mirror of https://github.com/mkerrisk/man-pages
253 lines
8.2 KiB
Groff
253 lines
8.2 KiB
Groff
.\" Copyright (c) 1992 Drew Eckhardt, March 28, 1992
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.\" and Copyright (c) 2002 Michael Kerrisk
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.\" 2004-11-16 -- mtk: the getrlimit.2 page, which formerly included
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.\" coverage of getrusage(2), has been split, so that the latter is
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.\" now covered in its own getrusage.2. For older details of change
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.\" history, etc., see getrlimit.2
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.\"
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.\" Modified 2004-11-16, mtk, Noted that the nonconformance
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.\" when SIGCHLD is being ignored is fixed in 2.6.9.
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.\" 2008-02-22, Sripathi Kodi <sripathik@in.ibm.com>: Document RUSAGE_THREAD
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.\" 2008-05-25, mtk, clarify RUSAGE_CHILDREN + other clean-ups.
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.\" 2010-05-24, Mark Hills <mark@pogo.org.uk>: Description of fields,
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.\" document ru_maxrss
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.\" 2010-05-24, mtk, enhanced description of various fields
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.\"
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.TH GETRUSAGE 2 2010-09-26 "Linux" "Linux Programmer's Manual"
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.SH NAME
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getrusage \- get resource usage
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.SH SYNOPSIS
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.B #include <sys/time.h>
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.br
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.B #include <sys/resource.h>
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.sp
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.BI "int getrusage(int " who ", struct rusage *" usage );
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.SH DESCRIPTION
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.PP
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.BR getrusage ()
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returns resource usage measures for
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.IR who ,
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which can be one of the following:
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.TP
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.B RUSAGE_SELF
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Return resource usage statistics for the calling process,
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which is the sum of resources used by all threads in the process.
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.TP
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.B RUSAGE_CHILDREN
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Return resource usage statistics for all children of the
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calling process that have terminated and been waited for.
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These statistics will include the resources used by grandchildren,
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and further removed descendants,
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if all of the intervening descendants waited on their terminated children.
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.TP
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.BR RUSAGE_THREAD " (since Linux 2.6.26)"
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Return resource usage statistics for the calling thread.
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.PP
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The resource usages are returned in the structure pointed to by
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.IR usage ,
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which has the following form:
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.PP
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.in +4n
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.nf
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struct rusage {
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struct timeval ru_utime; /* user CPU time used */
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struct timeval ru_stime; /* system CPU time used */
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long ru_maxrss; /* maximum resident set size */
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long ru_ixrss; /* integral shared memory size */
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long ru_idrss; /* integral unshared data size */
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long ru_isrss; /* integral unshared stack size */
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long ru_minflt; /* page reclaims (soft page faults) */
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long ru_majflt; /* page faults (hard page faults) */
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long ru_nswap; /* swaps */
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long ru_inblock; /* block input operations */
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long ru_oublock; /* block output operations */
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long ru_msgsnd; /* IPC messages sent */
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long ru_msgrcv; /* IPC messages received */
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long ru_nsignals; /* signals received */
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long ru_nvcsw; /* voluntary context switches */
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long ru_nivcsw; /* involuntary context switches */
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};
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.fi
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.in
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.PP
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Not all fields are completed;
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unmaintained fields are set to zero by the kernel.
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(The unmaintained fields are provided for compatibility with other systems,
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and because they may one day be supported on Linux.)
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The fields are interpreted as follows:
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.TP
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.I ru_utime
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This is the total amount of time spent executing in user mode,
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expressed in a
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.I timeval
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structure (seconds plus microseconds).
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.TP
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.I ru_stime
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This is the total amount of time spent executing in kernel mode,
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expressed in a
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.I timeval
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structure (seconds plus microseconds).
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.TP
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.IR ru_maxrss " (since Linux 2.6.32)"
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This is the maximum resident set size used (in kilobytes).
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For
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.BR RUSAGE_CHILDREN ,
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this is the resident set size of the largest child, not the maximum
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resident set size of the process tree.
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.TP
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.IR ru_ixrss " (unmaintained)"
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This field is currently unused on Linux.
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.\" On some systems,
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.\" this is the integral of the text segment memory consumption,
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.\" expressed in kilobyte-seconds.
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.TP
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.IR ru_idrss " (unmaintained)"
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This field is currently unused on Linux.
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.\" On some systems, this is the integral of the data segment memory consumption,
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.\" expressed in kilobyte-seconds.
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.TP
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.IR ru_isrss " (unmaintained)"
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This field is currently unused on Linux.
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.\" On some systems, this is the integral of the stack memory consumption,
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.\" expressed in kilobyte-seconds.
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.TP
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.I ru_minflt
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The number of page faults serviced without any I/O activity; here
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I/O activity is avoided by \*(lqreclaiming\*(rq a page frame from
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the list of pages awaiting reallocation.
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.TP
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.I ru_majflt
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The number of page faults serviced that required I/O activity.
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.TP
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.IR ru_nswap " (unmaintained)"
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This field is currently unused on Linux.
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.\" On some systems, this is the number of swaps out of physical memory.
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.TP
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.IR ru_inblock " (since Linux 2.6.22)"
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The number of times the filesystem had to perform input.
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.TP
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.IR ru_oublock " (since Linux 2.6.22)"
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The number of times the filesystem had to perform output.
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.TP
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.IR ru_msgsnd " (unmaintained)"
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This field is currently unused on Linux.
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.\" On FreeBSD 6.2, this appears to measure messages sent over sockets
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.\" On some systems,
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.\" this field records the number of messages sent over sockets.
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.TP
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.IR ru_msgrcv " (unmaintained)"
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This field is currently unused on Linux.
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.\" On FreeBSD 6.2, this appears to measure messages received over sockets
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.\" On some systems,
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.\" this field records the number of messages received over sockets.
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.TP
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.IR ru_nsignals " (unmaintained)"
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This field is currently unused on Linux.
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.\" On some systems, this field records the number of signals received.
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.TP
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.IR ru_nvcsw " (since Linux 2.6)"
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The number of times a context switch resulted due to a process
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voluntarily giving up the processor before its time slice was
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completed (usually to await availability of a resource).
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.TP
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.IR ru_nivcsw " (since Linux 2.6)"
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The number of times a context switch resulted due to a higher
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priority process becoming runnable or because the current process
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exceeded its time slice.
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.PP
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.SH RETURN VALUE
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On success, zero is returned.
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On error, \-1 is returned, and
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.I errno
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is set appropriately.
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.SH ERRORS
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.TP
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.B EFAULT
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.I usage
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points outside the accessible address space.
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.TP
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.B EINVAL
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.I who
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is invalid.
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.SH CONFORMING TO
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SVr4, 4.3BSD.
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POSIX.1-2001 specifies
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.BR getrusage (),
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but specifies only the fields
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.I ru_utime
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and
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.IR ru_stime .
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.B RUSAGE_THREAD
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is Linux-specific.
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.SH NOTES
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Resource usage metrics are preserved across an
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.BR execve (2).
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Including
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.I <sys/time.h>
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is not required these days, but increases portability.
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(Indeed,
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.I struct timeval
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is defined in
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.IR <sys/time.h> .)
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.PP
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In Linux kernel versions before 2.6.9, if the disposition of
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.B SIGCHLD
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is set to
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.B SIG_IGN
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then the resource usages of child processes
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are automatically included in the value returned by
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.BR RUSAGE_CHILDREN ,
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although POSIX.1-2001 explicitly prohibits this.
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This nonconformance is rectified in Linux 2.6.9 and later.
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.\" See the description of getrusage() in XSH.
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.\" A similar statement was also in SUSv2.
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.LP
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The structure definition shown at the start of this page
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was taken from 4.3BSD Reno.
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Ancient systems provided a
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.BR vtimes ()
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function with a similar purpose to
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.BR getrusage ().
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For backward compatibility, glibc also provides
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.BR vtimes ().
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All new applications should be written using
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.BR getrusage ().
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See also the description of
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.IR /proc/PID/stat
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in
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.BR proc (5).
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.SH SEE ALSO
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.BR clock_gettime (2),
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.BR getrlimit (2),
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.BR times (2),
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.BR wait (2),
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.BR wait4 (2),
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.BR clock (3)
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