blob: b7413cb46dcb1f1a331068861e766a6c03a5da40 [file] [log] [blame]
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
Shen Feng760df932009-04-02 16:57:20 -070031 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 Rientjesa63d83f2010-08-09 17:19:46 -070036 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer
37 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
Shen Feng760df932009-04-02 16:57:20 -070043
Vasiliy Kulikov04996802012-01-10 15:11:31 -080044 4 Configuring procfs
45 4.1 Mount options
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
47------------------------------------------------------------------------------
48Preface
49------------------------------------------------------------------------------
50
510.1 Introduction/Credits
52------------------------
53
54This documentation is part of a soon (or so we hope) to be released book on
55the SuSE Linux distribution. As there is no complete documentation for the
56/proc file system and we've used many freely available sources to write these
57chapters, it seems only fair to give the work back to the Linux community.
58This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm
59afraid it's still far from complete, but we hope it will be useful. As far as
60we know, it is the first 'all-in-one' document about the /proc file system. It
61is focused on the Intel x86 hardware, so if you are looking for PPC, ARM,
62SPARC, AXP, etc., features, you probably won't find what you are looking for.
63It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
64additions and patches are welcome and will be added to this document if you
65mail them to Bodo.
66
67We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of
68other people for help compiling this documentation. We'd also like to extend a
69special thank you to Andi Kleen for documentation, which we relied on heavily
70to create this document, as well as the additional information he provided.
71Thanks to everybody else who contributed source or docs to the Linux kernel
72and helped create a great piece of software... :)
73
74If you have any comments, corrections or additions, please don't hesitate to
75contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this
76document.
77
78The latest version of this document is available online at
Justin P. Mattock0ea6e612010-07-23 20:51:24 -070079http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html
Linus Torvalds1da177e2005-04-16 15:20:36 -070080
Justin P. Mattock0ea6e612010-07-23 20:51:24 -070081If the above direction does not works for you, you could try the kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -070082mailing list at linux-kernel@vger.kernel.org and/or try to reach me at
83comandante@zaralinux.com.
84
850.2 Legal Stuff
86---------------
87
88We don't guarantee the correctness of this document, and if you come to us
89complaining about how you screwed up your system because of incorrect
90documentation, we won't feel responsible...
91
92------------------------------------------------------------------------------
93CHAPTER 1: COLLECTING SYSTEM INFORMATION
94------------------------------------------------------------------------------
95
96------------------------------------------------------------------------------
97In This Chapter
98------------------------------------------------------------------------------
99* Investigating the properties of the pseudo file system /proc and its
100 ability to provide information on the running Linux system
101* Examining /proc's structure
102* Uncovering various information about the kernel and the processes running
103 on the system
104------------------------------------------------------------------------------
105
106
107The proc file system acts as an interface to internal data structures in the
108kernel. It can be used to obtain information about the system and to change
109certain kernel parameters at runtime (sysctl).
110
111First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
112show you how you can use /proc/sys to change settings.
113
1141.1 Process-Specific Subdirectories
115-----------------------------------
116
117The directory /proc contains (among other things) one subdirectory for each
118process running on the system, which is named after the process ID (PID).
119
120The link self points to the process reading the file system. Each process
121subdirectory has the entries listed in Table 1-1.
122
123
Stefani Seibold349888e2009-06-17 16:26:01 -0700124Table 1-1: Process specific entries in /proc
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125..............................................................................
David Rientjesb813e932007-05-06 14:49:24 -0700126 File Content
127 clear_refs Clears page referenced bits shown in smaps output
128 cmdline Command line arguments
129 cpu Current and last cpu in which it was executed (2.4)(smp)
130 cwd Link to the current working directory
131 environ Values of environment variables
132 exe Link to the executable of this process
133 fd Directory, which contains all file descriptors
134 maps Memory maps to executables and library files (2.4)
135 mem Memory held by this process
136 root Link to the root directory of this process
137 stat Process status
138 statm Process memory status information
139 status Process status in human readable form
140 wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
Nikanth Karthikesan03f890f2010-10-27 15:34:11 -0700141 pagemap Page table
Ken Chen2ec220e2008-11-10 11:26:08 +0300142 stack Report full stack trace, enable via CONFIG_STACKTRACE
Stefani Seibold349888e2009-06-17 16:26:01 -0700143 smaps a extension based on maps, showing the memory consumption of
144 each mapping
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145..............................................................................
146
147For example, to get the status information of a process, all you have to do is
148read the file /proc/PID/status:
149
Stefani Seibold349888e2009-06-17 16:26:01 -0700150 >cat /proc/self/status
151 Name: cat
152 State: R (running)
153 Tgid: 5452
154 Pid: 5452
155 PPid: 743
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 TracerPid: 0 (2.4)
Stefani Seibold349888e2009-06-17 16:26:01 -0700157 Uid: 501 501 501 501
158 Gid: 100 100 100 100
159 FDSize: 256
160 Groups: 100 14 16
161 VmPeak: 5004 kB
162 VmSize: 5004 kB
163 VmLck: 0 kB
164 VmHWM: 476 kB
165 VmRSS: 476 kB
166 VmData: 156 kB
167 VmStk: 88 kB
168 VmExe: 68 kB
169 VmLib: 1412 kB
170 VmPTE: 20 kb
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -0800171 VmSwap: 0 kB
Stefani Seibold349888e2009-06-17 16:26:01 -0700172 Threads: 1
173 SigQ: 0/28578
174 SigPnd: 0000000000000000
175 ShdPnd: 0000000000000000
176 SigBlk: 0000000000000000
177 SigIgn: 0000000000000000
178 SigCgt: 0000000000000000
179 CapInh: 00000000fffffeff
180 CapPrm: 0000000000000000
181 CapEff: 0000000000000000
182 CapBnd: ffffffffffffffff
183 voluntary_ctxt_switches: 0
184 nonvoluntary_ctxt_switches: 1
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185
186This shows you nearly the same information you would get if you viewed it with
187the ps command. In fact, ps uses the proc file system to obtain its
Stefani Seibold349888e2009-06-17 16:26:01 -0700188information. But you get a more detailed view of the process by reading the
189file /proc/PID/status. It fields are described in table 1-2.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190
Stefani Seibold349888e2009-06-17 16:26:01 -0700191The statm file contains more detailed information about the process
192memory usage. Its seven fields are explained in Table 1-3. The stat file
193contains details information about the process itself. Its fields are
194explained in Table 1-4.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -0800196(for SMP CONFIG users)
197For making accounting scalable, RSS related information are handled in
198asynchronous manner and the vaule may not be very precise. To see a precise
199snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
200It's slow but very precise.
201
Mulyadi Santosacb2992a2010-02-18 01:22:40 +0700202Table 1-2: Contents of the status files (as of 2.6.30-rc7)
Stefani Seibold349888e2009-06-17 16:26:01 -0700203..............................................................................
204 Field Content
205 Name filename of the executable
206 State state (R is running, S is sleeping, D is sleeping
207 in an uninterruptible wait, Z is zombie,
208 T is traced or stopped)
209 Tgid thread group ID
210 Pid process id
211 PPid process id of the parent process
212 TracerPid PID of process tracing this process (0 if not)
213 Uid Real, effective, saved set, and file system UIDs
214 Gid Real, effective, saved set, and file system GIDs
215 FDSize number of file descriptor slots currently allocated
216 Groups supplementary group list
217 VmPeak peak virtual memory size
218 VmSize total program size
219 VmLck locked memory size
220 VmHWM peak resident set size ("high water mark")
221 VmRSS size of memory portions
222 VmData size of data, stack, and text segments
223 VmStk size of data, stack, and text segments
224 VmExe size of text segment
225 VmLib size of shared library code
226 VmPTE size of page table entries
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -0800227 VmSwap size of swap usage (the number of referred swapents)
Stefani Seibold349888e2009-06-17 16:26:01 -0700228 Threads number of threads
229 SigQ number of signals queued/max. number for queue
230 SigPnd bitmap of pending signals for the thread
231 ShdPnd bitmap of shared pending signals for the process
232 SigBlk bitmap of blocked signals
233 SigIgn bitmap of ignored signals
234 SigCgt bitmap of catched signals
235 CapInh bitmap of inheritable capabilities
236 CapPrm bitmap of permitted capabilities
237 CapEff bitmap of effective capabilities
238 CapBnd bitmap of capabilities bounding set
239 Cpus_allowed mask of CPUs on which this process may run
240 Cpus_allowed_list Same as previous, but in "list format"
241 Mems_allowed mask of memory nodes allowed to this process
242 Mems_allowed_list Same as previous, but in "list format"
243 voluntary_ctxt_switches number of voluntary context switches
244 nonvoluntary_ctxt_switches number of non voluntary context switches
245..............................................................................
246
247Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248..............................................................................
249 Field Content
250 size total program size (pages) (same as VmSize in status)
251 resident size of memory portions (pages) (same as VmRSS in status)
252 shared number of pages that are shared (i.e. backed by a file)
253 trs number of pages that are 'code' (not including libs; broken,
254 includes data segment)
255 lrs number of pages of library (always 0 on 2.6)
256 drs number of pages of data/stack (including libs; broken,
257 includes library text)
258 dt number of dirty pages (always 0 on 2.6)
259..............................................................................
260
Kees Cook18d96772007-07-15 23:40:38 -0700261
Stefani Seibold349888e2009-06-17 16:26:01 -0700262Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
Kees Cook18d96772007-07-15 23:40:38 -0700263..............................................................................
264 Field Content
265 pid process id
266 tcomm filename of the executable
267 state state (R is running, S is sleeping, D is sleeping in an
268 uninterruptible wait, Z is zombie, T is traced or stopped)
269 ppid process id of the parent process
270 pgrp pgrp of the process
271 sid session id
272 tty_nr tty the process uses
273 tty_pgrp pgrp of the tty
274 flags task flags
275 min_flt number of minor faults
276 cmin_flt number of minor faults with child's
277 maj_flt number of major faults
278 cmaj_flt number of major faults with child's
279 utime user mode jiffies
280 stime kernel mode jiffies
281 cutime user mode jiffies with child's
282 cstime kernel mode jiffies with child's
283 priority priority level
284 nice nice level
285 num_threads number of threads
Leonardo Chiquitto2e01e002008-02-03 16:17:16 +0200286 it_real_value (obsolete, always 0)
Kees Cook18d96772007-07-15 23:40:38 -0700287 start_time time the process started after system boot
288 vsize virtual memory size
289 rss resident set memory size
290 rsslim current limit in bytes on the rss
291 start_code address above which program text can run
292 end_code address below which program text can run
Siddhesh Poyarekarb7643752012-03-21 16:34:04 -0700293 start_stack address of the start of the main process stack
Kees Cook18d96772007-07-15 23:40:38 -0700294 esp current value of ESP
295 eip current value of EIP
Stefani Seibold349888e2009-06-17 16:26:01 -0700296 pending bitmap of pending signals
297 blocked bitmap of blocked signals
298 sigign bitmap of ignored signals
299 sigcatch bitmap of catched signals
Kees Cook18d96772007-07-15 23:40:38 -0700300 wchan address where process went to sleep
301 0 (place holder)
302 0 (place holder)
303 exit_signal signal to send to parent thread on exit
304 task_cpu which CPU the task is scheduled on
305 rt_priority realtime priority
306 policy scheduling policy (man sched_setscheduler)
307 blkio_ticks time spent waiting for block IO
Stefani Seibold349888e2009-06-17 16:26:01 -0700308 gtime guest time of the task in jiffies
309 cgtime guest time of the task children in jiffies
Cyrill Gorcunovb3f7f572012-01-12 17:20:53 -0800310 start_data address above which program data+bss is placed
311 end_data address below which program data+bss is placed
312 start_brk address above which program heap can be expanded with brk()
Kees Cook18d96772007-07-15 23:40:38 -0700313..............................................................................
314
Rob Landley32e688b2010-03-15 15:21:31 +0100315The /proc/PID/maps file containing the currently mapped memory regions and
Stefani Seibold349888e2009-06-17 16:26:01 -0700316their access permissions.
317
318The format is:
319
320address perms offset dev inode pathname
321
32208048000-08049000 r-xp 00000000 03:00 8312 /opt/test
32308049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
3240804a000-0806b000 rw-p 00000000 00:00 0 [heap]
325a7cb1000-a7cb2000 ---p 00000000 00:00 0
Robin Holt34441422010-05-11 14:06:46 -0700326a7cb2000-a7eb2000 rw-p 00000000 00:00 0
Stefani Seibold349888e2009-06-17 16:26:01 -0700327a7eb2000-a7eb3000 ---p 00000000 00:00 0
Siddhesh Poyarekarb7643752012-03-21 16:34:04 -0700328a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack:1001]
Stefani Seibold349888e2009-06-17 16:26:01 -0700329a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
330a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
331a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
332a800b000-a800e000 rw-p 00000000 00:00 0
333a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
334a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
335a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
336a8024000-a8027000 rw-p 00000000 00:00 0
337a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
338a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
339a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
340aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
341ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
342
343where "address" is the address space in the process that it occupies, "perms"
344is a set of permissions:
345
346 r = read
347 w = write
348 x = execute
349 s = shared
350 p = private (copy on write)
351
352"offset" is the offset into the mapping, "dev" is the device (major:minor), and
353"inode" is the inode on that device. 0 indicates that no inode is associated
354with the memory region, as the case would be with BSS (uninitialized data).
355The "pathname" shows the name associated file for this mapping. If the mapping
356is not associated with a file:
357
358 [heap] = the heap of the program
359 [stack] = the stack of the main process
Siddhesh Poyarekarb7643752012-03-21 16:34:04 -0700360 [stack:1001] = the stack of the thread with tid 1001
Stefani Seibold349888e2009-06-17 16:26:01 -0700361 [vdso] = the "virtual dynamic shared object",
362 the kernel system call handler
363
364 or if empty, the mapping is anonymous.
365
Siddhesh Poyarekarb7643752012-03-21 16:34:04 -0700366The /proc/PID/task/TID/maps is a view of the virtual memory from the viewpoint
367of the individual tasks of a process. In this file you will see a mapping marked
368as [stack] if that task sees it as a stack. This is a key difference from the
369content of /proc/PID/maps, where you will see all mappings that are being used
370as stack by all of those tasks. Hence, for the example above, the task-level
371map, i.e. /proc/PID/task/TID/maps for thread 1001 will look like this:
372
37308048000-08049000 r-xp 00000000 03:00 8312 /opt/test
37408049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
3750804a000-0806b000 rw-p 00000000 00:00 0 [heap]
376a7cb1000-a7cb2000 ---p 00000000 00:00 0
377a7cb2000-a7eb2000 rw-p 00000000 00:00 0
378a7eb2000-a7eb3000 ---p 00000000 00:00 0
379a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack]
380a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
381a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
382a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
383a800b000-a800e000 rw-p 00000000 00:00 0
384a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
385a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
386a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
387a8024000-a8027000 rw-p 00000000 00:00 0
388a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
389a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
390a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
391aff35000-aff4a000 rw-p 00000000 00:00 0
392ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
Stefani Seibold349888e2009-06-17 16:26:01 -0700393
394The /proc/PID/smaps is an extension based on maps, showing the memory
395consumption for each of the process's mappings. For each of mappings there
396is a series of lines such as the following:
397
39808048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
399Size: 1084 kB
400Rss: 892 kB
401Pss: 374 kB
402Shared_Clean: 892 kB
403Shared_Dirty: 0 kB
404Private_Clean: 0 kB
405Private_Dirty: 0 kB
406Referenced: 892 kB
Nikanth Karthikesanb40d4f82010-10-27 15:34:10 -0700407Anonymous: 0 kB
Stefani Seibold349888e2009-06-17 16:26:01 -0700408Swap: 0 kB
409KernelPageSize: 4 kB
410MMUPageSize: 4 kB
Nikanth Karthikesan2d905082011-01-13 15:45:53 -0800411Locked: 374 kB
Stefani Seibold349888e2009-06-17 16:26:01 -0700412
Matt Mackall0f4d2082010-10-26 14:21:22 -0700413The first of these lines shows the same information as is displayed for the
414mapping in /proc/PID/maps. The remaining lines show the size of the mapping
415(size), the amount of the mapping that is currently resident in RAM (RSS), the
416process' proportional share of this mapping (PSS), the number of clean and
Nikanth Karthikesanb40d4f82010-10-27 15:34:10 -0700417dirty private pages in the mapping. Note that even a page which is part of a
418MAP_SHARED mapping, but has only a single pte mapped, i.e. is currently used
419by only one process, is accounted as private and not as shared. "Referenced"
420indicates the amount of memory currently marked as referenced or accessed.
421"Anonymous" shows the amount of memory that does not belong to any file. Even
422a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
423and a page is modified, the file page is replaced by a private anonymous copy.
424"Swap" shows how much would-be-anonymous memory is also used, but out on
425swap.
Stefani Seibold349888e2009-06-17 16:26:01 -0700426
427This file is only present if the CONFIG_MMU kernel configuration option is
428enabled.
Kees Cook18d96772007-07-15 23:40:38 -0700429
Moussa A. Ba398499d2009-09-21 17:02:29 -0700430The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
431bits on both physical and virtual pages associated with a process.
432To clear the bits for all the pages associated with the process
433 > echo 1 > /proc/PID/clear_refs
434
435To clear the bits for the anonymous pages associated with the process
436 > echo 2 > /proc/PID/clear_refs
437
438To clear the bits for the file mapped pages associated with the process
439 > echo 3 > /proc/PID/clear_refs
440Any other value written to /proc/PID/clear_refs will have no effect.
441
Nikanth Karthikesan03f890f2010-10-27 15:34:11 -0700442The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
443using /proc/kpageflags and number of times a page is mapped using
444/proc/kpagecount. For detailed explanation, see Documentation/vm/pagemap.txt.
Moussa A. Ba398499d2009-09-21 17:02:29 -0700445
Linus Torvalds1da177e2005-04-16 15:20:36 -07004461.2 Kernel data
447---------------
448
449Similar to the process entries, the kernel data files give information about
450the running kernel. The files used to obtain this information are contained in
Stefani Seibold349888e2009-06-17 16:26:01 -0700451/proc and are listed in Table 1-5. Not all of these will be present in your
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452system. It depends on the kernel configuration and the loaded modules, which
453files are there, and which are missing.
454
Stefani Seibold349888e2009-06-17 16:26:01 -0700455Table 1-5: Kernel info in /proc
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456..............................................................................
457 File Content
458 apm Advanced power management info
459 buddyinfo Kernel memory allocator information (see text) (2.5)
460 bus Directory containing bus specific information
461 cmdline Kernel command line
462 cpuinfo Info about the CPU
463 devices Available devices (block and character)
464 dma Used DMS channels
465 filesystems Supported filesystems
466 driver Various drivers grouped here, currently rtc (2.4)
467 execdomains Execdomains, related to security (2.4)
468 fb Frame Buffer devices (2.4)
469 fs File system parameters, currently nfs/exports (2.4)
470 ide Directory containing info about the IDE subsystem
471 interrupts Interrupt usage
472 iomem Memory map (2.4)
473 ioports I/O port usage
474 irq Masks for irq to cpu affinity (2.4)(smp?)
475 isapnp ISA PnP (Plug&Play) Info (2.4)
476 kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
477 kmsg Kernel messages
478 ksyms Kernel symbol table
479 loadavg Load average of last 1, 5 & 15 minutes
480 locks Kernel locks
481 meminfo Memory info
482 misc Miscellaneous
483 modules List of loaded modules
484 mounts Mounted filesystems
485 net Networking info (see text)
Mel Gormana1b57ac2010-03-05 13:42:15 -0800486 pagetypeinfo Additional page allocator information (see text) (2.5)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 partitions Table of partitions known to the system
Randy Dunlap8b607562007-05-09 07:19:14 +0200488 pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489 decoupled by lspci (2.4)
490 rtc Real time clock
491 scsi SCSI info (see text)
492 slabinfo Slab pool info
Keika Kobayashid3d64df2009-06-17 16:25:55 -0700493 softirqs softirq usage
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 stat Overall statistics
495 swaps Swap space utilization
496 sys See chapter 2
497 sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
498 tty Info of tty drivers
499 uptime System uptime
500 version Kernel version
501 video bttv info of video resources (2.4)
Eric Dumazeta47a1262008-07-23 21:27:38 -0700502 vmallocinfo Show vmalloced areas
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503..............................................................................
504
505You can, for example, check which interrupts are currently in use and what
506they are used for by looking in the file /proc/interrupts:
507
508 > cat /proc/interrupts
509 CPU0
510 0: 8728810 XT-PIC timer
511 1: 895 XT-PIC keyboard
512 2: 0 XT-PIC cascade
513 3: 531695 XT-PIC aha152x
514 4: 2014133 XT-PIC serial
515 5: 44401 XT-PIC pcnet_cs
516 8: 2 XT-PIC rtc
517 11: 8 XT-PIC i82365
518 12: 182918 XT-PIC PS/2 Mouse
519 13: 1 XT-PIC fpu
520 14: 1232265 XT-PIC ide0
521 15: 7 XT-PIC ide1
522 NMI: 0
523
524In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
525output of a SMP machine):
526
527 > cat /proc/interrupts
528
529 CPU0 CPU1
530 0: 1243498 1214548 IO-APIC-edge timer
531 1: 8949 8958 IO-APIC-edge keyboard
532 2: 0 0 XT-PIC cascade
533 5: 11286 10161 IO-APIC-edge soundblaster
534 8: 1 0 IO-APIC-edge rtc
535 9: 27422 27407 IO-APIC-edge 3c503
536 12: 113645 113873 IO-APIC-edge PS/2 Mouse
537 13: 0 0 XT-PIC fpu
538 14: 22491 24012 IO-APIC-edge ide0
539 15: 2183 2415 IO-APIC-edge ide1
540 17: 30564 30414 IO-APIC-level eth0
541 18: 177 164 IO-APIC-level bttv
542 NMI: 2457961 2457959
543 LOC: 2457882 2457881
544 ERR: 2155
545
546NMI is incremented in this case because every timer interrupt generates a NMI
547(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups.
548
549LOC is the local interrupt counter of the internal APIC of every CPU.
550
551ERR is incremented in the case of errors in the IO-APIC bus (the bus that
552connects the CPUs in a SMP system. This means that an error has been detected,
553the IO-APIC automatically retry the transmission, so it should not be a big
554problem, but you should read the SMP-FAQ.
555
Joe Korty38e760a2007-10-17 18:04:40 +0200556In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
557/proc/interrupts to display every IRQ vector in use by the system, not
558just those considered 'most important'. The new vectors are:
559
560 THR -- interrupt raised when a machine check threshold counter
561 (typically counting ECC corrected errors of memory or cache) exceeds
562 a configurable threshold. Only available on some systems.
563
564 TRM -- a thermal event interrupt occurs when a temperature threshold
565 has been exceeded for the CPU. This interrupt may also be generated
566 when the temperature drops back to normal.
567
568 SPU -- a spurious interrupt is some interrupt that was raised then lowered
569 by some IO device before it could be fully processed by the APIC. Hence
570 the APIC sees the interrupt but does not know what device it came from.
571 For this case the APIC will generate the interrupt with a IRQ vector
572 of 0xff. This might also be generated by chipset bugs.
573
574 RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are
575 sent from one CPU to another per the needs of the OS. Typically,
576 their statistics are used by kernel developers and interested users to
Matt LaPlante19f59462009-04-27 15:06:31 +0200577 determine the occurrence of interrupts of the given type.
Joe Korty38e760a2007-10-17 18:04:40 +0200578
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300579The above IRQ vectors are displayed only when relevant. For example,
Joe Korty38e760a2007-10-17 18:04:40 +0200580the threshold vector does not exist on x86_64 platforms. Others are
581suppressed when the system is a uniprocessor. As of this writing, only
582i386 and x86_64 platforms support the new IRQ vector displays.
583
584Of some interest is the introduction of the /proc/irq directory to 2.4.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585It could be used to set IRQ to CPU affinity, this means that you can "hook" an
586IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
Max Krasnyansky18404752008-05-29 11:02:52 -0700587irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and
588prof_cpu_mask.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589
590For example
591 > ls /proc/irq/
592 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
Max Krasnyansky18404752008-05-29 11:02:52 -0700593 1 11 13 15 17 19 3 5 7 9 default_smp_affinity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 > ls /proc/irq/0/
595 smp_affinity
596
Max Krasnyansky18404752008-05-29 11:02:52 -0700597smp_affinity is a bitmask, in which you can specify which CPUs can handle the
598IRQ, you can set it by doing:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599
Max Krasnyansky18404752008-05-29 11:02:52 -0700600 > echo 1 > /proc/irq/10/smp_affinity
601
602This means that only the first CPU will handle the IRQ, but you can also echo
6035 which means that only the first and fourth CPU can handle the IRQ.
604
605The contents of each smp_affinity file is the same by default:
606
607 > cat /proc/irq/0/smp_affinity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608 ffffffff
609
Mike Travis4b060422011-05-24 17:13:12 -0700610There is an alternate interface, smp_affinity_list which allows specifying
611a cpu range instead of a bitmask:
612
613 > cat /proc/irq/0/smp_affinity_list
614 1024-1031
615
Max Krasnyansky18404752008-05-29 11:02:52 -0700616The default_smp_affinity mask applies to all non-active IRQs, which are the
617IRQs which have not yet been allocated/activated, and hence which lack a
618/proc/irq/[0-9]* directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619
Dimitri Sivanich92d6b712010-03-11 14:08:56 -0800620The node file on an SMP system shows the node to which the device using the IRQ
621reports itself as being attached. This hardware locality information does not
622include information about any possible driver locality preference.
623
Max Krasnyansky18404752008-05-29 11:02:52 -0700624prof_cpu_mask specifies which CPUs are to be profiled by the system wide
Mike Travis4b060422011-05-24 17:13:12 -0700625profiler. Default value is ffffffff (all cpus if there are only 32 of them).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626
627The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
628between all the CPUs which are allowed to handle it. As usual the kernel has
629more info than you and does a better job than you, so the defaults are the
Mike Travis4b060422011-05-24 17:13:12 -0700630best choice for almost everyone. [Note this applies only to those IO-APIC's
631that support "Round Robin" interrupt distribution.]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632
633There are three more important subdirectories in /proc: net, scsi, and sys.
634The general rule is that the contents, or even the existence of these
635directories, depend on your kernel configuration. If SCSI is not enabled, the
636directory scsi may not exist. The same is true with the net, which is there
637only when networking support is present in the running kernel.
638
639The slabinfo file gives information about memory usage at the slab level.
640Linux uses slab pools for memory management above page level in version 2.2.
641Commonly used objects have their own slab pool (such as network buffers,
642directory cache, and so on).
643
644..............................................................................
645
646> cat /proc/buddyinfo
647
648Node 0, zone DMA 0 4 5 4 4 3 ...
649Node 0, zone Normal 1 0 0 1 101 8 ...
650Node 0, zone HighMem 2 0 0 1 1 0 ...
651
Mel Gormana1b57ac2010-03-05 13:42:15 -0800652External fragmentation is a problem under some workloads, and buddyinfo is a
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653useful tool for helping diagnose these problems. Buddyinfo will give you a
654clue as to how big an area you can safely allocate, or why a previous
655allocation failed.
656
657Each column represents the number of pages of a certain order which are
658available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in
659ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
660available in ZONE_NORMAL, etc...
661
Mel Gormana1b57ac2010-03-05 13:42:15 -0800662More information relevant to external fragmentation can be found in
663pagetypeinfo.
664
665> cat /proc/pagetypeinfo
666Page block order: 9
667Pages per block: 512
668
669Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
670Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
671Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
672Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
673Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
674Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
675Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
676Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
677Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
678Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
679Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
680
681Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
682Node 0, zone DMA 2 0 5 1 0
683Node 0, zone DMA32 41 6 967 2 0
684
685Fragmentation avoidance in the kernel works by grouping pages of different
686migrate types into the same contiguous regions of memory called page blocks.
687A page block is typically the size of the default hugepage size e.g. 2MB on
688X86-64. By keeping pages grouped based on their ability to move, the kernel
689can reclaim pages within a page block to satisfy a high-order allocation.
690
691The pagetypinfo begins with information on the size of a page block. It
692then gives the same type of information as buddyinfo except broken down
693by migrate-type and finishes with details on how many page blocks of each
694type exist.
695
696If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
697from libhugetlbfs http://sourceforge.net/projects/libhugetlbfs/), one can
698make an estimate of the likely number of huge pages that can be allocated
699at a given point in time. All the "Movable" blocks should be allocatable
700unless memory has been mlock()'d. Some of the Reclaimable blocks should
701also be allocatable although a lot of filesystem metadata may have to be
702reclaimed to achieve this.
703
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704..............................................................................
705
706meminfo:
707
708Provides information about distribution and utilization of memory. This
709varies by architecture and compile options. The following is from a
71016GB PIII, which has highmem enabled. You may not have all of these fields.
711
712> cat /proc/meminfo
713
Nikanth Karthikesan2d905082011-01-13 15:45:53 -0800714The "Locked" indicates whether the mapping is locked in memory or not.
715
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716
717MemTotal: 16344972 kB
718MemFree: 13634064 kB
719Buffers: 3656 kB
720Cached: 1195708 kB
721SwapCached: 0 kB
722Active: 891636 kB
723Inactive: 1077224 kB
724HighTotal: 15597528 kB
725HighFree: 13629632 kB
726LowTotal: 747444 kB
727LowFree: 4432 kB
728SwapTotal: 0 kB
729SwapFree: 0 kB
730Dirty: 968 kB
731Writeback: 0 kB
Miklos Szeredib88473f2008-04-30 00:54:39 -0700732AnonPages: 861800 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733Mapped: 280372 kB
Miklos Szeredib88473f2008-04-30 00:54:39 -0700734Slab: 284364 kB
735SReclaimable: 159856 kB
736SUnreclaim: 124508 kB
737PageTables: 24448 kB
738NFS_Unstable: 0 kB
739Bounce: 0 kB
740WritebackTmp: 0 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741CommitLimit: 7669796 kB
742Committed_AS: 100056 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743VmallocTotal: 112216 kB
744VmallocUsed: 428 kB
745VmallocChunk: 111088 kB
746
747 MemTotal: Total usable ram (i.e. physical ram minus a few reserved
748 bits and the kernel binary code)
749 MemFree: The sum of LowFree+HighFree
750 Buffers: Relatively temporary storage for raw disk blocks
751 shouldn't get tremendously large (20MB or so)
752 Cached: in-memory cache for files read from the disk (the
753 pagecache). Doesn't include SwapCached
754 SwapCached: Memory that once was swapped out, is swapped back in but
755 still also is in the swapfile (if memory is needed it
756 doesn't need to be swapped out AGAIN because it is already
757 in the swapfile. This saves I/O)
758 Active: Memory that has been used more recently and usually not
759 reclaimed unless absolutely necessary.
760 Inactive: Memory which has been less recently used. It is more
761 eligible to be reclaimed for other purposes
762 HighTotal:
763 HighFree: Highmem is all memory above ~860MB of physical memory
764 Highmem areas are for use by userspace programs, or
765 for the pagecache. The kernel must use tricks to access
766 this memory, making it slower to access than lowmem.
767 LowTotal:
768 LowFree: Lowmem is memory which can be used for everything that
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200769 highmem can be used for, but it is also available for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 kernel's use for its own data structures. Among many
771 other things, it is where everything from the Slab is
772 allocated. Bad things happen when you're out of lowmem.
773 SwapTotal: total amount of swap space available
774 SwapFree: Memory which has been evicted from RAM, and is temporarily
775 on the disk
776 Dirty: Memory which is waiting to get written back to the disk
777 Writeback: Memory which is actively being written back to the disk
Miklos Szeredib88473f2008-04-30 00:54:39 -0700778 AnonPages: Non-file backed pages mapped into userspace page tables
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 Mapped: files which have been mmaped, such as libraries
Adrian Bunke82443c2006-01-10 00:20:30 +0100780 Slab: in-kernel data structures cache
Miklos Szeredib88473f2008-04-30 00:54:39 -0700781SReclaimable: Part of Slab, that might be reclaimed, such as caches
782 SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure
783 PageTables: amount of memory dedicated to the lowest level of page
784 tables.
785NFS_Unstable: NFS pages sent to the server, but not yet committed to stable
786 storage
787 Bounce: Memory used for block device "bounce buffers"
788WritebackTmp: Memory used by FUSE for temporary writeback buffers
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'),
790 this is the total amount of memory currently available to
791 be allocated on the system. This limit is only adhered to
792 if strict overcommit accounting is enabled (mode 2 in
793 'vm.overcommit_memory').
794 The CommitLimit is calculated with the following formula:
795 CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap
796 For example, on a system with 1G of physical RAM and 7G
797 of swap with a `vm.overcommit_ratio` of 30 it would
798 yield a CommitLimit of 7.3G.
799 For more details, see the memory overcommit documentation
800 in vm/overcommit-accounting.
801Committed_AS: The amount of memory presently allocated on the system.
802 The committed memory is a sum of all of the memory which
803 has been allocated by processes, even if it has not been
804 "used" by them as of yet. A process which malloc()'s 1G
805 of memory, but only touches 300M of it will only show up
806 as using 300M of memory even if it has the address space
807 allocated for the entire 1G. This 1G is memory which has
808 been "committed" to by the VM and can be used at any time
809 by the allocating application. With strict overcommit
810 enabled on the system (mode 2 in 'vm.overcommit_memory'),
811 allocations which would exceed the CommitLimit (detailed
812 above) will not be permitted. This is useful if one needs
813 to guarantee that processes will not fail due to lack of
814 memory once that memory has been successfully allocated.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815VmallocTotal: total size of vmalloc memory area
816 VmallocUsed: amount of vmalloc area which is used
Matt LaPlante19f59462009-04-27 15:06:31 +0200817VmallocChunk: largest contiguous block of vmalloc area which is free
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818
Eric Dumazeta47a1262008-07-23 21:27:38 -0700819..............................................................................
820
821vmallocinfo:
822
823Provides information about vmalloced/vmaped areas. One line per area,
824containing the virtual address range of the area, size in bytes,
825caller information of the creator, and optional information depending
826on the kind of area :
827
828 pages=nr number of pages
829 phys=addr if a physical address was specified
830 ioremap I/O mapping (ioremap() and friends)
831 vmalloc vmalloc() area
832 vmap vmap()ed pages
833 user VM_USERMAP area
834 vpages buffer for pages pointers was vmalloced (huge area)
835 N<node>=nr (Only on NUMA kernels)
836 Number of pages allocated on memory node <node>
837
838> cat /proc/vmallocinfo
8390xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
840 /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
8410xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
842 /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
8430xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
844 phys=7fee8000 ioremap
8450xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
846 phys=7fee7000 ioremap
8470xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
8480xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
849 /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
8500xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
851 pages=2 vmalloc N1=2
8520xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
853 /0x130 [x_tables] pages=4 vmalloc N0=4
8540xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
855 pages=14 vmalloc N2=14
8560xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
857 pages=4 vmalloc N1=4
8580xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
859 pages=2 vmalloc N1=2
8600xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
861 pages=10 vmalloc N0=10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862
Keika Kobayashid3d64df2009-06-17 16:25:55 -0700863..............................................................................
864
865softirqs:
866
867Provides counts of softirq handlers serviced since boot time, for each cpu.
868
869> cat /proc/softirqs
870 CPU0 CPU1 CPU2 CPU3
871 HI: 0 0 0 0
872 TIMER: 27166 27120 27097 27034
873 NET_TX: 0 0 0 17
874 NET_RX: 42 0 0 39
875 BLOCK: 0 0 107 1121
876 TASKLET: 0 0 0 290
877 SCHED: 27035 26983 26971 26746
878 HRTIMER: 0 0 0 0
Shaohua Li09223372011-06-14 13:26:25 +0800879 RCU: 1678 1769 2178 2250
Keika Kobayashid3d64df2009-06-17 16:25:55 -0700880
881
Linus Torvalds1da177e2005-04-16 15:20:36 -07008821.3 IDE devices in /proc/ide
883----------------------------
884
885The subdirectory /proc/ide contains information about all IDE devices of which
886the kernel is aware. There is one subdirectory for each IDE controller, the
887file drivers and a link for each IDE device, pointing to the device directory
888in the controller specific subtree.
889
890The file drivers contains general information about the drivers used for the
891IDE devices:
892
893 > cat /proc/ide/drivers
894 ide-cdrom version 4.53
895 ide-disk version 1.08
896
897More detailed information can be found in the controller specific
898subdirectories. These are named ide0, ide1 and so on. Each of these
Stefani Seibold349888e2009-06-17 16:26:01 -0700899directories contains the files shown in table 1-6.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900
901
Stefani Seibold349888e2009-06-17 16:26:01 -0700902Table 1-6: IDE controller info in /proc/ide/ide?
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903..............................................................................
904 File Content
905 channel IDE channel (0 or 1)
906 config Configuration (only for PCI/IDE bridge)
907 mate Mate name
908 model Type/Chipset of IDE controller
909..............................................................................
910
911Each device connected to a controller has a separate subdirectory in the
Stefani Seibold349888e2009-06-17 16:26:01 -0700912controllers directory. The files listed in table 1-7 are contained in these
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913directories.
914
915
Stefani Seibold349888e2009-06-17 16:26:01 -0700916Table 1-7: IDE device information
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917..............................................................................
918 File Content
919 cache The cache
920 capacity Capacity of the medium (in 512Byte blocks)
921 driver driver and version
922 geometry physical and logical geometry
923 identify device identify block
924 media media type
925 model device identifier
926 settings device setup
927 smart_thresholds IDE disk management thresholds
928 smart_values IDE disk management values
929..............................................................................
930
931The most interesting file is settings. This file contains a nice overview of
932the drive parameters:
933
934 # cat /proc/ide/ide0/hda/settings
935 name value min max mode
936 ---- ----- --- --- ----
937 bios_cyl 526 0 65535 rw
938 bios_head 255 0 255 rw
939 bios_sect 63 0 63 rw
940 breada_readahead 4 0 127 rw
941 bswap 0 0 1 r
942 file_readahead 72 0 2097151 rw
943 io_32bit 0 0 3 rw
944 keepsettings 0 0 1 rw
945 max_kb_per_request 122 1 127 rw
946 multcount 0 0 8 rw
947 nice1 1 0 1 rw
948 nowerr 0 0 1 rw
949 pio_mode write-only 0 255 w
950 slow 0 0 1 rw
951 unmaskirq 0 0 1 rw
952 using_dma 0 0 1 rw
953
954
9551.4 Networking info in /proc/net
956--------------------------------
957
Stefani Seibold349888e2009-06-17 16:26:01 -0700958The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959additional values you get for IP version 6 if you configure the kernel to
Stefani Seibold349888e2009-06-17 16:26:01 -0700960support this. Table 1-9 lists the files and their meaning.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961
962
Stefani Seibold349888e2009-06-17 16:26:01 -0700963Table 1-8: IPv6 info in /proc/net
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964..............................................................................
965 File Content
966 udp6 UDP sockets (IPv6)
967 tcp6 TCP sockets (IPv6)
968 raw6 Raw device statistics (IPv6)
969 igmp6 IP multicast addresses, which this host joined (IPv6)
970 if_inet6 List of IPv6 interface addresses
971 ipv6_route Kernel routing table for IPv6
972 rt6_stats Global IPv6 routing tables statistics
973 sockstat6 Socket statistics (IPv6)
974 snmp6 Snmp data (IPv6)
975..............................................................................
976
977
Stefani Seibold349888e2009-06-17 16:26:01 -0700978Table 1-9: Network info in /proc/net
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979..............................................................................
980 File Content
981 arp Kernel ARP table
982 dev network devices with statistics
983 dev_mcast the Layer2 multicast groups a device is listening too
984 (interface index, label, number of references, number of bound
985 addresses).
986 dev_stat network device status
987 ip_fwchains Firewall chain linkage
988 ip_fwnames Firewall chain names
989 ip_masq Directory containing the masquerading tables
990 ip_masquerade Major masquerading table
991 netstat Network statistics
992 raw raw device statistics
993 route Kernel routing table
994 rpc Directory containing rpc info
995 rt_cache Routing cache
996 snmp SNMP data
997 sockstat Socket statistics
998 tcp TCP sockets
999 tr_rif Token ring RIF routing table
1000 udp UDP sockets
1001 unix UNIX domain sockets
1002 wireless Wireless interface data (Wavelan etc)
1003 igmp IP multicast addresses, which this host joined
1004 psched Global packet scheduler parameters.
1005 netlink List of PF_NETLINK sockets
1006 ip_mr_vifs List of multicast virtual interfaces
1007 ip_mr_cache List of multicast routing cache
1008..............................................................................
1009
1010You can use this information to see which network devices are available in
1011your system and how much traffic was routed over those devices:
1012
1013 > cat /proc/net/dev
1014 Inter-|Receive |[...
1015 face |bytes packets errs drop fifo frame compressed multicast|[...
1016 lo: 908188 5596 0 0 0 0 0 0 [...
1017 ppp0:15475140 20721 410 0 0 410 0 0 [...
1018 eth0: 614530 7085 0 0 0 0 0 1 [...
1019
1020 ...] Transmit
1021 ...] bytes packets errs drop fifo colls carrier compressed
1022 ...] 908188 5596 0 0 0 0 0 0
1023 ...] 1375103 17405 0 0 0 0 0 0
1024 ...] 1703981 5535 0 0 0 3 0 0
1025
Francis Galieguea33f3222010-04-23 00:08:02 +02001026In addition, each Channel Bond interface has its own directory. For
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027example, the bond0 device will have a directory called /proc/net/bond0/.
1028It will contain information that is specific to that bond, such as the
1029current slaves of the bond, the link status of the slaves, and how
1030many times the slaves link has failed.
1031
10321.5 SCSI info
1033-------------
1034
1035If you have a SCSI host adapter in your system, you'll find a subdirectory
1036named after the driver for this adapter in /proc/scsi. You'll also see a list
1037of all recognized SCSI devices in /proc/scsi:
1038
1039 >cat /proc/scsi/scsi
1040 Attached devices:
1041 Host: scsi0 Channel: 00 Id: 00 Lun: 00
1042 Vendor: IBM Model: DGHS09U Rev: 03E0
1043 Type: Direct-Access ANSI SCSI revision: 03
1044 Host: scsi0 Channel: 00 Id: 06 Lun: 00
1045 Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
1046 Type: CD-ROM ANSI SCSI revision: 02
1047
1048
1049The directory named after the driver has one file for each adapter found in
1050the system. These files contain information about the controller, including
1051the used IRQ and the IO address range. The amount of information shown is
1052dependent on the adapter you use. The example shows the output for an Adaptec
1053AHA-2940 SCSI adapter:
1054
1055 > cat /proc/scsi/aic7xxx/0
1056
1057 Adaptec AIC7xxx driver version: 5.1.19/3.2.4
1058 Compile Options:
1059 TCQ Enabled By Default : Disabled
1060 AIC7XXX_PROC_STATS : Disabled
1061 AIC7XXX_RESET_DELAY : 5
1062 Adapter Configuration:
1063 SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
1064 Ultra Wide Controller
1065 PCI MMAPed I/O Base: 0xeb001000
1066 Adapter SEEPROM Config: SEEPROM found and used.
1067 Adaptec SCSI BIOS: Enabled
1068 IRQ: 10
1069 SCBs: Active 0, Max Active 2,
1070 Allocated 15, HW 16, Page 255
1071 Interrupts: 160328
1072 BIOS Control Word: 0x18b6
1073 Adapter Control Word: 0x005b
1074 Extended Translation: Enabled
1075 Disconnect Enable Flags: 0xffff
1076 Ultra Enable Flags: 0x0001
1077 Tag Queue Enable Flags: 0x0000
1078 Ordered Queue Tag Flags: 0x0000
1079 Default Tag Queue Depth: 8
1080 Tagged Queue By Device array for aic7xxx host instance 0:
1081 {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
1082 Actual queue depth per device for aic7xxx host instance 0:
1083 {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
1084 Statistics:
1085 (scsi0:0:0:0)
1086 Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
1087 Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0)
1088 Total transfers 160151 (74577 reads and 85574 writes)
1089 (scsi0:0:6:0)
1090 Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
1091 Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0)
1092 Total transfers 0 (0 reads and 0 writes)
1093
1094
10951.6 Parallel port info in /proc/parport
1096---------------------------------------
1097
1098The directory /proc/parport contains information about the parallel ports of
1099your system. It has one subdirectory for each port, named after the port
1100number (0,1,2,...).
1101
Stefani Seibold349888e2009-06-17 16:26:01 -07001102These directories contain the four files shown in Table 1-10.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103
1104
Stefani Seibold349888e2009-06-17 16:26:01 -07001105Table 1-10: Files in /proc/parport
Linus Torvalds1da177e2005-04-16 15:20:36 -07001106..............................................................................
1107 File Content
1108 autoprobe Any IEEE-1284 device ID information that has been acquired.
1109 devices list of the device drivers using that port. A + will appear by the
1110 name of the device currently using the port (it might not appear
1111 against any).
1112 hardware Parallel port's base address, IRQ line and DMA channel.
1113 irq IRQ that parport is using for that port. This is in a separate
1114 file to allow you to alter it by writing a new value in (IRQ
1115 number or none).
1116..............................................................................
1117
11181.7 TTY info in /proc/tty
1119-------------------------
1120
1121Information about the available and actually used tty's can be found in the
1122directory /proc/tty.You'll find entries for drivers and line disciplines in
Stefani Seibold349888e2009-06-17 16:26:01 -07001123this directory, as shown in Table 1-11.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124
1125
Stefani Seibold349888e2009-06-17 16:26:01 -07001126Table 1-11: Files in /proc/tty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127..............................................................................
1128 File Content
1129 drivers list of drivers and their usage
1130 ldiscs registered line disciplines
1131 driver/serial usage statistic and status of single tty lines
1132..............................................................................
1133
1134To see which tty's are currently in use, you can simply look into the file
1135/proc/tty/drivers:
1136
1137 > cat /proc/tty/drivers
1138 pty_slave /dev/pts 136 0-255 pty:slave
1139 pty_master /dev/ptm 128 0-255 pty:master
1140 pty_slave /dev/ttyp 3 0-255 pty:slave
1141 pty_master /dev/pty 2 0-255 pty:master
1142 serial /dev/cua 5 64-67 serial:callout
1143 serial /dev/ttyS 4 64-67 serial
1144 /dev/tty0 /dev/tty0 4 0 system:vtmaster
1145 /dev/ptmx /dev/ptmx 5 2 system
1146 /dev/console /dev/console 5 1 system:console
1147 /dev/tty /dev/tty 5 0 system:/dev/tty
1148 unknown /dev/tty 4 1-63 console
1149
1150
11511.8 Miscellaneous kernel statistics in /proc/stat
1152-------------------------------------------------
1153
1154Various pieces of information about kernel activity are available in the
1155/proc/stat file. All of the numbers reported in this file are aggregates
1156since the system first booted. For a quick look, simply cat the file:
1157
1158 > cat /proc/stat
Eric Dumazetc5743582009-09-21 17:01:06 -07001159 cpu 2255 34 2290 22625563 6290 127 456 0 0
1160 cpu0 1132 34 1441 11311718 3675 127 438 0 0
1161 cpu1 1123 0 849 11313845 2614 0 18 0 0
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
1163 ctxt 1990473
1164 btime 1062191376
1165 processes 2915
1166 procs_running 1
1167 procs_blocked 0
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001168 softirq 183433 0 21755 12 39 1137 231 21459 2263
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169
1170The very first "cpu" line aggregates the numbers in all of the other "cpuN"
1171lines. These numbers identify the amount of time the CPU has spent performing
1172different kinds of work. Time units are in USER_HZ (typically hundredths of a
1173second). The meanings of the columns are as follows, from left to right:
1174
1175- user: normal processes executing in user mode
1176- nice: niced processes executing in user mode
1177- system: processes executing in kernel mode
1178- idle: twiddling thumbs
1179- iowait: waiting for I/O to complete
1180- irq: servicing interrupts
1181- softirq: servicing softirqs
Leonardo Chiquittob68f2c3a2007-10-20 03:03:38 +02001182- steal: involuntary wait
Ryota Ozakice0e7b22009-10-24 01:20:10 +09001183- guest: running a normal guest
1184- guest_nice: running a niced guest
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185
1186The "intr" line gives counts of interrupts serviced since boot time, for each
1187of the possible system interrupts. The first column is the total of all
1188interrupts serviced; each subsequent column is the total for that particular
1189interrupt.
1190
1191The "ctxt" line gives the total number of context switches across all CPUs.
1192
1193The "btime" line gives the time at which the system booted, in seconds since
1194the Unix epoch.
1195
1196The "processes" line gives the number of processes and threads created, which
1197includes (but is not limited to) those created by calls to the fork() and
1198clone() system calls.
1199
Luis Garces-Ericee3cc2222009-12-06 18:30:44 -08001200The "procs_running" line gives the total number of threads that are
1201running or ready to run (i.e., the total number of runnable threads).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001202
1203The "procs_blocked" line gives the number of processes currently blocked,
1204waiting for I/O to complete.
1205
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001206The "softirq" line gives counts of softirqs serviced since boot time, for each
1207of the possible system softirqs. The first column is the total of all
1208softirqs serviced; each subsequent column is the total for that particular
1209softirq.
1210
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001211
Alex Tomasc9de5602008-01-29 00:19:52 -050012121.9 Ext4 file system parameters
1213------------------------------
Alex Tomasc9de5602008-01-29 00:19:52 -05001214
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001215Information about mounted ext4 file systems can be found in
1216/proc/fs/ext4. Each mounted filesystem will have a directory in
1217/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
1218/proc/fs/ext4/dm-0). The files in each per-device directory are shown
Stefani Seibold349888e2009-06-17 16:26:01 -07001219in Table 1-12, below.
Alex Tomasc9de5602008-01-29 00:19:52 -05001220
Stefani Seibold349888e2009-06-17 16:26:01 -07001221Table 1-12: Files in /proc/fs/ext4/<devname>
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001222..............................................................................
1223 File Content
1224 mb_groups details of multiblock allocator buddy cache of free blocks
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001225..............................................................................
Alex Tomasc9de5602008-01-29 00:19:52 -05001226
Jiri Slaby23308ba2010-11-04 16:20:24 +010012272.0 /proc/consoles
1228------------------
1229Shows registered system console lines.
1230
1231To see which character device lines are currently used for the system console
1232/dev/console, you may simply look into the file /proc/consoles:
1233
1234 > cat /proc/consoles
1235 tty0 -WU (ECp) 4:7
1236 ttyS0 -W- (Ep) 4:64
1237
1238The columns are:
1239
1240 device name of the device
1241 operations R = can do read operations
1242 W = can do write operations
1243 U = can do unblank
1244 flags E = it is enabled
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001245 C = it is preferred console
Jiri Slaby23308ba2010-11-04 16:20:24 +01001246 B = it is primary boot console
1247 p = it is used for printk buffer
1248 b = it is not a TTY but a Braille device
1249 a = it is safe to use when cpu is offline
1250 major:minor major and minor number of the device separated by a colon
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251
1252------------------------------------------------------------------------------
1253Summary
1254------------------------------------------------------------------------------
1255The /proc file system serves information about the running system. It not only
1256allows access to process data but also allows you to request the kernel status
1257by reading files in the hierarchy.
1258
1259The directory structure of /proc reflects the types of information and makes
1260it easy, if not obvious, where to look for specific data.
1261------------------------------------------------------------------------------
1262
1263------------------------------------------------------------------------------
1264CHAPTER 2: MODIFYING SYSTEM PARAMETERS
1265------------------------------------------------------------------------------
1266
1267------------------------------------------------------------------------------
1268In This Chapter
1269------------------------------------------------------------------------------
1270* Modifying kernel parameters by writing into files found in /proc/sys
1271* Exploring the files which modify certain parameters
1272* Review of the /proc/sys file tree
1273------------------------------------------------------------------------------
1274
1275
1276A very interesting part of /proc is the directory /proc/sys. This is not only
1277a source of information, it also allows you to change parameters within the
1278kernel. Be very careful when attempting this. You can optimize your system,
1279but you can also cause it to crash. Never alter kernel parameters on a
1280production system. Set up a development machine and test to make sure that
1281everything works the way you want it to. You may have no alternative but to
1282reboot the machine once an error has been made.
1283
1284To change a value, simply echo the new value into the file. An example is
1285given below in the section on the file system data. You need to be root to do
1286this. You can create your own boot script to perform this every time your
1287system boots.
1288
1289The files in /proc/sys can be used to fine tune and monitor miscellaneous and
1290general things in the operation of the Linux kernel. Since some of the files
1291can inadvertently disrupt your system, it is advisable to read both
1292documentation and source before actually making adjustments. In any case, be
1293very careful when writing to any of these files. The entries in /proc may
1294change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
1295review the kernel documentation in the directory /usr/src/linux/Documentation.
1296This chapter is heavily based on the documentation included in the pre 2.2
1297kernels, and became part of it in version 2.2.1 of the Linux kernel.
1298
Paul Bolle395cf962011-08-15 02:02:26 +02001299Please see: Documentation/sysctl/ directory for descriptions of these
Peter W Morrealedb0fb182009-01-15 13:50:42 -08001300entries.
Andrew Morton9d0243b2006-01-08 01:00:39 -08001301
Shen Feng760df932009-04-02 16:57:20 -07001302------------------------------------------------------------------------------
1303Summary
1304------------------------------------------------------------------------------
1305Certain aspects of kernel behavior can be modified at runtime, without the
1306need to recompile the kernel, or even to reboot the system. The files in the
1307/proc/sys tree can not only be read, but also modified. You can use the echo
1308command to write value into these files, thereby changing the default settings
1309of the kernel.
1310------------------------------------------------------------------------------
Andrew Morton9d0243b2006-01-08 01:00:39 -08001311
Shen Feng760df932009-04-02 16:57:20 -07001312------------------------------------------------------------------------------
1313CHAPTER 3: PER-PROCESS PARAMETERS
1314------------------------------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315
David Rientjesa63d83f2010-08-09 17:19:46 -070013163.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
1317--------------------------------------------------------------------------------
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001318
David Rientjesa63d83f2010-08-09 17:19:46 -07001319These file can be used to adjust the badness heuristic used to select which
1320process gets killed in out of memory conditions.
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001321
David Rientjesa63d83f2010-08-09 17:19:46 -07001322The badness heuristic assigns a value to each candidate task ranging from 0
1323(never kill) to 1000 (always kill) to determine which process is targeted. The
1324units are roughly a proportion along that range of allowed memory the process
1325may allocate from based on an estimation of its current memory and swap use.
1326For example, if a task is using all allowed memory, its badness score will be
13271000. If it is using half of its allowed memory, its score will be 500.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001328
David Rientjesa63d83f2010-08-09 17:19:46 -07001329There is an additional factor included in the badness score: root
1330processes are given 3% extra memory over other tasks.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001331
David Rientjesa63d83f2010-08-09 17:19:46 -07001332The amount of "allowed" memory depends on the context in which the oom killer
1333was called. If it is due to the memory assigned to the allocating task's cpuset
1334being exhausted, the allowed memory represents the set of mems assigned to that
1335cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed
1336memory represents the set of mempolicy nodes. If it is due to a memory
1337limit (or swap limit) being reached, the allowed memory is that configured
1338limit. Finally, if it is due to the entire system being out of memory, the
1339allowed memory represents all allocatable resources.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001340
David Rientjesa63d83f2010-08-09 17:19:46 -07001341The value of /proc/<pid>/oom_score_adj is added to the badness score before it
1342is used to determine which task to kill. Acceptable values range from -1000
1343(OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to
1344polarize the preference for oom killing either by always preferring a certain
1345task or completely disabling it. The lowest possible value, -1000, is
1346equivalent to disabling oom killing entirely for that task since it will always
1347report a badness score of 0.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001348
David Rientjesa63d83f2010-08-09 17:19:46 -07001349Consequently, it is very simple for userspace to define the amount of memory to
1350consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for
1351example, is roughly equivalent to allowing the remainder of tasks sharing the
1352same system, cpuset, mempolicy, or memory controller resources to use at least
135350% more memory. A value of -500, on the other hand, would be roughly
1354equivalent to discounting 50% of the task's allowed memory from being considered
1355as scoring against the task.
1356
1357For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
1358be used to tune the badness score. Its acceptable values range from -16
1359(OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
1360(OOM_DISABLE) to disable oom killing entirely for that task. Its value is
1361scaled linearly with /proc/<pid>/oom_score_adj.
1362
1363Writing to /proc/<pid>/oom_score_adj or /proc/<pid>/oom_adj will change the
1364other with its scaled value.
1365
Mandeep Singh Bainesdabb16f2011-01-13 15:46:05 -08001366The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
1367value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
1368requires CAP_SYS_RESOURCE.
1369
David Rientjes51b1bd22010-08-09 17:19:47 -07001370NOTICE: /proc/<pid>/oom_adj is deprecated and will be removed, please see
1371Documentation/feature-removal-schedule.txt.
1372
David Rientjesa63d83f2010-08-09 17:19:46 -07001373Caveat: when a parent task is selected, the oom killer will sacrifice any first
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001374generation children with separate address spaces instead, if possible. This
David Rientjesa63d83f2010-08-09 17:19:46 -07001375avoids servers and important system daemons from being killed and loses the
1376minimal amount of work.
1377
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001378
Shen Feng760df932009-04-02 16:57:20 -070013793.2 /proc/<pid>/oom_score - Display current oom-killer score
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001380-------------------------------------------------------------
1381
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001382This file can be used to check the current score used by the oom-killer is for
1383any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which
1384process should be killed in an out-of-memory situation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385
Roland Kletzingf9c99462007-03-05 00:30:54 -08001386
Shen Feng760df932009-04-02 16:57:20 -070013873.3 /proc/<pid>/io - Display the IO accounting fields
Roland Kletzingf9c99462007-03-05 00:30:54 -08001388-------------------------------------------------------
1389
1390This file contains IO statistics for each running process
1391
1392Example
1393-------
1394
1395test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
1396[1] 3828
1397
1398test:/tmp # cat /proc/3828/io
1399rchar: 323934931
1400wchar: 323929600
1401syscr: 632687
1402syscw: 632675
1403read_bytes: 0
1404write_bytes: 323932160
1405cancelled_write_bytes: 0
1406
1407
1408Description
1409-----------
1410
1411rchar
1412-----
1413
1414I/O counter: chars read
1415The number of bytes which this task has caused to be read from storage. This
1416is simply the sum of bytes which this process passed to read() and pread().
1417It includes things like tty IO and it is unaffected by whether or not actual
1418physical disk IO was required (the read might have been satisfied from
1419pagecache)
1420
1421
1422wchar
1423-----
1424
1425I/O counter: chars written
1426The number of bytes which this task has caused, or shall cause to be written
1427to disk. Similar caveats apply here as with rchar.
1428
1429
1430syscr
1431-----
1432
1433I/O counter: read syscalls
1434Attempt to count the number of read I/O operations, i.e. syscalls like read()
1435and pread().
1436
1437
1438syscw
1439-----
1440
1441I/O counter: write syscalls
1442Attempt to count the number of write I/O operations, i.e. syscalls like
1443write() and pwrite().
1444
1445
1446read_bytes
1447----------
1448
1449I/O counter: bytes read
1450Attempt to count the number of bytes which this process really did cause to
1451be fetched from the storage layer. Done at the submit_bio() level, so it is
1452accurate for block-backed filesystems. <please add status regarding NFS and
1453CIFS at a later time>
1454
1455
1456write_bytes
1457-----------
1458
1459I/O counter: bytes written
1460Attempt to count the number of bytes which this process caused to be sent to
1461the storage layer. This is done at page-dirtying time.
1462
1463
1464cancelled_write_bytes
1465---------------------
1466
1467The big inaccuracy here is truncate. If a process writes 1MB to a file and
1468then deletes the file, it will in fact perform no writeout. But it will have
1469been accounted as having caused 1MB of write.
1470In other words: The number of bytes which this process caused to not happen,
1471by truncating pagecache. A task can cause "negative" IO too. If this task
1472truncates some dirty pagecache, some IO which another task has been accounted
Francis Galieguea33f3222010-04-23 00:08:02 +02001473for (in its write_bytes) will not be happening. We _could_ just subtract that
Roland Kletzingf9c99462007-03-05 00:30:54 -08001474from the truncating task's write_bytes, but there is information loss in doing
1475that.
1476
1477
1478Note
1479----
1480
1481At its current implementation state, this is a bit racy on 32-bit machines: if
1482process A reads process B's /proc/pid/io while process B is updating one of
1483those 64-bit counters, process A could see an intermediate result.
1484
1485
1486More information about this can be found within the taskstats documentation in
1487Documentation/accounting.
1488
Shen Feng760df932009-04-02 16:57:20 -070014893.4 /proc/<pid>/coredump_filter - Core dump filtering settings
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001490---------------------------------------------------------------
1491When a process is dumped, all anonymous memory is written to a core file as
1492long as the size of the core file isn't limited. But sometimes we don't want
1493to dump some memory segments, for example, huge shared memory. Conversely,
1494sometimes we want to save file-backed memory segments into a core file, not
1495only the individual files.
1496
1497/proc/<pid>/coredump_filter allows you to customize which memory segments
1498will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
1499of memory types. If a bit of the bitmask is set, memory segments of the
1500corresponding memory type are dumped, otherwise they are not dumped.
1501
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001502The following 7 memory types are supported:
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001503 - (bit 0) anonymous private memory
1504 - (bit 1) anonymous shared memory
1505 - (bit 2) file-backed private memory
1506 - (bit 3) file-backed shared memory
Hidehiro Kawaib261dfe2008-09-13 02:33:10 -07001507 - (bit 4) ELF header pages in file-backed private memory areas (it is
1508 effective only if the bit 2 is cleared)
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001509 - (bit 5) hugetlb private memory
1510 - (bit 6) hugetlb shared memory
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001511
1512 Note that MMIO pages such as frame buffer are never dumped and vDSO pages
1513 are always dumped regardless of the bitmask status.
1514
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001515 Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only
1516 effected by bit 5-6.
1517
1518Default value of coredump_filter is 0x23; this means all anonymous memory
1519segments and hugetlb private memory are dumped.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001520
1521If you don't want to dump all shared memory segments attached to pid 1234,
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001522write 0x21 to the process's proc file.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001523
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001524 $ echo 0x21 > /proc/1234/coredump_filter
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001525
1526When a new process is created, the process inherits the bitmask status from its
1527parent. It is useful to set up coredump_filter before the program runs.
1528For example:
1529
1530 $ echo 0x7 > /proc/self/coredump_filter
1531 $ ./some_program
1532
Shen Feng760df932009-04-02 16:57:20 -070015333.5 /proc/<pid>/mountinfo - Information about mounts
Ram Pai2d4d4862008-03-27 13:06:25 +01001534--------------------------------------------------------
1535
1536This file contains lines of the form:
1537
153836 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
1539(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
1540
1541(1) mount ID: unique identifier of the mount (may be reused after umount)
1542(2) parent ID: ID of parent (or of self for the top of the mount tree)
1543(3) major:minor: value of st_dev for files on filesystem
1544(4) root: root of the mount within the filesystem
1545(5) mount point: mount point relative to the process's root
1546(6) mount options: per mount options
1547(7) optional fields: zero or more fields of the form "tag[:value]"
1548(8) separator: marks the end of the optional fields
1549(9) filesystem type: name of filesystem of the form "type[.subtype]"
1550(10) mount source: filesystem specific information or "none"
1551(11) super options: per super block options
1552
1553Parsers should ignore all unrecognised optional fields. Currently the
1554possible optional fields are:
1555
1556shared:X mount is shared in peer group X
1557master:X mount is slave to peer group X
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +01001558propagate_from:X mount is slave and receives propagation from peer group X (*)
Ram Pai2d4d4862008-03-27 13:06:25 +01001559unbindable mount is unbindable
1560
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +01001561(*) X is the closest dominant peer group under the process's root. If
1562X is the immediate master of the mount, or if there's no dominant peer
1563group under the same root, then only the "master:X" field is present
1564and not the "propagate_from:X" field.
1565
Ram Pai2d4d4862008-03-27 13:06:25 +01001566For more information on mount propagation see:
1567
1568 Documentation/filesystems/sharedsubtree.txt
1569
john stultz4614a696b2009-12-14 18:00:05 -08001570
15713.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
1572--------------------------------------------------------
1573These files provide a method to access a tasks comm value. It also allows for
1574a task to set its own or one of its thread siblings comm value. The comm value
1575is limited in size compared to the cmdline value, so writing anything longer
1576then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
1577comm value.
Vasiliy Kulikov04996802012-01-10 15:11:31 -08001578
1579
1580------------------------------------------------------------------------------
1581Configuring procfs
1582------------------------------------------------------------------------------
1583
15844.1 Mount options
1585---------------------
1586
1587The following mount options are supported:
1588
1589 hidepid= Set /proc/<pid>/ access mode.
1590 gid= Set the group authorized to learn processes information.
1591
1592hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories
1593(default).
1594
1595hidepid=1 means users may not access any /proc/<pid>/ directories but their
1596own. Sensitive files like cmdline, sched*, status are now protected against
1597other users. This makes it impossible to learn whether any user runs
1598specific program (given the program doesn't reveal itself by its behaviour).
1599As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users,
1600poorly written programs passing sensitive information via program arguments are
1601now protected against local eavesdroppers.
1602
1603hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other
1604users. It doesn't mean that it hides a fact whether a process with a specific
1605pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"),
1606but it hides process' uid and gid, which may be learned by stat()'ing
1607/proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering
1608information about running processes, whether some daemon runs with elevated
1609privileges, whether other user runs some sensitive program, whether other users
1610run any program at all, etc.
1611
1612gid= defines a group authorized to learn processes information otherwise
1613prohibited by hidepid=. If you use some daemon like identd which needs to learn
1614information about processes information, just add identd to this group.