.\" to see what information could be imported from that file
.\" into this file.
.\"
-.TH PROC 5 2013-03-15 "Linux" "Linux Programmer's Manual"
+.TH PROC 5 2014-07-08 "Linux" "Linux Programmer's Manual"
.SH NAME
-proc \- process information pseudo-file system
+proc \- process information pseudo-filesystem
.SH DESCRIPTION
The
.I proc
-file system is a pseudo-file system which is used as an interface to
+filesystem is a pseudo-filesystem which provides an interface to
kernel data structures.
It is commonly mounted at
.IR /proc .
Most of it is read-only, but some files allow kernel variables to be
changed.
.LP
-The following outline gives a quick tour through the
+The following list describes many of the files and directories under the
.I /proc
hierarchy.
.PD 1
Each such subdirectory contains the following
pseudo-files and directories.
.\" FIXME Describe /proc/[pid]/attr and
-.\" /proc/[pid]/task/[tid]/attr
-.\" This is a directory
-.\" Added in ???
-.\" CONFIG_SECURITY
+.\" /proc/[pid]/task/[tid]/attr
+.\" This is a directory
+.\" Added in 2.6.0
+.\" CONFIG_SECURITY
+.\" https://lwn.net/Articles/28222/
+.\" http://www.nsa.gov/research/_files/selinux/papers/module/x362.shtml
+.\"
+.\" fscreate, current, prev, and exec present in Linux 2.6.0
+.\" keycreate added in Linux 2.6.18
+.\" commit 4eb582cf1fbd7b9e5f466e3718a59c957e75254e
+.\" /Documentation/keys.txt
+.\" sockcreate added in Linux 2.6.18
+.\" commit 42c3e03ef6b298813557cdb997bd6db619cd65a2
+.\"
+.\" FIXME Describe /proc/[pid]/autogroup
+.\" 2.6.38
+.\" commit 5091faa449ee0b7d73bc296a93bca9540fc51d0a
+.\" CONFIG_SCHED_AUTOGROUP
.\"
.TP
.IR /proc/[pid]/auxv " (since 2.6.0-test7)"
The format is one \fIunsigned long\fP ID
plus one \fIunsigned long\fP value for each entry.
The last entry contains two zeros.
+See also
+.BR getauxval (3).
.TP
.IR /proc/[pid]/cgroup " (since Linux 2.6.24)"
.\" Info in Documentation/cgroups/cgroups.txt
This file is present only if the
.B CONFIG_CGROUPS
kernel configuration option is enabled.
+.TP
+.IR /proc/[pid]/clear_refs " (since Linux 2.6.22)"
+.\" commit b813e931b4c8235bb42e301096ea97dbdee3e8fe (2.6.22)
+.\" commit 398499d5f3613c47f2143b8c54a04efb5d7a6da9 (2.6.32)
+.\" commit 040fa02077de01c7e08fa75be6125e4ca5636011 (3.11)
.\"
-.\" FIXME Describe /proc/[pid]/clear_refs
-.\" Added in 2.6.22
.\" "Clears page referenced bits shown in smaps output"
-.\" write-only
-.\" CONFIG_PROC_PAGE_MONITOR
+.\" write-only, writable only by the owner of the process
+
+This is a write-only file, writable only by owner of the process.
+
+The following values may be written to the file:
+.RS
+.TP
+1 (since Linux 2.6.22)
+.\" Internally: CLEAR_REFS_ALL
+Reset the PG_Referenced and ACCESSED/YOUNG
+bits for all the pages associated with the process.
+(Before kernel 2.6.32, writing any nonzero value to this file
+had this effect.)
+.TP
+2 (since Linux 2.6.32)
+.\" Internally: CLEAR_REFS_ANON
+Reset the PG_Referenced and ACCESSED/YOUNG
+bits for all anonymous pages associated with the process.
+.TP
+3 (since Linux 2.6.32)
+.\" Internally: CLEAR_REFS_MAPPED
+Reset the PG_Referenced and ACCESSED/YOUNG
+bits for all file-mapped pages associated with the process.
+.RE
+.IP
+Clearing the PG_Referenced and ACCESSED/YOUNG bits provides a method
+to measure approximately how much memory a process is using.
+One first inspects the values in the "Referenced" fields
+for the VMAs shown in
+.IR /proc/[pid]/smaps
+to get an idea of the memory footprint of the
+process.
+One then clears the PG_Referenced and ACCESSED/YOUNG bits
+and, after some measured time interval,
+once again inspects the values in the "Referenced" fields
+to get an idea of the change in memory footprint of the
+process during the measured interval.
+If one is interested only in inspecting the selected mapping types,
+then the value 2 or 3 can be used instead of 1.
+
+A further value can be written to affect a different bit:
+.RS
+.TP
+4 (since Linux 3.11)
+Clear the soft-dirty bit for all the pages associated with the process.
+.\" Internally: CLEAR_REFS_SOFT_DIRTY
+This is used (in conjunction with
+.IR /proc/[pid]/pagemap )
+by the check-point restore system to discover which pages of a process
+have been dirtied since the file
+.IR /proc/[pid]/clear_refs
+was written to.
+.RE
+.IP
+Writing any value to
+.IR /proc/[pid]/clear_refs
+other than those listed above has no effect.
+
+The
+.IR /proc/[pid]/clear_refs
+file is present only if the
+.B CONFIG_PROC_PAGE_MONITOR
+kernel configuration option is enabled.
.TP
.I /proc/[pid]/cmdline
-This holds the complete command line for the process,
+This read-only file holds the complete command line for the process,
unless the process is a zombie.
.\" In 2.3.26, this also used to be true if the process was swapped out.
In the latter case, there is nothing in this file:
strings separated by null bytes (\(aq\\0\(aq),
with a further null byte after the last string.
.TP
+.IR /proc/[pid]/comm " (since Linux 2.6.33)"
+.\" commit 4614a696bd1c3a9af3a08f0e5874830a85b889d4
+This file exposes the process's
+.I comm
+value\(emthat is, the command name associated with the process.
+Different threads in the same process may have different
+.I comm
+values, accessible via
+.IR /proc/[pid]/task/[tid]/comm .
+A thread may modify its
+.I comm
+value, or that of any of other thread in the same thread group (see
+the discussion of
+.B CLONE_THREAD
+in
+.BR clone (2)),
+by writing to the file
+.IR /proc/self/task/[tid]/comm .
+Strings longer than
+.B TASK_COMM_LEN
+(16) characters are silently truncated.
+
+This file provides a superset of the
+.BR prctl (2)
+.B PR_SET_NAME
+and
+.B PR_GET_NAME
+operations, and is employed by
+.BR pthread_setname_np (3)
+when used to rename threads other than the caller.
+.TP
.IR /proc/[pid]/coredump_filter " (since kernel 2.6.23)"
See
.BR core (5).
.TP
.IR /proc/[pid]/cpuset " (since kernel 2.6.12)"
-.\" and/proc/[pid]/task/[tid]/cpuset
+.\" and /proc/[pid]/task/[tid]/cpuset
See
.BR cpuset (7).
.TP
(typically by calling
.BR pthread_exit (3)).
-Under Linux 2.0 and earlier
+Under Linux 2.0 and earlier,
.I /proc/[pid]/exe
is a pointer to the binary which was executed,
and appears as a symbolic link.
.I \-inum
option can be used to locate the file.
.TP
-.I /proc/[pid]/fd
+.I /proc/[pid]/fd/
This is a subdirectory containing one entry for each file which the
process has open, named by its file descriptor, and which is a
symbolic link to the actual file.
-Thus, 0 is standard input, 1 standard output, 2 standard error, etc.
+Thus, 0 is standard input, 1 standard output, 2 standard error, and so on.
-.\" The following was still true as at kernel 2.6.13
+For file descriptors for pipes and sockets,
+the entries will be symbolic links whose content is the
+file type with the inode.
+A
+.BR readlink (2)
+call on this file returns a string in the format:
+
+ type:[inode]
+
+For example,
+.I socket:[2248868]
+will be a socket and its inode is 2248868.
+For sockets, that inode can be used to find more information
+in one of the files under
+.IR /proc/net/ .
+
+For file descriptors that have no corresponding inode
+(e.g., file descriptors produced by
+.BR epoll_create (2),
+.BR eventfd (2),
+.BR inotify_init (2),
+.BR signalfd (2),
+and
+.BR timerfd (2)),
+the entry will be a symbolic link with contents of the form
+
+ anon_inode:<file-type>
+
+In some cases, the
+.I file-type
+is surrounded by square brackets.
+
+For example, an epoll file descriptor will have a symbolic link
+whose content is the string
+.IR "anon_inode:[eventpoll]" .
+
+.\"The following was still true as at kernel 2.6.13
In a multithreaded process, the contents of this directory
are not available if the main thread has already terminated
(typically by calling
.BR open (2)).
The files in this directory are readable only by the owner of the process.
-.\" FIXME document /proc/[pid]/io
-.\" .TP
-.\" .IR /proc/[pid]/io " (since kernel 2.6.20)"
+.\" FIXME
+.\" Certain file types include additional info; see
+.\" Documentation/filesystems/proc.txt
+.\"
+.\" Especially interesting is this:
+.\"
+.\" commit ab49bdecc3ebb46ab661f5f05d5c5ea9606406c6
+.\" Author: Cyrill Gorcunov <gorcunov@openvz.org>
+.\" Date: Mon Dec 17 16:05:06 2012 -0800
+.\"
+.\" Basically, the /proc/PID/fdinfo/ entry for an inotify FD
+.\" includes the file handles for all watched FDs
+.\"
+.TP
+.IR /proc/[pid]/io " (since kernel 2.6.20)"
+.\" commit 7c3ab7381e79dfc7db14a67c6f4f3285664e1ec2
+This file contains I/O statistics for the process, for example:
+.in +4n
+.nf
+
+.RB "#" " cat /proc/3828/io"
+rchar: 323934931
+wchar: 323929600
+syscr: 632687
+syscw: 632675
+read_bytes: 0
+write_bytes: 323932160
+cancelled_write_bytes: 0
+.fi
+.in
+
+The fields are as follows:
+.RS
+.TP
+.IR rchar ": characters read"
+The number of bytes which this task has caused to be read from storage.
+This is simply the sum of bytes which this process passed to
+.BR read (2)
+and similar system calls.
+It includes things such as terminal I/O and
+is unaffected by whether or not actual
+physical disk I/O was required (the read might have been satisfied from
+pagecache).
+.TP
+.IR wchar ": characters written"
+The number of bytes which this task has caused, or shall cause to be written
+to disk.
+Similar caveats apply here as with
+.IR rchar .
+.TP
+.IR syscr ": read syscalls"
+Attempt to count the number of read I/O operations\(emthat is,
+system calls such as
+.BR read (2)
+and
+.BR pread (2).
+.TP
+.IR syscw ": write syscalls"
+Attempt to count the number of write I/O operations\(emthat is,
+system calls such as
+.BR write (2)
+and
+.BR pwrite (2).
+.TP
+.IR read_bytes ": bytes read"
+Attempt to count the number of bytes which this process really did cause to
+be fetched from the storage layer.
+This is accurate for block-backed filesystems.
+.TP
+.IR write_bytes ": bytes written"
+Attempt to count the number of bytes which this process caused to be sent to
+the storage layer.
+.TP
+.IR cancelled_write_bytes :
+The big inaccuracy here is truncate.
+If a process writes 1MB to a file and then deletes the file,
+it will in fact perform no writeout.
+But it will have been accounted as having caused 1MB of write.
+In other words: this field represents the number of bytes which this process
+caused to not happen, by truncating pagecache.
+A task can cause "negative" I/O too.
+If this task truncates some dirty pagecache,
+some I/O which another task has been accounted for
+(in its
+.IR write_bytes )
+will not be happening.
+.RE
+.IP
+.IR Note :
+In the current implementation, things are a bit racy on 32-bit systems:
+if process A reads process B's
+.I /proc/[pid]/io
+while process B is updating one of these 64-bit counters,
+process A could see an intermediate result.
.TP
.IR /proc/[pid]/limits " (since kernel 2.6.24)"
This file displays the soft limit, hard limit, and units of measurement
.\" commit 3036e7b490bf7878c6dae952eec5fb87b1106589
this file is readable by all users on the system.
.TP
+.IR /proc/[pid]/map_files/ " (since kernel 3.3)
+.\" commit 640708a2cff7f81e246243b0073c66e6ece7e53e
+This subdirectory contains entries corresponding to memory-mapped
+files (see
+.BR mmap (2)).
+Entries are named by memory region start and end
+address pair (expressed as hexadecimal numbers),
+and are symbolic links to the mapped files themselves.
+Here is an example, with the output wrapped and reformatted to fit on an 80-column display:
+.in +4n
+.nf
+
+.RB "$" " ls -l /proc/self/map_files/"
+lr\-\-\-\-\-\-\-\-. 1 root root 64 Apr 16 21:31
+ 3252e00000\-3252e20000 \-> /usr/lib64/ld-2.15.so
+\&...
+.fi
+.in
+
+Although these entries are present for memory regions that were
+mapped with the
+.BR MAP_FILE
+flag, the way anonymous shared memory (regions created with the
+.B MAP_ANON | MAP_SHARED
+flags)
+is implemented in Linux
+means that such regions also appear on this directory.
+Here is an example where the target file is the deleted
+.I /dev/zero
+one:
+.in +4n
+.nf
+
+.RB
+lrw\-\-\-\-\-\-\-. 1 root root 64 Apr 16 21:33
+ 7fc075d2f000\-7fc075e6f000 \-> /dev/zero (deleted)
+.fi
+.in
+
+This directory appears only if the
+.B CONFIG_CHECKPOINT_RESTORE
+kernel configuration option is enabled.
+.TP
.I /proc/[pid]/maps
A file containing the currently mapped memory regions and their access
permissions.
35b1800000-35b1820000 r-xp 00000000 08:02 135522 /usr/lib64/ld-2.15.so
35b1a1f000-35b1a20000 r--p 0001f000 08:02 135522 /usr/lib64/ld-2.15.so
35b1a20000-35b1a21000 rw-p 00020000 08:02 135522 /usr/lib64/ld-2.15.so
-35b1a21000-35b1a22000 rw-p 00000000 00:00 0
+35b1a21000-35b1a22000 rw-p 00000000 00:00 0
35b1c00000-35b1dac000 r-xp 00000000 08:02 135870 /usr/lib64/libc-2.15.so
35b1dac000-35b1fac000 ---p 001ac000 08:02 135870 /usr/lib64/libc-2.15.so
35b1fac000-35b1fb0000 r--p 001ac000 08:02 135870 /usr/lib64/libc-2.15.so
.fi
.in
-The
+The
.I address
field is the address space in the process that the mapping occupies.
The
.IR /proc/[pid]/task/[tid]/
path.
.TP
-.IR [vdso]
+.IR [vdso]
The virtual dynamically linked shared object.
.TP
-.IR [heap]
+.IR [heap]
The process's heap.
.in
-.fi
.RE
.IP
If the
.BR strace (1),
or similar.
-Under Linux 2.0 there is no field giving pathname.
+Under Linux 2.0, there is no field giving pathname.
.TP
.I /proc/[pid]/mem
This file can be used to access the pages of a process's memory through
(3)
major:minor: value of
.I st_dev
-for files on file system (see
+for files on filesystem (see
.BR stat (2)).
.TP
(4)
-root: root of the mount within the file system.
+root: root of the mount within the filesystem.
.TP
(5)
mount point: mount point relative to the process's root.
separator: marks the end of the optional fields.
.TP
(9)
-file system type: name of file system in the form "type[.subtype]".
+filesystem type: name of filesystem in the form "type[.subtype]".
.TP
(10)
-mount source: file system-specific information or "none".
+mount source: filesystem-specific information or "none".
.TP
(11)
-super options: per-super block options.
+super options: per-superblock options.
.RE
.IP
Parsers should ignore all unrecognized optional fields.
in the Linux kernel source tree.
.TP
.IR /proc/[pid]/mounts " (since Linux 2.4.19)"
-This is a list of all the file systems currently mounted in the
+This is a list of all the filesystems currently mounted in the
process's mount namespace.
The format of this file is documented in
.BR fstab (5).
Since kernel version 2.6.15, this file is pollable:
after opening the file for reading, a change in this file
-(i.e., a file system mount or unmount) causes
+(i.e., a filesystem mount or unmount) causes
.BR select (2)
to mark the file descriptor as readable, and
.BR poll (2)
(or "nodevice" if there is no corresponding device).
.TP
(2)
-The mount point within the file system tree.
+The mount point within the filesystem tree.
.TP
(3)
-The file system type.
+The filesystem type.
.TP
(4)
Optional statistics and configuration information.
-Currently (as at Linux 2.6.26), only NFS file systems export
+Currently (as at Linux 2.6.26), only NFS filesystems export
information via this field.
.RE
.IP
or
.IR /proc/[pid]/oom_adj
will change the other with its scaled value.
-.\" FIXME Describe /proc/[pid]/pagemap
-.\" Added in 2.6.25
-.\" CONFIG_PROC_PAGE_MONITOR
+.TP
+.IR /proc/[pid]/pagemap " (since Linux 2.6.25)"
+This file shows the mapping of each of the process's virtual pages
+into physical page frames or swap area.
+It contains one 64-bit value for each virtual page,
+with the bits set as follows:
+.RS 12
+.TP
+63
+If set, the page is present in RAM.
+.TP
+62
+If set, the page is in swap space
+.TP
+61 (since Linux 3.5)
+The page is a file-mapped page or a shared anonymous page.
+.TP
+60-56 (since Linux 3.11)
+Zero
+.\" Not quite true; see commit 541c237c0923f567c9c4cabb8a81635baadc713f
+.TP
+55 (Since Linux 3.11)
+PTE is soft-dirty
+(see the kernel source file
+.IR Documentation/vm/soft-dirty.txt ).
+.TP
+54-0
+If the page is present in RAM (bit 63), then these bits
+provide the page frame number, which can be used to index
+.IR /proc/kpageflags
+and
+.IR /proc/kpagecount .
+If the page is present in swap (bit 62),
+then bits 4-0 give the swap type, and bits 54-5 encode the swap offset.
+.RE
+.IP
+Before Linux 3.11, bits 60-55 were
+used to encode the base-2 log of the page size.
+.IP
+To employ
+.IR /proc/[pid]/pagemap
+efficiently, use
+.IR /proc/[pid]/maps
+to determine which areas of memory are actually mapped and seek
+to skip over unmapped regions.
+.IP
+The
+.IR /proc/[pid]/pagemap
+file is present only if the
+.B CONFIG_PROC_PAGE_MONITOR
+kernel configuration option is enabled.
+.TP
+.IR /proc/[pid]/personality " (since Linux 2.6.28)"
+.\" commit 478307230810d7e2a753ed220db9066dfdf88718
+This read-only file exposes the process's execution domain, as set by
+.BR personality (2).
+The value is displayed in hexadecimal notation.
.TP
.I /proc/[pid]/root
UNIX and Linux support the idea of a per-process root of the
-file system, set by the
+filesystem, set by the
.BR chroot (2)
system call.
This file is a symbolic link that points to the process's
-root directory, and behaves as exe, fd/*, etc. do.
+root directory, and behaves in the same way as
+.IR exe ,
+and
+.IR fd/* .
.\" The following was still true as at kernel 2.6.13
In a multithreaded process, the contents of this symbolic link
.\" Added in 2.6.12
.\" FIXME Describe /proc/[pid]/sessionid
.\" Added in 2.6.25; read-only; only readable by real UID
+.\" commit 1e0bd7550ea9cf474b1ad4c6ff5729a507f75fdc
.\" CONFIG_AUDITSYSCALL
.\" FIXME Describe /proc/[pid]/sched
.\" Added in 2.6.23
.\" CONFIG_SCHED_DEBUG, and additional fields if CONFIG_SCHEDSTATS
.\" Displays various scheduling parameters
.\" This file can be written, to reset stats
+.\" The set of fields exposed by this file have changed
+.\" significantly over time.
+.\" commit 43ae34cb4cd650d1eb4460a8253a8e747ba052ac
+.\"
.\" FIXME Describe /proc/[pid]/schedstats and
.\" /proc/[pid]/task/[tid]/schedstats
.\" Added in 2.6.9
.\" CONFIG_SCHEDSTATS
.TP
.IR /proc/[pid]/smaps " (since Linux 2.6.14)"
-.\" CONFIG_PROC_PAGE_MONITOR
This file shows memory consumption for each of the process's mappings.
-For each of mappings there is a series of lines such as the following:
+For each mapping there is a series of lines such as the following:
.in +4n
.nf
-08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
-Size: 464 kB
-Rss: 424 kB
-Shared_Clean: 424 kB
-Shared_Dirty: 0 kB
-Private_Clean: 0 kB
-Private_Dirty: 0 kB
+00400000-0048a000 r-xp 00000000 fd:03 960637 /bin/bash
+Size: 552 kB
+Rss: 460 kB
+Pss: 100 kB
+Shared_Clean: 452 kB
+Shared_Dirty: 0 kB
+Private_Clean: 8 kB
+Private_Dirty: 0 kB
+Referenced: 460 kB
+Anonymous: 0 kB
+AnonHugePages: 0 kB
+Swap: 0 kB
+KernelPageSize: 4 kB
+MMUPageSize: 4 kB
+Locked: 0 kB
.fi
.in
for the mapping in
.IR /proc/[pid]/maps .
The remaining lines show the size of the mapping,
-the amount of the mapping that is currently resident in RAM,
+the amount of the mapping that is currently resident in RAM ("Rss"),
+the process' proportional share of this mapping ("Pss"),
the number of clean and dirty shared pages in the mapping,
and the number of clean and dirty private pages in the mapping.
+"Referenced" indicates the amount of memory currently marked as
+referenced or accessed.
+"Anonymous" shows the amount of memory
+that does not belong to any file.
+"Swap" shows how much
+would-be-anonymous memory is also used, but out on swap.
-This file is present only if the
-.B CONFIG_MMU
-kernel configuration
-option is enabled.
+The "KernelPageSize" entry is the page size used by the kernel to back a VMA.
+This matches the size used by the MMU in the majority of cases.
+However, one counter-example occurs on PPC64 kernels
+whereby a kernel using 64K as a base page size may still use 4K
+pages for the MMU on older processors.
+To distinguish, this
+patch reports "MMUPageSize" as the page size used by the MMU.
+
+The "Locked" indicates whether the mapping is locked in memory
+or not.
+
+"VmFlags" field represents the kernel flags associated with
+the particular virtual memory area in two letter encoded manner.
+The codes are the following:
+
+ rd - readable
+ wr - writable
+ ex - executable
+ sh - shared
+ mr - may read
+ mw - may write
+ me - may execute
+ ms - may share
+ gd - stack segment grows down
+ pf - pure PFN range
+ dw - disabled write to the mapped file
+ lo - pages are locked in memory
+ io - memory mapped I/O area
+ sr - sequential read advise provided
+ rr - random read advise provided
+ dc - do not copy area on fork
+ de - do not expand area on remapping
+ ac - area is accountable
+ nr - swap space is not reserved for the area
+ ht - area uses huge tlb pages
+ nl - non-linear mapping
+ ar - architecture specific flag
+ dd - do not include area into core dump
+ sd - soft-dirty flag
+ mm - mixed map area
+ hg - huge page advise flag
+ nh - no-huge page advise flag
+ mg - mergeable advise flag
+
+The
+.IR /proc/[pid]/smaps
+file is present only if the
+.B CONFIG_PROC_PAGE_MONITOR
+kernel configuration option is enabled.
+.TP
+.IR /proc/[pid]/stack " (since Linux 2.6.29)"
+.\" 2ec220e27f5040aec1e88901c1b6ea3d135787ad
+This file provides a symbolic trace of the function calls in this
+process's kernel stack.
+This file is provided only if the kernel was built with the
+.B CONFIG_STACKTRACE
+configuration option.
.TP
.I /proc/[pid]/stat
Status information about the process.
This is used by
.BR ps (1).
-It is defined in
-.IR /usr/src/linux/fs/proc/array.c "."
+It is defined in the kernel source file
+.IR fs/proc/array.c "."
The fields, in order, with their proper
.BR scanf (3)
format specifiers, are:
.RS
-.TP 12
-\fIpid\fP %d
-(1) The process ID.
+.TP 10
+(1) \fIpid\fP \ %d
+.br
+The process ID.
.TP
-\fIcomm\fP %s
-(2) The filename of the executable, in parentheses.
+(2) \fIcomm\fP \ %s
+The filename of the executable, in parentheses.
This is visible whether or not the executable is swapped out.
.TP
-\fIstate\fP %c
-(3) One character from the string "RSDZTW" where R is running, S is
-sleeping in an interruptible wait, D is waiting in uninterruptible
-disk sleep, Z is zombie, T is traced or stopped (on a signal),
-and W is paging.
+(3) \fIstate\fP \ %c
+One of the following characters, indicating process state:
+.RS
+.IP R 3
+Running
+.IP S
+Sleeping in an interruptible wait
+.IP D
+Waiting in uninterruptible
+disk sleep
+.IP Z
+Zombie
+.IP T
+Stopped (on a signal) or (before Linux 2.6.33) trace stopped
+.IP t
+.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29
+Tracing stop (Linux 2.6.33 onward)
+.IP W
+Paging (only before Linux 2.6.0)
+.IP X
+Dead (from Linux 2.6.0 onward)
+.IP x
+.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29
+Dead (Linux 2.6.33 to
+.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457
+3.13 only)
+.IP K
+.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29
+Wakekill (Linux 2.6.33 to
+.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457
+3.13 only)
+.IP W
+.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29
+Waking (Linux 2.6.33 to
+.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457
+3.13 only)
+.IP P
+.\" commit f2530dc71cf0822f90bb63ea4600caaef33a66bb
+Parked (Linux 3.9 to
+.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457
+3.13 only)
+.RE
.TP
-\fIppid\fP %d
-(4) The PID of the parent.
+(4) \fIppid\fP \ %d
+The PID of the parent of this process.
.TP
-\fIpgrp\fP %d
-(5) The process group ID of the process.
+(5) \fIpgrp\fP \ %d
+The process group ID of the process.
.TP
-\fIsession\fP %d
-(6) The session ID of the process.
+(6) \fIsession\fP \ %d
+The session ID of the process.
.TP
-\fItty_nr\fP %d
-(7) The controlling terminal of the process.
+(7) \fItty_nr\fP \ %d
+The controlling terminal of the process.
(The minor device number is contained in the combination of bits
31 to 20 and 7 to 0;
the major device number is in bits 15 to 8.)
.TP
-\fItpgid\fP %d
+(8) \fItpgid\fP \ %d
.\" This field and following, up to and including wchan added 0.99.1
-(8) The ID of the foreground process group of the controlling
+The ID of the foreground process group of the controlling
terminal of the process.
.TP
-\fIflags\fP %u (%lu before Linux 2.6.22)
-(9) The kernel flags word of the process.
+(9) \fIflags\fP \ %u
+The kernel flags word of the process.
For bit meanings,
see the PF_* defines in the Linux kernel source file
.IR include/linux/sched.h .
Details depend on the kernel version.
+
+The format for this field was %lu before Linux 2.6.
.TP
-\fIminflt\fP %lu
-(10) The number of minor faults the process has made which have not
+(1) \fIminflt\fP \ %lu
+The number of minor faults the process has made which have not
required loading a memory page from disk.
.TP
-.\" field 11
-\fIcminflt\fP %lu
-(11) The number of minor faults that the process's
+(11) \fIcminflt\fP \ %lu
+The number of minor faults that the process's
waited-for children have made.
.TP
-\fImajflt\fP %lu
-(12) The number of major faults the process has made which have
+(12) \fImajflt\fP \ %lu
+The number of major faults the process has made which have
required loading a memory page from disk.
.TP
-\fIcmajflt\fP %lu
-(13) The number of major faults that the process's
+(13) \fIcmajflt\fP \ %lu
+The number of major faults that the process's
waited-for children have made.
.TP
-\fIutime\fP %lu
-(14) Amount of time that this process has been scheduled in user mode,
+(14) \fIutime\fP \ %lu
+Amount of time that this process has been scheduled in user mode,
measured in clock ticks (divide by
.IR sysconf(_SC_CLK_TCK) ).
This includes guest time, \fIguest_time\fP
so that applications that are not aware of the guest time field
do not lose that time from their calculations.
.TP
-\fIstime\fP %lu
-(15) Amount of time that this process has been scheduled in kernel mode,
+(15) \fIstime\fP \ %lu
+Amount of time that this process has been scheduled in kernel mode,
measured in clock ticks (divide by
.IR sysconf(_SC_CLK_TCK) ).
.TP
-\fIcutime\fP %ld
-(16) Amount of time that this process's
+(16) \fIcutime\fP \ %ld
+Amount of time that this process's
waited-for children have been scheduled in user mode,
measured in clock ticks (divide by
.IR sysconf(_SC_CLK_TCK) ).
This includes guest time, \fIcguest_time\fP
(time spent running a virtual CPU, see below).
.TP
-\fIcstime\fP %ld
-(17) Amount of time that this process's
+(17) \fIcstime\fP \ %ld
+Amount of time that this process's
waited-for children have been scheduled in kernel mode,
measured in clock ticks (divide by
.IR sysconf(_SC_CLK_TCK) ).
.TP
-\fIpriority\fP %ld
-(18) (Explanation for Linux 2.6)
+(18) \fIpriority\fP \ %ld
+(Explanation for Linux 2.6)
For processes running a real-time scheduling policy
.RI ( policy
below; see
the scheduler weighting given to this process.
.\" And back in kernel 1.2 days things were different again.
.TP
-\fInice\fP %ld
-(19) The nice value (see
+(19) \fInice\fP \ %ld
+The nice value (see
.BR setpriority (2)),
a value in the range 19 (low priority) to \-20 (high priority).
.\" Back in kernel 1.2 days things were different.
.\" The time in jiffies of the process's next timeout.
.\" timeout was removed sometime around 2.1/2.2
.TP
-\fInum_threads\fP %ld
-(20) Number of threads in this process (since Linux 2.6).
+(20) \fInum_threads\fP \ %ld
+Number of threads in this process (since Linux 2.6).
Before kernel 2.6, this field was hard coded to 0 as a placeholder
for an earlier removed field.
.TP
-.\" field 21
-\fIitrealvalue\fP %ld
-(21) The time in jiffies before the next
+(21) \fIitrealvalue\fP \ %ld
+The time in jiffies before the next
.B SIGALRM
is sent to the process due to an interval timer.
Since kernel 2.6.17, this field is no longer maintained,
and is hard coded as 0.
.TP
-\fIstarttime\fP %llu (was %lu before Linux 2.6)
-(22) The time the process started after system boot.
+(22) \fIstarttime\fP \ %llu
+The time the process started after system boot.
In kernels before Linux 2.6, this value was expressed in jiffies.
Since Linux 2.6, the value is expressed in clock ticks (divide by
.IR sysconf(_SC_CLK_TCK) ).
+
+The format for this field was %lu before Linux 2.6.
.TP
-\fIvsize\fP %lu
-(23) Virtual memory size in bytes.
+(23) \fIvsize\fP \ %lu
+Virtual memory size in bytes.
.TP
-\fIrss\fP %ld
-(24) Resident Set Size: number of pages the process has in real memory.
+(24) \fIrss\fP \ %ld
+Resident Set Size: number of pages the process has in real memory.
This is just the pages which
count toward text, data, or stack space.
This does not include pages
which have not been demand-loaded in, or which are swapped out.
.TP
-\fIrsslim\fP %lu
-(25) Current soft limit in bytes on the rss of the process;
+(25) \fIrsslim\fP \ %lu
+Current soft limit in bytes on the rss of the process;
see the description of
.B RLIMIT_RSS
in
.BR getrlimit (2).
.TP
-\fIstartcode\fP %lu
-(26) The address above which program text can run.
+(26) \fIstartcode\fP \ %lu
+The address above which program text can run.
.TP
-\fIendcode\fP %lu
-(27) The address below which program text can run.
+(27) \fIendcode\fP \ %lu
+The address below which program text can run.
.TP
-\fIstartstack\fP %lu
-(28) The address of the start (i.e., bottom) of the stack.
+(28) \fIstartstack\fP \ %lu
+The address of the start (i.e., bottom) of the stack.
.TP
-\fIkstkesp\fP %lu
-(29) The current value of ESP (stack pointer), as found in the
+(29) \fIkstkesp\fP \ %lu
+The current value of ESP (stack pointer), as found in the
kernel stack page for the process.
.TP
-\fIkstkeip\fP %lu
-(30) The current EIP (instruction pointer).
+(30) \fIkstkeip\fP \ %lu
+The current EIP (instruction pointer).
.TP
-.\" field 31
-\fIsignal\fP %lu
-(31) The bitmap of pending signals, displayed as a decimal number.
+(31) \fIsignal\fP \ %lu
+The bitmap of pending signals, displayed as a decimal number.
Obsolete, because it does not provide information on real-time signals; use
.I /proc/[pid]/status
instead.
.TP
-\fIblocked\fP %lu
-(32) The bitmap of blocked signals, displayed as a decimal number.
+(32) \fIblocked\fP \ %lu
+The bitmap of blocked signals, displayed as a decimal number.
Obsolete, because it does not provide information on real-time signals; use
.I /proc/[pid]/status
instead.
.TP
-\fIsigignore\fP %lu
-(33) The bitmap of ignored signals, displayed as a decimal number.
+(33) \fIsigignore\fP \ %lu
+The bitmap of ignored signals, displayed as a decimal number.
Obsolete, because it does not provide information on real-time signals; use
.I /proc/[pid]/status
instead.
.TP
-\fIsigcatch\fP %lu
-(34) The bitmap of caught signals, displayed as a decimal number.
+(34) \fIsigcatch\fP \ %lu
+The bitmap of caught signals, displayed as a decimal number.
Obsolete, because it does not provide information on real-time signals; use
.I /proc/[pid]/status
instead.
.TP
-\fIwchan\fP %lu
-(35) This is the "channel" in which the process is waiting.
-It is the
-address of a system call, and can be looked up in a namelist if you
-need a textual name.
-(If you have an up-to-date
-.IR /etc/psdatabase ,
-then
-try \fIps \-l\fP to see the WCHAN field in action.)
-.TP
-\fInswap\fP %lu
-(36)
+(35) \fIwchan\fP \ %lu
+This is the "channel" in which the process is waiting.
+It is the address of a location in the kernel where the process is sleeping.
+The corresponding symbolic name can be found in
+.IR /proc/[pid]/wchan .
+.TP
+(36) \fInswap\fP \ %lu
.\" nswap was added in 2.0
Number of pages swapped (not maintained).
.TP
-\fIcnswap\fP %lu
-(37)
+(37) \fIcnswap\fP \ %lu
.\" cnswap was added in 2.0
Cumulative \fInswap\fP for child processes (not maintained).
.TP
-\fIexit_signal\fP %d (since Linux 2.1.22)
-(38) Signal to be sent to parent when we die.
+(38) \fIexit_signal\fP \ %d \ (since Linux 2.1.22)
+Signal to be sent to parent when we die.
.TP
-\fIprocessor\fP %d (since Linux 2.2.8)
-(39) CPU number last executed on.
+(39) \fIprocessor\fP \ %d \ (since Linux 2.2.8)
+CPU number last executed on.
.TP
-\fIrt_priority\fP %u (since Linux 2.5.19; was %lu before Linux 2.6.22)
-(40) Real-time scheduling priority, a number in the range 1 to 99 for
+(40) \fIrt_priority\fP \ %u \ (since Linux 2.5.19)
+Real-time scheduling priority, a number in the range 1 to 99 for
processes scheduled under a real-time policy,
or 0, for non-real-time processes (see
.BR sched_setscheduler (2)).
.TP
-.\" field 41
-\fIpolicy\fP %u (since Linux 2.5.19; was %lu before Linux 2.6.22)
-(41) Scheduling policy (see
+(41) \fIpolicy\fP \ %u \ (since Linux 2.5.19)
+Scheduling policy (see
.BR sched_setscheduler (2)).
Decode using the SCHED_* constants in
.IR linux/sched.h .
+
+The format for this field was %lu before Linux 2.6.22.
.TP
-\fIdelayacct_blkio_ticks\fP %llu (since Linux 2.6.18)
-(42) Aggregated block I/O delays, measured in clock ticks (centiseconds).
+(42) \fIdelayacct_blkio_ticks\fP \ %llu \ (since Linux 2.6.18)
+Aggregated block I/O delays, measured in clock ticks (centiseconds).
.TP
-\fIguest_time\fP %lu (since Linux 2.6.24)
-(43) Guest time of the process (time spent running a virtual CPU
+(43) \fIguest_time\fP \ %lu \ (since Linux 2.6.24)
+Guest time of the process (time spent running a virtual CPU
for a guest operating system), measured in clock ticks (divide by
.IR sysconf(_SC_CLK_TCK) ).
.TP
-\fIcguest_time\fP %ld (since Linux 2.6.24)
-(44) Guest time of the process's children, measured in clock ticks (divide by
+(44) \fIcguest_time\fP \ %ld \ (since Linux 2.6.24)
+Guest time of the process's children, measured in clock ticks (divide by
.IR sysconf(_SC_CLK_TCK) ).
+.TP
+(45) \fIstart_data\fP \ %lu \ (since Linux 3.3)
+.\" commit b3f7f573a20081910e34e99cbc91831f4f02f1ff
+Address above which program initialized and
+uninitialized (BSS) data are placed.
+.TP
+(46) \fIend_data\fP \ %lu \ (since Linux 3.3)
+.\" commit b3f7f573a20081910e34e99cbc91831f4f02f1ff
+Address below which program initialized and
+uninitialized (BSS) data are placed.
+.TP
+(47) \fIstart_brk\fP \ %lu \ (since Linux 3.3)
+.\" commit b3f7f573a20081910e34e99cbc91831f4f02f1ff
+Address above which program heap can be expanded with
+.BR brk (2).
+.TP
+(48) \fIarg_start\fP \ %lu \ (since Linux 3.5)
+.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3
+Address above which program command-line arguments
+.RI ( argv )
+are placed.
+.TP
+(49) \fIarg_end\fP \ %lu \ (since Linux 3.5)
+.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3
+Address below program command-line arguments
+.RI ( argv )
+are placed.
+.TP
+(50) \fIenv_start\fP \ %lu \ (since Linux 3.5)
+.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3
+Address above which program environment is placed.
+.TP
+(51) \fIenv_end\fP \ %lu \ (since Linux 3.5)
+.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3
+Address below which program environment is placed.
+.TP
+(52) \fIexit_code\fP \ %d \ (since Linux 3.5)
+.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3
+The thread's exit status in the form reported by
+.BR waitpid (2).
.RE
.TP
.I /proc/[pid]/statm
PID of process tracing this process (0 if not being traced).
.IP *
.IR Uid ", " Gid :
-Real, effective, saved set, and file system UIDs (GIDs).
+Real, effective, saved set, and filesystem UIDs (GIDs).
.IP *
.IR FDSize :
Number of file descriptor slots currently allocated.
(since Linux 2.6.26, see
.BR cpuset (7)).
.IP *
-.IR voluntary_context_switches ", " nonvoluntary_context_switches :
+.IR voluntary_ctxt_switches ", " nonvoluntary_ctxt_switches :
Number of voluntary and involuntary context switches (since Linux 2.6.23).
.RE
.TP
+.IR /proc/[pid]/syscall " (since Linux 2.6.27)"
+.\" commit ebcb67341fee34061430f3367f2e507e52ee051b
+This file exposes the system call number and argument registers for the
+system call currently being executed by the process,
+followed by the values of the stack pointer and program counter registers.
+The values of all six argument registers are exposed,
+although most system calls use fewer registers.
+
+If the process is blocked, but not in a system call,
+then the file displays -1 in place of the system call number,
+followed by just the values of the stack pointer and program counter.
+If process is not blocked, then file contains just the string "running".
+
+This file is present only if the kernel was configured with
+.BR CONFIG_HAVE_ARCH_TRACEHOOK .
+.TP
.IR /proc/[pid]/task " (since Linux 2.6.0-test6)"
This is a directory that contains one subdirectory
for each thread in the process.
(typically by calling
.BR pthread_exit (3)).
.TP
+.IR /proc/[pid]/wchan " (since Linux 2.6.0)"
+The symbolic name corresponding to the location
+in the kernel where the process is sleeping.
+.TP
.I /proc/apm
Advanced power management version and battery information when
.B CONFIG_APM
.B CONFIG_PCMCIA
is set at kernel compilation time.
.TP
+.IR /proc/[pid]/timers " (since Linux 3.10)"
+.\" commit 5ed67f05f66c41e39880a6d61358438a25f9fee5
+.\" commit 48f6a7a511ef8823fdff39afee0320092d43a8a0
+A list of the POSIX timers for this process.
+Each timer is listed with a line that started with the string "ID:".
+For example:
+
+.in +4n
+.nf
+ID: 1
+signal: 60/00007fff86e452a8
+notify: signal/pid.2634
+ClockID: 0
+ID: 0
+signal: 60/00007fff86e452a8
+notify: signal/pid.2634
+ClockID: 1
+.fi
+.in
+
+The lines shown for each timer have the following meanings:
+.RS
+.TP
+.I ID
+The ID for this timer.
+This is not the same as the timer ID returned by
+.BR timer_create (2);
+rather, it is the same kernel-internal ID that is available via the
+.I si_timerid
+field of the
+.IR siginfo_t
+structure (see
+.BR sigaction (2)).
+.TP
+.I signal
+This is the signal number that this timer uses to deliver notifications
+followed by a slash, and then the
+.I sigev_value.sival_ptr
+value supplied to the signal handler.
+Valid only for timers that notify via a signal.
+.TP
+.I notify
+The part before the slash specifies the mechanism
+that this timer uses to deliver notifications,
+and is one of "thread", "signal", or "none".
+Immediately following the slash is either the string "tid" for timers
+with
+.B SIGEV_THREAD_ID
+notification, or "pid" for timers that notify by other mechanisms.
+Following the "." is the PID of the process that will be delivered
+a signal if the timer delivers notifications via a signal.
+.TP
+.I ClockID
+This field identifies the clock that the timer uses for measuring time.
+For most clocks, this is a number that matches one of the user-space
+.BR CLOCK_*
+constants exposed via
+.IR <time.h> .
+.B CLOCK_PROCESS_CPUTIME_ID
+timers display with a value of -6
+in this field.
+.B CLOCK_THREAD_CPUTIME_ID
+timers display with a value of -2
+in this field.
+.RE
+.TP
.I /proc/bus/pccard/drivers
.TP
.I /proc/bus/pci
.IR "make config" ,
or similar).
The file contents are compressed; view or search them using
-.BR zcat (1),
-.BR zgrep (1),
-etc.
+.BR zcat (1)
+and
+.BR zgrep (1).
As long as no changes have been made to the following file,
the contents of
.I /proc/config.gz
is defined during kernel compilation.
.TP
.I /proc/filesystems
-A text listing of the file systems which are supported by the kernel,
-namely file systems which were compiled into the kernel or whose kernel
+A text listing of the filesystems which are supported by the kernel,
+namely filesystems which were compiled into the kernel or whose kernel
modules are currently loaded.
(See also
.BR filesystems (5).)
-If a file system is marked with "nodev",
+If a filesystem is marked with "nodev",
this means that it does not require a block device to be mounted
-(e.g., virtual file system, network file system).
+(e.g., virtual filesystem, network filesystem).
Incidentally, this file may be used by
.BR mount (8)
-when no file system is specified and it didn't manage to determine the
-file system type.
-Then file systems contained in this file are tried
+when no filesystem is specified and it didn't manage to determine the
+filesystem type.
+Then filesystems contained in this file are tried
(excepted those that are marked with "nodev").
.TP
.I /proc/fs
-Empty subdirectory.
+.\" FIXME Much more needs to be said about /proc/fs
+.\"
+Contains subdirectories that in turn contain files
+with information about (certain) mounted filesystems.
.TP
.I /proc/ide
This directory
.BR dmesg (1)
program.
.TP
+.IR /proc/kpagecount " (since Linux 2.6.25)"
+This file contains a 64-bit count of the number of
+times each physical page frame is mapped,
+indexed by page frame number (see the discussion of
+.IR /proc/[pid]/pagemap ).
+.IP
+The
+.IR /proc/kpagecount
+file is present only if the
+.B CONFIG_PROC_PAGE_MONITOR
+kernel configuration option is enabled.
+.TP
+.IR /proc/kpageflags " (since Linux 2.6.25)"
+This file contains 64-bit masks corresponding to each physical page frame;
+it is indexed by page frame number (see the discussion of
+.IR /proc/[pid]/pagemap ).
+The bits are as follows:
+
+ 0 - KPF_LOCKED
+ 1 - KPF_ERROR
+ 2 - KPF_REFERENCED
+ 3 - KPF_UPTODATE
+ 4 - KPF_DIRTY
+ 5 - KPF_LRU
+ 6 - KPF_ACTIVE
+ 7 - KPF_SLAB
+ 8 - KPF_WRITEBACK
+ 9 - KPF_RECLAIM
+ 10 - KPF_BUDDY
+ 11 - KPF_MMAP (since Linux 2.6.31)
+ 12 - KPF_ANON (since Linux 2.6.31)
+ 13 - KPF_SWAPCACHE (since Linux 2.6.31)
+ 14 - KPF_SWAPBACKED (since Linux 2.6.31)
+ 15 - KPF_COMPOUND_HEAD (since Linux 2.6.31)
+ 16 - KPF_COMPOUND_TAIL (since Linux 2.6.31)
+ 16 - KPF_HUGE (since Linux 2.6.31)
+ 18 - KPF_UNEVICTABLE (since Linux 2.6.31)
+ 19 - KPF_HWPOISON (since Linux 2.6.31)
+ 20 - KPF_NOPAGE (since Linux 2.6.31)
+ 21 - KPF_KSM (since Linux 2.6.32)
+ 22 - KPF_THP (since Linux 3.4)
+
+For further details on the meanings of these bits,
+see the kernel source file
+.IR Documentation/vm/pagemap.txt .
+Before kernel 2.6.29,
+.\" commit ad3bdefe877afb47480418fdb05ecd42842de65e
+.\" commit e07a4b9217d1e97d2f3a62b6b070efdc61212110
+.BR KPF_WRITEBACK ,
+.BR KPF_RECLAIM ,
+.BR KPF_BUDDY ,
+and
+.BR KPF_LOCKED
+did not report correctly.
+.IP
+The
+.IR /proc/kpageflags
+file is present only if the
+.B CONFIG_PROC_PAGE_MONITOR
+kernel configuration option is enabled.
+.TP
.IR /proc/ksyms " (Linux 1.1.23-2.5.47)"
See
.IR /proc/kallsyms .
the format specifier required to read the field value.
Except as noted below,
all of the fields have been present since at least Linux 2.6.0.
-Some fileds are displayed only if the kernel was configured
+Some fields are displayed only if the kernel was configured
with various options; those dependencies are noted in the list.
.RS
.TP
.IR MemTotal " %lu"
-Total usable RAM (i.e. physical RAM minus a few reserved
+Total usable RAM (i.e., physical RAM minus a few reserved
bits and the kernel binary code).
.TP
.IR MemFree " %lu"
Non-file backed pages mapped into user-space page tables.
.TP
.IR Mapped " %lu"
-Files which have been mmaped, such as libraries.
+Files which have been mapped into memory (with
+.BR mmap (2)),
+such as libraries.
.TP
.IR Shmem " %lu (since Linux 2.6.32)"
[To be documented.]
Memory used by FUSE for temporary writeback buffers.
.TP
.IR CommitLimit " %lu (since Linux 2.6.10)"
-Based on the overcommit ratio ('vm.overcommit_ratio'),
-this is the total amount of memory currently available to
-be allocated on the system.
+This is the total amount of memory currently available to
+be allocated on the system, expressed in kilobytes.
This limit is adhered to
only if strict overcommit accounting is enabled (mode 2 in
-.IR /proc/sys/vm/overcommit_ratio ).
-The
-.I CommitLimit
-is calculated using the following formula:
-
- CommitLimit = (overcommit_ratio * Physical RAM) + Swap
-
-For example, on a system with 1GB of physical RAM and 7GB
-of swap with a
-.I overcommit_ratio
-of 30, this formula yields a
-.I CommitLimit
-of 7.3GB.
-For more details, see the memory overcommit documentation
-in the kernel source file
+.IR /proc/sys/vm/overcommit_memory ).
+The limit is calculated according to the formula described under
+.IR /proc/sys/vm/overcommit_memory .
+For further details, see the kernel source file
.IR Documentation/vm/overcommit-accounting .
.TP
.IR Committed_AS " %lu"
or similar), but touches only 300MB of that memory will show up
as using only 300MB of memory even if it has the address space
allocated for the entire 1GB.
+
This 1GB is memory which has been "committed" to by the VM
and can be used at any time by the allocating application.
-With strict overcommit enabled on the system (mode 2
-.IR /proc/sys/vm/overcommit_memory ),
+With strict overcommit enabled on the system (mode 2 in
+IR /proc/sys/vm/overcommit_memory ),
allocations which would exceed the
.I CommitLimit
-(detailed above) will not be permitted.
+will not be permitted.
This is useful if one needs to guarantee that processes will not
fail due to lack of memory once that memory has been successfully allocated.
.TP
.TP
.I /proc/mounts
Before kernel 2.4.19, this file was a list
-of all the file systems currently mounted on the system.
+of all the filesystems currently mounted on the system.
With the introduction of per-process mount namespaces in
Linux 2.4.19, this file became a link to
.IR /proc/self/mounts ,
socket and Path is the bound path (if any) of the socket.
.TP
.I /proc/partitions
-Contains major and minor numbers of each partition as well as number
-of blocks and partition name.
+Contains the major and minor numbers of each partition as well as the number
+of 1024-byte blocks and the partition name.
.TP
.I /proc/pci
This is a listing of all PCI devices found during kernel initialization
initialization.
Reading these files will usually show driver and host configuration,
-statistics, etc.
+statistics, and so on.
Writing to these files allows different things on different hosts.
For example, with the \fIlatency\fP and \fInolatency\fP commands,
.I /proc/self
This directory refers to the process accessing the
.I /proc
-file system,
+filesystem,
and is identical to the
.I /proc
directory named by the process ID of the same process.
\fIintr 1462898\fP
This line shows counts of interrupts serviced since boot time,
for each of the possible system interrupts.
-The first column is the total of all interrupts serviced;
-each subsequent column is the total for a particular interrupt.
+The first column is the total of all interrupts serviced
+including unnumbered architecture specific interrupts;
+each subsequent column is the total for that particular numbered interrupt.
+Unnumbered interrupts are not shown, only summed into the total.
.TP
\fIdisk_io: (2,0):(31,30,5764,1,2) (3,0):\fP...
(major,disk_idx):(noinfo, read_io_ops, blks_read, write_io_ops, blks_written)
This directory (present since 1.3.57) contains a number of files
and subdirectories corresponding to kernel variables.
These variables can be read and sometimes modified using
-the \fI/proc\fP file system, and the (deprecated)
+the \fI/proc\fP filesystem, and the (deprecated)
.BR sysctl (2)
system call.
.TP
.TP
.I /proc/sys/fs
This directory contains the files and subdirectories for kernel variables
-related to file systems.
+related to filesystems.
.TP
.I /proc/sys/fs/binfmt_misc
Documentation for files in this directory can be found
imposes an upper limit on the value that may be placed in
.IR file-max .
-If you increase
-.IR /proc/sys/fs/file-max ","
-be sure to increase
-.I /proc/sys/fs/inode-max
-to 3-4 times the new
-value of
-.IR /proc/sys/fs/file-max ","
-or you will run out of inodes.
-
Privileged processes
.RB ( CAP_SYS_ADMIN )
can override the
Since Linux 2.6, the kernel does deallocate freed file handles,
and the "free file handles" value is always zero.
.TP
-.I /proc/sys/fs/inode-max
+.IR /proc/sys/fs/inode-max " (only present until Linux 2.2)"
This file contains the maximum number of in-memory inodes.
-On some (2.4) systems, it may not be present.
This value should be 3-4 times larger
than the value in
.IR file-max ,
since \fIstdin\fP, \fIstdout\fP
and network sockets also need an inode to handle them.
When you regularly run out of inodes, you need to increase this value.
+
+Starting with Linux 2.4,
+there is no longer a static limit on the number of inodes,
+and this file is removed.
.TP
.I /proc/sys/fs/inode-nr
This file contains the first two values from
.IR nr_inodes ,
.IR nr_free_inodes ,
.IR preshrink ,
-and four dummy values.
+and four dummy values (always zero).
+
.I nr_inodes
is the number of inodes the system has allocated.
-This can be slightly more than
-.I inode-max
-because Linux allocates them one page full at a time.
+.\" This can be slightly more than
+.\" .I inode-max
+.\" because Linux allocates them one page full at a time.
.I nr_free_inodes
represents the number of free inodes.
+
.I preshrink
is nonzero when the
.I nr_inodes
>
.I inode-max
-and the system needs to prune the inode list instead of allocating more.
+and the system needs to prune the inode list instead of allocating more;
+since Linux 2.4, this field is a dummy value (always zero).
.TP
.IR /proc/sys/fs/inotify " (since Linux 2.6.13)"
This directory contains files
These files
allow you to change the value of the fixed UID and GID.
The default is 65534.
-Some file systems support only 16-bit UIDs and GIDs, although in Linux
+Some filesystems support only 16-bit UIDs and GIDs, although in Linux
UIDs and GIDs are 32 bits.
-When one of these file systems is mounted
+When one of these filesystems is mounted
with writes enabled, any UID or GID that would exceed 65535 is translated
to the overflow value before being written to disk.
.TP
.\" commit 800179c9b8a1e796e441674776d11cd4c05d61d7
When the value in this file is 0,
no restrictions are placed on the creation of hard links
-(i.e., this is the historical behaviour before Linux 3.6).
+(i.e., this is the historical behavior before Linux 3.6).
When the value in this file is 1,
a hard link can be created to a target file
only if one of the following conditions is true:
.BR CAP_FOWNER
capability.
.IP *
-The file system UID of the process creating the link matches
+The filesystem UID of the process creating the link matches
the owner (UID) of the target file
(as described in
.BR credentials (7),
-a process's file system UID is normally the same as its effective UID).
+a process's filesystem UID is normally the same as its effective UID).
.IP *
All of the following conditions are true:
.RS 4
.\" commit 800179c9b8a1e796e441674776d11cd4c05d61d7
When the value in this file is 0,
no restrictions are placed on following symbolic links
-(i.e., this is the historical behaviour before Linux 3.6).
+(i.e., this is the historical behavior before Linux 3.6).
When the value in this file is 1, symbolic links are followed only
in the following circumstances:
.RS
.IP * 3
-the file system UID of the process following the link matches
+the filesystem UID of the process following the link matches
the owner (UID) of the symbolic link
(as described in
.BR credentials (7),
-a process's file system UID is normally the same as its effective UID);
+a process's filesystem UID is normally the same as its effective UID);
.IP *
the link is not in a sticky world-writable directory; or
.IP *
-the symbolic link and and its parent directory have the same owner (UID)
+the symbolic link and its parent directory have the same owner (UID)
.RE
.IP
A system call that fails to follow a symbolic link
.TP
\fI1\ ("debug")\fP
All processes dump core when possible.
-The core dump is owned by the file system user ID of the dumping process
+The core dump is owned by the filesystem user ID of the dumping process
and no security is applied.
This is intended for system debugging situations only.
Ptrace is unchecked.
.I /proc/sys/fs/super-max
This file
controls the maximum number of superblocks, and
-thus the maximum number of mounted file systems the kernel
+thus the maximum number of mounted filesystems the kernel
can have.
You need increase only
.I super-max
-if you need to mount more file systems than the current value in
+if you need to mount more filesystems than the current value in
.I super-max
allows you to.
.TP
.I /proc/sys/fs/super-nr
This file
-contains the number of file systems currently mounted.
+contains the number of filesystems currently mounted.
.TP
.I /proc/sys/kernel
This directory contains files controlling a range of kernel parameters,
.IR lowwater ,
and
.IR frequency .
-If BSD-style process accounting is enabled these values control
+If BSD-style process accounting is enabled, these values control
its behavior.
-If free space on file system where the log lives goes below
+If free space on filesystem where the log lives goes below
.I lowwater
-percent accounting suspends.
+percent, accounting suspends.
If free space gets above
.I highwater
-percent accounting resumes.
+percent, accounting resumes.
.I frequency
determines
how often the kernel checks the amount of free space (value is in
.B CONFIG_MODULES
option enabled.
.TP
-.I /proc/sys/kernel/msgmax
+.IR /proc/sys/kernel/msgmax " (since Linux 2.2)"
This file defines
a system-wide limit specifying the maximum number of bytes in
a single message written on a System V message queue.
This file defines the system-wide limit on the number of
message queue identifiers.
.TP
-.I /proc/sys/kernel/msgmnb
+.IR /proc/sys/kernel/msgmnb " (since Linux 2.2)"
This file defines a system-wide parameter used to initialize the
.I msg_qbytes
setting for subsequently created message queues.
setting specifies the maximum number of bytes that may be written to the
message queue.
.TP
+.IR /proc/sys/kernel/ngroups_max " (since Linux 2.6.4)"
+This is a read-only file that displays the upper limit on the
+number of a process's group memberships.
+.TP
.IR /proc/sys/kernel/ostype " and " /proc/sys/kernel/osrelease
These files
give substrings of
.I /proc/sys/kernel/panic
This file gives read/write access to the kernel variable
.IR panic_timeout .
-If this is zero, the kernel will loop on a panic; if nonzero
+If this is zero, the kernel will loop on a panic; if nonzero,
it indicates that the kernel should autoreboot after this number
of seconds.
When you use the
and then panics.
If the
.I /proc/sys/kernel/panic
-file is also nonzero then the machine will be rebooted.
+file is also nonzero, then the machine will be rebooted.
.TP
.IR /proc/sys/kernel/pid_max " (since Linux 2.5.34)"
This file specifies the value at which PIDs wrap around
(i.e., the value in this file is one greater than the maximum PID).
+PIDs greater than this value not allocated;
+thus, the value in this file also acts as a system-wide limit
+on the total number of processes and threads.
The default value for this file, 32768,
results in the same range of PIDs as on earlier kernels.
On 32-bit platforms, 32768 is the maximum value for
otherwise the "doze" mode will be used.
.TP
.I /proc/sys/kernel/printk
-The four values in this file are
-.IR console_loglevel ,
-.IR default_message_loglevel ,
-.IR minimum_console_level ,
-and
-.IR default_console_loglevel .
-These values influence
-.I printk()
-behavior when printing or logging error messages.
See
-.BR syslog (2)
-for more info on the different loglevels.
-Messages with a higher priority than
-.I console_loglevel
-will be printed to the console.
-Messages without an explicit priority will be printed with priority
-.IR default_message_level .
-.I minimum_console_loglevel
-is the minimum (highest) value to which
-.I console_loglevel
-can be set.
-.I default_console_loglevel
-is the default value for
-.IR console_loglevel .
+.BR syslog (2).
.TP
.IR /proc/sys/kernel/pty " (since Linux 2.6.4)"
This directory contains two files relating to the number of UNIX 98
.BR random (4)
for further information.
.TP
+.IR /proc/sys/kernel/random/uuid " (since Linux 2.4)"
+Each read from this read-only file returns a randomly generated 128-bit UUID,
+as a string in the standard UUID format.
+.TP
.I /proc/sys/kernel/real-root-dev
This file is documented in the Linux kernel source file
.IR Documentation/initrd.txt .
(Only in kernels up to and including 2.6.7.)
This file shows the number POSIX real-time signals currently queued.
.TP
+.IR /proc/sys/kernel/sched_rr_timeslice_ms " (since Linux 3.9)"
+See
+.BR sched_rr_get_interval (2).
+.TP
+.IR /proc/sys/kernel/sched_rt_period_us " (Since Linux 2.6.25)"
+See
+.BR sched (7).
+.TP
+.IR /proc/sys/kernel/sched_rt_runtime_us " (Since Linux 2.6.25)"
+See
+.BR sched (7).
+.TP
.IR /proc/sys/kernel/sem " (since Linux 2.4)"
This file contains 4 numbers defining limits for System V IPC semaphores.
These fields are, in order:
.BR SG_BIG_BUFF .
However, there shouldn't be any reason to change this value.
.TP
-.I /proc/sys/kernel/shmall
+.IR /proc/sys/kernel/shm_rmid_forced " (since Linux 3.1)"
+.\" commit b34a6b1da371ed8af1221459a18c67970f7e3d53
+.\" See also Documentation/sysctl/kernel.txt
+If this file is set to 1, all System V shared memory segments will
+be marked for destruction as soon as the number of attached processes
+falls to zero;
+in other words, it is no longer possible to create shared memory segments
+that exist independently of any attached process.
+.IP
+The effect is as though a
+.BR shmctl (2)
+.B IPC_RMID
+is performed on all existing segments as well as all segments
+created in the future (until this file is reset to 0).
+Note that existing segments that are attached to no process will be
+immediately destroyed when this file is set to 1.
+Setting this option will also destroy segments that were created,
+but never attached,
+upon termination of the process that created the segment with
+.BR shmget (2).
+.IP
+Setting this file to 1 provides a way of ensuring that
+all System V shared memory segments are counted against the
+resource usage and resource limits (see the description of
+.B RLIMIT_AS
+in
+.BR getrlimit (2))
+of at least one process.
+.IP
+Because setting this file to 1 produces behavior that is nonstandard
+and could also break existing applications,
+the default value in this file is 0.
+Only set this file to 1 if you have a good understanding
+of the semantics of the applications using
+System V shared memory on your system.
+.TP
+.IR /proc/sys/kernel/shmall " (since Linux 2.2)"
This file
contains the system-wide limit on the total number of pages of
System V shared memory.
.TP
-.I /proc/sys/kernel/shmmax
+.IR /proc/sys/kernel/shmmax " (since Linux 2.2)"
This file
can be used to query and set the run-time limit
on the maximum (System V IPC) shared memory segment size that can be
8 - enable debugging dumps of processes etc.
16 - enable sync command
32 - enable remount read-only
- 64 - enable signalling of processes (term, kill, oom-kill)
+ 64 - enable signaling of processes (term, kill, oom-kill)
128 - allow reboot/poweroff
256 - allow nicing of all real-time tasks
This directory may be empty.
.TP
.I /proc/sys/sunrpc
-This directory supports Sun remote procedure call for network file system
+This directory supports Sun remote procedure call for network filesystem
(NFS).
On some systems, it is not present.
.TP
cache management.
.TP
.IR /proc/sys/vm/drop_caches " (since Linux 2.6.16)"
-Writing to this file causes the kernel to drop clean caches, dentries and
+Writing to this file causes the kernel to drop clean caches, dentries, and
inodes from memory, causing that memory to become free.
+This can be useful for memory management testing and
+performing reproducible filesystem benchmarks.
+Because writing to this file causes the benefits of caching to be lost,
+it can degrade overall system performance.
+
+To free pagecache, use:
+
+ echo 1 > /proc/sys/vm/drop_caches
+
+To free dentries and inodes, use:
-To free pagecache, use
-.IR "echo 1 > /proc/sys/vm/drop_caches" ;
-to free dentries and inodes, use
-.IR "echo 2 > /proc/sys/vm/drop_caches" ;
-to free pagecache, dentries and inodes, use
-.IR "echo 3 > /proc/sys/vm/drop_caches" .
+ echo 2 > /proc/sys/vm/drop_caches
-Because this is a nondestructive operation and dirty objects
+To free pagecache, dentries and inodes, use:
+
+ echo 3 > /proc/sys/vm/drop_caches
+
+Because writing to this file is a nondestructive operation and dirty objects
are not freeable, the
user should run
.BR sync (8)
The default value is 0.
.TP
+.IR /proc/sys/vm/overcommit_kbytes " (since Linux 3.14)"
+.\" commit 49f0ce5f92321cdcf741e35f385669a421013cb7
+This writable file provides an alternative to
+.IR /proc/sys/vm/overcommit_ratio
+for controlling the
+.I CommitLimit
+when
+.IR /proc/sys/vm/overcommit_memory
+has the value 2.
+It allows the amount of memory overcommitting to be specified as
+an absolute value (in kB),
+rather than as a percentage, as is done with
+.IR overcommit_ratio .
+This allows for finer-grained control of
+.IR CommitLimit
+on systems with extremely large memory sizes.
+
+Only one of
+.IR overcommit_kbytes
+or
+.IR overcommit_ratio
+can have an effect:
+if
+.IR overcommit_kbytes
+has a nonzero value, then it is used to calculate
+.IR CommitLimit ,
+otherwise
+.IR overcommit_ratio
+is used.
+Writing a value to either of these files causes the
+value in the other file to be set to zero.
+.TP
.I /proc/sys/vm/overcommit_memory
This file contains the kernel virtual memory accounting mode.
Values are:
.B MAP_NORESERVE
are not checked, and the default check is very weak,
leading to the risk of getting a process "OOM-killed".
-Under Linux 2.4 any nonzero value implies mode 1.
+Under Linux 2.4, any nonzero value implies mode 1.
+
In mode 2 (available since Linux 2.6), the total virtual address space
-on the system is limited to (SS + RAM*(r/100)),
-where SS is the size of the swap space, and RAM
-is the size of the physical memory, and r is the contents of the file
-.IR /proc/sys/vm/overcommit_ratio .
+that can be allocated
+.RI ( CommitLimit
+in
+.IR /proc/meminfo )
+is calculated as
+
+ CommitLimit = (total_RAM - total_huge_TLB) *
+ overcommit_ratio / 100 + total_swap
+
+where:
+.RS 12
+.IP * 3
+.I total_RAM
+is the total amount of RAM on the system;
+.IP *
+.I total_huge_TLB
+is the amount of memory set aside for huge pages;
+.IP *
+.I overcommit_ratio
+is the value in
+.IR /proc/sys/vm/overcommit_ratio ;
+and
+.IP *
+.I total_swap
+is the amount of swap space.
+.RE
+.IP
+For example, on a system with 16GB of physical RAM, 16GB
+of swap, no space dedicated to huge pages, and an
+.I overcommit_ratio
+of 50, this formula yields a
+.I CommitLimit
+of 24GB.
+
+Since Linux 3.14, if the value in
+.I /proc/sys/vm/overcommit_kbytes
+is nonzero, then
+.I CommitLimit
+is instead calculated as:
+
+ CommitLimit = overcommit_kbytes + total_swap
.TP
-.I /proc/sys/vm/overcommit_ratio
+.IR /proc/sys/vm/overcommit_ratio " (since Linux 2.6.0)"
+This writable file defines a percentage by which memory
+can be overcommitted.
+The default value in the file is 50.
See the description of
.IR /proc/sys/vm/overcommit_memory .
.TP
then the kernel normally panics when out-of-memory happens.
However, if a process limits allocations to certain nodes
using memory policies
-.RB ( mbind (2)
+.RB ( mbind (2)
.BR MPOL_BIND )
or cpusets
.RB ( cpuset (7))
.TP
.I /proc/sysvipc
Subdirectory containing the pseudo-files
-.IR msg ", " sem " and " shm "."
+.IR msg ", " sem " and " shm "."
These files list the System V Interprocess Communication (IPC) objects
(respectively: message queues, semaphores, and shared memory)
that currently exist on the system,
.BR svipc (7)
provides further background on the information shown by these files.
.TP
+.IR /proc/timer_list " (since Linux 2.6.21)"
+.\" commit 289f480af87e45f7a6de6ba9b4c061c2e259fe98
+This read-only file exposes a list of all currently pending
+(high-resolution) timers,
+all clock-event sources, and their parameters in a human-readable form.
+.TP
+.IR /proc/timer_stats " (since Linux 2.6.21)"
+.\" commit 82f67cd9fca8c8762c15ba7ed0d5747588c1e221
+.\" Date: Fri Feb 16 01:28:13 2007 -0800
+.\" Text largely derived from Documentation/timers/timer_stats.txt
+This is a debugging facility to make timer (ab)use in a Linux
+system visible to kernel and user-space developers.
+It can be used by kernel and user-space developers to verify that
+their code does not make undue use of timers.
+The goal is to avoid unnecessary wakeups,
+thereby optimizing power consumption.
+
+If enabled in the kernel
+.RB ( CONFIG_TIMER_STATS ),
+but not used,
+it has almost zero runtime overhead and a relatively small
+data-structure overhead.
+Even if collection is enabled at runtime, overhead is low:
+all the locking is per-CPU and lookup is hashed.
+
+The
+.I /proc/timer_stats
+file is used both to control sampling facility and to read out the
+sampled information.
+
+timer_stats collects information about the timer events which are fired in a
+Linux system over a sample period:
+
+- the pid of the task(process) which initialized the timer
+- the name of the process which initialized the timer
+- the function where the timer was initialized
+- the callback function which is associated to the timer
+- the number of events (callbacks)
+
+The timer_stats functionality is inactive on bootup.
+A sampling period can be started using the following command:
+
+ # echo 1 > /proc/timer_stats
+
+The following command stops a sampling period:
+
+ # echo 0 > /proc/timer_stats
+
+The statistics can be retrieved by:
+
+ $ cat /proc/timer_stats
+
+While sampling is enabled, each readout from /proc/timer_stats will see
+newly updated statistics.
+Once sampling is disabled, the sampled information
+is kept until a new sample period is started.
+This allows multiple readouts.
+
+Sample output from
+.IR /proc/timer_stats :
+
+.nf
+.RS -4
+.RB $ " cat /proc/timer_stats"
+Timer Stats Version: v0.3
+Sample period: 1.764 s
+Collection: active
+ 255, 0 swapper/3 hrtimer_start_range_ns (tick_sched_timer)
+ 71, 0 swapper/1 hrtimer_start_range_ns (tick_sched_timer)
+ 58, 0 swapper/0 hrtimer_start_range_ns (tick_sched_timer)
+ 4, 1694 gnome-shell mod_delayed_work_on (delayed_work_timer_fn)
+ 17, 7 rcu_sched rcu_gp_kthread (process_timeout)
+\&...
+ 1, 4911 kworker/u16:0 mod_delayed_work_on (delayed_work_timer_fn)
+ 1D, 2522 kworker/0:0 queue_delayed_work_on (delayed_work_timer_fn)
+1029 total events, 583.333 events/sec
+
+.fi
+.RE
+.IP
+The output columns are:
+.RS
+.IP * 3
+a count of the number of events,
+optionally (since Linux 2.6.23) followed by the letter \(aqD\(aq
+.\" commit c5c061b8f9726bc2c25e19dec227933a13d1e6b7 deferrable timers
+if this is a deferrable timer;
+.IP *
+the PID of the process that initialized the timer;
+.IP *
+the name of the process that initialized the timer;
+.IP *
+the function where the timer was initialized; and
+.IP *
+(in parentheses)
+the callback function that is associated with the timer.
+.RE
+.TP
.I /proc/tty
Subdirectory containing the pseudo-files and subdirectories for
tty drivers and line disciplines.
.ft
.in +2
.fi
-.\" FIXME Document /proc/timer_list
-.\" .TP
-.\" .IR /proc/timer_list " (since Linux 2.6.21)"
-.\" See the 2.6.21 Change log
-.\" FIXME Document /proc/timer_stats
-.\" .TP
-.\" .IR /proc/timer_stats " (since Linux 2.6.21)"
-.\" See the 2.6.21 Change log
.TP
.IR /proc/vmstat " (since Linux 2.6)"
This file displays various virtual memory statistics.
The Linux kernel source files:
.IR Documentation/filesystems/proc.txt
+.IR Documentation/sysctl/fs.txt ,
+.IR Documentation/sysctl/kernel.txt ,
+.IR Documentation/sysctl/net.txt ,
and
.IR Documentation/sysctl/vm.txt .
projects / thirdparty / man-pages.git / blobdiff