xr gettimeofday 2 ,
173.Xr wait 2 ,
174.Xr clocks 7
175.Sh HISTORY
176The
177.Fn getrusage
178system call appeared in
179.Bx 4.2 .
180The
181.Dv RUSAGE_THREAD
182facility first appeared in
183.Fx 8.1 .
184.Sh BUGS
185There is no way to obtain information about a child process
186that has not yet terminated.
187