blob: a76a26a1db8a6fe855b0eeea32dee251296c0c8a [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
293 start_stack address of the start of the stack
294 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
328a7eb3000-a7ed5000 rw-p 00000000 00:00 0
329a7ed5000-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
360 [vdso] = the "virtual dynamic shared object",
361 the kernel system call handler
362
363 or if empty, the mapping is anonymous.
364
365
366The /proc/PID/smaps is an extension based on maps, showing the memory
367consumption for each of the process's mappings. For each of mappings there
368is a series of lines such as the following:
369
37008048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
371Size: 1084 kB
372Rss: 892 kB
373Pss: 374 kB
374Shared_Clean: 892 kB
375Shared_Dirty: 0 kB
376Private_Clean: 0 kB
377Private_Dirty: 0 kB
378Referenced: 892 kB
Nikanth Karthikesanb40d4f82010-10-27 15:34:10 -0700379Anonymous: 0 kB
Stefani Seibold349888e2009-06-17 16:26:01 -0700380Swap: 0 kB
381KernelPageSize: 4 kB
382MMUPageSize: 4 kB
Nikanth Karthikesan2d905082011-01-13 15:45:53 -0800383Locked: 374 kB
Stefani Seibold349888e2009-06-17 16:26:01 -0700384
Matt Mackall0f4d2082010-10-26 14:21:22 -0700385The first of these lines shows the same information as is displayed for the
386mapping in /proc/PID/maps. The remaining lines show the size of the mapping
387(size), the amount of the mapping that is currently resident in RAM (RSS), the
388process' proportional share of this mapping (PSS), the number of clean and
Nikanth Karthikesanb40d4f82010-10-27 15:34:10 -0700389dirty private pages in the mapping. Note that even a page which is part of a
390MAP_SHARED mapping, but has only a single pte mapped, i.e. is currently used
391by only one process, is accounted as private and not as shared. "Referenced"
392indicates the amount of memory currently marked as referenced or accessed.
393"Anonymous" shows the amount of memory that does not belong to any file. Even
394a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
395and a page is modified, the file page is replaced by a private anonymous copy.
396"Swap" shows how much would-be-anonymous memory is also used, but out on
397swap.
Stefani Seibold349888e2009-06-17 16:26:01 -0700398
399This file is only present if the CONFIG_MMU kernel configuration option is
400enabled.
Kees Cook18d96772007-07-15 23:40:38 -0700401
Moussa A. Ba398499d2009-09-21 17:02:29 -0700402The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
403bits on both physical and virtual pages associated with a process.
404To clear the bits for all the pages associated with the process
405 > echo 1 > /proc/PID/clear_refs
406
407To clear the bits for the anonymous pages associated with the process
408 > echo 2 > /proc/PID/clear_refs
409
410To clear the bits for the file mapped pages associated with the process
411 > echo 3 > /proc/PID/clear_refs
412Any other value written to /proc/PID/clear_refs will have no effect.
413
Nikanth Karthikesan03f890f2010-10-27 15:34:11 -0700414The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
415using /proc/kpageflags and number of times a page is mapped using
416/proc/kpagecount. For detailed explanation, see Documentation/vm/pagemap.txt.
Moussa A. Ba398499d2009-09-21 17:02:29 -0700417
Linus Torvalds1da177e2005-04-16 15:20:36 -07004181.2 Kernel data
419---------------
420
421Similar to the process entries, the kernel data files give information about
422the running kernel. The files used to obtain this information are contained in
Stefani Seibold349888e2009-06-17 16:26:01 -0700423/proc and are listed in Table 1-5. Not all of these will be present in your
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424system. It depends on the kernel configuration and the loaded modules, which
425files are there, and which are missing.
426
Stefani Seibold349888e2009-06-17 16:26:01 -0700427Table 1-5: Kernel info in /proc
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428..............................................................................
429 File Content
430 apm Advanced power management info
431 buddyinfo Kernel memory allocator information (see text) (2.5)
432 bus Directory containing bus specific information
433 cmdline Kernel command line
434 cpuinfo Info about the CPU
435 devices Available devices (block and character)
436 dma Used DMS channels
437 filesystems Supported filesystems
438 driver Various drivers grouped here, currently rtc (2.4)
439 execdomains Execdomains, related to security (2.4)
440 fb Frame Buffer devices (2.4)
441 fs File system parameters, currently nfs/exports (2.4)
442 ide Directory containing info about the IDE subsystem
443 interrupts Interrupt usage
444 iomem Memory map (2.4)
445 ioports I/O port usage
446 irq Masks for irq to cpu affinity (2.4)(smp?)
447 isapnp ISA PnP (Plug&Play) Info (2.4)
448 kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
449 kmsg Kernel messages
450 ksyms Kernel symbol table
451 loadavg Load average of last 1, 5 & 15 minutes
452 locks Kernel locks
453 meminfo Memory info
454 misc Miscellaneous
455 modules List of loaded modules
456 mounts Mounted filesystems
457 net Networking info (see text)
Mel Gormana1b57ac2010-03-05 13:42:15 -0800458 pagetypeinfo Additional page allocator information (see text) (2.5)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 partitions Table of partitions known to the system
Randy Dunlap8b607562007-05-09 07:19:14 +0200460 pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 decoupled by lspci (2.4)
462 rtc Real time clock
463 scsi SCSI info (see text)
464 slabinfo Slab pool info
Keika Kobayashid3d64df2009-06-17 16:25:55 -0700465 softirqs softirq usage
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 stat Overall statistics
467 swaps Swap space utilization
468 sys See chapter 2
469 sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
470 tty Info of tty drivers
471 uptime System uptime
472 version Kernel version
473 video bttv info of video resources (2.4)
Eric Dumazeta47a1262008-07-23 21:27:38 -0700474 vmallocinfo Show vmalloced areas
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475..............................................................................
476
477You can, for example, check which interrupts are currently in use and what
478they are used for by looking in the file /proc/interrupts:
479
480 > cat /proc/interrupts
481 CPU0
482 0: 8728810 XT-PIC timer
483 1: 895 XT-PIC keyboard
484 2: 0 XT-PIC cascade
485 3: 531695 XT-PIC aha152x
486 4: 2014133 XT-PIC serial
487 5: 44401 XT-PIC pcnet_cs
488 8: 2 XT-PIC rtc
489 11: 8 XT-PIC i82365
490 12: 182918 XT-PIC PS/2 Mouse
491 13: 1 XT-PIC fpu
492 14: 1232265 XT-PIC ide0
493 15: 7 XT-PIC ide1
494 NMI: 0
495
496In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
497output of a SMP machine):
498
499 > cat /proc/interrupts
500
501 CPU0 CPU1
502 0: 1243498 1214548 IO-APIC-edge timer
503 1: 8949 8958 IO-APIC-edge keyboard
504 2: 0 0 XT-PIC cascade
505 5: 11286 10161 IO-APIC-edge soundblaster
506 8: 1 0 IO-APIC-edge rtc
507 9: 27422 27407 IO-APIC-edge 3c503
508 12: 113645 113873 IO-APIC-edge PS/2 Mouse
509 13: 0 0 XT-PIC fpu
510 14: 22491 24012 IO-APIC-edge ide0
511 15: 2183 2415 IO-APIC-edge ide1
512 17: 30564 30414 IO-APIC-level eth0
513 18: 177 164 IO-APIC-level bttv
514 NMI: 2457961 2457959
515 LOC: 2457882 2457881
516 ERR: 2155
517
518NMI is incremented in this case because every timer interrupt generates a NMI
519(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups.
520
521LOC is the local interrupt counter of the internal APIC of every CPU.
522
523ERR is incremented in the case of errors in the IO-APIC bus (the bus that
524connects the CPUs in a SMP system. This means that an error has been detected,
525the IO-APIC automatically retry the transmission, so it should not be a big
526problem, but you should read the SMP-FAQ.
527
Joe Korty38e760a2007-10-17 18:04:40 +0200528In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
529/proc/interrupts to display every IRQ vector in use by the system, not
530just those considered 'most important'. The new vectors are:
531
532 THR -- interrupt raised when a machine check threshold counter
533 (typically counting ECC corrected errors of memory or cache) exceeds
534 a configurable threshold. Only available on some systems.
535
536 TRM -- a thermal event interrupt occurs when a temperature threshold
537 has been exceeded for the CPU. This interrupt may also be generated
538 when the temperature drops back to normal.
539
540 SPU -- a spurious interrupt is some interrupt that was raised then lowered
541 by some IO device before it could be fully processed by the APIC. Hence
542 the APIC sees the interrupt but does not know what device it came from.
543 For this case the APIC will generate the interrupt with a IRQ vector
544 of 0xff. This might also be generated by chipset bugs.
545
546 RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are
547 sent from one CPU to another per the needs of the OS. Typically,
548 their statistics are used by kernel developers and interested users to
Matt LaPlante19f59462009-04-27 15:06:31 +0200549 determine the occurrence of interrupts of the given type.
Joe Korty38e760a2007-10-17 18:04:40 +0200550
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300551The above IRQ vectors are displayed only when relevant. For example,
Joe Korty38e760a2007-10-17 18:04:40 +0200552the threshold vector does not exist on x86_64 platforms. Others are
553suppressed when the system is a uniprocessor. As of this writing, only
554i386 and x86_64 platforms support the new IRQ vector displays.
555
556Of some interest is the introduction of the /proc/irq directory to 2.4.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557It could be used to set IRQ to CPU affinity, this means that you can "hook" an
558IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
Max Krasnyansky18404752008-05-29 11:02:52 -0700559irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and
560prof_cpu_mask.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561
562For example
563 > ls /proc/irq/
564 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
Max Krasnyansky18404752008-05-29 11:02:52 -0700565 1 11 13 15 17 19 3 5 7 9 default_smp_affinity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 > ls /proc/irq/0/
567 smp_affinity
568
Max Krasnyansky18404752008-05-29 11:02:52 -0700569smp_affinity is a bitmask, in which you can specify which CPUs can handle the
570IRQ, you can set it by doing:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571
Max Krasnyansky18404752008-05-29 11:02:52 -0700572 > echo 1 > /proc/irq/10/smp_affinity
573
574This means that only the first CPU will handle the IRQ, but you can also echo
5755 which means that only the first and fourth CPU can handle the IRQ.
576
577The contents of each smp_affinity file is the same by default:
578
579 > cat /proc/irq/0/smp_affinity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 ffffffff
581
Mike Travis4b060422011-05-24 17:13:12 -0700582There is an alternate interface, smp_affinity_list which allows specifying
583a cpu range instead of a bitmask:
584
585 > cat /proc/irq/0/smp_affinity_list
586 1024-1031
587
Max Krasnyansky18404752008-05-29 11:02:52 -0700588The default_smp_affinity mask applies to all non-active IRQs, which are the
589IRQs which have not yet been allocated/activated, and hence which lack a
590/proc/irq/[0-9]* directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591
Dimitri Sivanich92d6b712010-03-11 14:08:56 -0800592The node file on an SMP system shows the node to which the device using the IRQ
593reports itself as being attached. This hardware locality information does not
594include information about any possible driver locality preference.
595
Max Krasnyansky18404752008-05-29 11:02:52 -0700596prof_cpu_mask specifies which CPUs are to be profiled by the system wide
Mike Travis4b060422011-05-24 17:13:12 -0700597profiler. Default value is ffffffff (all cpus if there are only 32 of them).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598
599The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
600between all the CPUs which are allowed to handle it. As usual the kernel has
601more info than you and does a better job than you, so the defaults are the
Mike Travis4b060422011-05-24 17:13:12 -0700602best choice for almost everyone. [Note this applies only to those IO-APIC's
603that support "Round Robin" interrupt distribution.]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604
605There are three more important subdirectories in /proc: net, scsi, and sys.
606The general rule is that the contents, or even the existence of these
607directories, depend on your kernel configuration. If SCSI is not enabled, the
608directory scsi may not exist. The same is true with the net, which is there
609only when networking support is present in the running kernel.
610
611The slabinfo file gives information about memory usage at the slab level.
612Linux uses slab pools for memory management above page level in version 2.2.
613Commonly used objects have their own slab pool (such as network buffers,
614directory cache, and so on).
615
616..............................................................................
617
618> cat /proc/buddyinfo
619
620Node 0, zone DMA 0 4 5 4 4 3 ...
621Node 0, zone Normal 1 0 0 1 101 8 ...
622Node 0, zone HighMem 2 0 0 1 1 0 ...
623
Mel Gormana1b57ac2010-03-05 13:42:15 -0800624External fragmentation is a problem under some workloads, and buddyinfo is a
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625useful tool for helping diagnose these problems. Buddyinfo will give you a
626clue as to how big an area you can safely allocate, or why a previous
627allocation failed.
628
629Each column represents the number of pages of a certain order which are
630available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in
631ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
632available in ZONE_NORMAL, etc...
633
Mel Gormana1b57ac2010-03-05 13:42:15 -0800634More information relevant to external fragmentation can be found in
635pagetypeinfo.
636
637> cat /proc/pagetypeinfo
638Page block order: 9
639Pages per block: 512
640
641Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
642Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
643Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
644Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
645Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
646Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
647Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
648Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
649Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
650Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
651Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
652
653Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
654Node 0, zone DMA 2 0 5 1 0
655Node 0, zone DMA32 41 6 967 2 0
656
657Fragmentation avoidance in the kernel works by grouping pages of different
658migrate types into the same contiguous regions of memory called page blocks.
659A page block is typically the size of the default hugepage size e.g. 2MB on
660X86-64. By keeping pages grouped based on their ability to move, the kernel
661can reclaim pages within a page block to satisfy a high-order allocation.
662
663The pagetypinfo begins with information on the size of a page block. It
664then gives the same type of information as buddyinfo except broken down
665by migrate-type and finishes with details on how many page blocks of each
666type exist.
667
668If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
669from libhugetlbfs http://sourceforge.net/projects/libhugetlbfs/), one can
670make an estimate of the likely number of huge pages that can be allocated
671at a given point in time. All the "Movable" blocks should be allocatable
672unless memory has been mlock()'d. Some of the Reclaimable blocks should
673also be allocatable although a lot of filesystem metadata may have to be
674reclaimed to achieve this.
675
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676..............................................................................
677
678meminfo:
679
680Provides information about distribution and utilization of memory. This
681varies by architecture and compile options. The following is from a
68216GB PIII, which has highmem enabled. You may not have all of these fields.
683
684> cat /proc/meminfo
685
Nikanth Karthikesan2d905082011-01-13 15:45:53 -0800686The "Locked" indicates whether the mapping is locked in memory or not.
687
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688
689MemTotal: 16344972 kB
690MemFree: 13634064 kB
691Buffers: 3656 kB
692Cached: 1195708 kB
693SwapCached: 0 kB
694Active: 891636 kB
695Inactive: 1077224 kB
696HighTotal: 15597528 kB
697HighFree: 13629632 kB
698LowTotal: 747444 kB
699LowFree: 4432 kB
700SwapTotal: 0 kB
701SwapFree: 0 kB
702Dirty: 968 kB
703Writeback: 0 kB
Miklos Szeredib88473f2008-04-30 00:54:39 -0700704AnonPages: 861800 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705Mapped: 280372 kB
Miklos Szeredib88473f2008-04-30 00:54:39 -0700706Slab: 284364 kB
707SReclaimable: 159856 kB
708SUnreclaim: 124508 kB
709PageTables: 24448 kB
710NFS_Unstable: 0 kB
711Bounce: 0 kB
712WritebackTmp: 0 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713CommitLimit: 7669796 kB
714Committed_AS: 100056 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715VmallocTotal: 112216 kB
716VmallocUsed: 428 kB
717VmallocChunk: 111088 kB
718
719 MemTotal: Total usable ram (i.e. physical ram minus a few reserved
720 bits and the kernel binary code)
721 MemFree: The sum of LowFree+HighFree
722 Buffers: Relatively temporary storage for raw disk blocks
723 shouldn't get tremendously large (20MB or so)
724 Cached: in-memory cache for files read from the disk (the
725 pagecache). Doesn't include SwapCached
726 SwapCached: Memory that once was swapped out, is swapped back in but
727 still also is in the swapfile (if memory is needed it
728 doesn't need to be swapped out AGAIN because it is already
729 in the swapfile. This saves I/O)
730 Active: Memory that has been used more recently and usually not
731 reclaimed unless absolutely necessary.
732 Inactive: Memory which has been less recently used. It is more
733 eligible to be reclaimed for other purposes
734 HighTotal:
735 HighFree: Highmem is all memory above ~860MB of physical memory
736 Highmem areas are for use by userspace programs, or
737 for the pagecache. The kernel must use tricks to access
738 this memory, making it slower to access than lowmem.
739 LowTotal:
740 LowFree: Lowmem is memory which can be used for everything that
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200741 highmem can be used for, but it is also available for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742 kernel's use for its own data structures. Among many
743 other things, it is where everything from the Slab is
744 allocated. Bad things happen when you're out of lowmem.
745 SwapTotal: total amount of swap space available
746 SwapFree: Memory which has been evicted from RAM, and is temporarily
747 on the disk
748 Dirty: Memory which is waiting to get written back to the disk
749 Writeback: Memory which is actively being written back to the disk
Miklos Szeredib88473f2008-04-30 00:54:39 -0700750 AnonPages: Non-file backed pages mapped into userspace page tables
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751 Mapped: files which have been mmaped, such as libraries
Adrian Bunke82443c2006-01-10 00:20:30 +0100752 Slab: in-kernel data structures cache
Miklos Szeredib88473f2008-04-30 00:54:39 -0700753SReclaimable: Part of Slab, that might be reclaimed, such as caches
754 SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure
755 PageTables: amount of memory dedicated to the lowest level of page
756 tables.
757NFS_Unstable: NFS pages sent to the server, but not yet committed to stable
758 storage
759 Bounce: Memory used for block device "bounce buffers"
760WritebackTmp: Memory used by FUSE for temporary writeback buffers
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'),
762 this is the total amount of memory currently available to
763 be allocated on the system. This limit is only adhered to
764 if strict overcommit accounting is enabled (mode 2 in
765 'vm.overcommit_memory').
766 The CommitLimit is calculated with the following formula:
767 CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap
768 For example, on a system with 1G of physical RAM and 7G
769 of swap with a `vm.overcommit_ratio` of 30 it would
770 yield a CommitLimit of 7.3G.
771 For more details, see the memory overcommit documentation
772 in vm/overcommit-accounting.
773Committed_AS: The amount of memory presently allocated on the system.
774 The committed memory is a sum of all of the memory which
775 has been allocated by processes, even if it has not been
776 "used" by them as of yet. A process which malloc()'s 1G
777 of memory, but only touches 300M of it will only show up
778 as using 300M of memory even if it has the address space
779 allocated for the entire 1G. This 1G is memory which has
780 been "committed" to by the VM and can be used at any time
781 by the allocating application. With strict overcommit
782 enabled on the system (mode 2 in 'vm.overcommit_memory'),
783 allocations which would exceed the CommitLimit (detailed
784 above) will not be permitted. This is useful if one needs
785 to guarantee that processes will not fail due to lack of
786 memory once that memory has been successfully allocated.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787VmallocTotal: total size of vmalloc memory area
788 VmallocUsed: amount of vmalloc area which is used
Matt LaPlante19f59462009-04-27 15:06:31 +0200789VmallocChunk: largest contiguous block of vmalloc area which is free
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790
Eric Dumazeta47a1262008-07-23 21:27:38 -0700791..............................................................................
792
793vmallocinfo:
794
795Provides information about vmalloced/vmaped areas. One line per area,
796containing the virtual address range of the area, size in bytes,
797caller information of the creator, and optional information depending
798on the kind of area :
799
800 pages=nr number of pages
801 phys=addr if a physical address was specified
802 ioremap I/O mapping (ioremap() and friends)
803 vmalloc vmalloc() area
804 vmap vmap()ed pages
805 user VM_USERMAP area
806 vpages buffer for pages pointers was vmalloced (huge area)
807 N<node>=nr (Only on NUMA kernels)
808 Number of pages allocated on memory node <node>
809
810> cat /proc/vmallocinfo
8110xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
812 /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
8130xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
814 /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
8150xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
816 phys=7fee8000 ioremap
8170xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
818 phys=7fee7000 ioremap
8190xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
8200xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
821 /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
8220xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
823 pages=2 vmalloc N1=2
8240xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
825 /0x130 [x_tables] pages=4 vmalloc N0=4
8260xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
827 pages=14 vmalloc N2=14
8280xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
829 pages=4 vmalloc N1=4
8300xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
831 pages=2 vmalloc N1=2
8320xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
833 pages=10 vmalloc N0=10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700834
Keika Kobayashid3d64df2009-06-17 16:25:55 -0700835..............................................................................
836
837softirqs:
838
839Provides counts of softirq handlers serviced since boot time, for each cpu.
840
841> cat /proc/softirqs
842 CPU0 CPU1 CPU2 CPU3
843 HI: 0 0 0 0
844 TIMER: 27166 27120 27097 27034
845 NET_TX: 0 0 0 17
846 NET_RX: 42 0 0 39
847 BLOCK: 0 0 107 1121
848 TASKLET: 0 0 0 290
849 SCHED: 27035 26983 26971 26746
850 HRTIMER: 0 0 0 0
Shaohua Li09223372011-06-14 13:26:25 +0800851 RCU: 1678 1769 2178 2250
Keika Kobayashid3d64df2009-06-17 16:25:55 -0700852
853
Linus Torvalds1da177e2005-04-16 15:20:36 -07008541.3 IDE devices in /proc/ide
855----------------------------
856
857The subdirectory /proc/ide contains information about all IDE devices of which
858the kernel is aware. There is one subdirectory for each IDE controller, the
859file drivers and a link for each IDE device, pointing to the device directory
860in the controller specific subtree.
861
862The file drivers contains general information about the drivers used for the
863IDE devices:
864
865 > cat /proc/ide/drivers
866 ide-cdrom version 4.53
867 ide-disk version 1.08
868
869More detailed information can be found in the controller specific
870subdirectories. These are named ide0, ide1 and so on. Each of these
Stefani Seibold349888e2009-06-17 16:26:01 -0700871directories contains the files shown in table 1-6.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872
873
Stefani Seibold349888e2009-06-17 16:26:01 -0700874Table 1-6: IDE controller info in /proc/ide/ide?
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875..............................................................................
876 File Content
877 channel IDE channel (0 or 1)
878 config Configuration (only for PCI/IDE bridge)
879 mate Mate name
880 model Type/Chipset of IDE controller
881..............................................................................
882
883Each device connected to a controller has a separate subdirectory in the
Stefani Seibold349888e2009-06-17 16:26:01 -0700884controllers directory. The files listed in table 1-7 are contained in these
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885directories.
886
887
Stefani Seibold349888e2009-06-17 16:26:01 -0700888Table 1-7: IDE device information
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889..............................................................................
890 File Content
891 cache The cache
892 capacity Capacity of the medium (in 512Byte blocks)
893 driver driver and version
894 geometry physical and logical geometry
895 identify device identify block
896 media media type
897 model device identifier
898 settings device setup
899 smart_thresholds IDE disk management thresholds
900 smart_values IDE disk management values
901..............................................................................
902
903The most interesting file is settings. This file contains a nice overview of
904the drive parameters:
905
906 # cat /proc/ide/ide0/hda/settings
907 name value min max mode
908 ---- ----- --- --- ----
909 bios_cyl 526 0 65535 rw
910 bios_head 255 0 255 rw
911 bios_sect 63 0 63 rw
912 breada_readahead 4 0 127 rw
913 bswap 0 0 1 r
914 file_readahead 72 0 2097151 rw
915 io_32bit 0 0 3 rw
916 keepsettings 0 0 1 rw
917 max_kb_per_request 122 1 127 rw
918 multcount 0 0 8 rw
919 nice1 1 0 1 rw
920 nowerr 0 0 1 rw
921 pio_mode write-only 0 255 w
922 slow 0 0 1 rw
923 unmaskirq 0 0 1 rw
924 using_dma 0 0 1 rw
925
926
9271.4 Networking info in /proc/net
928--------------------------------
929
Stefani Seibold349888e2009-06-17 16:26:01 -0700930The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931additional values you get for IP version 6 if you configure the kernel to
Stefani Seibold349888e2009-06-17 16:26:01 -0700932support this. Table 1-9 lists the files and their meaning.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933
934
Stefani Seibold349888e2009-06-17 16:26:01 -0700935Table 1-8: IPv6 info in /proc/net
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936..............................................................................
937 File Content
938 udp6 UDP sockets (IPv6)
939 tcp6 TCP sockets (IPv6)
940 raw6 Raw device statistics (IPv6)
941 igmp6 IP multicast addresses, which this host joined (IPv6)
942 if_inet6 List of IPv6 interface addresses
943 ipv6_route Kernel routing table for IPv6
944 rt6_stats Global IPv6 routing tables statistics
945 sockstat6 Socket statistics (IPv6)
946 snmp6 Snmp data (IPv6)
947..............................................................................
948
949
Stefani Seibold349888e2009-06-17 16:26:01 -0700950Table 1-9: Network info in /proc/net
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951..............................................................................
952 File Content
953 arp Kernel ARP table
954 dev network devices with statistics
955 dev_mcast the Layer2 multicast groups a device is listening too
956 (interface index, label, number of references, number of bound
957 addresses).
958 dev_stat network device status
959 ip_fwchains Firewall chain linkage
960 ip_fwnames Firewall chain names
961 ip_masq Directory containing the masquerading tables
962 ip_masquerade Major masquerading table
963 netstat Network statistics
964 raw raw device statistics
965 route Kernel routing table
966 rpc Directory containing rpc info
967 rt_cache Routing cache
968 snmp SNMP data
969 sockstat Socket statistics
970 tcp TCP sockets
971 tr_rif Token ring RIF routing table
972 udp UDP sockets
973 unix UNIX domain sockets
974 wireless Wireless interface data (Wavelan etc)
975 igmp IP multicast addresses, which this host joined
976 psched Global packet scheduler parameters.
977 netlink List of PF_NETLINK sockets
978 ip_mr_vifs List of multicast virtual interfaces
979 ip_mr_cache List of multicast routing cache
980..............................................................................
981
982You can use this information to see which network devices are available in
983your system and how much traffic was routed over those devices:
984
985 > cat /proc/net/dev
986 Inter-|Receive |[...
987 face |bytes packets errs drop fifo frame compressed multicast|[...
988 lo: 908188 5596 0 0 0 0 0 0 [...
989 ppp0:15475140 20721 410 0 0 410 0 0 [...
990 eth0: 614530 7085 0 0 0 0 0 1 [...
991
992 ...] Transmit
993 ...] bytes packets errs drop fifo colls carrier compressed
994 ...] 908188 5596 0 0 0 0 0 0
995 ...] 1375103 17405 0 0 0 0 0 0
996 ...] 1703981 5535 0 0 0 3 0 0
997
Francis Galieguea33f3222010-04-23 00:08:02 +0200998In addition, each Channel Bond interface has its own directory. For
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999example, the bond0 device will have a directory called /proc/net/bond0/.
1000It will contain information that is specific to that bond, such as the
1001current slaves of the bond, the link status of the slaves, and how
1002many times the slaves link has failed.
1003
10041.5 SCSI info
1005-------------
1006
1007If you have a SCSI host adapter in your system, you'll find a subdirectory
1008named after the driver for this adapter in /proc/scsi. You'll also see a list
1009of all recognized SCSI devices in /proc/scsi:
1010
1011 >cat /proc/scsi/scsi
1012 Attached devices:
1013 Host: scsi0 Channel: 00 Id: 00 Lun: 00
1014 Vendor: IBM Model: DGHS09U Rev: 03E0
1015 Type: Direct-Access ANSI SCSI revision: 03
1016 Host: scsi0 Channel: 00 Id: 06 Lun: 00
1017 Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
1018 Type: CD-ROM ANSI SCSI revision: 02
1019
1020
1021The directory named after the driver has one file for each adapter found in
1022the system. These files contain information about the controller, including
1023the used IRQ and the IO address range. The amount of information shown is
1024dependent on the adapter you use. The example shows the output for an Adaptec
1025AHA-2940 SCSI adapter:
1026
1027 > cat /proc/scsi/aic7xxx/0
1028
1029 Adaptec AIC7xxx driver version: 5.1.19/3.2.4
1030 Compile Options:
1031 TCQ Enabled By Default : Disabled
1032 AIC7XXX_PROC_STATS : Disabled
1033 AIC7XXX_RESET_DELAY : 5
1034 Adapter Configuration:
1035 SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
1036 Ultra Wide Controller
1037 PCI MMAPed I/O Base: 0xeb001000
1038 Adapter SEEPROM Config: SEEPROM found and used.
1039 Adaptec SCSI BIOS: Enabled
1040 IRQ: 10
1041 SCBs: Active 0, Max Active 2,
1042 Allocated 15, HW 16, Page 255
1043 Interrupts: 160328
1044 BIOS Control Word: 0x18b6
1045 Adapter Control Word: 0x005b
1046 Extended Translation: Enabled
1047 Disconnect Enable Flags: 0xffff
1048 Ultra Enable Flags: 0x0001
1049 Tag Queue Enable Flags: 0x0000
1050 Ordered Queue Tag Flags: 0x0000
1051 Default Tag Queue Depth: 8
1052 Tagged Queue By Device array for aic7xxx host instance 0:
1053 {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
1054 Actual queue depth per device for aic7xxx host instance 0:
1055 {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
1056 Statistics:
1057 (scsi0:0:0:0)
1058 Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
1059 Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0)
1060 Total transfers 160151 (74577 reads and 85574 writes)
1061 (scsi0:0:6:0)
1062 Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
1063 Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0)
1064 Total transfers 0 (0 reads and 0 writes)
1065
1066
10671.6 Parallel port info in /proc/parport
1068---------------------------------------
1069
1070The directory /proc/parport contains information about the parallel ports of
1071your system. It has one subdirectory for each port, named after the port
1072number (0,1,2,...).
1073
Stefani Seibold349888e2009-06-17 16:26:01 -07001074These directories contain the four files shown in Table 1-10.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075
1076
Stefani Seibold349888e2009-06-17 16:26:01 -07001077Table 1-10: Files in /proc/parport
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078..............................................................................
1079 File Content
1080 autoprobe Any IEEE-1284 device ID information that has been acquired.
1081 devices list of the device drivers using that port. A + will appear by the
1082 name of the device currently using the port (it might not appear
1083 against any).
1084 hardware Parallel port's base address, IRQ line and DMA channel.
1085 irq IRQ that parport is using for that port. This is in a separate
1086 file to allow you to alter it by writing a new value in (IRQ
1087 number or none).
1088..............................................................................
1089
10901.7 TTY info in /proc/tty
1091-------------------------
1092
1093Information about the available and actually used tty's can be found in the
1094directory /proc/tty.You'll find entries for drivers and line disciplines in
Stefani Seibold349888e2009-06-17 16:26:01 -07001095this directory, as shown in Table 1-11.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096
1097
Stefani Seibold349888e2009-06-17 16:26:01 -07001098Table 1-11: Files in /proc/tty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099..............................................................................
1100 File Content
1101 drivers list of drivers and their usage
1102 ldiscs registered line disciplines
1103 driver/serial usage statistic and status of single tty lines
1104..............................................................................
1105
1106To see which tty's are currently in use, you can simply look into the file
1107/proc/tty/drivers:
1108
1109 > cat /proc/tty/drivers
1110 pty_slave /dev/pts 136 0-255 pty:slave
1111 pty_master /dev/ptm 128 0-255 pty:master
1112 pty_slave /dev/ttyp 3 0-255 pty:slave
1113 pty_master /dev/pty 2 0-255 pty:master
1114 serial /dev/cua 5 64-67 serial:callout
1115 serial /dev/ttyS 4 64-67 serial
1116 /dev/tty0 /dev/tty0 4 0 system:vtmaster
1117 /dev/ptmx /dev/ptmx 5 2 system
1118 /dev/console /dev/console 5 1 system:console
1119 /dev/tty /dev/tty 5 0 system:/dev/tty
1120 unknown /dev/tty 4 1-63 console
1121
1122
11231.8 Miscellaneous kernel statistics in /proc/stat
1124-------------------------------------------------
1125
1126Various pieces of information about kernel activity are available in the
1127/proc/stat file. All of the numbers reported in this file are aggregates
1128since the system first booted. For a quick look, simply cat the file:
1129
1130 > cat /proc/stat
Eric Dumazetc5743582009-09-21 17:01:06 -07001131 cpu 2255 34 2290 22625563 6290 127 456 0 0
1132 cpu0 1132 34 1441 11311718 3675 127 438 0 0
1133 cpu1 1123 0 849 11313845 2614 0 18 0 0
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
1135 ctxt 1990473
1136 btime 1062191376
1137 processes 2915
1138 procs_running 1
1139 procs_blocked 0
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001140 softirq 183433 0 21755 12 39 1137 231 21459 2263
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141
1142The very first "cpu" line aggregates the numbers in all of the other "cpuN"
1143lines. These numbers identify the amount of time the CPU has spent performing
1144different kinds of work. Time units are in USER_HZ (typically hundredths of a
1145second). The meanings of the columns are as follows, from left to right:
1146
1147- user: normal processes executing in user mode
1148- nice: niced processes executing in user mode
1149- system: processes executing in kernel mode
1150- idle: twiddling thumbs
1151- iowait: waiting for I/O to complete
1152- irq: servicing interrupts
1153- softirq: servicing softirqs
Leonardo Chiquittob68f2c32007-10-20 03:03:38 +02001154- steal: involuntary wait
Ryota Ozakice0e7b22009-10-24 01:20:10 +09001155- guest: running a normal guest
1156- guest_nice: running a niced guest
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157
1158The "intr" line gives counts of interrupts serviced since boot time, for each
1159of the possible system interrupts. The first column is the total of all
1160interrupts serviced; each subsequent column is the total for that particular
1161interrupt.
1162
1163The "ctxt" line gives the total number of context switches across all CPUs.
1164
1165The "btime" line gives the time at which the system booted, in seconds since
1166the Unix epoch.
1167
1168The "processes" line gives the number of processes and threads created, which
1169includes (but is not limited to) those created by calls to the fork() and
1170clone() system calls.
1171
Luis Garces-Ericee3cc2222009-12-06 18:30:44 -08001172The "procs_running" line gives the total number of threads that are
1173running or ready to run (i.e., the total number of runnable threads).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174
1175The "procs_blocked" line gives the number of processes currently blocked,
1176waiting for I/O to complete.
1177
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001178The "softirq" line gives counts of softirqs serviced since boot time, for each
1179of the possible system softirqs. The first column is the total of all
1180softirqs serviced; each subsequent column is the total for that particular
1181softirq.
1182
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001183
Alex Tomasc9de5602008-01-29 00:19:52 -050011841.9 Ext4 file system parameters
1185------------------------------
Alex Tomasc9de5602008-01-29 00:19:52 -05001186
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001187Information about mounted ext4 file systems can be found in
1188/proc/fs/ext4. Each mounted filesystem will have a directory in
1189/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
1190/proc/fs/ext4/dm-0). The files in each per-device directory are shown
Stefani Seibold349888e2009-06-17 16:26:01 -07001191in Table 1-12, below.
Alex Tomasc9de5602008-01-29 00:19:52 -05001192
Stefani Seibold349888e2009-06-17 16:26:01 -07001193Table 1-12: Files in /proc/fs/ext4/<devname>
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001194..............................................................................
1195 File Content
1196 mb_groups details of multiblock allocator buddy cache of free blocks
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001197..............................................................................
Alex Tomasc9de5602008-01-29 00:19:52 -05001198
Jiri Slaby23308ba2010-11-04 16:20:24 +010011992.0 /proc/consoles
1200------------------
1201Shows registered system console lines.
1202
1203To see which character device lines are currently used for the system console
1204/dev/console, you may simply look into the file /proc/consoles:
1205
1206 > cat /proc/consoles
1207 tty0 -WU (ECp) 4:7
1208 ttyS0 -W- (Ep) 4:64
1209
1210The columns are:
1211
1212 device name of the device
1213 operations R = can do read operations
1214 W = can do write operations
1215 U = can do unblank
1216 flags E = it is enabled
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001217 C = it is preferred console
Jiri Slaby23308ba2010-11-04 16:20:24 +01001218 B = it is primary boot console
1219 p = it is used for printk buffer
1220 b = it is not a TTY but a Braille device
1221 a = it is safe to use when cpu is offline
1222 major:minor major and minor number of the device separated by a colon
Linus Torvalds1da177e2005-04-16 15:20:36 -07001223
1224------------------------------------------------------------------------------
1225Summary
1226------------------------------------------------------------------------------
1227The /proc file system serves information about the running system. It not only
1228allows access to process data but also allows you to request the kernel status
1229by reading files in the hierarchy.
1230
1231The directory structure of /proc reflects the types of information and makes
1232it easy, if not obvious, where to look for specific data.
1233------------------------------------------------------------------------------
1234
1235------------------------------------------------------------------------------
1236CHAPTER 2: MODIFYING SYSTEM PARAMETERS
1237------------------------------------------------------------------------------
1238
1239------------------------------------------------------------------------------
1240In This Chapter
1241------------------------------------------------------------------------------
1242* Modifying kernel parameters by writing into files found in /proc/sys
1243* Exploring the files which modify certain parameters
1244* Review of the /proc/sys file tree
1245------------------------------------------------------------------------------
1246
1247
1248A very interesting part of /proc is the directory /proc/sys. This is not only
1249a source of information, it also allows you to change parameters within the
1250kernel. Be very careful when attempting this. You can optimize your system,
1251but you can also cause it to crash. Never alter kernel parameters on a
1252production system. Set up a development machine and test to make sure that
1253everything works the way you want it to. You may have no alternative but to
1254reboot the machine once an error has been made.
1255
1256To change a value, simply echo the new value into the file. An example is
1257given below in the section on the file system data. You need to be root to do
1258this. You can create your own boot script to perform this every time your
1259system boots.
1260
1261The files in /proc/sys can be used to fine tune and monitor miscellaneous and
1262general things in the operation of the Linux kernel. Since some of the files
1263can inadvertently disrupt your system, it is advisable to read both
1264documentation and source before actually making adjustments. In any case, be
1265very careful when writing to any of these files. The entries in /proc may
1266change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
1267review the kernel documentation in the directory /usr/src/linux/Documentation.
1268This chapter is heavily based on the documentation included in the pre 2.2
1269kernels, and became part of it in version 2.2.1 of the Linux kernel.
1270
Paul Bolle395cf962011-08-15 02:02:26 +02001271Please see: Documentation/sysctl/ directory for descriptions of these
Peter W Morrealedb0fb182009-01-15 13:50:42 -08001272entries.
Andrew Morton9d0243b2006-01-08 01:00:39 -08001273
Shen Feng760df932009-04-02 16:57:20 -07001274------------------------------------------------------------------------------
1275Summary
1276------------------------------------------------------------------------------
1277Certain aspects of kernel behavior can be modified at runtime, without the
1278need to recompile the kernel, or even to reboot the system. The files in the
1279/proc/sys tree can not only be read, but also modified. You can use the echo
1280command to write value into these files, thereby changing the default settings
1281of the kernel.
1282------------------------------------------------------------------------------
Andrew Morton9d0243b2006-01-08 01:00:39 -08001283
Shen Feng760df932009-04-02 16:57:20 -07001284------------------------------------------------------------------------------
1285CHAPTER 3: PER-PROCESS PARAMETERS
1286------------------------------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001287
David Rientjesa63d83f2010-08-09 17:19:46 -070012883.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
1289--------------------------------------------------------------------------------
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001290
David Rientjesa63d83f2010-08-09 17:19:46 -07001291These file can be used to adjust the badness heuristic used to select which
1292process gets killed in out of memory conditions.
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001293
David Rientjesa63d83f2010-08-09 17:19:46 -07001294The badness heuristic assigns a value to each candidate task ranging from 0
1295(never kill) to 1000 (always kill) to determine which process is targeted. The
1296units are roughly a proportion along that range of allowed memory the process
1297may allocate from based on an estimation of its current memory and swap use.
1298For example, if a task is using all allowed memory, its badness score will be
12991000. If it is using half of its allowed memory, its score will be 500.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001300
David Rientjesa63d83f2010-08-09 17:19:46 -07001301There is an additional factor included in the badness score: root
1302processes are given 3% extra memory over other tasks.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001303
David Rientjesa63d83f2010-08-09 17:19:46 -07001304The amount of "allowed" memory depends on the context in which the oom killer
1305was called. If it is due to the memory assigned to the allocating task's cpuset
1306being exhausted, the allowed memory represents the set of mems assigned to that
1307cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed
1308memory represents the set of mempolicy nodes. If it is due to a memory
1309limit (or swap limit) being reached, the allowed memory is that configured
1310limit. Finally, if it is due to the entire system being out of memory, the
1311allowed memory represents all allocatable resources.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001312
David Rientjesa63d83f2010-08-09 17:19:46 -07001313The value of /proc/<pid>/oom_score_adj is added to the badness score before it
1314is used to determine which task to kill. Acceptable values range from -1000
1315(OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to
1316polarize the preference for oom killing either by always preferring a certain
1317task or completely disabling it. The lowest possible value, -1000, is
1318equivalent to disabling oom killing entirely for that task since it will always
1319report a badness score of 0.
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001320
David Rientjesa63d83f2010-08-09 17:19:46 -07001321Consequently, it is very simple for userspace to define the amount of memory to
1322consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for
1323example, is roughly equivalent to allowing the remainder of tasks sharing the
1324same system, cpuset, mempolicy, or memory controller resources to use at least
132550% more memory. A value of -500, on the other hand, would be roughly
1326equivalent to discounting 50% of the task's allowed memory from being considered
1327as scoring against the task.
1328
1329For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
1330be used to tune the badness score. Its acceptable values range from -16
1331(OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
1332(OOM_DISABLE) to disable oom killing entirely for that task. Its value is
1333scaled linearly with /proc/<pid>/oom_score_adj.
1334
1335Writing to /proc/<pid>/oom_score_adj or /proc/<pid>/oom_adj will change the
1336other with its scaled value.
1337
Mandeep Singh Bainesdabb16f2011-01-13 15:46:05 -08001338The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
1339value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
1340requires CAP_SYS_RESOURCE.
1341
David Rientjes51b1bd22010-08-09 17:19:47 -07001342NOTICE: /proc/<pid>/oom_adj is deprecated and will be removed, please see
1343Documentation/feature-removal-schedule.txt.
1344
David Rientjesa63d83f2010-08-09 17:19:46 -07001345Caveat: when a parent task is selected, the oom killer will sacrifice any first
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001346generation children with separate address spaces instead, if possible. This
David Rientjesa63d83f2010-08-09 17:19:46 -07001347avoids servers and important system daemons from being killed and loses the
1348minimal amount of work.
1349
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001350
Shen Feng760df932009-04-02 16:57:20 -070013513.2 /proc/<pid>/oom_score - Display current oom-killer score
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001352-------------------------------------------------------------
1353
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001354This file can be used to check the current score used by the oom-killer is for
1355any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which
1356process should be killed in an out-of-memory situation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357
Roland Kletzingf9c99462007-03-05 00:30:54 -08001358
Shen Feng760df932009-04-02 16:57:20 -070013593.3 /proc/<pid>/io - Display the IO accounting fields
Roland Kletzingf9c99462007-03-05 00:30:54 -08001360-------------------------------------------------------
1361
1362This file contains IO statistics for each running process
1363
1364Example
1365-------
1366
1367test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
1368[1] 3828
1369
1370test:/tmp # cat /proc/3828/io
1371rchar: 323934931
1372wchar: 323929600
1373syscr: 632687
1374syscw: 632675
1375read_bytes: 0
1376write_bytes: 323932160
1377cancelled_write_bytes: 0
1378
1379
1380Description
1381-----------
1382
1383rchar
1384-----
1385
1386I/O counter: chars read
1387The number of bytes which this task has caused to be read from storage. This
1388is simply the sum of bytes which this process passed to read() and pread().
1389It includes things like tty IO and it is unaffected by whether or not actual
1390physical disk IO was required (the read might have been satisfied from
1391pagecache)
1392
1393
1394wchar
1395-----
1396
1397I/O counter: chars written
1398The number of bytes which this task has caused, or shall cause to be written
1399to disk. Similar caveats apply here as with rchar.
1400
1401
1402syscr
1403-----
1404
1405I/O counter: read syscalls
1406Attempt to count the number of read I/O operations, i.e. syscalls like read()
1407and pread().
1408
1409
1410syscw
1411-----
1412
1413I/O counter: write syscalls
1414Attempt to count the number of write I/O operations, i.e. syscalls like
1415write() and pwrite().
1416
1417
1418read_bytes
1419----------
1420
1421I/O counter: bytes read
1422Attempt to count the number of bytes which this process really did cause to
1423be fetched from the storage layer. Done at the submit_bio() level, so it is
1424accurate for block-backed filesystems. <please add status regarding NFS and
1425CIFS at a later time>
1426
1427
1428write_bytes
1429-----------
1430
1431I/O counter: bytes written
1432Attempt to count the number of bytes which this process caused to be sent to
1433the storage layer. This is done at page-dirtying time.
1434
1435
1436cancelled_write_bytes
1437---------------------
1438
1439The big inaccuracy here is truncate. If a process writes 1MB to a file and
1440then deletes the file, it will in fact perform no writeout. But it will have
1441been accounted as having caused 1MB of write.
1442In other words: The number of bytes which this process caused to not happen,
1443by truncating pagecache. A task can cause "negative" IO too. If this task
1444truncates some dirty pagecache, some IO which another task has been accounted
Francis Galieguea33f3222010-04-23 00:08:02 +02001445for (in its write_bytes) will not be happening. We _could_ just subtract that
Roland Kletzingf9c99462007-03-05 00:30:54 -08001446from the truncating task's write_bytes, but there is information loss in doing
1447that.
1448
1449
1450Note
1451----
1452
1453At its current implementation state, this is a bit racy on 32-bit machines: if
1454process A reads process B's /proc/pid/io while process B is updating one of
1455those 64-bit counters, process A could see an intermediate result.
1456
1457
1458More information about this can be found within the taskstats documentation in
1459Documentation/accounting.
1460
Shen Feng760df932009-04-02 16:57:20 -070014613.4 /proc/<pid>/coredump_filter - Core dump filtering settings
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001462---------------------------------------------------------------
1463When a process is dumped, all anonymous memory is written to a core file as
1464long as the size of the core file isn't limited. But sometimes we don't want
1465to dump some memory segments, for example, huge shared memory. Conversely,
1466sometimes we want to save file-backed memory segments into a core file, not
1467only the individual files.
1468
1469/proc/<pid>/coredump_filter allows you to customize which memory segments
1470will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
1471of memory types. If a bit of the bitmask is set, memory segments of the
1472corresponding memory type are dumped, otherwise they are not dumped.
1473
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001474The following 7 memory types are supported:
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001475 - (bit 0) anonymous private memory
1476 - (bit 1) anonymous shared memory
1477 - (bit 2) file-backed private memory
1478 - (bit 3) file-backed shared memory
Hidehiro Kawaib261dfe2008-09-13 02:33:10 -07001479 - (bit 4) ELF header pages in file-backed private memory areas (it is
1480 effective only if the bit 2 is cleared)
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001481 - (bit 5) hugetlb private memory
1482 - (bit 6) hugetlb shared memory
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001483
1484 Note that MMIO pages such as frame buffer are never dumped and vDSO pages
1485 are always dumped regardless of the bitmask status.
1486
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001487 Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only
1488 effected by bit 5-6.
1489
1490Default value of coredump_filter is 0x23; this means all anonymous memory
1491segments and hugetlb private memory are dumped.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001492
1493If you don't want to dump all shared memory segments attached to pid 1234,
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001494write 0x21 to the process's proc file.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001495
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001496 $ echo 0x21 > /proc/1234/coredump_filter
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001497
1498When a new process is created, the process inherits the bitmask status from its
1499parent. It is useful to set up coredump_filter before the program runs.
1500For example:
1501
1502 $ echo 0x7 > /proc/self/coredump_filter
1503 $ ./some_program
1504
Shen Feng760df932009-04-02 16:57:20 -070015053.5 /proc/<pid>/mountinfo - Information about mounts
Ram Pai2d4d4862008-03-27 13:06:25 +01001506--------------------------------------------------------
1507
1508This file contains lines of the form:
1509
151036 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
1511(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
1512
1513(1) mount ID: unique identifier of the mount (may be reused after umount)
1514(2) parent ID: ID of parent (or of self for the top of the mount tree)
1515(3) major:minor: value of st_dev for files on filesystem
1516(4) root: root of the mount within the filesystem
1517(5) mount point: mount point relative to the process's root
1518(6) mount options: per mount options
1519(7) optional fields: zero or more fields of the form "tag[:value]"
1520(8) separator: marks the end of the optional fields
1521(9) filesystem type: name of filesystem of the form "type[.subtype]"
1522(10) mount source: filesystem specific information or "none"
1523(11) super options: per super block options
1524
1525Parsers should ignore all unrecognised optional fields. Currently the
1526possible optional fields are:
1527
1528shared:X mount is shared in peer group X
1529master:X mount is slave to peer group X
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +01001530propagate_from:X mount is slave and receives propagation from peer group X (*)
Ram Pai2d4d4862008-03-27 13:06:25 +01001531unbindable mount is unbindable
1532
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +01001533(*) X is the closest dominant peer group under the process's root. If
1534X is the immediate master of the mount, or if there's no dominant peer
1535group under the same root, then only the "master:X" field is present
1536and not the "propagate_from:X" field.
1537
Ram Pai2d4d4862008-03-27 13:06:25 +01001538For more information on mount propagation see:
1539
1540 Documentation/filesystems/sharedsubtree.txt
1541
john stultz4614a696b2009-12-14 18:00:05 -08001542
15433.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
1544--------------------------------------------------------
1545These files provide a method to access a tasks comm value. It also allows for
1546a task to set its own or one of its thread siblings comm value. The comm value
1547is limited in size compared to the cmdline value, so writing anything longer
1548then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
1549comm value.
Vasiliy Kulikov04996802012-01-10 15:11:31 -08001550
1551
1552------------------------------------------------------------------------------
1553Configuring procfs
1554------------------------------------------------------------------------------
1555
15564.1 Mount options
1557---------------------
1558
1559The following mount options are supported:
1560
1561 hidepid= Set /proc/<pid>/ access mode.
1562 gid= Set the group authorized to learn processes information.
1563
1564hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories
1565(default).
1566
1567hidepid=1 means users may not access any /proc/<pid>/ directories but their
1568own. Sensitive files like cmdline, sched*, status are now protected against
1569other users. This makes it impossible to learn whether any user runs
1570specific program (given the program doesn't reveal itself by its behaviour).
1571As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users,
1572poorly written programs passing sensitive information via program arguments are
1573now protected against local eavesdroppers.
1574
1575hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other
1576users. It doesn't mean that it hides a fact whether a process with a specific
1577pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"),
1578but it hides process' uid and gid, which may be learned by stat()'ing
1579/proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering
1580information about running processes, whether some daemon runs with elevated
1581privileges, whether other user runs some sensitive program, whether other users
1582run any program at all, etc.
1583
1584gid= defines a group authorized to learn processes information otherwise
1585prohibited by hidepid=. If you use some daemon like identd which needs to learn
1586information about processes information, just add identd to this group.