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Linus Torvalds1da177e2005-04-16 15:20:36 -07001------------------------------------------------------------------------------
2 T H E /proc F I L E S Y S T E M
3------------------------------------------------------------------------------
4/proc/sys Terrehon Bowden <terrehon@pacbell.net> October 7 1999
5 Bodo Bauer <bb@ricochet.net>
6
72.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000
Stefani Seibold349888e2009-06-17 16:26:01 -07008move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
Linus Torvalds1da177e2005-04-16 15:20:36 -07009------------------------------------------------------------------------------
10Version 1.3 Kernel version 2.2.12
11 Kernel version 2.4.0-test11-pre4
12------------------------------------------------------------------------------
Stefani Seibold349888e2009-06-17 16:26:01 -070013fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009
Linus Torvalds1da177e2005-04-16 15:20:36 -070014
15Table of Contents
16-----------------
17
18 0 Preface
19 0.1 Introduction/Credits
20 0.2 Legal Stuff
21
22 1 Collecting System Information
23 1.1 Process-Specific Subdirectories
24 1.2 Kernel data
25 1.3 IDE devices in /proc/ide
26 1.4 Networking info in /proc/net
27 1.5 SCSI info
28 1.6 Parallel port info in /proc/parport
29 1.7 TTY info in /proc/tty
30 1.8 Miscellaneous kernel statistics in /proc/stat
Trace Pillarsae96b342015-01-23 11:45:05 -050031 1.9 Ext4 file system parameters
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
33 2 Modifying System Parameters
Shen Feng760df932009-04-02 16:57:20 -070034
35 3 Per-Process Parameters
David Rientjesfa0cbbf2012-11-12 17:53:04 -080036 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer
David Rientjesa63d83f2010-08-09 17:19:46 -070037 score
Shen Feng760df932009-04-02 16:57:20 -070038 3.2 /proc/<pid>/oom_score - Display current oom-killer score
39 3.3 /proc/<pid>/io - Display the IO accounting fields
40 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
41 3.5 /proc/<pid>/mountinfo - Information about mounts
john stultz4614a696b2009-12-14 18:00:05 -080042 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
Cyrill Gorcunov818411612012-05-31 16:26:43 -070043 3.7 /proc/<pid>/task/<tid>/children - Information about task children
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -080044 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
Cyrill Gorcunov740a5dd2015-02-11 15:28:31 -080045 3.9 /proc/<pid>/map_files - Information about memory mapped files
John Stultz5de23d42016-03-17 14:20:54 -070046 3.10 /proc/<pid>/timerslack_ns - Task timerslack value
Shen Feng760df932009-04-02 16:57:20 -070047
Vasiliy Kulikov04996802012-01-10 15:11:31 -080048 4 Configuring procfs
49 4.1 Mount options
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
51------------------------------------------------------------------------------
52Preface
53------------------------------------------------------------------------------
54
550.1 Introduction/Credits
56------------------------
57
58This documentation is part of a soon (or so we hope) to be released book on
59the SuSE Linux distribution. As there is no complete documentation for the
60/proc file system and we've used many freely available sources to write these
61chapters, it seems only fair to give the work back to the Linux community.
62This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm
63afraid it's still far from complete, but we hope it will be useful. As far as
64we know, it is the first 'all-in-one' document about the /proc file system. It
65is focused on the Intel x86 hardware, so if you are looking for PPC, ARM,
66SPARC, AXP, etc., features, you probably won't find what you are looking for.
67It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
68additions and patches are welcome and will be added to this document if you
69mail them to Bodo.
70
71We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of
72other people for help compiling this documentation. We'd also like to extend a
73special thank you to Andi Kleen for documentation, which we relied on heavily
74to create this document, as well as the additional information he provided.
75Thanks to everybody else who contributed source or docs to the Linux kernel
76and helped create a great piece of software... :)
77
78If you have any comments, corrections or additions, please don't hesitate to
79contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this
80document.
81
82The latest version of this document is available online at
Justin P. Mattock0ea6e612010-07-23 20:51:24 -070083http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
Justin P. Mattock0ea6e612010-07-23 20:51:24 -070085If the above direction does not works for you, you could try the kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -070086mailing list at linux-kernel@vger.kernel.org and/or try to reach me at
87comandante@zaralinux.com.
88
890.2 Legal Stuff
90---------------
91
92We don't guarantee the correctness of this document, and if you come to us
93complaining about how you screwed up your system because of incorrect
94documentation, we won't feel responsible...
95
96------------------------------------------------------------------------------
97CHAPTER 1: COLLECTING SYSTEM INFORMATION
98------------------------------------------------------------------------------
99
100------------------------------------------------------------------------------
101In This Chapter
102------------------------------------------------------------------------------
103* Investigating the properties of the pseudo file system /proc and its
104 ability to provide information on the running Linux system
105* Examining /proc's structure
106* Uncovering various information about the kernel and the processes running
107 on the system
108------------------------------------------------------------------------------
109
110
111The proc file system acts as an interface to internal data structures in the
112kernel. It can be used to obtain information about the system and to change
113certain kernel parameters at runtime (sysctl).
114
115First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
116show you how you can use /proc/sys to change settings.
117
1181.1 Process-Specific Subdirectories
119-----------------------------------
120
121The directory /proc contains (among other things) one subdirectory for each
122process running on the system, which is named after the process ID (PID).
123
124The link self points to the process reading the file system. Each process
125subdirectory has the entries listed in Table 1-1.
126
127
Stefani Seibold349888e2009-06-17 16:26:01 -0700128Table 1-1: Process specific entries in /proc
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129..............................................................................
David Rientjesb813e932007-05-06 14:49:24 -0700130 File Content
131 clear_refs Clears page referenced bits shown in smaps output
132 cmdline Command line arguments
133 cpu Current and last cpu in which it was executed (2.4)(smp)
134 cwd Link to the current working directory
135 environ Values of environment variables
136 exe Link to the executable of this process
137 fd Directory, which contains all file descriptors
138 maps Memory maps to executables and library files (2.4)
139 mem Memory held by this process
140 root Link to the root directory of this process
141 stat Process status
142 statm Process memory status information
143 status Process status in human readable form
Ingo Molnarb2f73922015-09-30 15:59:17 +0200144 wchan Present with CONFIG_KALLSYMS=y: it shows the kernel function
145 symbol the task is blocked in - or "0" if not blocked.
Nikanth Karthikesan03f890f2010-10-27 15:34:11 -0700146 pagemap Page table
Ken Chen2ec220e2008-11-10 11:26:08 +0300147 stack Report full stack trace, enable via CONFIG_STACKTRACE
Stefani Seibold349888e2009-06-17 16:26:01 -0700148 smaps a extension based on maps, showing the memory consumption of
Cyrill Gorcunov834f82e2012-12-17 16:03:13 -0800149 each mapping and flags associated with it
Rafael Aquini0c369712015-02-12 15:01:05 -0800150 numa_maps an extension based on maps, showing the memory locality and
151 binding policy as well as mem usage (in pages) of each mapping.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152..............................................................................
153
154For example, to get the status information of a process, all you have to do is
155read the file /proc/PID/status:
156
Stefani Seibold349888e2009-06-17 16:26:01 -0700157 >cat /proc/self/status
158 Name: cat
159 State: R (running)
160 Tgid: 5452
161 Pid: 5452
162 PPid: 743
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 TracerPid: 0 (2.4)
Stefani Seibold349888e2009-06-17 16:26:01 -0700164 Uid: 501 501 501 501
165 Gid: 100 100 100 100
166 FDSize: 256
167 Groups: 100 14 16
168 VmPeak: 5004 kB
169 VmSize: 5004 kB
170 VmLck: 0 kB
171 VmHWM: 476 kB
172 VmRSS: 476 kB
Jerome Marchand8cee8522016-01-14 15:19:29 -0800173 RssAnon: 352 kB
174 RssFile: 120 kB
175 RssShmem: 4 kB
Stefani Seibold349888e2009-06-17 16:26:01 -0700176 VmData: 156 kB
177 VmStk: 88 kB
178 VmExe: 68 kB
179 VmLib: 1412 kB
180 VmPTE: 20 kb
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -0800181 VmSwap: 0 kB
Naoya Horiguchi5d317b22015-11-05 18:47:14 -0800182 HugetlbPages: 0 kB
Stefani Seibold349888e2009-06-17 16:26:01 -0700183 Threads: 1
184 SigQ: 0/28578
185 SigPnd: 0000000000000000
186 ShdPnd: 0000000000000000
187 SigBlk: 0000000000000000
188 SigIgn: 0000000000000000
189 SigCgt: 0000000000000000
190 CapInh: 00000000fffffeff
191 CapPrm: 0000000000000000
192 CapEff: 0000000000000000
193 CapBnd: ffffffffffffffff
Kees Cook2f4b3bf2012-12-17 16:03:14 -0800194 Seccomp: 0
Stefani Seibold349888e2009-06-17 16:26:01 -0700195 voluntary_ctxt_switches: 0
196 nonvoluntary_ctxt_switches: 1
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197
198This shows you nearly the same information you would get if you viewed it with
199the ps command. In fact, ps uses the proc file system to obtain its
Stefani Seibold349888e2009-06-17 16:26:01 -0700200information. But you get a more detailed view of the process by reading the
201file /proc/PID/status. It fields are described in table 1-2.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202
Stefani Seibold349888e2009-06-17 16:26:01 -0700203The statm file contains more detailed information about the process
204memory usage. Its seven fields are explained in Table 1-3. The stat file
205contains details information about the process itself. Its fields are
206explained in Table 1-4.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -0800208(for SMP CONFIG users)
Nathan Scott15eb42d2015-04-16 12:49:35 -0700209For making accounting scalable, RSS related information are handled in an
210asynchronous manner and the value may not be very precise. To see a precise
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -0800211snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
212It's slow but very precise.
213
Chen Hanxiao9eb05992015-04-20 22:48:23 -0400214Table 1-2: Contents of the status files (as of 4.1)
Stefani Seibold349888e2009-06-17 16:26:01 -0700215..............................................................................
216 Field Content
217 Name filename of the executable
218 State state (R is running, S is sleeping, D is sleeping
219 in an uninterruptible wait, Z is zombie,
220 T is traced or stopped)
221 Tgid thread group ID
Nathan Scott15eb42d2015-04-16 12:49:35 -0700222 Ngid NUMA group ID (0 if none)
Stefani Seibold349888e2009-06-17 16:26:01 -0700223 Pid process id
224 PPid process id of the parent process
225 TracerPid PID of process tracing this process (0 if not)
226 Uid Real, effective, saved set, and file system UIDs
227 Gid Real, effective, saved set, and file system GIDs
Richard W.M. Jones3e429792016-05-20 17:00:05 -0700228 Umask file mode creation mask
Stefani Seibold349888e2009-06-17 16:26:01 -0700229 FDSize number of file descriptor slots currently allocated
230 Groups supplementary group list
Nathan Scott15eb42d2015-04-16 12:49:35 -0700231 NStgid descendant namespace thread group ID hierarchy
232 NSpid descendant namespace process ID hierarchy
233 NSpgid descendant namespace process group ID hierarchy
234 NSsid descendant namespace session ID hierarchy
Stefani Seibold349888e2009-06-17 16:26:01 -0700235 VmPeak peak virtual memory size
236 VmSize total program size
237 VmLck locked memory size
238 VmHWM peak resident set size ("high water mark")
Jerome Marchand8cee8522016-01-14 15:19:29 -0800239 VmRSS size of memory portions. It contains the three
240 following parts (VmRSS = RssAnon + RssFile + RssShmem)
241 RssAnon size of resident anonymous memory
242 RssFile size of resident file mappings
243 RssShmem size of resident shmem memory (includes SysV shm,
244 mapping of tmpfs and shared anonymous mappings)
Konstantin Khlebnikov30bdbb72016-02-02 16:57:46 -0800245 VmData size of private data segments
246 VmStk size of stack segments
Stefani Seibold349888e2009-06-17 16:26:01 -0700247 VmExe size of text segment
248 VmLib size of shared library code
249 VmPTE size of page table entries
Chen Hanxiaoc0d21432015-04-24 03:44:17 -0400250 VmPMD size of second level page tables
Vlastimil Babkabf9683d2016-01-14 15:19:14 -0800251 VmSwap amount of swap used by anonymous private data
252 (shmem swap usage is not included)
Naoya Horiguchi5d317b22015-11-05 18:47:14 -0800253 HugetlbPages size of hugetlb memory portions
Stefani Seibold349888e2009-06-17 16:26:01 -0700254 Threads number of threads
255 SigQ number of signals queued/max. number for queue
256 SigPnd bitmap of pending signals for the thread
257 ShdPnd bitmap of shared pending signals for the process
258 SigBlk bitmap of blocked signals
259 SigIgn bitmap of ignored signals
Carlos Garciac98be0c2014-04-04 22:31:00 -0400260 SigCgt bitmap of caught signals
Stefani Seibold349888e2009-06-17 16:26:01 -0700261 CapInh bitmap of inheritable capabilities
262 CapPrm bitmap of permitted capabilities
263 CapEff bitmap of effective capabilities
264 CapBnd bitmap of capabilities bounding set
Kees Cook2f4b3bf2012-12-17 16:03:14 -0800265 Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...)
Stefani Seibold349888e2009-06-17 16:26:01 -0700266 Cpus_allowed mask of CPUs on which this process may run
267 Cpus_allowed_list Same as previous, but in "list format"
268 Mems_allowed mask of memory nodes allowed to this process
269 Mems_allowed_list Same as previous, but in "list format"
270 voluntary_ctxt_switches number of voluntary context switches
271 nonvoluntary_ctxt_switches number of non voluntary context switches
272..............................................................................
273
274Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275..............................................................................
276 Field Content
277 size total program size (pages) (same as VmSize in status)
278 resident size of memory portions (pages) (same as VmRSS in status)
Jerome Marchand8cee8522016-01-14 15:19:29 -0800279 shared number of pages that are shared (i.e. backed by a file, same
280 as RssFile+RssShmem in status)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 trs number of pages that are 'code' (not including libs; broken,
282 includes data segment)
283 lrs number of pages of library (always 0 on 2.6)
284 drs number of pages of data/stack (including libs; broken,
285 includes library text)
286 dt number of dirty pages (always 0 on 2.6)
287..............................................................................
288
Kees Cook18d96772007-07-15 23:40:38 -0700289
Stefani Seibold349888e2009-06-17 16:26:01 -0700290Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
Kees Cook18d96772007-07-15 23:40:38 -0700291..............................................................................
292 Field Content
293 pid process id
294 tcomm filename of the executable
295 state state (R is running, S is sleeping, D is sleeping in an
296 uninterruptible wait, Z is zombie, T is traced or stopped)
297 ppid process id of the parent process
298 pgrp pgrp of the process
299 sid session id
300 tty_nr tty the process uses
301 tty_pgrp pgrp of the tty
302 flags task flags
303 min_flt number of minor faults
304 cmin_flt number of minor faults with child's
305 maj_flt number of major faults
306 cmaj_flt number of major faults with child's
307 utime user mode jiffies
308 stime kernel mode jiffies
309 cutime user mode jiffies with child's
310 cstime kernel mode jiffies with child's
311 priority priority level
312 nice nice level
313 num_threads number of threads
Leonardo Chiquitto2e01e002008-02-03 16:17:16 +0200314 it_real_value (obsolete, always 0)
Kees Cook18d96772007-07-15 23:40:38 -0700315 start_time time the process started after system boot
316 vsize virtual memory size
317 rss resident set memory size
318 rsslim current limit in bytes on the rss
319 start_code address above which program text can run
320 end_code address below which program text can run
Siddhesh Poyarekarb7643752012-03-21 16:34:04 -0700321 start_stack address of the start of the main process stack
Kees Cook18d96772007-07-15 23:40:38 -0700322 esp current value of ESP
323 eip current value of EIP
Stefani Seibold349888e2009-06-17 16:26:01 -0700324 pending bitmap of pending signals
325 blocked bitmap of blocked signals
326 sigign bitmap of ignored signals
Carlos Garciac98be0c2014-04-04 22:31:00 -0400327 sigcatch bitmap of caught signals
Ingo Molnarb2f73922015-09-30 15:59:17 +0200328 0 (place holder, used to be the wchan address, use /proc/PID/wchan instead)
Kees Cook18d96772007-07-15 23:40:38 -0700329 0 (place holder)
330 0 (place holder)
331 exit_signal signal to send to parent thread on exit
332 task_cpu which CPU the task is scheduled on
333 rt_priority realtime priority
334 policy scheduling policy (man sched_setscheduler)
335 blkio_ticks time spent waiting for block IO
Stefani Seibold349888e2009-06-17 16:26:01 -0700336 gtime guest time of the task in jiffies
337 cgtime guest time of the task children in jiffies
Cyrill Gorcunovb3f7f572012-01-12 17:20:53 -0800338 start_data address above which program data+bss is placed
339 end_data address below which program data+bss is placed
340 start_brk address above which program heap can be expanded with brk()
Cyrill Gorcunov5b1720872012-05-31 16:26:44 -0700341 arg_start address above which program command line is placed
342 arg_end address below which program command line is placed
343 env_start address above which program environment is placed
344 env_end address below which program environment is placed
345 exit_code the thread's exit_code in the form reported by the waitpid system call
Kees Cook18d96772007-07-15 23:40:38 -0700346..............................................................................
347
Rob Landley32e688b2010-03-15 15:21:31 +0100348The /proc/PID/maps file containing the currently mapped memory regions and
Stefani Seibold349888e2009-06-17 16:26:01 -0700349their access permissions.
350
351The format is:
352
353address perms offset dev inode pathname
354
35508048000-08049000 r-xp 00000000 03:00 8312 /opt/test
35608049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
3570804a000-0806b000 rw-p 00000000 00:00 0 [heap]
358a7cb1000-a7cb2000 ---p 00000000 00:00 0
Robin Holt34441422010-05-11 14:06:46 -0700359a7cb2000-a7eb2000 rw-p 00000000 00:00 0
Stefani Seibold349888e2009-06-17 16:26:01 -0700360a7eb2000-a7eb3000 ---p 00000000 00:00 0
Johannes Weiner65376df2016-02-02 16:57:29 -0800361a7eb3000-a7ed5000 rw-p 00000000 00:00 0
Stefani Seibold349888e2009-06-17 16:26:01 -0700362a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
363a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
364a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
365a800b000-a800e000 rw-p 00000000 00:00 0
366a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
367a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
368a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
369a8024000-a8027000 rw-p 00000000 00:00 0
370a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
371a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
372a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
373aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
374ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
375
376where "address" is the address space in the process that it occupies, "perms"
377is a set of permissions:
378
379 r = read
380 w = write
381 x = execute
382 s = shared
383 p = private (copy on write)
384
385"offset" is the offset into the mapping, "dev" is the device (major:minor), and
386"inode" is the inode on that device. 0 indicates that no inode is associated
387with the memory region, as the case would be with BSS (uninitialized data).
388The "pathname" shows the name associated file for this mapping. If the mapping
389is not associated with a file:
390
391 [heap] = the heap of the program
392 [stack] = the stack of the main process
393 [vdso] = the "virtual dynamic shared object",
394 the kernel system call handler
395
396 or if empty, the mapping is anonymous.
397
Siddhesh Poyarekarb7643752012-03-21 16:34:04 -0700398The /proc/PID/task/TID/maps is a view of the virtual memory from the viewpoint
399of the individual tasks of a process. In this file you will see a mapping marked
Johannes Weiner65376df2016-02-02 16:57:29 -0800400as [stack] if that task sees it as a stack. Hence, for the example above, the
401task-level map, i.e. /proc/PID/task/TID/maps for thread 1001 will look like this:
Siddhesh Poyarekarb7643752012-03-21 16:34:04 -0700402
40308048000-08049000 r-xp 00000000 03:00 8312 /opt/test
40408049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
4050804a000-0806b000 rw-p 00000000 00:00 0 [heap]
406a7cb1000-a7cb2000 ---p 00000000 00:00 0
407a7cb2000-a7eb2000 rw-p 00000000 00:00 0
408a7eb2000-a7eb3000 ---p 00000000 00:00 0
409a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack]
410a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
411a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
412a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
413a800b000-a800e000 rw-p 00000000 00:00 0
414a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
415a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
416a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
417a8024000-a8027000 rw-p 00000000 00:00 0
418a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
419a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
420a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
421aff35000-aff4a000 rw-p 00000000 00:00 0
422ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
Stefani Seibold349888e2009-06-17 16:26:01 -0700423
424The /proc/PID/smaps is an extension based on maps, showing the memory
425consumption for each of the process's mappings. For each of mappings there
426is a series of lines such as the following:
427
42808048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
429Size: 1084 kB
430Rss: 892 kB
431Pss: 374 kB
432Shared_Clean: 892 kB
433Shared_Dirty: 0 kB
434Private_Clean: 0 kB
435Private_Dirty: 0 kB
436Referenced: 892 kB
Nikanth Karthikesanb40d4f82010-10-27 15:34:10 -0700437Anonymous: 0 kB
Naoya Horiguchi25ee01a2015-11-05 18:47:11 -0800438AnonHugePages: 0 kB
Kirill A. Shutemov1b5946a2016-07-26 15:26:40 -0700439ShmemPmdMapped: 0 kB
Naoya Horiguchi25ee01a2015-11-05 18:47:11 -0800440Shared_Hugetlb: 0 kB
441Private_Hugetlb: 0 kB
Stefani Seibold349888e2009-06-17 16:26:01 -0700442Swap: 0 kB
Minchan Kim8334b962015-09-08 15:00:24 -0700443SwapPss: 0 kB
Stefani Seibold349888e2009-06-17 16:26:01 -0700444KernelPageSize: 4 kB
445MMUPageSize: 4 kB
Hugh Dickinsa5be3562015-11-05 18:50:37 -0800446Locked: 0 kB
447VmFlags: rd ex mr mw me dw
Stefani Seibold349888e2009-06-17 16:26:01 -0700448
Cyrill Gorcunov834f82e2012-12-17 16:03:13 -0800449the first of these lines shows the same information as is displayed for the
Matt Mackall0f4d2082010-10-26 14:21:22 -0700450mapping in /proc/PID/maps. The remaining lines show the size of the mapping
451(size), the amount of the mapping that is currently resident in RAM (RSS), the
452process' proportional share of this mapping (PSS), the number of clean and
Minchan Kim8334b962015-09-08 15:00:24 -0700453dirty private pages in the mapping.
454
455The "proportional set size" (PSS) of a process is the count of pages it has
456in memory, where each page is divided by the number of processes sharing it.
457So if a process has 1000 pages all to itself, and 1000 shared with one other
458process, its PSS will be 1500.
459Note that even a page which is part of a MAP_SHARED mapping, but has only
460a single pte mapped, i.e. is currently used by only one process, is accounted
461as private and not as shared.
462"Referenced" indicates the amount of memory currently marked as referenced or
463accessed.
Nikanth Karthikesanb40d4f82010-10-27 15:34:10 -0700464"Anonymous" shows the amount of memory that does not belong to any file. Even
465a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
466and a page is modified, the file page is replaced by a private anonymous copy.
Naoya Horiguchi25ee01a2015-11-05 18:47:11 -0800467"AnonHugePages" shows the ammount of memory backed by transparent hugepage.
Kirill A. Shutemov1b5946a2016-07-26 15:26:40 -0700468"ShmemPmdMapped" shows the ammount of shared (shmem/tmpfs) memory backed by
469huge pages.
Naoya Horiguchi25ee01a2015-11-05 18:47:11 -0800470"Shared_Hugetlb" and "Private_Hugetlb" show the ammounts of memory backed by
471hugetlbfs page which is *not* counted in "RSS" or "PSS" field for historical
472reasons. And these are not included in {Shared,Private}_{Clean,Dirty} field.
Hugh Dickinsa5be3562015-11-05 18:50:37 -0800473"Swap" shows how much would-be-anonymous memory is also used, but out on swap.
Vlastimil Babkac261e7d2016-01-14 15:19:17 -0800474For shmem mappings, "Swap" includes also the size of the mapped (and not
475replaced by copy-on-write) part of the underlying shmem object out on swap.
476"SwapPss" shows proportional swap share of this mapping. Unlike "Swap", this
477does not take into account swapped out page of underlying shmem objects.
Hugh Dickinsa5be3562015-11-05 18:50:37 -0800478"Locked" indicates whether the mapping is locked in memory or not.
Naoya Horiguchi25ee01a2015-11-05 18:47:11 -0800479
Cyrill Gorcunov834f82e2012-12-17 16:03:13 -0800480"VmFlags" field deserves a separate description. This member represents the kernel
481flags associated with the particular virtual memory area in two letter encoded
482manner. The codes are the following:
483 rd - readable
484 wr - writeable
485 ex - executable
486 sh - shared
487 mr - may read
488 mw - may write
489 me - may execute
490 ms - may share
491 gd - stack segment growns down
492 pf - pure PFN range
493 dw - disabled write to the mapped file
494 lo - pages are locked in memory
495 io - memory mapped I/O area
496 sr - sequential read advise provided
497 rr - random read advise provided
498 dc - do not copy area on fork
499 de - do not expand area on remapping
500 ac - area is accountable
501 nr - swap space is not reserved for the area
502 ht - area uses huge tlb pages
Cyrill Gorcunov834f82e2012-12-17 16:03:13 -0800503 ar - architecture specific flag
504 dd - do not include area into core dump
Naoya Horiguchiec8e41a2013-11-12 15:07:49 -0800505 sd - soft-dirty flag
Cyrill Gorcunov834f82e2012-12-17 16:03:13 -0800506 mm - mixed map area
507 hg - huge page advise flag
508 nh - no-huge page advise flag
509 mg - mergable advise flag
510
511Note that there is no guarantee that every flag and associated mnemonic will
512be present in all further kernel releases. Things get changed, the flags may
513be vanished or the reverse -- new added.
514
Stefani Seibold349888e2009-06-17 16:26:01 -0700515This file is only present if the CONFIG_MMU kernel configuration option is
516enabled.
Kees Cook18d96772007-07-15 23:40:38 -0700517
Moussa A. Ba398499d2009-09-21 17:02:29 -0700518The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700519bits on both physical and virtual pages associated with a process, and the
520soft-dirty bit on pte (see Documentation/vm/soft-dirty.txt for details).
Moussa A. Ba398499d2009-09-21 17:02:29 -0700521To clear the bits for all the pages associated with the process
522 > echo 1 > /proc/PID/clear_refs
523
524To clear the bits for the anonymous pages associated with the process
525 > echo 2 > /proc/PID/clear_refs
526
527To clear the bits for the file mapped pages associated with the process
528 > echo 3 > /proc/PID/clear_refs
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700529
530To clear the soft-dirty bit
531 > echo 4 > /proc/PID/clear_refs
532
Petr Cermak695f0552015-02-12 15:01:00 -0800533To reset the peak resident set size ("high water mark") to the process's
534current value:
535 > echo 5 > /proc/PID/clear_refs
536
Moussa A. Ba398499d2009-09-21 17:02:29 -0700537Any other value written to /proc/PID/clear_refs will have no effect.
538
Nikanth Karthikesan03f890f2010-10-27 15:34:11 -0700539The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
540using /proc/kpageflags and number of times a page is mapped using
541/proc/kpagecount. For detailed explanation, see Documentation/vm/pagemap.txt.
Moussa A. Ba398499d2009-09-21 17:02:29 -0700542
Rafael Aquini0c369712015-02-12 15:01:05 -0800543The /proc/pid/numa_maps is an extension based on maps, showing the memory
544locality and binding policy, as well as the memory usage (in pages) of
545each mapping. The output follows a general format where mapping details get
546summarized separated by blank spaces, one mapping per each file line:
547
548address policy mapping details
549
Rafael Aquini198d1592015-02-12 15:01:08 -080055000400000 default file=/usr/local/bin/app mapped=1 active=0 N3=1 kernelpagesize_kB=4
55100600000 default file=/usr/local/bin/app anon=1 dirty=1 N3=1 kernelpagesize_kB=4
5523206000000 default file=/lib64/ld-2.12.so mapped=26 mapmax=6 N0=24 N3=2 kernelpagesize_kB=4
553320621f000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
5543206220000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
5553206221000 default anon=1 dirty=1 N3=1 kernelpagesize_kB=4
5563206800000 default file=/lib64/libc-2.12.so mapped=59 mapmax=21 active=55 N0=41 N3=18 kernelpagesize_kB=4
Rafael Aquini0c369712015-02-12 15:01:05 -0800557320698b000 default file=/lib64/libc-2.12.so
Rafael Aquini198d1592015-02-12 15:01:08 -08005583206b8a000 default file=/lib64/libc-2.12.so anon=2 dirty=2 N3=2 kernelpagesize_kB=4
5593206b8e000 default file=/lib64/libc-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
5603206b8f000 default anon=3 dirty=3 active=1 N3=3 kernelpagesize_kB=4
5617f4dc10a2000 default anon=3 dirty=3 N3=3 kernelpagesize_kB=4
5627f4dc10b4000 default anon=2 dirty=2 active=1 N3=2 kernelpagesize_kB=4
5637f4dc1200000 default file=/anon_hugepage\040(deleted) huge anon=1 dirty=1 N3=1 kernelpagesize_kB=2048
5647fff335f0000 default stack anon=3 dirty=3 N3=3 kernelpagesize_kB=4
5657fff3369d000 default mapped=1 mapmax=35 active=0 N3=1 kernelpagesize_kB=4
Rafael Aquini0c369712015-02-12 15:01:05 -0800566
567Where:
568"address" is the starting address for the mapping;
569"policy" reports the NUMA memory policy set for the mapping (see vm/numa_memory_policy.txt);
570"mapping details" summarizes mapping data such as mapping type, page usage counters,
571node locality page counters (N0 == node0, N1 == node1, ...) and the kernel page
572size, in KB, that is backing the mapping up.
573
Linus Torvalds1da177e2005-04-16 15:20:36 -07005741.2 Kernel data
575---------------
576
577Similar to the process entries, the kernel data files give information about
578the running kernel. The files used to obtain this information are contained in
Stefani Seibold349888e2009-06-17 16:26:01 -0700579/proc and are listed in Table 1-5. Not all of these will be present in your
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580system. It depends on the kernel configuration and the loaded modules, which
581files are there, and which are missing.
582
Stefani Seibold349888e2009-06-17 16:26:01 -0700583Table 1-5: Kernel info in /proc
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584..............................................................................
585 File Content
586 apm Advanced power management info
587 buddyinfo Kernel memory allocator information (see text) (2.5)
588 bus Directory containing bus specific information
589 cmdline Kernel command line
590 cpuinfo Info about the CPU
591 devices Available devices (block and character)
592 dma Used DMS channels
593 filesystems Supported filesystems
594 driver Various drivers grouped here, currently rtc (2.4)
595 execdomains Execdomains, related to security (2.4)
596 fb Frame Buffer devices (2.4)
597 fs File system parameters, currently nfs/exports (2.4)
598 ide Directory containing info about the IDE subsystem
599 interrupts Interrupt usage
600 iomem Memory map (2.4)
601 ioports I/O port usage
602 irq Masks for irq to cpu affinity (2.4)(smp?)
603 isapnp ISA PnP (Plug&Play) Info (2.4)
604 kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
605 kmsg Kernel messages
606 ksyms Kernel symbol table
607 loadavg Load average of last 1, 5 & 15 minutes
608 locks Kernel locks
609 meminfo Memory info
610 misc Miscellaneous
611 modules List of loaded modules
612 mounts Mounted filesystems
613 net Networking info (see text)
Mel Gormana1b57ac2010-03-05 13:42:15 -0800614 pagetypeinfo Additional page allocator information (see text) (2.5)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 partitions Table of partitions known to the system
Randy Dunlap8b607562007-05-09 07:19:14 +0200616 pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 decoupled by lspci (2.4)
618 rtc Real time clock
619 scsi SCSI info (see text)
620 slabinfo Slab pool info
Keika Kobayashid3d64df2009-06-17 16:25:55 -0700621 softirqs softirq usage
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622 stat Overall statistics
623 swaps Swap space utilization
624 sys See chapter 2
625 sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
626 tty Info of tty drivers
Rob Landley49457892013-12-31 22:34:04 -0600627 uptime Wall clock since boot, combined idle time of all cpus
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 version Kernel version
629 video bttv info of video resources (2.4)
Eric Dumazeta47a1262008-07-23 21:27:38 -0700630 vmallocinfo Show vmalloced areas
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631..............................................................................
632
633You can, for example, check which interrupts are currently in use and what
634they are used for by looking in the file /proc/interrupts:
635
636 > cat /proc/interrupts
637 CPU0
638 0: 8728810 XT-PIC timer
639 1: 895 XT-PIC keyboard
640 2: 0 XT-PIC cascade
641 3: 531695 XT-PIC aha152x
642 4: 2014133 XT-PIC serial
643 5: 44401 XT-PIC pcnet_cs
644 8: 2 XT-PIC rtc
645 11: 8 XT-PIC i82365
646 12: 182918 XT-PIC PS/2 Mouse
647 13: 1 XT-PIC fpu
648 14: 1232265 XT-PIC ide0
649 15: 7 XT-PIC ide1
650 NMI: 0
651
652In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
653output of a SMP machine):
654
655 > cat /proc/interrupts
656
657 CPU0 CPU1
658 0: 1243498 1214548 IO-APIC-edge timer
659 1: 8949 8958 IO-APIC-edge keyboard
660 2: 0 0 XT-PIC cascade
661 5: 11286 10161 IO-APIC-edge soundblaster
662 8: 1 0 IO-APIC-edge rtc
663 9: 27422 27407 IO-APIC-edge 3c503
664 12: 113645 113873 IO-APIC-edge PS/2 Mouse
665 13: 0 0 XT-PIC fpu
666 14: 22491 24012 IO-APIC-edge ide0
667 15: 2183 2415 IO-APIC-edge ide1
668 17: 30564 30414 IO-APIC-level eth0
669 18: 177 164 IO-APIC-level bttv
670 NMI: 2457961 2457959
671 LOC: 2457882 2457881
672 ERR: 2155
673
674NMI is incremented in this case because every timer interrupt generates a NMI
675(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups.
676
677LOC is the local interrupt counter of the internal APIC of every CPU.
678
679ERR is incremented in the case of errors in the IO-APIC bus (the bus that
680connects the CPUs in a SMP system. This means that an error has been detected,
681the IO-APIC automatically retry the transmission, so it should not be a big
682problem, but you should read the SMP-FAQ.
683
Joe Korty38e760a2007-10-17 18:04:40 +0200684In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
685/proc/interrupts to display every IRQ vector in use by the system, not
686just those considered 'most important'. The new vectors are:
687
688 THR -- interrupt raised when a machine check threshold counter
689 (typically counting ECC corrected errors of memory or cache) exceeds
690 a configurable threshold. Only available on some systems.
691
692 TRM -- a thermal event interrupt occurs when a temperature threshold
693 has been exceeded for the CPU. This interrupt may also be generated
694 when the temperature drops back to normal.
695
696 SPU -- a spurious interrupt is some interrupt that was raised then lowered
697 by some IO device before it could be fully processed by the APIC. Hence
698 the APIC sees the interrupt but does not know what device it came from.
699 For this case the APIC will generate the interrupt with a IRQ vector
700 of 0xff. This might also be generated by chipset bugs.
701
702 RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are
703 sent from one CPU to another per the needs of the OS. Typically,
704 their statistics are used by kernel developers and interested users to
Matt LaPlante19f59462009-04-27 15:06:31 +0200705 determine the occurrence of interrupts of the given type.
Joe Korty38e760a2007-10-17 18:04:40 +0200706
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300707The above IRQ vectors are displayed only when relevant. For example,
Joe Korty38e760a2007-10-17 18:04:40 +0200708the threshold vector does not exist on x86_64 platforms. Others are
709suppressed when the system is a uniprocessor. As of this writing, only
710i386 and x86_64 platforms support the new IRQ vector displays.
711
712Of some interest is the introduction of the /proc/irq directory to 2.4.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713It could be used to set IRQ to CPU affinity, this means that you can "hook" an
714IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
Max Krasnyansky18404752008-05-29 11:02:52 -0700715irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and
716prof_cpu_mask.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717
718For example
719 > ls /proc/irq/
720 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
Max Krasnyansky18404752008-05-29 11:02:52 -0700721 1 11 13 15 17 19 3 5 7 9 default_smp_affinity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 > ls /proc/irq/0/
723 smp_affinity
724
Max Krasnyansky18404752008-05-29 11:02:52 -0700725smp_affinity is a bitmask, in which you can specify which CPUs can handle the
726IRQ, you can set it by doing:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727
Max Krasnyansky18404752008-05-29 11:02:52 -0700728 > echo 1 > /proc/irq/10/smp_affinity
729
730This means that only the first CPU will handle the IRQ, but you can also echo
John Kacur99e9d952016-06-17 15:05:15 +02007315 which means that only the first and third CPU can handle the IRQ.
Max Krasnyansky18404752008-05-29 11:02:52 -0700732
733The contents of each smp_affinity file is the same by default:
734
735 > cat /proc/irq/0/smp_affinity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736 ffffffff
737
Mike Travis4b060422011-05-24 17:13:12 -0700738There is an alternate interface, smp_affinity_list which allows specifying
739a cpu range instead of a bitmask:
740
741 > cat /proc/irq/0/smp_affinity_list
742 1024-1031
743
Max Krasnyansky18404752008-05-29 11:02:52 -0700744The default_smp_affinity mask applies to all non-active IRQs, which are the
745IRQs which have not yet been allocated/activated, and hence which lack a
746/proc/irq/[0-9]* directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747
Dimitri Sivanich92d6b712010-03-11 14:08:56 -0800748The node file on an SMP system shows the node to which the device using the IRQ
749reports itself as being attached. This hardware locality information does not
750include information about any possible driver locality preference.
751
Max Krasnyansky18404752008-05-29 11:02:52 -0700752prof_cpu_mask specifies which CPUs are to be profiled by the system wide
Mike Travis4b060422011-05-24 17:13:12 -0700753profiler. Default value is ffffffff (all cpus if there are only 32 of them).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754
755The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
756between all the CPUs which are allowed to handle it. As usual the kernel has
757more info than you and does a better job than you, so the defaults are the
Mike Travis4b060422011-05-24 17:13:12 -0700758best choice for almost everyone. [Note this applies only to those IO-APIC's
759that support "Round Robin" interrupt distribution.]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760
761There are three more important subdirectories in /proc: net, scsi, and sys.
762The general rule is that the contents, or even the existence of these
763directories, depend on your kernel configuration. If SCSI is not enabled, the
764directory scsi may not exist. The same is true with the net, which is there
765only when networking support is present in the running kernel.
766
767The slabinfo file gives information about memory usage at the slab level.
768Linux uses slab pools for memory management above page level in version 2.2.
769Commonly used objects have their own slab pool (such as network buffers,
770directory cache, and so on).
771
772..............................................................................
773
774> cat /proc/buddyinfo
775
776Node 0, zone DMA 0 4 5 4 4 3 ...
777Node 0, zone Normal 1 0 0 1 101 8 ...
778Node 0, zone HighMem 2 0 0 1 1 0 ...
779
Mel Gormana1b57ac2010-03-05 13:42:15 -0800780External fragmentation is a problem under some workloads, and buddyinfo is a
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781useful tool for helping diagnose these problems. Buddyinfo will give you a
782clue as to how big an area you can safely allocate, or why a previous
783allocation failed.
784
785Each column represents the number of pages of a certain order which are
786available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in
787ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
788available in ZONE_NORMAL, etc...
789
Mel Gormana1b57ac2010-03-05 13:42:15 -0800790More information relevant to external fragmentation can be found in
791pagetypeinfo.
792
793> cat /proc/pagetypeinfo
794Page block order: 9
795Pages per block: 512
796
797Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
798Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
799Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
800Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
801Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
802Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
803Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
804Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
805Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
806Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
807Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
808
809Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
810Node 0, zone DMA 2 0 5 1 0
811Node 0, zone DMA32 41 6 967 2 0
812
813Fragmentation avoidance in the kernel works by grouping pages of different
814migrate types into the same contiguous regions of memory called page blocks.
815A page block is typically the size of the default hugepage size e.g. 2MB on
816X86-64. By keeping pages grouped based on their ability to move, the kernel
817can reclaim pages within a page block to satisfy a high-order allocation.
818
819The pagetypinfo begins with information on the size of a page block. It
820then gives the same type of information as buddyinfo except broken down
821by migrate-type and finishes with details on how many page blocks of each
822type exist.
823
824If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
SeongJae Parkceec86ec2016-01-13 16:47:56 +0900825from libhugetlbfs https://github.com/libhugetlbfs/libhugetlbfs/), one can
Mel Gormana1b57ac2010-03-05 13:42:15 -0800826make an estimate of the likely number of huge pages that can be allocated
827at a given point in time. All the "Movable" blocks should be allocatable
828unless memory has been mlock()'d. Some of the Reclaimable blocks should
829also be allocatable although a lot of filesystem metadata may have to be
830reclaimed to achieve this.
831
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832..............................................................................
833
834meminfo:
835
836Provides information about distribution and utilization of memory. This
837varies by architecture and compile options. The following is from a
83816GB PIII, which has highmem enabled. You may not have all of these fields.
839
840> cat /proc/meminfo
841
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842MemTotal: 16344972 kB
843MemFree: 13634064 kB
Rik van Riel34e431b2014-01-21 15:49:05 -0800844MemAvailable: 14836172 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845Buffers: 3656 kB
846Cached: 1195708 kB
847SwapCached: 0 kB
848Active: 891636 kB
849Inactive: 1077224 kB
850HighTotal: 15597528 kB
851HighFree: 13629632 kB
852LowTotal: 747444 kB
853LowFree: 4432 kB
854SwapTotal: 0 kB
855SwapFree: 0 kB
856Dirty: 968 kB
857Writeback: 0 kB
Miklos Szeredib88473f2008-04-30 00:54:39 -0700858AnonPages: 861800 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859Mapped: 280372 kB
Rodrigo Freire0bc126d2016-01-14 15:21:58 -0800860Shmem: 644 kB
Miklos Szeredib88473f2008-04-30 00:54:39 -0700861Slab: 284364 kB
862SReclaimable: 159856 kB
863SUnreclaim: 124508 kB
864PageTables: 24448 kB
865NFS_Unstable: 0 kB
866Bounce: 0 kB
867WritebackTmp: 0 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868CommitLimit: 7669796 kB
869Committed_AS: 100056 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870VmallocTotal: 112216 kB
871VmallocUsed: 428 kB
872VmallocChunk: 111088 kB
Mel Gorman69256992012-05-29 15:06:45 -0700873AnonHugePages: 49152 kB
Kirill A. Shutemov1b5946a2016-07-26 15:26:40 -0700874ShmemHugePages: 0 kB
875ShmemPmdMapped: 0 kB
876
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877
878 MemTotal: Total usable ram (i.e. physical ram minus a few reserved
879 bits and the kernel binary code)
880 MemFree: The sum of LowFree+HighFree
Rik van Riel34e431b2014-01-21 15:49:05 -0800881MemAvailable: An estimate of how much memory is available for starting new
882 applications, without swapping. Calculated from MemFree,
883 SReclaimable, the size of the file LRU lists, and the low
884 watermarks in each zone.
885 The estimate takes into account that the system needs some
886 page cache to function well, and that not all reclaimable
887 slab will be reclaimable, due to items being in use. The
888 impact of those factors will vary from system to system.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889 Buffers: Relatively temporary storage for raw disk blocks
890 shouldn't get tremendously large (20MB or so)
891 Cached: in-memory cache for files read from the disk (the
892 pagecache). Doesn't include SwapCached
893 SwapCached: Memory that once was swapped out, is swapped back in but
894 still also is in the swapfile (if memory is needed it
895 doesn't need to be swapped out AGAIN because it is already
896 in the swapfile. This saves I/O)
897 Active: Memory that has been used more recently and usually not
898 reclaimed unless absolutely necessary.
899 Inactive: Memory which has been less recently used. It is more
900 eligible to be reclaimed for other purposes
901 HighTotal:
902 HighFree: Highmem is all memory above ~860MB of physical memory
903 Highmem areas are for use by userspace programs, or
904 for the pagecache. The kernel must use tricks to access
905 this memory, making it slower to access than lowmem.
906 LowTotal:
907 LowFree: Lowmem is memory which can be used for everything that
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200908 highmem can be used for, but it is also available for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 kernel's use for its own data structures. Among many
910 other things, it is where everything from the Slab is
911 allocated. Bad things happen when you're out of lowmem.
912 SwapTotal: total amount of swap space available
913 SwapFree: Memory which has been evicted from RAM, and is temporarily
914 on the disk
915 Dirty: Memory which is waiting to get written back to the disk
916 Writeback: Memory which is actively being written back to the disk
Miklos Szeredib88473f2008-04-30 00:54:39 -0700917 AnonPages: Non-file backed pages mapped into userspace page tables
Mel Gorman69256992012-05-29 15:06:45 -0700918AnonHugePages: Non-file backed huge pages mapped into userspace page tables
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919 Mapped: files which have been mmaped, such as libraries
Rodrigo Freire0bc126d2016-01-14 15:21:58 -0800920 Shmem: Total memory used by shared memory (shmem) and tmpfs
Kirill A. Shutemov1b5946a2016-07-26 15:26:40 -0700921ShmemHugePages: Memory used by shared memory (shmem) and tmpfs allocated
922 with huge pages
923ShmemPmdMapped: Shared memory mapped into userspace with huge pages
Adrian Bunke82443c2006-01-10 00:20:30 +0100924 Slab: in-kernel data structures cache
Miklos Szeredib88473f2008-04-30 00:54:39 -0700925SReclaimable: Part of Slab, that might be reclaimed, such as caches
926 SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure
927 PageTables: amount of memory dedicated to the lowest level of page
928 tables.
929NFS_Unstable: NFS pages sent to the server, but not yet committed to stable
930 storage
931 Bounce: Memory used for block device "bounce buffers"
932WritebackTmp: Memory used by FUSE for temporary writeback buffers
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933 CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'),
934 this is the total amount of memory currently available to
935 be allocated on the system. This limit is only adhered to
936 if strict overcommit accounting is enabled (mode 2 in
937 'vm.overcommit_memory').
938 The CommitLimit is calculated with the following formula:
Petr Oros7a9e6da2014-05-22 14:04:44 +0200939 CommitLimit = ([total RAM pages] - [total huge TLB pages]) *
940 overcommit_ratio / 100 + [total swap pages]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700941 For example, on a system with 1G of physical RAM and 7G
942 of swap with a `vm.overcommit_ratio` of 30 it would
943 yield a CommitLimit of 7.3G.
944 For more details, see the memory overcommit documentation
945 in vm/overcommit-accounting.
946Committed_AS: The amount of memory presently allocated on the system.
947 The committed memory is a sum of all of the memory which
948 has been allocated by processes, even if it has not been
949 "used" by them as of yet. A process which malloc()'s 1G
Minto Joseph46496022013-09-11 14:24:35 -0700950 of memory, but only touches 300M of it will show up as
951 using 1G. This 1G is memory which has been "committed" to
952 by the VM and can be used at any time by the allocating
953 application. With strict overcommit enabled on the system
954 (mode 2 in 'vm.overcommit_memory'),allocations which would
955 exceed the CommitLimit (detailed above) will not be permitted.
956 This is useful if one needs to guarantee that processes will
957 not fail due to lack of memory once that memory has been
958 successfully allocated.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959VmallocTotal: total size of vmalloc memory area
960 VmallocUsed: amount of vmalloc area which is used
Matt LaPlante19f59462009-04-27 15:06:31 +0200961VmallocChunk: largest contiguous block of vmalloc area which is free
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962
Eric Dumazeta47a1262008-07-23 21:27:38 -0700963..............................................................................
964
965vmallocinfo:
966
967Provides information about vmalloced/vmaped areas. One line per area,
968containing the virtual address range of the area, size in bytes,
969caller information of the creator, and optional information depending
970on the kind of area :
971
972 pages=nr number of pages
973 phys=addr if a physical address was specified
974 ioremap I/O mapping (ioremap() and friends)
975 vmalloc vmalloc() area
976 vmap vmap()ed pages
977 user VM_USERMAP area
978 vpages buffer for pages pointers was vmalloced (huge area)
979 N<node>=nr (Only on NUMA kernels)
980 Number of pages allocated on memory node <node>
981
982> cat /proc/vmallocinfo
9830xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
984 /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
9850xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
986 /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
9870xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
988 phys=7fee8000 ioremap
9890xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
990 phys=7fee7000 ioremap
9910xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
9920xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
993 /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
9940xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
995 pages=2 vmalloc N1=2
9960xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
997 /0x130 [x_tables] pages=4 vmalloc N0=4
9980xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
999 pages=14 vmalloc N2=14
10000xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
1001 pages=4 vmalloc N1=4
10020xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
1003 pages=2 vmalloc N1=2
10040xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
1005 pages=10 vmalloc N0=10
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001007..............................................................................
1008
1009softirqs:
1010
1011Provides counts of softirq handlers serviced since boot time, for each cpu.
1012
1013> cat /proc/softirqs
1014 CPU0 CPU1 CPU2 CPU3
1015 HI: 0 0 0 0
1016 TIMER: 27166 27120 27097 27034
1017 NET_TX: 0 0 0 17
1018 NET_RX: 42 0 0 39
1019 BLOCK: 0 0 107 1121
1020 TASKLET: 0 0 0 290
1021 SCHED: 27035 26983 26971 26746
1022 HRTIMER: 0 0 0 0
Shaohua Li09223372011-06-14 13:26:25 +08001023 RCU: 1678 1769 2178 2250
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001024
1025
Linus Torvalds1da177e2005-04-16 15:20:36 -070010261.3 IDE devices in /proc/ide
1027----------------------------
1028
1029The subdirectory /proc/ide contains information about all IDE devices of which
1030the kernel is aware. There is one subdirectory for each IDE controller, the
1031file drivers and a link for each IDE device, pointing to the device directory
1032in the controller specific subtree.
1033
1034The file drivers contains general information about the drivers used for the
1035IDE devices:
1036
1037 > cat /proc/ide/drivers
1038 ide-cdrom version 4.53
1039 ide-disk version 1.08
1040
1041More detailed information can be found in the controller specific
1042subdirectories. These are named ide0, ide1 and so on. Each of these
Stefani Seibold349888e2009-06-17 16:26:01 -07001043directories contains the files shown in table 1-6.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044
1045
Stefani Seibold349888e2009-06-17 16:26:01 -07001046Table 1-6: IDE controller info in /proc/ide/ide?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047..............................................................................
1048 File Content
1049 channel IDE channel (0 or 1)
1050 config Configuration (only for PCI/IDE bridge)
1051 mate Mate name
1052 model Type/Chipset of IDE controller
1053..............................................................................
1054
1055Each device connected to a controller has a separate subdirectory in the
Stefani Seibold349888e2009-06-17 16:26:01 -07001056controllers directory. The files listed in table 1-7 are contained in these
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057directories.
1058
1059
Stefani Seibold349888e2009-06-17 16:26:01 -07001060Table 1-7: IDE device information
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061..............................................................................
1062 File Content
1063 cache The cache
1064 capacity Capacity of the medium (in 512Byte blocks)
1065 driver driver and version
1066 geometry physical and logical geometry
1067 identify device identify block
1068 media media type
1069 model device identifier
1070 settings device setup
1071 smart_thresholds IDE disk management thresholds
1072 smart_values IDE disk management values
1073..............................................................................
1074
1075The most interesting file is settings. This file contains a nice overview of
1076the drive parameters:
1077
1078 # cat /proc/ide/ide0/hda/settings
1079 name value min max mode
1080 ---- ----- --- --- ----
1081 bios_cyl 526 0 65535 rw
1082 bios_head 255 0 255 rw
1083 bios_sect 63 0 63 rw
1084 breada_readahead 4 0 127 rw
1085 bswap 0 0 1 r
1086 file_readahead 72 0 2097151 rw
1087 io_32bit 0 0 3 rw
1088 keepsettings 0 0 1 rw
1089 max_kb_per_request 122 1 127 rw
1090 multcount 0 0 8 rw
1091 nice1 1 0 1 rw
1092 nowerr 0 0 1 rw
1093 pio_mode write-only 0 255 w
1094 slow 0 0 1 rw
1095 unmaskirq 0 0 1 rw
1096 using_dma 0 0 1 rw
1097
1098
10991.4 Networking info in /proc/net
1100--------------------------------
1101
Stefani Seibold349888e2009-06-17 16:26:01 -07001102The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103additional values you get for IP version 6 if you configure the kernel to
Stefani Seibold349888e2009-06-17 16:26:01 -07001104support this. Table 1-9 lists the files and their meaning.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105
1106
Stefani Seibold349888e2009-06-17 16:26:01 -07001107Table 1-8: IPv6 info in /proc/net
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108..............................................................................
1109 File Content
1110 udp6 UDP sockets (IPv6)
1111 tcp6 TCP sockets (IPv6)
1112 raw6 Raw device statistics (IPv6)
1113 igmp6 IP multicast addresses, which this host joined (IPv6)
1114 if_inet6 List of IPv6 interface addresses
1115 ipv6_route Kernel routing table for IPv6
1116 rt6_stats Global IPv6 routing tables statistics
1117 sockstat6 Socket statistics (IPv6)
1118 snmp6 Snmp data (IPv6)
1119..............................................................................
1120
1121
Stefani Seibold349888e2009-06-17 16:26:01 -07001122Table 1-9: Network info in /proc/net
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123..............................................................................
1124 File Content
1125 arp Kernel ARP table
1126 dev network devices with statistics
1127 dev_mcast the Layer2 multicast groups a device is listening too
1128 (interface index, label, number of references, number of bound
1129 addresses).
1130 dev_stat network device status
1131 ip_fwchains Firewall chain linkage
1132 ip_fwnames Firewall chain names
1133 ip_masq Directory containing the masquerading tables
1134 ip_masquerade Major masquerading table
1135 netstat Network statistics
1136 raw raw device statistics
1137 route Kernel routing table
1138 rpc Directory containing rpc info
1139 rt_cache Routing cache
1140 snmp SNMP data
1141 sockstat Socket statistics
1142 tcp TCP sockets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 udp UDP sockets
1144 unix UNIX domain sockets
1145 wireless Wireless interface data (Wavelan etc)
1146 igmp IP multicast addresses, which this host joined
1147 psched Global packet scheduler parameters.
1148 netlink List of PF_NETLINK sockets
1149 ip_mr_vifs List of multicast virtual interfaces
1150 ip_mr_cache List of multicast routing cache
1151..............................................................................
1152
1153You can use this information to see which network devices are available in
1154your system and how much traffic was routed over those devices:
1155
1156 > cat /proc/net/dev
1157 Inter-|Receive |[...
1158 face |bytes packets errs drop fifo frame compressed multicast|[...
1159 lo: 908188 5596 0 0 0 0 0 0 [...
1160 ppp0:15475140 20721 410 0 0 410 0 0 [...
1161 eth0: 614530 7085 0 0 0 0 0 1 [...
1162
1163 ...] Transmit
1164 ...] bytes packets errs drop fifo colls carrier compressed
1165 ...] 908188 5596 0 0 0 0 0 0
1166 ...] 1375103 17405 0 0 0 0 0 0
1167 ...] 1703981 5535 0 0 0 3 0 0
1168
Francis Galieguea33f3222010-04-23 00:08:02 +02001169In addition, each Channel Bond interface has its own directory. For
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170example, the bond0 device will have a directory called /proc/net/bond0/.
1171It will contain information that is specific to that bond, such as the
1172current slaves of the bond, the link status of the slaves, and how
1173many times the slaves link has failed.
1174
11751.5 SCSI info
1176-------------
1177
1178If you have a SCSI host adapter in your system, you'll find a subdirectory
1179named after the driver for this adapter in /proc/scsi. You'll also see a list
1180of all recognized SCSI devices in /proc/scsi:
1181
1182 >cat /proc/scsi/scsi
1183 Attached devices:
1184 Host: scsi0 Channel: 00 Id: 00 Lun: 00
1185 Vendor: IBM Model: DGHS09U Rev: 03E0
1186 Type: Direct-Access ANSI SCSI revision: 03
1187 Host: scsi0 Channel: 00 Id: 06 Lun: 00
1188 Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
1189 Type: CD-ROM ANSI SCSI revision: 02
1190
1191
1192The directory named after the driver has one file for each adapter found in
1193the system. These files contain information about the controller, including
1194the used IRQ and the IO address range. The amount of information shown is
1195dependent on the adapter you use. The example shows the output for an Adaptec
1196AHA-2940 SCSI adapter:
1197
1198 > cat /proc/scsi/aic7xxx/0
1199
1200 Adaptec AIC7xxx driver version: 5.1.19/3.2.4
1201 Compile Options:
1202 TCQ Enabled By Default : Disabled
1203 AIC7XXX_PROC_STATS : Disabled
1204 AIC7XXX_RESET_DELAY : 5
1205 Adapter Configuration:
1206 SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
1207 Ultra Wide Controller
1208 PCI MMAPed I/O Base: 0xeb001000
1209 Adapter SEEPROM Config: SEEPROM found and used.
1210 Adaptec SCSI BIOS: Enabled
1211 IRQ: 10
1212 SCBs: Active 0, Max Active 2,
1213 Allocated 15, HW 16, Page 255
1214 Interrupts: 160328
1215 BIOS Control Word: 0x18b6
1216 Adapter Control Word: 0x005b
1217 Extended Translation: Enabled
1218 Disconnect Enable Flags: 0xffff
1219 Ultra Enable Flags: 0x0001
1220 Tag Queue Enable Flags: 0x0000
1221 Ordered Queue Tag Flags: 0x0000
1222 Default Tag Queue Depth: 8
1223 Tagged Queue By Device array for aic7xxx host instance 0:
1224 {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
1225 Actual queue depth per device for aic7xxx host instance 0:
1226 {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
1227 Statistics:
1228 (scsi0:0:0:0)
1229 Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
1230 Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0)
1231 Total transfers 160151 (74577 reads and 85574 writes)
1232 (scsi0:0:6:0)
1233 Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
1234 Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0)
1235 Total transfers 0 (0 reads and 0 writes)
1236
1237
12381.6 Parallel port info in /proc/parport
1239---------------------------------------
1240
1241The directory /proc/parport contains information about the parallel ports of
1242your system. It has one subdirectory for each port, named after the port
1243number (0,1,2,...).
1244
Stefani Seibold349888e2009-06-17 16:26:01 -07001245These directories contain the four files shown in Table 1-10.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246
1247
Stefani Seibold349888e2009-06-17 16:26:01 -07001248Table 1-10: Files in /proc/parport
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249..............................................................................
1250 File Content
1251 autoprobe Any IEEE-1284 device ID information that has been acquired.
1252 devices list of the device drivers using that port. A + will appear by the
1253 name of the device currently using the port (it might not appear
1254 against any).
1255 hardware Parallel port's base address, IRQ line and DMA channel.
1256 irq IRQ that parport is using for that port. This is in a separate
1257 file to allow you to alter it by writing a new value in (IRQ
1258 number or none).
1259..............................................................................
1260
12611.7 TTY info in /proc/tty
1262-------------------------
1263
1264Information about the available and actually used tty's can be found in the
1265directory /proc/tty.You'll find entries for drivers and line disciplines in
Stefani Seibold349888e2009-06-17 16:26:01 -07001266this directory, as shown in Table 1-11.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001267
1268
Stefani Seibold349888e2009-06-17 16:26:01 -07001269Table 1-11: Files in /proc/tty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270..............................................................................
1271 File Content
1272 drivers list of drivers and their usage
1273 ldiscs registered line disciplines
1274 driver/serial usage statistic and status of single tty lines
1275..............................................................................
1276
1277To see which tty's are currently in use, you can simply look into the file
1278/proc/tty/drivers:
1279
1280 > cat /proc/tty/drivers
1281 pty_slave /dev/pts 136 0-255 pty:slave
1282 pty_master /dev/ptm 128 0-255 pty:master
1283 pty_slave /dev/ttyp 3 0-255 pty:slave
1284 pty_master /dev/pty 2 0-255 pty:master
1285 serial /dev/cua 5 64-67 serial:callout
1286 serial /dev/ttyS 4 64-67 serial
1287 /dev/tty0 /dev/tty0 4 0 system:vtmaster
1288 /dev/ptmx /dev/ptmx 5 2 system
1289 /dev/console /dev/console 5 1 system:console
1290 /dev/tty /dev/tty 5 0 system:/dev/tty
1291 unknown /dev/tty 4 1-63 console
1292
1293
12941.8 Miscellaneous kernel statistics in /proc/stat
1295-------------------------------------------------
1296
1297Various pieces of information about kernel activity are available in the
1298/proc/stat file. All of the numbers reported in this file are aggregates
1299since the system first booted. For a quick look, simply cat the file:
1300
1301 > cat /proc/stat
Tobias Klauserc8a329c2015-03-30 15:49:26 +02001302 cpu 2255 34 2290 22625563 6290 127 456 0 0 0
1303 cpu0 1132 34 1441 11311718 3675 127 438 0 0 0
1304 cpu1 1123 0 849 11313845 2614 0 18 0 0 0
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305 intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
1306 ctxt 1990473
1307 btime 1062191376
1308 processes 2915
1309 procs_running 1
1310 procs_blocked 0
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001311 softirq 183433 0 21755 12 39 1137 231 21459 2263
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312
1313The very first "cpu" line aggregates the numbers in all of the other "cpuN"
1314lines. These numbers identify the amount of time the CPU has spent performing
1315different kinds of work. Time units are in USER_HZ (typically hundredths of a
1316second). The meanings of the columns are as follows, from left to right:
1317
1318- user: normal processes executing in user mode
1319- nice: niced processes executing in user mode
1320- system: processes executing in kernel mode
1321- idle: twiddling thumbs
1322- iowait: waiting for I/O to complete
1323- irq: servicing interrupts
1324- softirq: servicing softirqs
Leonardo Chiquittob68f2c3a2007-10-20 03:03:38 +02001325- steal: involuntary wait
Ryota Ozakice0e7b22009-10-24 01:20:10 +09001326- guest: running a normal guest
1327- guest_nice: running a niced guest
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328
1329The "intr" line gives counts of interrupts serviced since boot time, for each
1330of the possible system interrupts. The first column is the total of all
Jan Moskyto Matejka3568a1d2014-05-15 13:55:34 -07001331interrupts serviced including unnumbered architecture specific interrupts;
1332each subsequent column is the total for that particular numbered interrupt.
1333Unnumbered interrupts are not shown, only summed into the total.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334
1335The "ctxt" line gives the total number of context switches across all CPUs.
1336
1337The "btime" line gives the time at which the system booted, in seconds since
1338the Unix epoch.
1339
1340The "processes" line gives the number of processes and threads created, which
1341includes (but is not limited to) those created by calls to the fork() and
1342clone() system calls.
1343
Luis Garces-Ericee3cc2222009-12-06 18:30:44 -08001344The "procs_running" line gives the total number of threads that are
1345running or ready to run (i.e., the total number of runnable threads).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346
1347The "procs_blocked" line gives the number of processes currently blocked,
1348waiting for I/O to complete.
1349
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001350The "softirq" line gives counts of softirqs serviced since boot time, for each
1351of the possible system softirqs. The first column is the total of all
1352softirqs serviced; each subsequent column is the total for that particular
1353softirq.
1354
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001355
Alex Tomasc9de5602008-01-29 00:19:52 -050013561.9 Ext4 file system parameters
Maisa Roponen690b0542014-11-24 09:54:17 +02001357-------------------------------
Alex Tomasc9de5602008-01-29 00:19:52 -05001358
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001359Information about mounted ext4 file systems can be found in
1360/proc/fs/ext4. Each mounted filesystem will have a directory in
1361/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
1362/proc/fs/ext4/dm-0). The files in each per-device directory are shown
Stefani Seibold349888e2009-06-17 16:26:01 -07001363in Table 1-12, below.
Alex Tomasc9de5602008-01-29 00:19:52 -05001364
Stefani Seibold349888e2009-06-17 16:26:01 -07001365Table 1-12: Files in /proc/fs/ext4/<devname>
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001366..............................................................................
1367 File Content
1368 mb_groups details of multiblock allocator buddy cache of free blocks
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001369..............................................................................
Alex Tomasc9de5602008-01-29 00:19:52 -05001370
Jiri Slaby23308ba2010-11-04 16:20:24 +010013712.0 /proc/consoles
1372------------------
1373Shows registered system console lines.
1374
1375To see which character device lines are currently used for the system console
1376/dev/console, you may simply look into the file /proc/consoles:
1377
1378 > cat /proc/consoles
1379 tty0 -WU (ECp) 4:7
1380 ttyS0 -W- (Ep) 4:64
1381
1382The columns are:
1383
1384 device name of the device
1385 operations R = can do read operations
1386 W = can do write operations
1387 U = can do unblank
1388 flags E = it is enabled
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001389 C = it is preferred console
Jiri Slaby23308ba2010-11-04 16:20:24 +01001390 B = it is primary boot console
1391 p = it is used for printk buffer
1392 b = it is not a TTY but a Braille device
1393 a = it is safe to use when cpu is offline
1394 major:minor major and minor number of the device separated by a colon
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395
1396------------------------------------------------------------------------------
1397Summary
1398------------------------------------------------------------------------------
1399The /proc file system serves information about the running system. It not only
1400allows access to process data but also allows you to request the kernel status
1401by reading files in the hierarchy.
1402
1403The directory structure of /proc reflects the types of information and makes
1404it easy, if not obvious, where to look for specific data.
1405------------------------------------------------------------------------------
1406
1407------------------------------------------------------------------------------
1408CHAPTER 2: MODIFYING SYSTEM PARAMETERS
1409------------------------------------------------------------------------------
1410
1411------------------------------------------------------------------------------
1412In This Chapter
1413------------------------------------------------------------------------------
1414* Modifying kernel parameters by writing into files found in /proc/sys
1415* Exploring the files which modify certain parameters
1416* Review of the /proc/sys file tree
1417------------------------------------------------------------------------------
1418
1419
1420A very interesting part of /proc is the directory /proc/sys. This is not only
1421a source of information, it also allows you to change parameters within the
1422kernel. Be very careful when attempting this. You can optimize your system,
1423but you can also cause it to crash. Never alter kernel parameters on a
1424production system. Set up a development machine and test to make sure that
1425everything works the way you want it to. You may have no alternative but to
1426reboot the machine once an error has been made.
1427
1428To change a value, simply echo the new value into the file. An example is
1429given below in the section on the file system data. You need to be root to do
1430this. You can create your own boot script to perform this every time your
1431system boots.
1432
1433The files in /proc/sys can be used to fine tune and monitor miscellaneous and
1434general things in the operation of the Linux kernel. Since some of the files
1435can inadvertently disrupt your system, it is advisable to read both
1436documentation and source before actually making adjustments. In any case, be
1437very careful when writing to any of these files. The entries in /proc may
1438change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
1439review the kernel documentation in the directory /usr/src/linux/Documentation.
1440This chapter is heavily based on the documentation included in the pre 2.2
1441kernels, and became part of it in version 2.2.1 of the Linux kernel.
1442
Paul Bolle395cf962011-08-15 02:02:26 +02001443Please see: Documentation/sysctl/ directory for descriptions of these
Peter W Morrealedb0fb182009-01-15 13:50:42 -08001444entries.
Andrew Morton9d0243b2006-01-08 01:00:39 -08001445
Shen Feng760df932009-04-02 16:57:20 -07001446------------------------------------------------------------------------------
1447Summary
1448------------------------------------------------------------------------------
1449Certain aspects of kernel behavior can be modified at runtime, without the
1450need to recompile the kernel, or even to reboot the system. The files in the
1451/proc/sys tree can not only be read, but also modified. You can use the echo
1452command to write value into these files, thereby changing the default settings
1453of the kernel.
1454------------------------------------------------------------------------------
Andrew Morton9d0243b2006-01-08 01:00:39 -08001455
Shen Feng760df932009-04-02 16:57:20 -07001456------------------------------------------------------------------------------
1457CHAPTER 3: PER-PROCESS PARAMETERS
1458------------------------------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459
David Rientjesfa0cbbf2012-11-12 17:53:04 -080014603.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
David Rientjesa63d83f2010-08-09 17:19:46 -07001461--------------------------------------------------------------------------------
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001462
David Rientjesfa0cbbf2012-11-12 17:53:04 -08001463These file can be used to adjust the badness heuristic used to select which
David Rientjesa63d83f2010-08-09 17:19:46 -07001464process gets killed in out of memory conditions.
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001465
David Rientjesa63d83f2010-08-09 17:19:46 -07001466The badness heuristic assigns a value to each candidate task ranging from 0
1467(never kill) to 1000 (always kill) to determine which process is targeted. The
1468units are roughly a proportion along that range of allowed memory the process
1469may allocate from based on an estimation of its current memory and swap use.
1470For example, if a task is using all allowed memory, its badness score will be
14711000. If it is using half of its allowed memory, its score will be 500.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001472
David Rientjes778c14a2014-01-30 15:46:11 -08001473There is an additional factor included in the badness score: the current memory
1474and swap usage is discounted by 3% for root processes.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001475
David Rientjesa63d83f2010-08-09 17:19:46 -07001476The amount of "allowed" memory depends on the context in which the oom killer
1477was called. If it is due to the memory assigned to the allocating task's cpuset
1478being exhausted, the allowed memory represents the set of mems assigned to that
1479cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed
1480memory represents the set of mempolicy nodes. If it is due to a memory
1481limit (or swap limit) being reached, the allowed memory is that configured
1482limit. Finally, if it is due to the entire system being out of memory, the
1483allowed memory represents all allocatable resources.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001484
David Rientjesa63d83f2010-08-09 17:19:46 -07001485The value of /proc/<pid>/oom_score_adj is added to the badness score before it
1486is used to determine which task to kill. Acceptable values range from -1000
1487(OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to
1488polarize the preference for oom killing either by always preferring a certain
1489task or completely disabling it. The lowest possible value, -1000, is
1490equivalent to disabling oom killing entirely for that task since it will always
1491report a badness score of 0.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001492
David Rientjesa63d83f2010-08-09 17:19:46 -07001493Consequently, it is very simple for userspace to define the amount of memory to
1494consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for
1495example, is roughly equivalent to allowing the remainder of tasks sharing the
1496same system, cpuset, mempolicy, or memory controller resources to use at least
149750% more memory. A value of -500, on the other hand, would be roughly
1498equivalent to discounting 50% of the task's allowed memory from being considered
1499as scoring against the task.
1500
David Rientjesfa0cbbf2012-11-12 17:53:04 -08001501For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
1502be used to tune the badness score. Its acceptable values range from -16
1503(OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
1504(OOM_DISABLE) to disable oom killing entirely for that task. Its value is
1505scaled linearly with /proc/<pid>/oom_score_adj.
1506
Mandeep Singh Bainesdabb16f2011-01-13 15:46:05 -08001507The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
1508value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
1509requires CAP_SYS_RESOURCE.
1510
David Rientjesa63d83f2010-08-09 17:19:46 -07001511Caveat: when a parent task is selected, the oom killer will sacrifice any first
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001512generation children with separate address spaces instead, if possible. This
David Rientjesa63d83f2010-08-09 17:19:46 -07001513avoids servers and important system daemons from being killed and loses the
1514minimal amount of work.
1515
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001516
Shen Feng760df932009-04-02 16:57:20 -070015173.2 /proc/<pid>/oom_score - Display current oom-killer score
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001518-------------------------------------------------------------
1519
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001520This file can be used to check the current score used by the oom-killer is for
David Rientjesfa0cbbf2012-11-12 17:53:04 -08001521any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which
1522process should be killed in an out-of-memory situation.
1523
Roland Kletzingf9c99462007-03-05 00:30:54 -08001524
Shen Feng760df932009-04-02 16:57:20 -070015253.3 /proc/<pid>/io - Display the IO accounting fields
Roland Kletzingf9c99462007-03-05 00:30:54 -08001526-------------------------------------------------------
1527
1528This file contains IO statistics for each running process
1529
1530Example
1531-------
1532
1533test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
1534[1] 3828
1535
1536test:/tmp # cat /proc/3828/io
1537rchar: 323934931
1538wchar: 323929600
1539syscr: 632687
1540syscw: 632675
1541read_bytes: 0
1542write_bytes: 323932160
1543cancelled_write_bytes: 0
1544
1545
1546Description
1547-----------
1548
1549rchar
1550-----
1551
1552I/O counter: chars read
1553The number of bytes which this task has caused to be read from storage. This
1554is simply the sum of bytes which this process passed to read() and pread().
1555It includes things like tty IO and it is unaffected by whether or not actual
1556physical disk IO was required (the read might have been satisfied from
1557pagecache)
1558
1559
1560wchar
1561-----
1562
1563I/O counter: chars written
1564The number of bytes which this task has caused, or shall cause to be written
1565to disk. Similar caveats apply here as with rchar.
1566
1567
1568syscr
1569-----
1570
1571I/O counter: read syscalls
1572Attempt to count the number of read I/O operations, i.e. syscalls like read()
1573and pread().
1574
1575
1576syscw
1577-----
1578
1579I/O counter: write syscalls
1580Attempt to count the number of write I/O operations, i.e. syscalls like
1581write() and pwrite().
1582
1583
1584read_bytes
1585----------
1586
1587I/O counter: bytes read
1588Attempt to count the number of bytes which this process really did cause to
1589be fetched from the storage layer. Done at the submit_bio() level, so it is
1590accurate for block-backed filesystems. <please add status regarding NFS and
1591CIFS at a later time>
1592
1593
1594write_bytes
1595-----------
1596
1597I/O counter: bytes written
1598Attempt to count the number of bytes which this process caused to be sent to
1599the storage layer. This is done at page-dirtying time.
1600
1601
1602cancelled_write_bytes
1603---------------------
1604
1605The big inaccuracy here is truncate. If a process writes 1MB to a file and
1606then deletes the file, it will in fact perform no writeout. But it will have
1607been accounted as having caused 1MB of write.
1608In other words: The number of bytes which this process caused to not happen,
1609by truncating pagecache. A task can cause "negative" IO too. If this task
1610truncates some dirty pagecache, some IO which another task has been accounted
Francis Galieguea33f3222010-04-23 00:08:02 +02001611for (in its write_bytes) will not be happening. We _could_ just subtract that
Roland Kletzingf9c99462007-03-05 00:30:54 -08001612from the truncating task's write_bytes, but there is information loss in doing
1613that.
1614
1615
1616Note
1617----
1618
1619At its current implementation state, this is a bit racy on 32-bit machines: if
1620process A reads process B's /proc/pid/io while process B is updating one of
1621those 64-bit counters, process A could see an intermediate result.
1622
1623
1624More information about this can be found within the taskstats documentation in
1625Documentation/accounting.
1626
Shen Feng760df932009-04-02 16:57:20 -070016273.4 /proc/<pid>/coredump_filter - Core dump filtering settings
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001628---------------------------------------------------------------
1629When a process is dumped, all anonymous memory is written to a core file as
1630long as the size of the core file isn't limited. But sometimes we don't want
Ross Zwisler50378352015-10-05 16:33:36 -06001631to dump some memory segments, for example, huge shared memory or DAX.
1632Conversely, sometimes we want to save file-backed memory segments into a core
1633file, not only the individual files.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001634
1635/proc/<pid>/coredump_filter allows you to customize which memory segments
1636will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
1637of memory types. If a bit of the bitmask is set, memory segments of the
1638corresponding memory type are dumped, otherwise they are not dumped.
1639
Ross Zwisler50378352015-10-05 16:33:36 -06001640The following 9 memory types are supported:
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001641 - (bit 0) anonymous private memory
1642 - (bit 1) anonymous shared memory
1643 - (bit 2) file-backed private memory
1644 - (bit 3) file-backed shared memory
Hidehiro Kawaib261dfe2008-09-13 02:33:10 -07001645 - (bit 4) ELF header pages in file-backed private memory areas (it is
1646 effective only if the bit 2 is cleared)
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001647 - (bit 5) hugetlb private memory
1648 - (bit 6) hugetlb shared memory
Ross Zwisler50378352015-10-05 16:33:36 -06001649 - (bit 7) DAX private memory
1650 - (bit 8) DAX shared memory
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001651
1652 Note that MMIO pages such as frame buffer are never dumped and vDSO pages
1653 are always dumped regardless of the bitmask status.
1654
Ross Zwisler50378352015-10-05 16:33:36 -06001655 Note that bits 0-4 don't affect hugetlb or DAX memory. hugetlb memory is
1656 only affected by bit 5-6, and DAX is only affected by bits 7-8.
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001657
Ross Zwisler50378352015-10-05 16:33:36 -06001658The default value of coredump_filter is 0x33; this means all anonymous memory
1659segments, ELF header pages and hugetlb private memory are dumped.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001660
1661If you don't want to dump all shared memory segments attached to pid 1234,
Ross Zwisler50378352015-10-05 16:33:36 -06001662write 0x31 to the process's proc file.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001663
Ross Zwisler50378352015-10-05 16:33:36 -06001664 $ echo 0x31 > /proc/1234/coredump_filter
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001665
1666When a new process is created, the process inherits the bitmask status from its
1667parent. It is useful to set up coredump_filter before the program runs.
1668For example:
1669
1670 $ echo 0x7 > /proc/self/coredump_filter
1671 $ ./some_program
1672
Shen Feng760df932009-04-02 16:57:20 -070016733.5 /proc/<pid>/mountinfo - Information about mounts
Ram Pai2d4d4862008-03-27 13:06:25 +01001674--------------------------------------------------------
1675
1676This file contains lines of the form:
1677
167836 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
1679(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
1680
1681(1) mount ID: unique identifier of the mount (may be reused after umount)
1682(2) parent ID: ID of parent (or of self for the top of the mount tree)
1683(3) major:minor: value of st_dev for files on filesystem
1684(4) root: root of the mount within the filesystem
1685(5) mount point: mount point relative to the process's root
1686(6) mount options: per mount options
1687(7) optional fields: zero or more fields of the form "tag[:value]"
1688(8) separator: marks the end of the optional fields
1689(9) filesystem type: name of filesystem of the form "type[.subtype]"
1690(10) mount source: filesystem specific information or "none"
1691(11) super options: per super block options
1692
1693Parsers should ignore all unrecognised optional fields. Currently the
1694possible optional fields are:
1695
1696shared:X mount is shared in peer group X
1697master:X mount is slave to peer group X
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +01001698propagate_from:X mount is slave and receives propagation from peer group X (*)
Ram Pai2d4d4862008-03-27 13:06:25 +01001699unbindable mount is unbindable
1700
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +01001701(*) X is the closest dominant peer group under the process's root. If
1702X is the immediate master of the mount, or if there's no dominant peer
1703group under the same root, then only the "master:X" field is present
1704and not the "propagate_from:X" field.
1705
Ram Pai2d4d4862008-03-27 13:06:25 +01001706For more information on mount propagation see:
1707
1708 Documentation/filesystems/sharedsubtree.txt
1709
john stultz4614a696b2009-12-14 18:00:05 -08001710
17113.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
1712--------------------------------------------------------
1713These files provide a method to access a tasks comm value. It also allows for
1714a task to set its own or one of its thread siblings comm value. The comm value
1715is limited in size compared to the cmdline value, so writing anything longer
1716then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
1717comm value.
Vasiliy Kulikov04996802012-01-10 15:11:31 -08001718
1719
Cyrill Gorcunov818411612012-05-31 16:26:43 -070017203.7 /proc/<pid>/task/<tid>/children - Information about task children
1721-------------------------------------------------------------------------
1722This file provides a fast way to retrieve first level children pids
1723of a task pointed by <pid>/<tid> pair. The format is a space separated
1724stream of pids.
1725
1726Note the "first level" here -- if a child has own children they will
1727not be listed here, one needs to read /proc/<children-pid>/task/<tid>/children
1728to obtain the descendants.
1729
1730Since this interface is intended to be fast and cheap it doesn't
1731guarantee to provide precise results and some children might be
1732skipped, especially if they've exited right after we printed their
1733pids, so one need to either stop or freeze processes being inspected
1734if precise results are needed.
1735
1736
Andrey Vagin49d063c2014-04-07 15:38:34 -070017373.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001738---------------------------------------------------------------
1739This file provides information associated with an opened file. The regular
Andrey Vagin49d063c2014-04-07 15:38:34 -07001740files have at least three fields -- 'pos', 'flags' and mnt_id. The 'pos'
1741represents the current offset of the opened file in decimal form [see lseek(2)
1742for details], 'flags' denotes the octal O_xxx mask the file has been
1743created with [see open(2) for details] and 'mnt_id' represents mount ID of
1744the file system containing the opened file [see 3.5 /proc/<pid>/mountinfo
1745for details].
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001746
1747A typical output is
1748
1749 pos: 0
1750 flags: 0100002
Andrey Vagin49d063c2014-04-07 15:38:34 -07001751 mnt_id: 19
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001752
Andrey Vagin6c8c9032015-04-16 12:49:38 -07001753All locks associated with a file descriptor are shown in its fdinfo too.
1754
1755lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF
1756
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001757The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags
1758pair provide additional information particular to the objects they represent.
1759
1760 Eventfd files
1761 ~~~~~~~~~~~~~
1762 pos: 0
1763 flags: 04002
Andrey Vagin49d063c2014-04-07 15:38:34 -07001764 mnt_id: 9
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001765 eventfd-count: 5a
1766
1767 where 'eventfd-count' is hex value of a counter.
1768
1769 Signalfd files
1770 ~~~~~~~~~~~~~~
1771 pos: 0
1772 flags: 04002
Andrey Vagin49d063c2014-04-07 15:38:34 -07001773 mnt_id: 9
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001774 sigmask: 0000000000000200
1775
1776 where 'sigmask' is hex value of the signal mask associated
1777 with a file.
1778
1779 Epoll files
1780 ~~~~~~~~~~~
1781 pos: 0
1782 flags: 02
Andrey Vagin49d063c2014-04-07 15:38:34 -07001783 mnt_id: 9
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001784 tfd: 5 events: 1d data: ffffffffffffffff
1785
1786 where 'tfd' is a target file descriptor number in decimal form,
1787 'events' is events mask being watched and the 'data' is data
1788 associated with a target [see epoll(7) for more details].
1789
1790 Fsnotify files
1791 ~~~~~~~~~~~~~~
1792 For inotify files the format is the following
1793
1794 pos: 0
1795 flags: 02000000
1796 inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d
1797
1798 where 'wd' is a watch descriptor in decimal form, ie a target file
1799 descriptor number, 'ino' and 'sdev' are inode and device where the
1800 target file resides and the 'mask' is the mask of events, all in hex
1801 form [see inotify(7) for more details].
1802
1803 If the kernel was built with exportfs support, the path to the target
1804 file is encoded as a file handle. The file handle is provided by three
1805 fields 'fhandle-bytes', 'fhandle-type' and 'f_handle', all in hex
1806 format.
1807
1808 If the kernel is built without exportfs support the file handle won't be
1809 printed out.
1810
Cyrill Gorcunove71ec592012-12-17 16:05:18 -08001811 If there is no inotify mark attached yet the 'inotify' line will be omitted.
1812
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001813 For fanotify files the format is
1814
1815 pos: 0
1816 flags: 02
Andrey Vagin49d063c2014-04-07 15:38:34 -07001817 mnt_id: 9
Cyrill Gorcunove71ec592012-12-17 16:05:18 -08001818 fanotify flags:10 event-flags:0
1819 fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003
1820 fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001821
Cyrill Gorcunove71ec592012-12-17 16:05:18 -08001822 where fanotify 'flags' and 'event-flags' are values used in fanotify_init
1823 call, 'mnt_id' is the mount point identifier, 'mflags' is the value of
1824 flags associated with mark which are tracked separately from events
1825 mask. 'ino', 'sdev' are target inode and device, 'mask' is the events
1826 mask and 'ignored_mask' is the mask of events which are to be ignored.
1827 All in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask'
1828 does provide information about flags and mask used in fanotify_mark
1829 call [see fsnotify manpage for details].
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001830
Cyrill Gorcunove71ec592012-12-17 16:05:18 -08001831 While the first three lines are mandatory and always printed, the rest is
1832 optional and may be omitted if no marks created yet.
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001833
Cyrill Gorcunov854d06d2014-07-16 01:54:53 +04001834 Timerfd files
1835 ~~~~~~~~~~~~~
1836
1837 pos: 0
1838 flags: 02
1839 mnt_id: 9
1840 clockid: 0
1841 ticks: 0
1842 settime flags: 01
1843 it_value: (0, 49406829)
1844 it_interval: (1, 0)
1845
1846 where 'clockid' is the clock type and 'ticks' is the number of the timer expirations
1847 that have occurred [see timerfd_create(2) for details]. 'settime flags' are
1848 flags in octal form been used to setup the timer [see timerfd_settime(2) for
1849 details]. 'it_value' is remaining time until the timer exiration.
1850 'it_interval' is the interval for the timer. Note the timer might be set up
1851 with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value'
1852 still exhibits timer's remaining time.
Cyrill Gorcunovf1d8c162012-12-17 16:05:14 -08001853
Cyrill Gorcunov740a5dd2015-02-11 15:28:31 -080018543.9 /proc/<pid>/map_files - Information about memory mapped files
1855---------------------------------------------------------------------
1856This directory contains symbolic links which represent memory mapped files
1857the process is maintaining. Example output:
1858
1859 | lr-------- 1 root root 64 Jan 27 11:24 333c600000-333c620000 -> /usr/lib64/ld-2.18.so
1860 | lr-------- 1 root root 64 Jan 27 11:24 333c81f000-333c820000 -> /usr/lib64/ld-2.18.so
1861 | lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so
1862 | ...
1863 | lr-------- 1 root root 64 Jan 27 11:24 35d0421000-35d0422000 -> /usr/lib64/libselinux.so.1
1864 | lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls
1865
1866The name of a link represents the virtual memory bounds of a mapping, i.e.
1867vm_area_struct::vm_start-vm_area_struct::vm_end.
1868
1869The main purpose of the map_files is to retrieve a set of memory mapped
1870files in a fast way instead of parsing /proc/<pid>/maps or
1871/proc/<pid>/smaps, both of which contain many more records. At the same
1872time one can open(2) mappings from the listings of two processes and
1873comparing their inode numbers to figure out which anonymous memory areas
1874are actually shared.
1875
John Stultz5de23d42016-03-17 14:20:54 -070018763.10 /proc/<pid>/timerslack_ns - Task timerslack value
1877---------------------------------------------------------
1878This file provides the value of the task's timerslack value in nanoseconds.
1879This value specifies a amount of time that normal timers may be deferred
1880in order to coalesce timers and avoid unnecessary wakeups.
1881
1882This allows a task's interactivity vs power consumption trade off to be
1883adjusted.
1884
1885Writing 0 to the file will set the tasks timerslack to the default value.
1886
1887Valid values are from 0 - ULLONG_MAX
1888
1889An application setting the value must have PTRACE_MODE_ATTACH_FSCREDS level
1890permissions on the task specified to change its timerslack_ns value.
1891
1892
Vasiliy Kulikov04996802012-01-10 15:11:31 -08001893------------------------------------------------------------------------------
1894Configuring procfs
1895------------------------------------------------------------------------------
1896
18974.1 Mount options
1898---------------------
1899
1900The following mount options are supported:
1901
1902 hidepid= Set /proc/<pid>/ access mode.
1903 gid= Set the group authorized to learn processes information.
1904
1905hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories
1906(default).
1907
1908hidepid=1 means users may not access any /proc/<pid>/ directories but their
1909own. Sensitive files like cmdline, sched*, status are now protected against
1910other users. This makes it impossible to learn whether any user runs
1911specific program (given the program doesn't reveal itself by its behaviour).
1912As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users,
1913poorly written programs passing sensitive information via program arguments are
1914now protected against local eavesdroppers.
1915
1916hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other
1917users. It doesn't mean that it hides a fact whether a process with a specific
1918pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"),
1919but it hides process' uid and gid, which may be learned by stat()'ing
1920/proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering
1921information about running processes, whether some daemon runs with elevated
1922privileges, whether other user runs some sensitive program, whether other users
1923run any program at all, etc.
1924
1925gid= defines a group authorized to learn processes information otherwise
1926prohibited by hidepid=. If you use some daemon like identd which needs to learn
1927information about processes information, just add identd to this group.