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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
Stefani Seibold349888e2009-06-17 16:26:01 -0700308The /proc/PID/map file containing the currently mapped memory regions and
309their 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
Max Krasnyansky18404752008-05-29 11:02:52 -0700568prof_cpu_mask specifies which CPUs are to be profiled by the system wide
569profiler. Default value is ffffffff (all cpus).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570
571The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
572between all the CPUs which are allowed to handle it. As usual the kernel has
573more info than you and does a better job than you, so the defaults are the
574best choice for almost everyone.
575
576There are three more important subdirectories in /proc: net, scsi, and sys.
577The general rule is that the contents, or even the existence of these
578directories, depend on your kernel configuration. If SCSI is not enabled, the
579directory scsi may not exist. The same is true with the net, which is there
580only when networking support is present in the running kernel.
581
582The slabinfo file gives information about memory usage at the slab level.
583Linux uses slab pools for memory management above page level in version 2.2.
584Commonly used objects have their own slab pool (such as network buffers,
585directory cache, and so on).
586
587..............................................................................
588
589> cat /proc/buddyinfo
590
591Node 0, zone DMA 0 4 5 4 4 3 ...
592Node 0, zone Normal 1 0 0 1 101 8 ...
593Node 0, zone HighMem 2 0 0 1 1 0 ...
594
Mel Gormana1b57ac2010-03-05 13:42:15 -0800595External fragmentation is a problem under some workloads, and buddyinfo is a
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596useful tool for helping diagnose these problems. Buddyinfo will give you a
597clue as to how big an area you can safely allocate, or why a previous
598allocation failed.
599
600Each column represents the number of pages of a certain order which are
601available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in
602ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
603available in ZONE_NORMAL, etc...
604
Mel Gormana1b57ac2010-03-05 13:42:15 -0800605More information relevant to external fragmentation can be found in
606pagetypeinfo.
607
608> cat /proc/pagetypeinfo
609Page block order: 9
610Pages per block: 512
611
612Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
613Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
614Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
615Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
616Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
617Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
618Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
619Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
620Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
621Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
622Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
623
624Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
625Node 0, zone DMA 2 0 5 1 0
626Node 0, zone DMA32 41 6 967 2 0
627
628Fragmentation avoidance in the kernel works by grouping pages of different
629migrate types into the same contiguous regions of memory called page blocks.
630A page block is typically the size of the default hugepage size e.g. 2MB on
631X86-64. By keeping pages grouped based on their ability to move, the kernel
632can reclaim pages within a page block to satisfy a high-order allocation.
633
634The pagetypinfo begins with information on the size of a page block. It
635then gives the same type of information as buddyinfo except broken down
636by migrate-type and finishes with details on how many page blocks of each
637type exist.
638
639If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
640from libhugetlbfs http://sourceforge.net/projects/libhugetlbfs/), one can
641make an estimate of the likely number of huge pages that can be allocated
642at a given point in time. All the "Movable" blocks should be allocatable
643unless memory has been mlock()'d. Some of the Reclaimable blocks should
644also be allocatable although a lot of filesystem metadata may have to be
645reclaimed to achieve this.
646
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647..............................................................................
648
649meminfo:
650
651Provides information about distribution and utilization of memory. This
652varies by architecture and compile options. The following is from a
65316GB PIII, which has highmem enabled. You may not have all of these fields.
654
655> cat /proc/meminfo
656
657
658MemTotal: 16344972 kB
659MemFree: 13634064 kB
660Buffers: 3656 kB
661Cached: 1195708 kB
662SwapCached: 0 kB
663Active: 891636 kB
664Inactive: 1077224 kB
665HighTotal: 15597528 kB
666HighFree: 13629632 kB
667LowTotal: 747444 kB
668LowFree: 4432 kB
669SwapTotal: 0 kB
670SwapFree: 0 kB
671Dirty: 968 kB
672Writeback: 0 kB
Miklos Szeredib88473f2008-04-30 00:54:39 -0700673AnonPages: 861800 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674Mapped: 280372 kB
Miklos Szeredib88473f2008-04-30 00:54:39 -0700675Slab: 284364 kB
676SReclaimable: 159856 kB
677SUnreclaim: 124508 kB
678PageTables: 24448 kB
679NFS_Unstable: 0 kB
680Bounce: 0 kB
681WritebackTmp: 0 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682CommitLimit: 7669796 kB
683Committed_AS: 100056 kB
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684VmallocTotal: 112216 kB
685VmallocUsed: 428 kB
686VmallocChunk: 111088 kB
687
688 MemTotal: Total usable ram (i.e. physical ram minus a few reserved
689 bits and the kernel binary code)
690 MemFree: The sum of LowFree+HighFree
691 Buffers: Relatively temporary storage for raw disk blocks
692 shouldn't get tremendously large (20MB or so)
693 Cached: in-memory cache for files read from the disk (the
694 pagecache). Doesn't include SwapCached
695 SwapCached: Memory that once was swapped out, is swapped back in but
696 still also is in the swapfile (if memory is needed it
697 doesn't need to be swapped out AGAIN because it is already
698 in the swapfile. This saves I/O)
699 Active: Memory that has been used more recently and usually not
700 reclaimed unless absolutely necessary.
701 Inactive: Memory which has been less recently used. It is more
702 eligible to be reclaimed for other purposes
703 HighTotal:
704 HighFree: Highmem is all memory above ~860MB of physical memory
705 Highmem areas are for use by userspace programs, or
706 for the pagecache. The kernel must use tricks to access
707 this memory, making it slower to access than lowmem.
708 LowTotal:
709 LowFree: Lowmem is memory which can be used for everything that
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200710 highmem can be used for, but it is also available for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 kernel's use for its own data structures. Among many
712 other things, it is where everything from the Slab is
713 allocated. Bad things happen when you're out of lowmem.
714 SwapTotal: total amount of swap space available
715 SwapFree: Memory which has been evicted from RAM, and is temporarily
716 on the disk
717 Dirty: Memory which is waiting to get written back to the disk
718 Writeback: Memory which is actively being written back to the disk
Miklos Szeredib88473f2008-04-30 00:54:39 -0700719 AnonPages: Non-file backed pages mapped into userspace page tables
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 Mapped: files which have been mmaped, such as libraries
Adrian Bunke82443c2006-01-10 00:20:30 +0100721 Slab: in-kernel data structures cache
Miklos Szeredib88473f2008-04-30 00:54:39 -0700722SReclaimable: Part of Slab, that might be reclaimed, such as caches
723 SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure
724 PageTables: amount of memory dedicated to the lowest level of page
725 tables.
726NFS_Unstable: NFS pages sent to the server, but not yet committed to stable
727 storage
728 Bounce: Memory used for block device "bounce buffers"
729WritebackTmp: Memory used by FUSE for temporary writeback buffers
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'),
731 this is the total amount of memory currently available to
732 be allocated on the system. This limit is only adhered to
733 if strict overcommit accounting is enabled (mode 2 in
734 'vm.overcommit_memory').
735 The CommitLimit is calculated with the following formula:
736 CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap
737 For example, on a system with 1G of physical RAM and 7G
738 of swap with a `vm.overcommit_ratio` of 30 it would
739 yield a CommitLimit of 7.3G.
740 For more details, see the memory overcommit documentation
741 in vm/overcommit-accounting.
742Committed_AS: The amount of memory presently allocated on the system.
743 The committed memory is a sum of all of the memory which
744 has been allocated by processes, even if it has not been
745 "used" by them as of yet. A process which malloc()'s 1G
746 of memory, but only touches 300M of it will only show up
747 as using 300M of memory even if it has the address space
748 allocated for the entire 1G. This 1G is memory which has
749 been "committed" to by the VM and can be used at any time
750 by the allocating application. With strict overcommit
751 enabled on the system (mode 2 in 'vm.overcommit_memory'),
752 allocations which would exceed the CommitLimit (detailed
753 above) will not be permitted. This is useful if one needs
754 to guarantee that processes will not fail due to lack of
755 memory once that memory has been successfully allocated.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756VmallocTotal: total size of vmalloc memory area
757 VmallocUsed: amount of vmalloc area which is used
Matt LaPlante19f59462009-04-27 15:06:31 +0200758VmallocChunk: largest contiguous block of vmalloc area which is free
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759
Eric Dumazeta47a1262008-07-23 21:27:38 -0700760..............................................................................
761
762vmallocinfo:
763
764Provides information about vmalloced/vmaped areas. One line per area,
765containing the virtual address range of the area, size in bytes,
766caller information of the creator, and optional information depending
767on the kind of area :
768
769 pages=nr number of pages
770 phys=addr if a physical address was specified
771 ioremap I/O mapping (ioremap() and friends)
772 vmalloc vmalloc() area
773 vmap vmap()ed pages
774 user VM_USERMAP area
775 vpages buffer for pages pointers was vmalloced (huge area)
776 N<node>=nr (Only on NUMA kernels)
777 Number of pages allocated on memory node <node>
778
779> cat /proc/vmallocinfo
7800xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
781 /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
7820xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
783 /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
7840xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
785 phys=7fee8000 ioremap
7860xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
787 phys=7fee7000 ioremap
7880xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
7890xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
790 /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
7910xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
792 pages=2 vmalloc N1=2
7930xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
794 /0x130 [x_tables] pages=4 vmalloc N0=4
7950xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
796 pages=14 vmalloc N2=14
7970xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
798 pages=4 vmalloc N1=4
7990xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
800 pages=2 vmalloc N1=2
8010xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
802 pages=10 vmalloc N0=10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700803
Keika Kobayashid3d64df2009-06-17 16:25:55 -0700804..............................................................................
805
806softirqs:
807
808Provides counts of softirq handlers serviced since boot time, for each cpu.
809
810> cat /proc/softirqs
811 CPU0 CPU1 CPU2 CPU3
812 HI: 0 0 0 0
813 TIMER: 27166 27120 27097 27034
814 NET_TX: 0 0 0 17
815 NET_RX: 42 0 0 39
816 BLOCK: 0 0 107 1121
817 TASKLET: 0 0 0 290
818 SCHED: 27035 26983 26971 26746
819 HRTIMER: 0 0 0 0
820 RCU: 1678 1769 2178 2250
821
822
Linus Torvalds1da177e2005-04-16 15:20:36 -07008231.3 IDE devices in /proc/ide
824----------------------------
825
826The subdirectory /proc/ide contains information about all IDE devices of which
827the kernel is aware. There is one subdirectory for each IDE controller, the
828file drivers and a link for each IDE device, pointing to the device directory
829in the controller specific subtree.
830
831The file drivers contains general information about the drivers used for the
832IDE devices:
833
834 > cat /proc/ide/drivers
835 ide-cdrom version 4.53
836 ide-disk version 1.08
837
838More detailed information can be found in the controller specific
839subdirectories. These are named ide0, ide1 and so on. Each of these
Stefani Seibold349888e2009-06-17 16:26:01 -0700840directories contains the files shown in table 1-6.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841
842
Stefani Seibold349888e2009-06-17 16:26:01 -0700843Table 1-6: IDE controller info in /proc/ide/ide?
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844..............................................................................
845 File Content
846 channel IDE channel (0 or 1)
847 config Configuration (only for PCI/IDE bridge)
848 mate Mate name
849 model Type/Chipset of IDE controller
850..............................................................................
851
852Each device connected to a controller has a separate subdirectory in the
Stefani Seibold349888e2009-06-17 16:26:01 -0700853controllers directory. The files listed in table 1-7 are contained in these
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854directories.
855
856
Stefani Seibold349888e2009-06-17 16:26:01 -0700857Table 1-7: IDE device information
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858..............................................................................
859 File Content
860 cache The cache
861 capacity Capacity of the medium (in 512Byte blocks)
862 driver driver and version
863 geometry physical and logical geometry
864 identify device identify block
865 media media type
866 model device identifier
867 settings device setup
868 smart_thresholds IDE disk management thresholds
869 smart_values IDE disk management values
870..............................................................................
871
872The most interesting file is settings. This file contains a nice overview of
873the drive parameters:
874
875 # cat /proc/ide/ide0/hda/settings
876 name value min max mode
877 ---- ----- --- --- ----
878 bios_cyl 526 0 65535 rw
879 bios_head 255 0 255 rw
880 bios_sect 63 0 63 rw
881 breada_readahead 4 0 127 rw
882 bswap 0 0 1 r
883 file_readahead 72 0 2097151 rw
884 io_32bit 0 0 3 rw
885 keepsettings 0 0 1 rw
886 max_kb_per_request 122 1 127 rw
887 multcount 0 0 8 rw
888 nice1 1 0 1 rw
889 nowerr 0 0 1 rw
890 pio_mode write-only 0 255 w
891 slow 0 0 1 rw
892 unmaskirq 0 0 1 rw
893 using_dma 0 0 1 rw
894
895
8961.4 Networking info in /proc/net
897--------------------------------
898
Stefani Seibold349888e2009-06-17 16:26:01 -0700899The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900additional values you get for IP version 6 if you configure the kernel to
Stefani Seibold349888e2009-06-17 16:26:01 -0700901support this. Table 1-9 lists the files and their meaning.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902
903
Stefani Seibold349888e2009-06-17 16:26:01 -0700904Table 1-8: IPv6 info in /proc/net
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905..............................................................................
906 File Content
907 udp6 UDP sockets (IPv6)
908 tcp6 TCP sockets (IPv6)
909 raw6 Raw device statistics (IPv6)
910 igmp6 IP multicast addresses, which this host joined (IPv6)
911 if_inet6 List of IPv6 interface addresses
912 ipv6_route Kernel routing table for IPv6
913 rt6_stats Global IPv6 routing tables statistics
914 sockstat6 Socket statistics (IPv6)
915 snmp6 Snmp data (IPv6)
916..............................................................................
917
918
Stefani Seibold349888e2009-06-17 16:26:01 -0700919Table 1-9: Network info in /proc/net
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920..............................................................................
921 File Content
922 arp Kernel ARP table
923 dev network devices with statistics
924 dev_mcast the Layer2 multicast groups a device is listening too
925 (interface index, label, number of references, number of bound
926 addresses).
927 dev_stat network device status
928 ip_fwchains Firewall chain linkage
929 ip_fwnames Firewall chain names
930 ip_masq Directory containing the masquerading tables
931 ip_masquerade Major masquerading table
932 netstat Network statistics
933 raw raw device statistics
934 route Kernel routing table
935 rpc Directory containing rpc info
936 rt_cache Routing cache
937 snmp SNMP data
938 sockstat Socket statistics
939 tcp TCP sockets
940 tr_rif Token ring RIF routing table
941 udp UDP sockets
942 unix UNIX domain sockets
943 wireless Wireless interface data (Wavelan etc)
944 igmp IP multicast addresses, which this host joined
945 psched Global packet scheduler parameters.
946 netlink List of PF_NETLINK sockets
947 ip_mr_vifs List of multicast virtual interfaces
948 ip_mr_cache List of multicast routing cache
949..............................................................................
950
951You can use this information to see which network devices are available in
952your system and how much traffic was routed over those devices:
953
954 > cat /proc/net/dev
955 Inter-|Receive |[...
956 face |bytes packets errs drop fifo frame compressed multicast|[...
957 lo: 908188 5596 0 0 0 0 0 0 [...
958 ppp0:15475140 20721 410 0 0 410 0 0 [...
959 eth0: 614530 7085 0 0 0 0 0 1 [...
960
961 ...] Transmit
962 ...] bytes packets errs drop fifo colls carrier compressed
963 ...] 908188 5596 0 0 0 0 0 0
964 ...] 1375103 17405 0 0 0 0 0 0
965 ...] 1703981 5535 0 0 0 3 0 0
966
967In addition, each Channel Bond interface has it's own directory. For
968example, the bond0 device will have a directory called /proc/net/bond0/.
969It will contain information that is specific to that bond, such as the
970current slaves of the bond, the link status of the slaves, and how
971many times the slaves link has failed.
972
9731.5 SCSI info
974-------------
975
976If you have a SCSI host adapter in your system, you'll find a subdirectory
977named after the driver for this adapter in /proc/scsi. You'll also see a list
978of all recognized SCSI devices in /proc/scsi:
979
980 >cat /proc/scsi/scsi
981 Attached devices:
982 Host: scsi0 Channel: 00 Id: 00 Lun: 00
983 Vendor: IBM Model: DGHS09U Rev: 03E0
984 Type: Direct-Access ANSI SCSI revision: 03
985 Host: scsi0 Channel: 00 Id: 06 Lun: 00
986 Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
987 Type: CD-ROM ANSI SCSI revision: 02
988
989
990The directory named after the driver has one file for each adapter found in
991the system. These files contain information about the controller, including
992the used IRQ and the IO address range. The amount of information shown is
993dependent on the adapter you use. The example shows the output for an Adaptec
994AHA-2940 SCSI adapter:
995
996 > cat /proc/scsi/aic7xxx/0
997
998 Adaptec AIC7xxx driver version: 5.1.19/3.2.4
999 Compile Options:
1000 TCQ Enabled By Default : Disabled
1001 AIC7XXX_PROC_STATS : Disabled
1002 AIC7XXX_RESET_DELAY : 5
1003 Adapter Configuration:
1004 SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
1005 Ultra Wide Controller
1006 PCI MMAPed I/O Base: 0xeb001000
1007 Adapter SEEPROM Config: SEEPROM found and used.
1008 Adaptec SCSI BIOS: Enabled
1009 IRQ: 10
1010 SCBs: Active 0, Max Active 2,
1011 Allocated 15, HW 16, Page 255
1012 Interrupts: 160328
1013 BIOS Control Word: 0x18b6
1014 Adapter Control Word: 0x005b
1015 Extended Translation: Enabled
1016 Disconnect Enable Flags: 0xffff
1017 Ultra Enable Flags: 0x0001
1018 Tag Queue Enable Flags: 0x0000
1019 Ordered Queue Tag Flags: 0x0000
1020 Default Tag Queue Depth: 8
1021 Tagged Queue By Device array for aic7xxx host instance 0:
1022 {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
1023 Actual queue depth per device for aic7xxx host instance 0:
1024 {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
1025 Statistics:
1026 (scsi0:0:0:0)
1027 Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
1028 Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0)
1029 Total transfers 160151 (74577 reads and 85574 writes)
1030 (scsi0:0:6:0)
1031 Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
1032 Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0)
1033 Total transfers 0 (0 reads and 0 writes)
1034
1035
10361.6 Parallel port info in /proc/parport
1037---------------------------------------
1038
1039The directory /proc/parport contains information about the parallel ports of
1040your system. It has one subdirectory for each port, named after the port
1041number (0,1,2,...).
1042
Stefani Seibold349888e2009-06-17 16:26:01 -07001043These directories contain the four files shown in Table 1-10.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044
1045
Stefani Seibold349888e2009-06-17 16:26:01 -07001046Table 1-10: Files in /proc/parport
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047..............................................................................
1048 File Content
1049 autoprobe Any IEEE-1284 device ID information that has been acquired.
1050 devices list of the device drivers using that port. A + will appear by the
1051 name of the device currently using the port (it might not appear
1052 against any).
1053 hardware Parallel port's base address, IRQ line and DMA channel.
1054 irq IRQ that parport is using for that port. This is in a separate
1055 file to allow you to alter it by writing a new value in (IRQ
1056 number or none).
1057..............................................................................
1058
10591.7 TTY info in /proc/tty
1060-------------------------
1061
1062Information about the available and actually used tty's can be found in the
1063directory /proc/tty.You'll find entries for drivers and line disciplines in
Stefani Seibold349888e2009-06-17 16:26:01 -07001064this directory, as shown in Table 1-11.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065
1066
Stefani Seibold349888e2009-06-17 16:26:01 -07001067Table 1-11: Files in /proc/tty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068..............................................................................
1069 File Content
1070 drivers list of drivers and their usage
1071 ldiscs registered line disciplines
1072 driver/serial usage statistic and status of single tty lines
1073..............................................................................
1074
1075To see which tty's are currently in use, you can simply look into the file
1076/proc/tty/drivers:
1077
1078 > cat /proc/tty/drivers
1079 pty_slave /dev/pts 136 0-255 pty:slave
1080 pty_master /dev/ptm 128 0-255 pty:master
1081 pty_slave /dev/ttyp 3 0-255 pty:slave
1082 pty_master /dev/pty 2 0-255 pty:master
1083 serial /dev/cua 5 64-67 serial:callout
1084 serial /dev/ttyS 4 64-67 serial
1085 /dev/tty0 /dev/tty0 4 0 system:vtmaster
1086 /dev/ptmx /dev/ptmx 5 2 system
1087 /dev/console /dev/console 5 1 system:console
1088 /dev/tty /dev/tty 5 0 system:/dev/tty
1089 unknown /dev/tty 4 1-63 console
1090
1091
10921.8 Miscellaneous kernel statistics in /proc/stat
1093-------------------------------------------------
1094
1095Various pieces of information about kernel activity are available in the
1096/proc/stat file. All of the numbers reported in this file are aggregates
1097since the system first booted. For a quick look, simply cat the file:
1098
1099 > cat /proc/stat
Eric Dumazetc5743582009-09-21 17:01:06 -07001100 cpu 2255 34 2290 22625563 6290 127 456 0 0
1101 cpu0 1132 34 1441 11311718 3675 127 438 0 0
1102 cpu1 1123 0 849 11313845 2614 0 18 0 0
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103 intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
1104 ctxt 1990473
1105 btime 1062191376
1106 processes 2915
1107 procs_running 1
1108 procs_blocked 0
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001109 softirq 183433 0 21755 12 39 1137 231 21459 2263
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110
1111The very first "cpu" line aggregates the numbers in all of the other "cpuN"
1112lines. These numbers identify the amount of time the CPU has spent performing
1113different kinds of work. Time units are in USER_HZ (typically hundredths of a
1114second). The meanings of the columns are as follows, from left to right:
1115
1116- user: normal processes executing in user mode
1117- nice: niced processes executing in user mode
1118- system: processes executing in kernel mode
1119- idle: twiddling thumbs
1120- iowait: waiting for I/O to complete
1121- irq: servicing interrupts
1122- softirq: servicing softirqs
Leonardo Chiquittob68f2c3a2007-10-20 03:03:38 +02001123- steal: involuntary wait
Ryota Ozakice0e7b22009-10-24 01:20:10 +09001124- guest: running a normal guest
1125- guest_nice: running a niced guest
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126
1127The "intr" line gives counts of interrupts serviced since boot time, for each
1128of the possible system interrupts. The first column is the total of all
1129interrupts serviced; each subsequent column is the total for that particular
1130interrupt.
1131
1132The "ctxt" line gives the total number of context switches across all CPUs.
1133
1134The "btime" line gives the time at which the system booted, in seconds since
1135the Unix epoch.
1136
1137The "processes" line gives the number of processes and threads created, which
1138includes (but is not limited to) those created by calls to the fork() and
1139clone() system calls.
1140
Luis Garces-Ericee3cc2222009-12-06 18:30:44 -08001141The "procs_running" line gives the total number of threads that are
1142running or ready to run (i.e., the total number of runnable threads).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143
1144The "procs_blocked" line gives the number of processes currently blocked,
1145waiting for I/O to complete.
1146
Keika Kobayashid3d64df2009-06-17 16:25:55 -07001147The "softirq" line gives counts of softirqs serviced since boot time, for each
1148of the possible system softirqs. The first column is the total of all
1149softirqs serviced; each subsequent column is the total for that particular
1150softirq.
1151
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001152
Alex Tomasc9de5602008-01-29 00:19:52 -050011531.9 Ext4 file system parameters
1154------------------------------
Alex Tomasc9de5602008-01-29 00:19:52 -05001155
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001156Information about mounted ext4 file systems can be found in
1157/proc/fs/ext4. Each mounted filesystem will have a directory in
1158/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
1159/proc/fs/ext4/dm-0). The files in each per-device directory are shown
Stefani Seibold349888e2009-06-17 16:26:01 -07001160in Table 1-12, below.
Alex Tomasc9de5602008-01-29 00:19:52 -05001161
Stefani Seibold349888e2009-06-17 16:26:01 -07001162Table 1-12: Files in /proc/fs/ext4/<devname>
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001163..............................................................................
1164 File Content
1165 mb_groups details of multiblock allocator buddy cache of free blocks
Theodore Ts'o37515fa2008-10-09 23:21:54 -04001166..............................................................................
Alex Tomasc9de5602008-01-29 00:19:52 -05001167
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168
1169------------------------------------------------------------------------------
1170Summary
1171------------------------------------------------------------------------------
1172The /proc file system serves information about the running system. It not only
1173allows access to process data but also allows you to request the kernel status
1174by reading files in the hierarchy.
1175
1176The directory structure of /proc reflects the types of information and makes
1177it easy, if not obvious, where to look for specific data.
1178------------------------------------------------------------------------------
1179
1180------------------------------------------------------------------------------
1181CHAPTER 2: MODIFYING SYSTEM PARAMETERS
1182------------------------------------------------------------------------------
1183
1184------------------------------------------------------------------------------
1185In This Chapter
1186------------------------------------------------------------------------------
1187* Modifying kernel parameters by writing into files found in /proc/sys
1188* Exploring the files which modify certain parameters
1189* Review of the /proc/sys file tree
1190------------------------------------------------------------------------------
1191
1192
1193A very interesting part of /proc is the directory /proc/sys. This is not only
1194a source of information, it also allows you to change parameters within the
1195kernel. Be very careful when attempting this. You can optimize your system,
1196but you can also cause it to crash. Never alter kernel parameters on a
1197production system. Set up a development machine and test to make sure that
1198everything works the way you want it to. You may have no alternative but to
1199reboot the machine once an error has been made.
1200
1201To change a value, simply echo the new value into the file. An example is
1202given below in the section on the file system data. You need to be root to do
1203this. You can create your own boot script to perform this every time your
1204system boots.
1205
1206The files in /proc/sys can be used to fine tune and monitor miscellaneous and
1207general things in the operation of the Linux kernel. Since some of the files
1208can inadvertently disrupt your system, it is advisable to read both
1209documentation and source before actually making adjustments. In any case, be
1210very careful when writing to any of these files. The entries in /proc may
1211change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
1212review the kernel documentation in the directory /usr/src/linux/Documentation.
1213This chapter is heavily based on the documentation included in the pre 2.2
1214kernels, and became part of it in version 2.2.1 of the Linux kernel.
1215
Shen Feng760df932009-04-02 16:57:20 -07001216Please see: Documentation/sysctls/ directory for descriptions of these
Peter W Morrealedb0fb182009-01-15 13:50:42 -08001217entries.
Andrew Morton9d0243b2006-01-08 01:00:39 -08001218
Shen Feng760df932009-04-02 16:57:20 -07001219------------------------------------------------------------------------------
1220Summary
1221------------------------------------------------------------------------------
1222Certain aspects of kernel behavior can be modified at runtime, without the
1223need to recompile the kernel, or even to reboot the system. The files in the
1224/proc/sys tree can not only be read, but also modified. You can use the echo
1225command to write value into these files, thereby changing the default settings
1226of the kernel.
1227------------------------------------------------------------------------------
Andrew Morton9d0243b2006-01-08 01:00:39 -08001228
Shen Feng760df932009-04-02 16:57:20 -07001229------------------------------------------------------------------------------
1230CHAPTER 3: PER-PROCESS PARAMETERS
1231------------------------------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001232
Shen Feng760df932009-04-02 16:57:20 -070012333.1 /proc/<pid>/oom_adj - Adjust the oom-killer score
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001234------------------------------------------------------
1235
KOSAKI Motohiro0753ba02009-08-18 14:11:10 -07001236This file can be used to adjust the score used to select which processes
1237should be killed in an out-of-memory situation. Giving it a high score will
1238increase the likelihood of this process being killed by the oom-killer. Valid
1239values are in the range -16 to +15, plus the special value -17, which disables
1240oom-killing altogether for this process.
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001241
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001242The process to be killed in an out-of-memory situation is selected among all others
1243based on its badness score. This value equals the original memory size of the process
1244and is then updated according to its CPU time (utime + stime) and the
1245run time (uptime - start time). The longer it runs the smaller is the score.
1246Badness score is divided by the square root of the CPU time and then by
1247the double square root of the run time.
1248
1249Swapped out tasks are killed first. Half of each child's memory size is added to
1250the parent's score if they do not share the same memory. Thus forking servers
1251are the prime candidates to be killed. Having only one 'hungry' child will make
1252parent less preferable than the child.
1253
1254/proc/<pid>/oom_score shows process' current badness score.
1255
1256The following heuristics are then applied:
1257 * if the task was reniced, its score doubles
1258 * superuser or direct hardware access tasks (CAP_SYS_ADMIN, CAP_SYS_RESOURCE
1259 or CAP_SYS_RAWIO) have their score divided by 4
KOSAKI Motohiro495789a2009-09-21 17:03:14 -07001260 * if oom condition happened in one cpuset and checked process does not belong
Evgeniy Polyakov9e9e3cb2009-01-29 14:25:09 -08001261 to it, its score is divided by 8
1262 * the resulting score is multiplied by two to the power of oom_adj, i.e.
1263 points <<= oom_adj when it is positive and
1264 points >>= -(oom_adj) otherwise
1265
1266The task with the highest badness score is then selected and its children
1267are killed, process itself will be killed in an OOM situation when it does
1268not have children or some of them disabled oom like described above.
1269
Shen Feng760df932009-04-02 16:57:20 -070012703.2 /proc/<pid>/oom_score - Display current oom-killer score
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001271-------------------------------------------------------------
1272
Jan-Frode Myklebustd7ff0db2006-09-29 01:59:45 -07001273This file can be used to check the current score used by the oom-killer is for
1274any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which
1275process should be killed in an out-of-memory situation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276
Roland Kletzingf9c99462007-03-05 00:30:54 -08001277
Shen Feng760df932009-04-02 16:57:20 -070012783.3 /proc/<pid>/io - Display the IO accounting fields
Roland Kletzingf9c99462007-03-05 00:30:54 -08001279-------------------------------------------------------
1280
1281This file contains IO statistics for each running process
1282
1283Example
1284-------
1285
1286test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
1287[1] 3828
1288
1289test:/tmp # cat /proc/3828/io
1290rchar: 323934931
1291wchar: 323929600
1292syscr: 632687
1293syscw: 632675
1294read_bytes: 0
1295write_bytes: 323932160
1296cancelled_write_bytes: 0
1297
1298
1299Description
1300-----------
1301
1302rchar
1303-----
1304
1305I/O counter: chars read
1306The number of bytes which this task has caused to be read from storage. This
1307is simply the sum of bytes which this process passed to read() and pread().
1308It includes things like tty IO and it is unaffected by whether or not actual
1309physical disk IO was required (the read might have been satisfied from
1310pagecache)
1311
1312
1313wchar
1314-----
1315
1316I/O counter: chars written
1317The number of bytes which this task has caused, or shall cause to be written
1318to disk. Similar caveats apply here as with rchar.
1319
1320
1321syscr
1322-----
1323
1324I/O counter: read syscalls
1325Attempt to count the number of read I/O operations, i.e. syscalls like read()
1326and pread().
1327
1328
1329syscw
1330-----
1331
1332I/O counter: write syscalls
1333Attempt to count the number of write I/O operations, i.e. syscalls like
1334write() and pwrite().
1335
1336
1337read_bytes
1338----------
1339
1340I/O counter: bytes read
1341Attempt to count the number of bytes which this process really did cause to
1342be fetched from the storage layer. Done at the submit_bio() level, so it is
1343accurate for block-backed filesystems. <please add status regarding NFS and
1344CIFS at a later time>
1345
1346
1347write_bytes
1348-----------
1349
1350I/O counter: bytes written
1351Attempt to count the number of bytes which this process caused to be sent to
1352the storage layer. This is done at page-dirtying time.
1353
1354
1355cancelled_write_bytes
1356---------------------
1357
1358The big inaccuracy here is truncate. If a process writes 1MB to a file and
1359then deletes the file, it will in fact perform no writeout. But it will have
1360been accounted as having caused 1MB of write.
1361In other words: The number of bytes which this process caused to not happen,
1362by truncating pagecache. A task can cause "negative" IO too. If this task
1363truncates some dirty pagecache, some IO which another task has been accounted
1364for (in it's write_bytes) will not be happening. We _could_ just subtract that
1365from the truncating task's write_bytes, but there is information loss in doing
1366that.
1367
1368
1369Note
1370----
1371
1372At its current implementation state, this is a bit racy on 32-bit machines: if
1373process A reads process B's /proc/pid/io while process B is updating one of
1374those 64-bit counters, process A could see an intermediate result.
1375
1376
1377More information about this can be found within the taskstats documentation in
1378Documentation/accounting.
1379
Shen Feng760df932009-04-02 16:57:20 -070013803.4 /proc/<pid>/coredump_filter - Core dump filtering settings
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001381---------------------------------------------------------------
1382When a process is dumped, all anonymous memory is written to a core file as
1383long as the size of the core file isn't limited. But sometimes we don't want
1384to dump some memory segments, for example, huge shared memory. Conversely,
1385sometimes we want to save file-backed memory segments into a core file, not
1386only the individual files.
1387
1388/proc/<pid>/coredump_filter allows you to customize which memory segments
1389will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
1390of memory types. If a bit of the bitmask is set, memory segments of the
1391corresponding memory type are dumped, otherwise they are not dumped.
1392
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001393The following 7 memory types are supported:
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001394 - (bit 0) anonymous private memory
1395 - (bit 1) anonymous shared memory
1396 - (bit 2) file-backed private memory
1397 - (bit 3) file-backed shared memory
Hidehiro Kawaib261dfe2008-09-13 02:33:10 -07001398 - (bit 4) ELF header pages in file-backed private memory areas (it is
1399 effective only if the bit 2 is cleared)
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001400 - (bit 5) hugetlb private memory
1401 - (bit 6) hugetlb shared memory
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001402
1403 Note that MMIO pages such as frame buffer are never dumped and vDSO pages
1404 are always dumped regardless of the bitmask status.
1405
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001406 Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only
1407 effected by bit 5-6.
1408
1409Default value of coredump_filter is 0x23; this means all anonymous memory
1410segments and hugetlb private memory are dumped.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001411
1412If you don't want to dump all shared memory segments attached to pid 1234,
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001413write 0x21 to the process's proc file.
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001414
KOSAKI Motohiroe575f112008-10-18 20:27:08 -07001415 $ echo 0x21 > /proc/1234/coredump_filter
Kawai, Hidehirobb901102007-07-19 01:48:31 -07001416
1417When a new process is created, the process inherits the bitmask status from its
1418parent. It is useful to set up coredump_filter before the program runs.
1419For example:
1420
1421 $ echo 0x7 > /proc/self/coredump_filter
1422 $ ./some_program
1423
Shen Feng760df932009-04-02 16:57:20 -070014243.5 /proc/<pid>/mountinfo - Information about mounts
Ram Pai2d4d4862008-03-27 13:06:25 +01001425--------------------------------------------------------
1426
1427This file contains lines of the form:
1428
142936 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
1430(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
1431
1432(1) mount ID: unique identifier of the mount (may be reused after umount)
1433(2) parent ID: ID of parent (or of self for the top of the mount tree)
1434(3) major:minor: value of st_dev for files on filesystem
1435(4) root: root of the mount within the filesystem
1436(5) mount point: mount point relative to the process's root
1437(6) mount options: per mount options
1438(7) optional fields: zero or more fields of the form "tag[:value]"
1439(8) separator: marks the end of the optional fields
1440(9) filesystem type: name of filesystem of the form "type[.subtype]"
1441(10) mount source: filesystem specific information or "none"
1442(11) super options: per super block options
1443
1444Parsers should ignore all unrecognised optional fields. Currently the
1445possible optional fields are:
1446
1447shared:X mount is shared in peer group X
1448master:X mount is slave to peer group X
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +01001449propagate_from:X mount is slave and receives propagation from peer group X (*)
Ram Pai2d4d4862008-03-27 13:06:25 +01001450unbindable mount is unbindable
1451
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +01001452(*) X is the closest dominant peer group under the process's root. If
1453X is the immediate master of the mount, or if there's no dominant peer
1454group under the same root, then only the "master:X" field is present
1455and not the "propagate_from:X" field.
1456
Ram Pai2d4d4862008-03-27 13:06:25 +01001457For more information on mount propagation see:
1458
1459 Documentation/filesystems/sharedsubtree.txt
1460
john stultz4614a696b2009-12-14 18:00:05 -08001461
14623.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
1463--------------------------------------------------------
1464These files provide a method to access a tasks comm value. It also allows for
1465a task to set its own or one of its thread siblings comm value. The comm value
1466is limited in size compared to the cmdline value, so writing anything longer
1467then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
1468comm value.