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Linus Torvalds1da177e2005-04-16 15:20:36 -07001------------------------------------------------------------------------------
2 T H E /proc F I L E S Y S T E M
3------------------------------------------------------------------------------
4/proc/sys Terrehon Bowden <terrehon@pacbell.net> October 7 1999
5 Bodo Bauer <bb@ricochet.net>
6
72.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000
Stefani Seibold349888e2009-06-17 16:26:01 -07008move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
Linus Torvalds1da177e2005-04-16 15:20:36 -07009------------------------------------------------------------------------------
10Version 1.3 Kernel version 2.2.12
11 Kernel version 2.4.0-test11-pre4
12------------------------------------------------------------------------------
Stefani Seibold349888e2009-06-17 16:26:01 -070013fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009
Linus Torvalds1da177e2005-04-16 15:20:36 -070014
15Table of Contents
16-----------------
17
18 0 Preface
19 0.1 Introduction/Credits
20 0.2 Legal Stuff
21
22 1 Collecting System Information
23 1.1 Process-Specific Subdirectories
24 1.2 Kernel data
25 1.3 IDE devices in /proc/ide
26 1.4 Networking info in /proc/net
27 1.5 SCSI info
28 1.6 Parallel port info in /proc/parport
29 1.7 TTY info in /proc/tty
30 1.8 Miscellaneous kernel statistics in /proc/stat
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
36 3.1 /proc/<pid>/oom_adj - Adjust the oom-killer score
37 3.2 /proc/<pid>/oom_score - Display current oom-killer score
38 3.3 /proc/<pid>/io - Display the IO accounting fields
39 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
40 3.5 /proc/<pid>/mountinfo - Information about mounts
john stultz4614a696b2009-12-14 18:00:05 -080041 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
Shen Feng760df932009-04-02 16:57:20 -070042
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44------------------------------------------------------------------------------
45Preface
46------------------------------------------------------------------------------
47
480.1 Introduction/Credits
49------------------------
50
51This documentation is part of a soon (or so we hope) to be released book on
52the SuSE Linux distribution. As there is no complete documentation for the
53/proc file system and we've used many freely available sources to write these
54chapters, it seems only fair to give the work back to the Linux community.
55This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm
56afraid it's still far from complete, but we hope it will be useful. As far as
57we know, it is the first 'all-in-one' document about the /proc file system. It
58is focused on the Intel x86 hardware, so if you are looking for PPC, ARM,
59SPARC, AXP, etc., features, you probably won't find what you are looking for.
60It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
61additions and patches are welcome and will be added to this document if you
62mail them to Bodo.
63
64We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of
65other people for help compiling this documentation. We'd also like to extend a
66special thank you to Andi Kleen for documentation, which we relied on heavily
67to create this document, as well as the additional information he provided.
68Thanks to everybody else who contributed source or docs to the Linux kernel
69and helped create a great piece of software... :)
70
71If you have any comments, corrections or additions, please don't hesitate to
72contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this
73document.
74
75The latest version of this document is available online at
76http://skaro.nightcrawler.com/~bb/Docs/Proc as HTML version.
77
78If the above direction does not works for you, ypu could try the kernel
79mailing list at linux-kernel@vger.kernel.org and/or try to reach me at
80comandante@zaralinux.com.
81
820.2 Legal Stuff
83---------------
84
85We don't guarantee the correctness of this document, and if you come to us
86complaining about how you screwed up your system because of incorrect
87documentation, we won't feel responsible...
88
89------------------------------------------------------------------------------
90CHAPTER 1: COLLECTING SYSTEM INFORMATION
91------------------------------------------------------------------------------
92
93------------------------------------------------------------------------------
94In This Chapter
95------------------------------------------------------------------------------
96* Investigating the properties of the pseudo file system /proc and its
97 ability to provide information on the running Linux system
98* Examining /proc's structure
99* Uncovering various information about the kernel and the processes running
100 on the system
101------------------------------------------------------------------------------
102
103
104The proc file system acts as an interface to internal data structures in the
105kernel. It can be used to obtain information about the system and to change
106certain kernel parameters at runtime (sysctl).
107
108First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
109show you how you can use /proc/sys to change settings.
110
1111.1 Process-Specific Subdirectories
112-----------------------------------
113
114The directory /proc contains (among other things) one subdirectory for each
115process running on the system, which is named after the process ID (PID).
116
117The link self points to the process reading the file system. Each process
118subdirectory has the entries listed in Table 1-1.
119
120
Stefani Seibold349888e2009-06-17 16:26:01 -0700121Table 1-1: Process specific entries in /proc
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122..............................................................................
David Rientjesb813e932007-05-06 14:49:24 -0700123 File Content
124 clear_refs Clears page referenced bits shown in smaps output
125 cmdline Command line arguments
126 cpu Current and last cpu in which it was executed (2.4)(smp)
127 cwd Link to the current working directory
128 environ Values of environment variables
129 exe Link to the executable of this process
130 fd Directory, which contains all file descriptors
131 maps Memory maps to executables and library files (2.4)
132 mem Memory held by this process
133 root Link to the root directory of this process
134 stat Process status
135 statm Process memory status information
136 status Process status in human readable form
137 wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
Ken Chen2ec220e2008-11-10 11:26:08 +0300138 stack Report full stack trace, enable via CONFIG_STACKTRACE
Stefani Seibold349888e2009-06-17 16:26:01 -0700139 smaps a extension based on maps, showing the memory consumption of
140 each mapping
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141..............................................................................
142
143For example, to get the status information of a process, all you have to do is
144read the file /proc/PID/status:
145
Stefani Seibold349888e2009-06-17 16:26:01 -0700146 >cat /proc/self/status
147 Name: cat
148 State: R (running)
149 Tgid: 5452
150 Pid: 5452
151 PPid: 743
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 TracerPid: 0 (2.4)
Stefani Seibold349888e2009-06-17 16:26:01 -0700153 Uid: 501 501 501 501
154 Gid: 100 100 100 100
155 FDSize: 256
156 Groups: 100 14 16
157 VmPeak: 5004 kB
158 VmSize: 5004 kB
159 VmLck: 0 kB
160 VmHWM: 476 kB
161 VmRSS: 476 kB
162 VmData: 156 kB
163 VmStk: 88 kB
164 VmExe: 68 kB
165 VmLib: 1412 kB
166 VmPTE: 20 kb
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -0800167 VmSwap: 0 kB
Stefani Seibold349888e2009-06-17 16:26:01 -0700168 Threads: 1
169 SigQ: 0/28578
170 SigPnd: 0000000000000000
171 ShdPnd: 0000000000000000
172 SigBlk: 0000000000000000
173 SigIgn: 0000000000000000
174 SigCgt: 0000000000000000
175 CapInh: 00000000fffffeff
176 CapPrm: 0000000000000000
177 CapEff: 0000000000000000
178 CapBnd: ffffffffffffffff
179 voluntary_ctxt_switches: 0
180 nonvoluntary_ctxt_switches: 1
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181
182This shows you nearly the same information you would get if you viewed it with
183the ps command. In fact, ps uses the proc file system to obtain its
Stefani Seibold349888e2009-06-17 16:26:01 -0700184information. But you get a more detailed view of the process by reading the
185file /proc/PID/status. It fields are described in table 1-2.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186
Stefani Seibold349888e2009-06-17 16:26:01 -0700187The statm file contains more detailed information about the process
188memory usage. Its seven fields are explained in Table 1-3. The stat file
189contains details information about the process itself. Its fields are
190explained in Table 1-4.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -0800192(for SMP CONFIG users)
193For making accounting scalable, RSS related information are handled in
194asynchronous manner and the vaule may not be very precise. To see a precise
195snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
196It's slow but very precise.
197
Mulyadi Santosacb2992a2010-02-18 01:22:40 +0700198Table 1-2: Contents of the status files (as of 2.6.30-rc7)
Stefani Seibold349888e2009-06-17 16:26:01 -0700199..............................................................................
200 Field Content
201 Name filename of the executable
202 State state (R is running, S is sleeping, D is sleeping
203 in an uninterruptible wait, Z is zombie,
204 T is traced or stopped)
205 Tgid thread group ID
206 Pid process id
207 PPid process id of the parent process
208 TracerPid PID of process tracing this process (0 if not)
209 Uid Real, effective, saved set, and file system UIDs
210 Gid Real, effective, saved set, and file system GIDs
211 FDSize number of file descriptor slots currently allocated
212 Groups supplementary group list
213 VmPeak peak virtual memory size
214 VmSize total program size
215 VmLck locked memory size
216 VmHWM peak resident set size ("high water mark")
217 VmRSS size of memory portions
218 VmData size of data, stack, and text segments
219 VmStk size of data, stack, and text segments
220 VmExe size of text segment
221 VmLib size of shared library code
222 VmPTE size of page table entries
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -0800223 VmSwap size of swap usage (the number of referred swapents)
Stefani Seibold349888e2009-06-17 16:26:01 -0700224 Threads number of threads
225 SigQ number of signals queued/max. number for queue
226 SigPnd bitmap of pending signals for the thread
227 ShdPnd bitmap of shared pending signals for the process
228 SigBlk bitmap of blocked signals
229 SigIgn bitmap of ignored signals
230 SigCgt bitmap of catched signals
231 CapInh bitmap of inheritable capabilities
232 CapPrm bitmap of permitted capabilities
233 CapEff bitmap of effective capabilities
234 CapBnd bitmap of capabilities bounding set
235 Cpus_allowed mask of CPUs on which this process may run
236 Cpus_allowed_list Same as previous, but in "list format"
237 Mems_allowed mask of memory nodes allowed to this process
238 Mems_allowed_list Same as previous, but in "list format"
239 voluntary_ctxt_switches number of voluntary context switches
240 nonvoluntary_ctxt_switches number of non voluntary context switches
241..............................................................................
242
243Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244..............................................................................
245 Field Content
246 size total program size (pages) (same as VmSize in status)
247 resident size of memory portions (pages) (same as VmRSS in status)
248 shared number of pages that are shared (i.e. backed by a file)
249 trs number of pages that are 'code' (not including libs; broken,
250 includes data segment)
251 lrs number of pages of library (always 0 on 2.6)
252 drs number of pages of data/stack (including libs; broken,
253 includes library text)
254 dt number of dirty pages (always 0 on 2.6)
255..............................................................................
256
Kees Cook18d96772007-07-15 23:40:38 -0700257
Stefani Seibold349888e2009-06-17 16:26:01 -0700258Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
Kees Cook18d96772007-07-15 23:40:38 -0700259..............................................................................
260 Field Content
261 pid process id
262 tcomm filename of the executable
263 state state (R is running, S is sleeping, D is sleeping in an
264 uninterruptible wait, Z is zombie, T is traced or stopped)
265 ppid process id of the parent process
266 pgrp pgrp of the process
267 sid session id
268 tty_nr tty the process uses
269 tty_pgrp pgrp of the tty
270 flags task flags
271 min_flt number of minor faults
272 cmin_flt number of minor faults with child's
273 maj_flt number of major faults
274 cmaj_flt number of major faults with child's
275 utime user mode jiffies
276 stime kernel mode jiffies
277 cutime user mode jiffies with child's
278 cstime kernel mode jiffies with child's
279 priority priority level
280 nice nice level
281 num_threads number of threads
Leonardo Chiquitto2e01e002008-02-03 16:17:16 +0200282 it_real_value (obsolete, always 0)
Kees Cook18d96772007-07-15 23:40:38 -0700283 start_time time the process started after system boot
284 vsize virtual memory size
285 rss resident set memory size
286 rsslim current limit in bytes on the rss
287 start_code address above which program text can run
288 end_code address below which program text can run
289 start_stack address of the start of the stack
290 esp current value of ESP
291 eip current value of EIP
Stefani Seibold349888e2009-06-17 16:26:01 -0700292 pending bitmap of pending signals
293 blocked bitmap of blocked signals
294 sigign bitmap of ignored signals
295 sigcatch bitmap of catched signals
Kees Cook18d96772007-07-15 23:40:38 -0700296 wchan address where process went to sleep
297 0 (place holder)
298 0 (place holder)
299 exit_signal signal to send to parent thread on exit
300 task_cpu which CPU the task is scheduled on
301 rt_priority realtime priority
302 policy scheduling policy (man sched_setscheduler)
303 blkio_ticks time spent waiting for block IO
Stefani Seibold349888e2009-06-17 16:26:01 -0700304 gtime guest time of the task in jiffies
305 cgtime guest time of the task children in jiffies
Kees Cook18d96772007-07-15 23:40:38 -0700306..............................................................................
307
Rob Landley32e688b2010-03-15 15:21:31 +0100308The /proc/PID/maps file containing the currently mapped memory regions and
Stefani Seibold349888e2009-06-17 16:26:01 -0700309their access permissions.
310
311The format is:
312
313address perms offset dev inode pathname
314
31508048000-08049000 r-xp 00000000 03:00 8312 /opt/test
31608049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
3170804a000-0806b000 rw-p 00000000 00:00 0 [heap]
318a7cb1000-a7cb2000 ---p 00000000 00:00 0
Robin Holt34441422010-05-11 14:06:46 -0700319a7cb2000-a7eb2000 rw-p 00000000 00:00 0
Stefani Seibold349888e2009-06-17 16:26:01 -0700320a7eb2000-a7eb3000 ---p 00000000 00:00 0
321a7eb3000-a7ed5000 rw-p 00000000 00:00 0
322a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
323a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
324a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
325a800b000-a800e000 rw-p 00000000 00:00 0
326a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
327a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
328a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
329a8024000-a8027000 rw-p 00000000 00:00 0
330a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
331a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
332a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
333aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
334ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
335
336where "address" is the address space in the process that it occupies, "perms"
337is a set of permissions:
338
339 r = read
340 w = write
341 x = execute
342 s = shared
343 p = private (copy on write)
344
345"offset" is the offset into the mapping, "dev" is the device (major:minor), and
346"inode" is the inode on that device. 0 indicates that no inode is associated
347with the memory region, as the case would be with BSS (uninitialized data).
348The "pathname" shows the name associated file for this mapping. If the mapping
349is not associated with a file:
350
351 [heap] = the heap of the program
352 [stack] = the stack of the main process
353 [vdso] = the "virtual dynamic shared object",
354 the kernel system call handler
355
356 or if empty, the mapping is anonymous.
357
358
359The /proc/PID/smaps is an extension based on maps, showing the memory
360consumption for each of the process's mappings. For each of mappings there
361is a series of lines such as the following:
362
36308048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
364Size: 1084 kB
365Rss: 892 kB
366Pss: 374 kB
367Shared_Clean: 892 kB
368Shared_Dirty: 0 kB
369Private_Clean: 0 kB
370Private_Dirty: 0 kB
371Referenced: 892 kB
372Swap: 0 kB
373KernelPageSize: 4 kB
374MMUPageSize: 4 kB
375
376The first of these lines shows the same information as is displayed for the
377mapping in /proc/PID/maps. The remaining lines show the size of the mapping,
378the amount of the mapping that is currently resident in RAM, the "proportional
379set size” (divide each shared page by the number of processes sharing it), the
380number of clean and dirty shared pages in the mapping, and the number of clean
381and dirty private pages in the mapping. The "Referenced" indicates the amount
382of memory currently marked as referenced or accessed.
383
384This file is only present if the CONFIG_MMU kernel configuration option is
385enabled.
Kees Cook18d96772007-07-15 23:40:38 -0700386
Moussa A. Ba398499d2009-09-21 17:02:29 -0700387The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
388bits on both physical and virtual pages associated with a process.
389To clear the bits for all the pages associated with the process
390 > echo 1 > /proc/PID/clear_refs
391
392To clear the bits for the anonymous pages associated with the process
393 > echo 2 > /proc/PID/clear_refs
394
395To clear the bits for the file mapped pages associated with the process
396 > echo 3 > /proc/PID/clear_refs
397Any other value written to /proc/PID/clear_refs will have no effect.
398
399
Linus Torvalds1da177e2005-04-16 15:20:36 -07004001.2 Kernel data
401---------------
402
403Similar to the process entries, the kernel data files give information about
404the running kernel. The files used to obtain this information are contained in
Stefani Seibold349888e2009-06-17 16:26:01 -0700405/proc and are listed in Table 1-5. Not all of these will be present in your
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406system. It depends on the kernel configuration and the loaded modules, which
407files are there, and which are missing.
408
Stefani Seibold349888e2009-06-17 16:26:01 -0700409Table 1-5: Kernel info in /proc
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410..............................................................................
411 File Content
412 apm Advanced power management info
413 buddyinfo Kernel memory allocator information (see text) (2.5)
414 bus Directory containing bus specific information
415 cmdline Kernel command line
416 cpuinfo Info about the CPU
417 devices Available devices (block and character)
418 dma Used DMS channels
419 filesystems Supported filesystems
420 driver Various drivers grouped here, currently rtc (2.4)
421 execdomains Execdomains, related to security (2.4)
422 fb Frame Buffer devices (2.4)
423 fs File system parameters, currently nfs/exports (2.4)
424 ide Directory containing info about the IDE subsystem
425 interrupts Interrupt usage
426 iomem Memory map (2.4)
427 ioports I/O port usage
428 irq Masks for irq to cpu affinity (2.4)(smp?)
429 isapnp ISA PnP (Plug&Play) Info (2.4)
430 kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
431 kmsg Kernel messages
432 ksyms Kernel symbol table
433 loadavg Load average of last 1, 5 & 15 minutes
434 locks Kernel locks
435 meminfo Memory info
436 misc Miscellaneous
437 modules List of loaded modules
438 mounts Mounted filesystems
439 net Networking info (see text)
Mel Gormana1b57ac2010-03-05 13:42:15 -0800440 pagetypeinfo Additional page allocator information (see text) (2.5)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 partitions Table of partitions known to the system
Randy Dunlap8b607562007-05-09 07:19:14 +0200442 pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 decoupled by lspci (2.4)
444 rtc Real time clock
445 scsi SCSI info (see text)
446 slabinfo Slab pool info
Keika Kobayashid3d64df2009-06-17 16:25:55 -0700447 softirqs softirq usage
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 stat Overall statistics
449 swaps Swap space utilization
450 sys See chapter 2
451 sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
452 tty Info of tty drivers
453 uptime System uptime
454 version Kernel version
455 video bttv info of video resources (2.4)
Eric Dumazeta47a1262008-07-23 21:27:38 -0700456 vmallocinfo Show vmalloced areas
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457..............................................................................
458
459You can, for example, check which interrupts are currently in use and what
460they are used for by looking in the file /proc/interrupts:
461
462 > cat /proc/interrupts
463 CPU0
464 0: 8728810 XT-PIC timer
465 1: 895 XT-PIC keyboard
466 2: 0 XT-PIC cascade
467 3: 531695 XT-PIC aha152x
468 4: 2014133 XT-PIC serial
469 5: 44401 XT-PIC pcnet_cs
470 8: 2 XT-PIC rtc
471 11: 8 XT-PIC i82365
472 12: 182918 XT-PIC PS/2 Mouse
473 13: 1 XT-PIC fpu
474 14: 1232265 XT-PIC ide0
475 15: 7 XT-PIC ide1
476 NMI: 0
477
478In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
479output of a SMP machine):
480
481 > cat /proc/interrupts
482
483 CPU0 CPU1
484 0: 1243498 1214548 IO-APIC-edge timer
485 1: 8949 8958 IO-APIC-edge keyboard
486 2: 0 0 XT-PIC cascade
487 5: 11286 10161 IO-APIC-edge soundblaster
488 8: 1 0 IO-APIC-edge rtc
489 9: 27422 27407 IO-APIC-edge 3c503
490 12: 113645 113873 IO-APIC-edge PS/2 Mouse
491 13: 0 0 XT-PIC fpu
492 14: 22491 24012 IO-APIC-edge ide0
493 15: 2183 2415 IO-APIC-edge ide1
494 17: 30564 30414 IO-APIC-level eth0
495 18: 177 164 IO-APIC-level bttv
496 NMI: 2457961 2457959
497 LOC: 2457882 2457881
498 ERR: 2155
499
500NMI is incremented in this case because every timer interrupt generates a NMI
501(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups.
502
503LOC is the local interrupt counter of the internal APIC of every CPU.
504
505ERR is incremented in the case of errors in the IO-APIC bus (the bus that
506connects the CPUs in a SMP system. This means that an error has been detected,
507the IO-APIC automatically retry the transmission, so it should not be a big
508problem, but you should read the SMP-FAQ.
509
Joe Korty38e760a2007-10-17 18:04:40 +0200510In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
511/proc/interrupts to display every IRQ vector in use by the system, not
512just those considered 'most important'. The new vectors are:
513
514 THR -- interrupt raised when a machine check threshold counter
515 (typically counting ECC corrected errors of memory or cache) exceeds
516 a configurable threshold. Only available on some systems.
517
518 TRM -- a thermal event interrupt occurs when a temperature threshold
519 has been exceeded for the CPU. This interrupt may also be generated
520 when the temperature drops back to normal.
521
522 SPU -- a spurious interrupt is some interrupt that was raised then lowered
523 by some IO device before it could be fully processed by the APIC. Hence
524 the APIC sees the interrupt but does not know what device it came from.
525 For this case the APIC will generate the interrupt with a IRQ vector
526 of 0xff. This might also be generated by chipset bugs.
527
528 RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are
529 sent from one CPU to another per the needs of the OS. Typically,
530 their statistics are used by kernel developers and interested users to
Matt LaPlante19f59462009-04-27 15:06:31 +0200531 determine the occurrence of interrupts of the given type.
Joe Korty38e760a2007-10-17 18:04:40 +0200532
533The above IRQ vectors are displayed only when relevent. For example,
534the threshold vector does not exist on x86_64 platforms. Others are
535suppressed when the system is a uniprocessor. As of this writing, only
536i386 and x86_64 platforms support the new IRQ vector displays.
537
538Of some interest is the introduction of the /proc/irq directory to 2.4.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539It could be used to set IRQ to CPU affinity, this means that you can "hook" an
540IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
Max Krasnyansky18404752008-05-29 11:02:52 -0700541irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and
542prof_cpu_mask.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543
544For example
545 > ls /proc/irq/
546 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
Max Krasnyansky18404752008-05-29 11:02:52 -0700547 1 11 13 15 17 19 3 5 7 9 default_smp_affinity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 > ls /proc/irq/0/
549 smp_affinity
550
Max Krasnyansky18404752008-05-29 11:02:52 -0700551smp_affinity is a bitmask, in which you can specify which CPUs can handle the
552IRQ, you can set it by doing:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553
Max Krasnyansky18404752008-05-29 11:02:52 -0700554 > echo 1 > /proc/irq/10/smp_affinity
555
556This means that only the first CPU will handle the IRQ, but you can also echo
5575 which means that only the first and fourth CPU can handle the IRQ.
558
559The contents of each smp_affinity file is the same by default:
560
561 > cat /proc/irq/0/smp_affinity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 ffffffff
563
Max Krasnyansky18404752008-05-29 11:02:52 -0700564The default_smp_affinity mask applies to all non-active IRQs, which are the
565IRQs which have not yet been allocated/activated, and hence which lack a
566/proc/irq/[0-9]* directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567
Dimitri Sivanich92d6b712010-03-11 14:08:56 -0800568The node file on an SMP system shows the node to which the device using the IRQ
569reports itself as being attached. This hardware locality information does not
570include information about any possible driver locality preference.
571
Max Krasnyansky18404752008-05-29 11:02:52 -0700572prof_cpu_mask specifies which CPUs are to be profiled by the system wide
573profiler. Default value is ffffffff (all cpus).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574
575The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
576between all the CPUs which are allowed to handle it. As usual the kernel has
577more info than you and does a better job than you, so the defaults are the
578best choice for almost everyone.
579
580There are three more important subdirectories in /proc: net, scsi, and sys.
581The general rule is that the contents, or even the existence of these
582directories, depend on your kernel configuration. If SCSI is not enabled, the
583directory scsi may not exist. The same is true with the net, which is there
584only when networking support is present in the running kernel.
585
586The slabinfo file gives information about memory usage at the slab level.
587Linux uses slab pools for memory management above page level in version 2.2.
588Commonly used objects have their own slab pool (such as network buffers,
589directory cache, and so on).
590
591..............................................................................
592
593> cat /proc/buddyinfo
594
595Node 0, zone DMA 0 4 5 4 4 3 ...
596Node 0, zone Normal 1 0 0 1 101 8 ...
597Node 0, zone HighMem 2 0 0 1 1 0 ...
598
Mel Gormana1b57ac2010-03-05 13:42:15 -0800599External fragmentation is a problem under some workloads, and buddyinfo is a
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600useful tool for helping diagnose these problems. Buddyinfo will give you a
601clue as to how big an area you can safely allocate, or why a previous
602allocation failed.
603
604Each column represents the number of pages of a certain order which are
605available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in
606ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
607available in ZONE_NORMAL, etc...
608
Mel Gormana1b57ac2010-03-05 13:42:15 -0800609More information relevant to external fragmentation can be found in
610pagetypeinfo.
611
612> cat /proc/pagetypeinfo
613Page block order: 9
614Pages per block: 512
615
616Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
617Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
618Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
619Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
620Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
621Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
622Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
623Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
624Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
625Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
626Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
627
628Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
629Node 0, zone DMA 2 0 5 1 0
630Node 0, zone DMA32 41 6 967 2 0
631
632Fragmentation avoidance in the kernel works by grouping pages of different
633migrate types into the same contiguous regions of memory called page blocks.
634A page block is typically the size of the default hugepage size e.g. 2MB on
635X86-64. By keeping pages grouped based on their ability to move, the kernel
636can reclaim pages within a page block to satisfy a high-order allocation.
637
638The pagetypinfo begins with information on the size of a page block. It
639then gives the same type of information as buddyinfo except broken down
640by migrate-type and finishes with details on how many page blocks of each
641type exist.
642
643If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
644from libhugetlbfs http://sourceforge.net/projects/libhugetlbfs/), one can
645make an estimate of the likely number of huge pages that can be allocated
646at a given point in time. All the "Movable" blocks should be allocatable
647unless memory has been mlock()'d. Some of the Reclaimable blocks should
648also be allocatable although a lot of filesystem metadata may have to be
649reclaimed to achieve this.
650
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651..............................................................................
652
653meminfo:
654
655Provides information about distribution and utilization of memory. This
656varies by architecture and compile options. The following is from a
65716GB PIII, which has highmem enabled. You may not have all of these fields.
658
659> cat /proc/meminfo
660
661
662MemTotal: 16344972 kB
663MemFree: 13634064 kB
664Buffers: 3656 kB
665Cached: 1195708 kB
666SwapCached: 0 kB
667Active: 891636 kB
668Inactive: 1077224 kB
669HighTotal: 15597528 kB
670HighFree: 13629632 kB
671LowTotal: 747444 kB
672LowFree: 4432 kB
673SwapTotal: 0 kB
674SwapFree: 0 kB
675Dirty: 968 kB
676Writeback: 0 kB
Miklos Szeredib88473f2008-04-30 00:54:39 -0700677AnonPages: 861800 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678Mapped: 280372 kB
Miklos Szeredib88473f2008-04-30 00:54:39 -0700679Slab: 284364 kB
680SReclaimable: 159856 kB
681SUnreclaim: 124508 kB
682PageTables: 24448 kB
683NFS_Unstable: 0 kB
684Bounce: 0 kB
685WritebackTmp: 0 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686CommitLimit: 7669796 kB
687Committed_AS: 100056 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688VmallocTotal: 112216 kB
689VmallocUsed: 428 kB
690VmallocChunk: 111088 kB
691
692 MemTotal: Total usable ram (i.e. physical ram minus a few reserved
693 bits and the kernel binary code)
694 MemFree: The sum of LowFree+HighFree
695 Buffers: Relatively temporary storage for raw disk blocks
696 shouldn't get tremendously large (20MB or so)
697 Cached: in-memory cache for files read from the disk (the
698 pagecache). Doesn't include SwapCached
699 SwapCached: Memory that once was swapped out, is swapped back in but
700 still also is in the swapfile (if memory is needed it
701 doesn't need to be swapped out AGAIN because it is already
702 in the swapfile. This saves I/O)
703 Active: Memory that has been used more recently and usually not
704 reclaimed unless absolutely necessary.
705 Inactive: Memory which has been less recently used. It is more
706 eligible to be reclaimed for other purposes
707 HighTotal:
708 HighFree: Highmem is all memory above ~860MB of physical memory
709 Highmem areas are for use by userspace programs, or
710 for the pagecache. The kernel must use tricks to access
711 this memory, making it slower to access than lowmem.
712 LowTotal:
713 LowFree: Lowmem is memory which can be used for everything that
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200714 highmem can be used for, but it is also available for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715 kernel's use for its own data structures. Among many
716 other things, it is where everything from the Slab is
717 allocated. Bad things happen when you're out of lowmem.
718 SwapTotal: total amount of swap space available
719 SwapFree: Memory which has been evicted from RAM, and is temporarily
720 on the disk
721 Dirty: Memory which is waiting to get written back to the disk
722 Writeback: Memory which is actively being written back to the disk
Miklos Szeredib88473f2008-04-30 00:54:39 -0700723 AnonPages: Non-file backed pages mapped into userspace page tables
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 Mapped: files which have been mmaped, such as libraries
Adrian Bunke82443c2006-01-10 00:20:30 +0100725 Slab: in-kernel data structures cache
Miklos Szeredib88473f2008-04-30 00:54:39 -0700726SReclaimable: Part of Slab, that might be reclaimed, such as caches
727 SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure
728 PageTables: amount of memory dedicated to the lowest level of page
729 tables.
730NFS_Unstable: NFS pages sent to the server, but not yet committed to stable
731 storage
732 Bounce: Memory used for block device "bounce buffers"
733WritebackTmp: Memory used by FUSE for temporary writeback buffers
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'),
735 this is the total amount of memory currently available to
736 be allocated on the system. This limit is only adhered to
737 if strict overcommit accounting is enabled (mode 2 in
738 'vm.overcommit_memory').
739 The CommitLimit is calculated with the following formula:
740 CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap
741 For example, on a system with 1G of physical RAM and 7G
742 of swap with a `vm.overcommit_ratio` of 30 it would
743 yield a CommitLimit of 7.3G.
744 For more details, see the memory overcommit documentation
745 in vm/overcommit-accounting.
746Committed_AS: The amount of memory presently allocated on the system.
747 The committed memory is a sum of all of the memory which
748 has been allocated by processes, even if it has not been
749 "used" by them as of yet. A process which malloc()'s 1G
750 of memory, but only touches 300M of it will only show up
751 as using 300M of memory even if it has the address space
752 allocated for the entire 1G. This 1G is memory which has
753 been "committed" to by the VM and can be used at any time
754 by the allocating application. With strict overcommit
755 enabled on the system (mode 2 in 'vm.overcommit_memory'),
756 allocations which would exceed the CommitLimit (detailed
757 above) will not be permitted. This is useful if one needs
758 to guarantee that processes will not fail due to lack of
759 memory once that memory has been successfully allocated.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760VmallocTotal: total size of vmalloc memory area
761 VmallocUsed: amount of vmalloc area which is used
Matt LaPlante19f59462009-04-27 15:06:31 +0200762VmallocChunk: largest contiguous block of vmalloc area which is free
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763
Eric Dumazeta47a1262008-07-23 21:27:38 -0700764..............................................................................
765
766vmallocinfo:
767
768Provides information about vmalloced/vmaped areas. One line per area,
769containing the virtual address range of the area, size in bytes,
770caller information of the creator, and optional information depending
771on the kind of area :
772
773 pages=nr number of pages
774 phys=addr if a physical address was specified
775 ioremap I/O mapping (ioremap() and friends)
776 vmalloc vmalloc() area
777 vmap vmap()ed pages
778 user VM_USERMAP area
779 vpages buffer for pages pointers was vmalloced (huge area)
780 N<node>=nr (Only on NUMA kernels)
781 Number of pages allocated on memory node <node>
782
783> cat /proc/vmallocinfo
7840xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
785 /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
7860xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
787 /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
7880xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
789 phys=7fee8000 ioremap
7900xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
791 phys=7fee7000 ioremap
7920xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
7930xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
794 /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
7950xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
796 pages=2 vmalloc N1=2
7970xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
798 /0x130 [x_tables] pages=4 vmalloc N0=4
7990xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
800 pages=14 vmalloc N2=14
8010xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
802 pages=4 vmalloc N1=4
8030xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
804 pages=2 vmalloc N1=2
8050xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
806 pages=10 vmalloc N0=10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807
Keika Kobayashid3d64df2009-06-17 16:25:55 -0700808..............................................................................
809
810softirqs:
811
812Provides counts of softirq handlers serviced since boot time, for each cpu.
813
814> cat /proc/softirqs
815 CPU0 CPU1 CPU2 CPU3
816 HI: 0 0 0 0
817 TIMER: 27166 27120 27097 27034
818 NET_TX: 0 0 0 17
819 NET_RX: 42 0 0 39
820 BLOCK: 0 0 107 1121
821 TASKLET: 0 0 0 290
822 SCHED: 27035 26983 26971 26746
823 HRTIMER: 0 0 0 0
824 RCU: 1678 1769 2178 2250
825
826
Linus Torvalds1da177e2005-04-16 15:20:36 -07008271.3 IDE devices in /proc/ide
828----------------------------
829
830The subdirectory /proc/ide contains information about all IDE devices of which
831the kernel is aware. There is one subdirectory for each IDE controller, the
832file drivers and a link for each IDE device, pointing to the device directory
833in the controller specific subtree.
834
835The file drivers contains general information about the drivers used for the
836IDE devices:
837
838 > cat /proc/ide/drivers
839 ide-cdrom version 4.53
840 ide-disk version 1.08
841
842More detailed information can be found in the controller specific
843subdirectories. These are named ide0, ide1 and so on. Each of these
Stefani Seibold349888e2009-06-17 16:26:01 -0700844directories contains the files shown in table 1-6.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845
846
Stefani Seibold349888e2009-06-17 16:26:01 -0700847Table 1-6: IDE controller info in /proc/ide/ide?
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848..............................................................................
849 File Content
850 channel IDE channel (0 or 1)
851 config Configuration (only for PCI/IDE bridge)
852 mate Mate name
853 model Type/Chipset of IDE controller
854..............................................................................
855
856Each device connected to a controller has a separate subdirectory in the
Stefani Seibold349888e2009-06-17 16:26:01 -0700857controllers directory. The files listed in table 1-7 are contained in these
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858directories.
859
860
Stefani Seibold349888e2009-06-17 16:26:01 -0700861Table 1-7: IDE device information
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862..............................................................................
863 File Content
864 cache The cache
865 capacity Capacity of the medium (in 512Byte blocks)
866 driver driver and version
867 geometry physical and logical geometry
868 identify device identify block
869 media media type
870 model device identifier
871 settings device setup
872 smart_thresholds IDE disk management thresholds
873 smart_values IDE disk management values
874..............................................................................
875
876The most interesting file is settings. This file contains a nice overview of
877the drive parameters:
878
879 # cat /proc/ide/ide0/hda/settings
880 name value min max mode
881 ---- ----- --- --- ----
882 bios_cyl 526 0 65535 rw
883 bios_head 255 0 255 rw
884 bios_sect 63 0 63 rw
885 breada_readahead 4 0 127 rw
886 bswap 0 0 1 r
887 file_readahead 72 0 2097151 rw
888 io_32bit 0 0 3 rw
889 keepsettings 0 0 1 rw
890 max_kb_per_request 122 1 127 rw
891 multcount 0 0 8 rw
892 nice1 1 0 1 rw
893 nowerr 0 0 1 rw
894 pio_mode write-only 0 255 w
895 slow 0 0 1 rw
896 unmaskirq 0 0 1 rw
897 using_dma 0 0 1 rw
898
899
9001.4 Networking info in /proc/net
901--------------------------------
902
Stefani Seibold349888e2009-06-17 16:26:01 -0700903The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904additional values you get for IP version 6 if you configure the kernel to
Stefani Seibold349888e2009-06-17 16:26:01 -0700905support this. Table 1-9 lists the files and their meaning.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906
907
Stefani Seibold349888e2009-06-17 16:26:01 -0700908Table 1-8: IPv6 info in /proc/net
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909..............................................................................
910 File Content
911 udp6 UDP sockets (IPv6)
912 tcp6 TCP sockets (IPv6)
913 raw6 Raw device statistics (IPv6)
914 igmp6 IP multicast addresses, which this host joined (IPv6)
915 if_inet6 List of IPv6 interface addresses
916 ipv6_route Kernel routing table for IPv6
917 rt6_stats Global IPv6 routing tables statistics
918 sockstat6 Socket statistics (IPv6)
919 snmp6 Snmp data (IPv6)
920..............................................................................
921
922
Stefani Seibold349888e2009-06-17 16:26:01 -0700923Table 1-9: Network info in /proc/net
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924..............................................................................
925 File Content
926 arp Kernel ARP table
927 dev network devices with statistics
928 dev_mcast the Layer2 multicast groups a device is listening too
929 (interface index, label, number of references, number of bound
930 addresses).
931 dev_stat network device status
932 ip_fwchains Firewall chain linkage
933 ip_fwnames Firewall chain names
934 ip_masq Directory containing the masquerading tables
935 ip_masquerade Major masquerading table
936 netstat Network statistics
937 raw raw device statistics
938 route Kernel routing table
939 rpc Directory containing rpc info
940 rt_cache Routing cache
941 snmp SNMP data
942 sockstat Socket statistics
943 tcp TCP sockets
944 tr_rif Token ring RIF routing table
945 udp UDP sockets
946 unix UNIX domain sockets
947 wireless Wireless interface data (Wavelan etc)
948 igmp IP multicast addresses, which this host joined
949 psched Global packet scheduler parameters.
950 netlink List of PF_NETLINK sockets
951 ip_mr_vifs List of multicast virtual interfaces
952 ip_mr_cache List of multicast routing cache
953..............................................................................
954
955You can use this information to see which network devices are available in
956your system and how much traffic was routed over those devices:
957
958 > cat /proc/net/dev
959 Inter-|Receive |[...
960 face |bytes packets errs drop fifo frame compressed multicast|[...
961 lo: 908188 5596 0 0 0 0 0 0 [...
962 ppp0:15475140 20721 410 0 0 410 0 0 [...
963 eth0: 614530 7085 0 0 0 0 0 1 [...
964
965 ...] Transmit
966 ...] bytes packets errs drop fifo colls carrier compressed
967 ...] 908188 5596 0 0 0 0 0 0
968 ...] 1375103 17405 0 0 0 0 0 0
969 ...] 1703981 5535 0 0 0 3 0 0
970
Francis Galieguea33f3222010-04-23 00:08:02 +0200971In addition, each Channel Bond interface has its own directory. For
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972example, the bond0 device will have a directory called /proc/net/bond0/.
973It will contain information that is specific to that bond, such as the
974current slaves of the bond, the link status of the slaves, and how
975many times the slaves link has failed.
976
9771.5 SCSI info
978-------------
979
980If you have a SCSI host adapter in your system, you'll find a subdirectory
981named after the driver for this adapter in /proc/scsi. You'll also see a list
982of all recognized SCSI devices in /proc/scsi:
983
984 >cat /proc/scsi/scsi
985 Attached devices:
986 Host: scsi0 Channel: 00 Id: 00 Lun: 00
987 Vendor: IBM Model: DGHS09U Rev: 03E0
988 Type: Direct-Access ANSI SCSI revision: 03
989 Host: scsi0 Channel: 00 Id: 06 Lun: 00
990 Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
991 Type: CD-ROM ANSI SCSI revision: 02
992
993
994The directory named after the driver has one file for each adapter found in
995the system. These files contain information about the controller, including
996the used IRQ and the IO address range. The amount of information shown is
997dependent on the adapter you use. The example shows the output for an Adaptec
998AHA-2940 SCSI adapter:
999
1000 > cat /proc/scsi/aic7xxx/0
1001
1002 Adaptec AIC7xxx driver version: 5.1.19/3.2.4
1003 Compile Options:
1004 TCQ Enabled By Default : Disabled
1005 AIC7XXX_PROC_STATS : Disabled
1006 AIC7XXX_RESET_DELAY : 5
1007 Adapter Configuration:
1008 SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
1009 Ultra Wide Controller
1010 PCI MMAPed I/O Base: 0xeb001000
1011 Adapter SEEPROM Config: SEEPROM found and used.
1012 Adaptec SCSI BIOS: Enabled
1013 IRQ: 10
1014 SCBs: Active 0, Max Active 2,
1015 Allocated 15, HW 16, Page 255
1016 Interrupts: 160328
1017 BIOS Control Word: 0x18b6
1018 Adapter Control Word: 0x005b
1019 Extended Translation: Enabled
1020 Disconnect Enable Flags: 0xffff
1021 Ultra Enable Flags: 0x0001
1022 Tag Queue Enable Flags: 0x0000
1023 Ordered Queue Tag Flags: 0x0000
1024 Default Tag Queue Depth: 8
1025 Tagged Queue By Device array for aic7xxx host instance 0:
1026 {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
1027 Actual queue depth per device for aic7xxx host instance 0:
1028 {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
1029 Statistics:
1030 (scsi0:0:0:0)
1031 Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
1032 Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0)
1033 Total transfers 160151 (74577 reads and 85574 writes)
1034 (scsi0:0:6:0)
1035 Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
1036 Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0)
1037 Total transfers 0 (0 reads and 0 writes)
1038
1039
10401.6 Parallel port info in /proc/parport
1041---------------------------------------
1042
1043The directory /proc/parport contains information about the parallel ports of
1044your system. It has one subdirectory for each port, named after the port
1045number (0,1,2,...).
1046
Stefani Seibold349888e2009-06-17 16:26:01 -07001047These directories contain the four files shown in Table 1-10.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048
1049
Stefani Seibold349888e2009-06-17 16:26:01 -07001050Table 1-10: Files in /proc/parport
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051..............................................................................
1052 File Content
1053 autoprobe Any IEEE-1284 device ID information that has been acquired.
1054 devices list of the device drivers using that port. A + will appear by the
1055 name of the device currently using the port (it might not appear
1056 against any).
1057 hardware Parallel port's base address, IRQ line and DMA channel.
1058 irq IRQ that parport is using for that port. This is in a separate
1059 file to allow you to alter it by writing a new value in (IRQ
1060 number or none).
1061..............................................................................
1062
10631.7 TTY info in /proc/tty
1064-------------------------
1065
1066Information about the available and actually used tty's can be found in the
1067directory /proc/tty.You'll find entries for drivers and line disciplines in
Stefani Seibold349888e2009-06-17 16:26:01 -07001068this directory, as shown in Table 1-11.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069
1070
Stefani Seibold349888e2009-06-17 16:26:01 -07001071Table 1-11: Files in /proc/tty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072..............................................................................
1073 File Content
1074 drivers list of drivers and their usage
1075 ldiscs registered line disciplines
1076 driver/serial usage statistic and status of single tty lines
1077..............................................................................
1078
1079To see which tty's are currently in use, you can simply look into the file
1080/proc/tty/drivers:
1081
1082 > cat /proc/tty/drivers
1083 pty_slave /dev/pts 136 0-255 pty:slave
1084 pty_master /dev/ptm 128 0-255 pty:master
1085 pty_slave /dev/ttyp 3 0-255 pty:slave
1086 pty_master /dev/pty 2 0-255 pty:master
1087 serial /dev/cua 5 64-67 serial:callout
1088 serial /dev/ttyS 4 64-67 serial
1089 /dev/tty0 /dev/tty0 4 0 system:vtmaster
1090 /dev/ptmx /dev/ptmx 5 2 system
1091 /dev/console /dev/console 5 1 system:console
1092 /dev/tty /dev/tty 5 0 system:/dev/tty
1093 unknown /dev/tty 4 1-63 console
1094
1095
10961.8 Miscellaneous kernel statistics in /proc/stat
1097-------------------------------------------------
1098
1099Various pieces of information about kernel activity are available in the
1100/proc/stat file. All of the numbers reported in this file are aggregates
1101since the system first booted. For a quick look, simply cat the file:
1102
1103 > cat /proc/stat
Eric Dumazetc5743582009-09-21 17:01:06 -07001104 cpu 2255 34 2290 22625563 6290 127 456 0 0
1105 cpu0 1132 34 1441 11311718 3675 127 438 0 0
1106 cpu1 1123 0 849 11313845 2614 0 18 0 0
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107 intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
1108 ctxt 1990473
1109 btime 1062191376
1110 processes 2915
1111 procs_running 1
1112 procs_blocked 0
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001113 softirq 183433 0 21755 12 39 1137 231 21459 2263
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114
1115The very first "cpu" line aggregates the numbers in all of the other "cpuN"
1116lines. These numbers identify the amount of time the CPU has spent performing
1117different kinds of work. Time units are in USER_HZ (typically hundredths of a
1118second). The meanings of the columns are as follows, from left to right:
1119
1120- user: normal processes executing in user mode
1121- nice: niced processes executing in user mode
1122- system: processes executing in kernel mode
1123- idle: twiddling thumbs
1124- iowait: waiting for I/O to complete
1125- irq: servicing interrupts
1126- softirq: servicing softirqs
Leonardo Chiquittob68f2c32007-10-20 03:03:38 +02001127- steal: involuntary wait
Ryota Ozakice0e7b22009-10-24 01:20:10 +09001128- guest: running a normal guest
1129- guest_nice: running a niced guest
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130
1131The "intr" line gives counts of interrupts serviced since boot time, for each
1132of the possible system interrupts. The first column is the total of all
1133interrupts serviced; each subsequent column is the total for that particular
1134interrupt.
1135
1136The "ctxt" line gives the total number of context switches across all CPUs.
1137
1138The "btime" line gives the time at which the system booted, in seconds since
1139the Unix epoch.
1140
1141The "processes" line gives the number of processes and threads created, which
1142includes (but is not limited to) those created by calls to the fork() and
1143clone() system calls.
1144
Luis Garces-Ericee3cc2222009-12-06 18:30:44 -08001145The "procs_running" line gives the total number of threads that are
1146running or ready to run (i.e., the total number of runnable threads).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001147
1148The "procs_blocked" line gives the number of processes currently blocked,
1149waiting for I/O to complete.
1150
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001151The "softirq" line gives counts of softirqs serviced since boot time, for each
1152of the possible system softirqs. The first column is the total of all
1153softirqs serviced; each subsequent column is the total for that particular
1154softirq.
1155
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001156
Alex Tomasc9de5602008-01-29 00:19:52 -050011571.9 Ext4 file system parameters
1158------------------------------
Alex Tomasc9de5602008-01-29 00:19:52 -05001159
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001160Information about mounted ext4 file systems can be found in
1161/proc/fs/ext4. Each mounted filesystem will have a directory in
1162/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
1163/proc/fs/ext4/dm-0). The files in each per-device directory are shown
Stefani Seibold349888e2009-06-17 16:26:01 -07001164in Table 1-12, below.
Alex Tomasc9de5602008-01-29 00:19:52 -05001165
Stefani Seibold349888e2009-06-17 16:26:01 -07001166Table 1-12: Files in /proc/fs/ext4/<devname>
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001167..............................................................................
1168 File Content
1169 mb_groups details of multiblock allocator buddy cache of free blocks
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001170..............................................................................
Alex Tomasc9de5602008-01-29 00:19:52 -05001171
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172
1173------------------------------------------------------------------------------
1174Summary
1175------------------------------------------------------------------------------
1176The /proc file system serves information about the running system. It not only
1177allows access to process data but also allows you to request the kernel status
1178by reading files in the hierarchy.
1179
1180The directory structure of /proc reflects the types of information and makes
1181it easy, if not obvious, where to look for specific data.
1182------------------------------------------------------------------------------
1183
1184------------------------------------------------------------------------------
1185CHAPTER 2: MODIFYING SYSTEM PARAMETERS
1186------------------------------------------------------------------------------
1187
1188------------------------------------------------------------------------------
1189In This Chapter
1190------------------------------------------------------------------------------
1191* Modifying kernel parameters by writing into files found in /proc/sys
1192* Exploring the files which modify certain parameters
1193* Review of the /proc/sys file tree
1194------------------------------------------------------------------------------
1195
1196
1197A very interesting part of /proc is the directory /proc/sys. This is not only
1198a source of information, it also allows you to change parameters within the
1199kernel. Be very careful when attempting this. You can optimize your system,
1200but you can also cause it to crash. Never alter kernel parameters on a
1201production system. Set up a development machine and test to make sure that
1202everything works the way you want it to. You may have no alternative but to
1203reboot the machine once an error has been made.
1204
1205To change a value, simply echo the new value into the file. An example is
1206given below in the section on the file system data. You need to be root to do
1207this. You can create your own boot script to perform this every time your
1208system boots.
1209
1210The files in /proc/sys can be used to fine tune and monitor miscellaneous and
1211general things in the operation of the Linux kernel. Since some of the files
1212can inadvertently disrupt your system, it is advisable to read both
1213documentation and source before actually making adjustments. In any case, be
1214very careful when writing to any of these files. The entries in /proc may
1215change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
1216review the kernel documentation in the directory /usr/src/linux/Documentation.
1217This chapter is heavily based on the documentation included in the pre 2.2
1218kernels, and became part of it in version 2.2.1 of the Linux kernel.
1219
Shen Feng760df932009-04-02 16:57:20 -07001220Please see: Documentation/sysctls/ directory for descriptions of these
Peter W Morrealedb0fb182009-01-15 13:50:42 -08001221entries.
Andrew Morton9d0243b2006-01-08 01:00:39 -08001222
Shen Feng760df932009-04-02 16:57:20 -07001223------------------------------------------------------------------------------
1224Summary
1225------------------------------------------------------------------------------
1226Certain aspects of kernel behavior can be modified at runtime, without the
1227need to recompile the kernel, or even to reboot the system. The files in the
1228/proc/sys tree can not only be read, but also modified. You can use the echo
1229command to write value into these files, thereby changing the default settings
1230of the kernel.
1231------------------------------------------------------------------------------
Andrew Morton9d0243b2006-01-08 01:00:39 -08001232
Shen Feng760df932009-04-02 16:57:20 -07001233------------------------------------------------------------------------------
1234CHAPTER 3: PER-PROCESS PARAMETERS
1235------------------------------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236
Shen Feng760df932009-04-02 16:57:20 -070012373.1 /proc/<pid>/oom_adj - Adjust the oom-killer score
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001238------------------------------------------------------
1239
KOSAKI Motohiro0753ba02009-08-18 14:11:10 -07001240This file can be used to adjust the score used to select which processes
1241should be killed in an out-of-memory situation. Giving it a high score will
1242increase the likelihood of this process being killed by the oom-killer. Valid
1243values are in the range -16 to +15, plus the special value -17, which disables
1244oom-killing altogether for this process.
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001245
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001246The process to be killed in an out-of-memory situation is selected among all others
1247based on its badness score. This value equals the original memory size of the process
1248and is then updated according to its CPU time (utime + stime) and the
1249run time (uptime - start time). The longer it runs the smaller is the score.
1250Badness score is divided by the square root of the CPU time and then by
1251the double square root of the run time.
1252
1253Swapped out tasks are killed first. Half of each child's memory size is added to
1254the parent's score if they do not share the same memory. Thus forking servers
1255are the prime candidates to be killed. Having only one 'hungry' child will make
1256parent less preferable than the child.
1257
1258/proc/<pid>/oom_score shows process' current badness score.
1259
1260The following heuristics are then applied:
1261 * if the task was reniced, its score doubles
1262 * superuser or direct hardware access tasks (CAP_SYS_ADMIN, CAP_SYS_RESOURCE
1263 or CAP_SYS_RAWIO) have their score divided by 4
KOSAKI Motohiro495789a2009-09-21 17:03:14 -07001264 * if oom condition happened in one cpuset and checked process does not belong
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001265 to it, its score is divided by 8
1266 * the resulting score is multiplied by two to the power of oom_adj, i.e.
1267 points <<= oom_adj when it is positive and
1268 points >>= -(oom_adj) otherwise
1269
1270The task with the highest badness score is then selected and its children
1271are killed, process itself will be killed in an OOM situation when it does
1272not have children or some of them disabled oom like described above.
1273
Shen Feng760df932009-04-02 16:57:20 -070012743.2 /proc/<pid>/oom_score - Display current oom-killer score
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001275-------------------------------------------------------------
1276
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001277This file can be used to check the current score used by the oom-killer is for
1278any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which
1279process should be killed in an out-of-memory situation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280
Roland Kletzingf9c99462007-03-05 00:30:54 -08001281
Shen Feng760df932009-04-02 16:57:20 -070012823.3 /proc/<pid>/io - Display the IO accounting fields
Roland Kletzingf9c99462007-03-05 00:30:54 -08001283-------------------------------------------------------
1284
1285This file contains IO statistics for each running process
1286
1287Example
1288-------
1289
1290test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
1291[1] 3828
1292
1293test:/tmp # cat /proc/3828/io
1294rchar: 323934931
1295wchar: 323929600
1296syscr: 632687
1297syscw: 632675
1298read_bytes: 0
1299write_bytes: 323932160
1300cancelled_write_bytes: 0
1301
1302
1303Description
1304-----------
1305
1306rchar
1307-----
1308
1309I/O counter: chars read
1310The number of bytes which this task has caused to be read from storage. This
1311is simply the sum of bytes which this process passed to read() and pread().
1312It includes things like tty IO and it is unaffected by whether or not actual
1313physical disk IO was required (the read might have been satisfied from
1314pagecache)
1315
1316
1317wchar
1318-----
1319
1320I/O counter: chars written
1321The number of bytes which this task has caused, or shall cause to be written
1322to disk. Similar caveats apply here as with rchar.
1323
1324
1325syscr
1326-----
1327
1328I/O counter: read syscalls
1329Attempt to count the number of read I/O operations, i.e. syscalls like read()
1330and pread().
1331
1332
1333syscw
1334-----
1335
1336I/O counter: write syscalls
1337Attempt to count the number of write I/O operations, i.e. syscalls like
1338write() and pwrite().
1339
1340
1341read_bytes
1342----------
1343
1344I/O counter: bytes read
1345Attempt to count the number of bytes which this process really did cause to
1346be fetched from the storage layer. Done at the submit_bio() level, so it is
1347accurate for block-backed filesystems. <please add status regarding NFS and
1348CIFS at a later time>
1349
1350
1351write_bytes
1352-----------
1353
1354I/O counter: bytes written
1355Attempt to count the number of bytes which this process caused to be sent to
1356the storage layer. This is done at page-dirtying time.
1357
1358
1359cancelled_write_bytes
1360---------------------
1361
1362The big inaccuracy here is truncate. If a process writes 1MB to a file and
1363then deletes the file, it will in fact perform no writeout. But it will have
1364been accounted as having caused 1MB of write.
1365In other words: The number of bytes which this process caused to not happen,
1366by truncating pagecache. A task can cause "negative" IO too. If this task
1367truncates some dirty pagecache, some IO which another task has been accounted
Francis Galieguea33f3222010-04-23 00:08:02 +02001368for (in its write_bytes) will not be happening. We _could_ just subtract that
Roland Kletzingf9c99462007-03-05 00:30:54 -08001369from the truncating task's write_bytes, but there is information loss in doing
1370that.
1371
1372
1373Note
1374----
1375
1376At its current implementation state, this is a bit racy on 32-bit machines: if
1377process A reads process B's /proc/pid/io while process B is updating one of
1378those 64-bit counters, process A could see an intermediate result.
1379
1380
1381More information about this can be found within the taskstats documentation in
1382Documentation/accounting.
1383
Shen Feng760df932009-04-02 16:57:20 -070013843.4 /proc/<pid>/coredump_filter - Core dump filtering settings
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001385---------------------------------------------------------------
1386When a process is dumped, all anonymous memory is written to a core file as
1387long as the size of the core file isn't limited. But sometimes we don't want
1388to dump some memory segments, for example, huge shared memory. Conversely,
1389sometimes we want to save file-backed memory segments into a core file, not
1390only the individual files.
1391
1392/proc/<pid>/coredump_filter allows you to customize which memory segments
1393will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
1394of memory types. If a bit of the bitmask is set, memory segments of the
1395corresponding memory type are dumped, otherwise they are not dumped.
1396
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001397The following 7 memory types are supported:
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001398 - (bit 0) anonymous private memory
1399 - (bit 1) anonymous shared memory
1400 - (bit 2) file-backed private memory
1401 - (bit 3) file-backed shared memory
Hidehiro Kawaib261dfe2008-09-13 02:33:10 -07001402 - (bit 4) ELF header pages in file-backed private memory areas (it is
1403 effective only if the bit 2 is cleared)
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001404 - (bit 5) hugetlb private memory
1405 - (bit 6) hugetlb shared memory
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001406
1407 Note that MMIO pages such as frame buffer are never dumped and vDSO pages
1408 are always dumped regardless of the bitmask status.
1409
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001410 Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only
1411 effected by bit 5-6.
1412
1413Default value of coredump_filter is 0x23; this means all anonymous memory
1414segments and hugetlb private memory are dumped.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001415
1416If you don't want to dump all shared memory segments attached to pid 1234,
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001417write 0x21 to the process's proc file.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001418
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001419 $ echo 0x21 > /proc/1234/coredump_filter
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001420
1421When a new process is created, the process inherits the bitmask status from its
1422parent. It is useful to set up coredump_filter before the program runs.
1423For example:
1424
1425 $ echo 0x7 > /proc/self/coredump_filter
1426 $ ./some_program
1427
Shen Feng760df932009-04-02 16:57:20 -070014283.5 /proc/<pid>/mountinfo - Information about mounts
Ram Pai2d4d4862008-03-27 13:06:25 +01001429--------------------------------------------------------
1430
1431This file contains lines of the form:
1432
143336 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
1434(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
1435
1436(1) mount ID: unique identifier of the mount (may be reused after umount)
1437(2) parent ID: ID of parent (or of self for the top of the mount tree)
1438(3) major:minor: value of st_dev for files on filesystem
1439(4) root: root of the mount within the filesystem
1440(5) mount point: mount point relative to the process's root
1441(6) mount options: per mount options
1442(7) optional fields: zero or more fields of the form "tag[:value]"
1443(8) separator: marks the end of the optional fields
1444(9) filesystem type: name of filesystem of the form "type[.subtype]"
1445(10) mount source: filesystem specific information or "none"
1446(11) super options: per super block options
1447
1448Parsers should ignore all unrecognised optional fields. Currently the
1449possible optional fields are:
1450
1451shared:X mount is shared in peer group X
1452master:X mount is slave to peer group X
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +01001453propagate_from:X mount is slave and receives propagation from peer group X (*)
Ram Pai2d4d4862008-03-27 13:06:25 +01001454unbindable mount is unbindable
1455
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +01001456(*) X is the closest dominant peer group under the process's root. If
1457X is the immediate master of the mount, or if there's no dominant peer
1458group under the same root, then only the "master:X" field is present
1459and not the "propagate_from:X" field.
1460
Ram Pai2d4d4862008-03-27 13:06:25 +01001461For more information on mount propagation see:
1462
1463 Documentation/filesystems/sharedsubtree.txt
1464
john stultz4614a696b2009-12-14 18:00:05 -08001465
14663.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
1467--------------------------------------------------------
1468These files provide a method to access a tasks comm value. It also allows for
1469a task to set its own or one of its thread siblings comm value. The comm value
1470is limited in size compared to the cmdline value, so writing anything longer
1471then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
1472comm value.