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1 | ------------------------------------------------------------------------------ |
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 | ||
7 | 2.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000 | |
349888ee | 8 | move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009 |
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9 | ------------------------------------------------------------------------------ |
10 | Version 1.3 Kernel version 2.2.12 | |
11 | Kernel version 2.4.0-test11-pre4 | |
12 | ------------------------------------------------------------------------------ | |
349888ee | 13 | fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009 |
1da177e4 LT |
14 | |
15 | Table 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 | |
760df93e | 31 | 1.9 Ext4 file system parameters |
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32 | |
33 | 2 Modifying System Parameters | |
760df93e SF |
34 | |
35 | 3 Per-Process Parameters | |
a63d83f4 DR |
36 | 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer |
37 | score | |
760df93e SF |
38 | 3.2 /proc/<pid>/oom_score - Display current oom-killer score |
39 | 3.3 /proc/<pid>/io - Display the IO accounting fields | |
40 | 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings | |
41 | 3.5 /proc/<pid>/mountinfo - Information about mounts | |
4614a696 | 42 | 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm |
81841161 | 43 | 3.7 /proc/<pid>/task/<tid>/children - Information about task children |
760df93e | 44 | |
0499680a VK |
45 | 4 Configuring procfs |
46 | 4.1 Mount options | |
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47 | |
48 | ------------------------------------------------------------------------------ | |
49 | Preface | |
50 | ------------------------------------------------------------------------------ | |
51 | ||
52 | 0.1 Introduction/Credits | |
53 | ------------------------ | |
54 | ||
55 | This documentation is part of a soon (or so we hope) to be released book on | |
56 | the SuSE Linux distribution. As there is no complete documentation for the | |
57 | /proc file system and we've used many freely available sources to write these | |
58 | chapters, it seems only fair to give the work back to the Linux community. | |
59 | This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm | |
60 | afraid it's still far from complete, but we hope it will be useful. As far as | |
61 | we know, it is the first 'all-in-one' document about the /proc file system. It | |
62 | is focused on the Intel x86 hardware, so if you are looking for PPC, ARM, | |
63 | SPARC, AXP, etc., features, you probably won't find what you are looking for. | |
64 | It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But | |
65 | additions and patches are welcome and will be added to this document if you | |
66 | mail them to Bodo. | |
67 | ||
68 | We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of | |
69 | other people for help compiling this documentation. We'd also like to extend a | |
70 | special thank you to Andi Kleen for documentation, which we relied on heavily | |
71 | to create this document, as well as the additional information he provided. | |
72 | Thanks to everybody else who contributed source or docs to the Linux kernel | |
73 | and helped create a great piece of software... :) | |
74 | ||
75 | If you have any comments, corrections or additions, please don't hesitate to | |
76 | contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this | |
77 | document. | |
78 | ||
79 | The latest version of this document is available online at | |
0ea6e611 | 80 | http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html |
1da177e4 | 81 | |
0ea6e611 | 82 | If the above direction does not works for you, you could try the kernel |
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83 | mailing list at linux-kernel@vger.kernel.org and/or try to reach me at |
84 | comandante@zaralinux.com. | |
85 | ||
86 | 0.2 Legal Stuff | |
87 | --------------- | |
88 | ||
89 | We don't guarantee the correctness of this document, and if you come to us | |
90 | complaining about how you screwed up your system because of incorrect | |
91 | documentation, we won't feel responsible... | |
92 | ||
93 | ------------------------------------------------------------------------------ | |
94 | CHAPTER 1: COLLECTING SYSTEM INFORMATION | |
95 | ------------------------------------------------------------------------------ | |
96 | ||
97 | ------------------------------------------------------------------------------ | |
98 | In This Chapter | |
99 | ------------------------------------------------------------------------------ | |
100 | * Investigating the properties of the pseudo file system /proc and its | |
101 | ability to provide information on the running Linux system | |
102 | * Examining /proc's structure | |
103 | * Uncovering various information about the kernel and the processes running | |
104 | on the system | |
105 | ------------------------------------------------------------------------------ | |
106 | ||
107 | ||
108 | The proc file system acts as an interface to internal data structures in the | |
109 | kernel. It can be used to obtain information about the system and to change | |
110 | certain kernel parameters at runtime (sysctl). | |
111 | ||
112 | First, we'll take a look at the read-only parts of /proc. In Chapter 2, we | |
113 | show you how you can use /proc/sys to change settings. | |
114 | ||
115 | 1.1 Process-Specific Subdirectories | |
116 | ----------------------------------- | |
117 | ||
118 | The directory /proc contains (among other things) one subdirectory for each | |
119 | process running on the system, which is named after the process ID (PID). | |
120 | ||
121 | The link self points to the process reading the file system. Each process | |
122 | subdirectory has the entries listed in Table 1-1. | |
123 | ||
124 | ||
349888ee | 125 | Table 1-1: Process specific entries in /proc |
1da177e4 | 126 | .............................................................................. |
b813e931 DR |
127 | File Content |
128 | clear_refs Clears page referenced bits shown in smaps output | |
129 | cmdline Command line arguments | |
130 | cpu Current and last cpu in which it was executed (2.4)(smp) | |
131 | cwd Link to the current working directory | |
132 | environ Values of environment variables | |
133 | exe Link to the executable of this process | |
134 | fd Directory, which contains all file descriptors | |
135 | maps Memory maps to executables and library files (2.4) | |
136 | mem Memory held by this process | |
137 | root Link to the root directory of this process | |
138 | stat Process status | |
139 | statm Process memory status information | |
140 | status Process status in human readable form | |
141 | wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan | |
03f890f8 | 142 | pagemap Page table |
2ec220e2 | 143 | stack Report full stack trace, enable via CONFIG_STACKTRACE |
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144 | smaps a extension based on maps, showing the memory consumption of |
145 | each mapping | |
1da177e4 LT |
146 | .............................................................................. |
147 | ||
148 | For example, to get the status information of a process, all you have to do is | |
149 | read the file /proc/PID/status: | |
150 | ||
349888ee SS |
151 | >cat /proc/self/status |
152 | Name: cat | |
153 | State: R (running) | |
154 | Tgid: 5452 | |
155 | Pid: 5452 | |
156 | PPid: 743 | |
1da177e4 | 157 | TracerPid: 0 (2.4) |
349888ee SS |
158 | Uid: 501 501 501 501 |
159 | Gid: 100 100 100 100 | |
160 | FDSize: 256 | |
161 | Groups: 100 14 16 | |
162 | VmPeak: 5004 kB | |
163 | VmSize: 5004 kB | |
164 | VmLck: 0 kB | |
165 | VmHWM: 476 kB | |
166 | VmRSS: 476 kB | |
167 | VmData: 156 kB | |
168 | VmStk: 88 kB | |
169 | VmExe: 68 kB | |
170 | VmLib: 1412 kB | |
171 | VmPTE: 20 kb | |
b084d435 | 172 | VmSwap: 0 kB |
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173 | Threads: 1 |
174 | SigQ: 0/28578 | |
175 | SigPnd: 0000000000000000 | |
176 | ShdPnd: 0000000000000000 | |
177 | SigBlk: 0000000000000000 | |
178 | SigIgn: 0000000000000000 | |
179 | SigCgt: 0000000000000000 | |
180 | CapInh: 00000000fffffeff | |
181 | CapPrm: 0000000000000000 | |
182 | CapEff: 0000000000000000 | |
183 | CapBnd: ffffffffffffffff | |
184 | voluntary_ctxt_switches: 0 | |
185 | nonvoluntary_ctxt_switches: 1 | |
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186 | |
187 | This shows you nearly the same information you would get if you viewed it with | |
188 | the ps command. In fact, ps uses the proc file system to obtain its | |
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189 | information. But you get a more detailed view of the process by reading the |
190 | file /proc/PID/status. It fields are described in table 1-2. | |
191 | ||
192 | The statm file contains more detailed information about the process | |
193 | memory usage. Its seven fields are explained in Table 1-3. The stat file | |
194 | contains details information about the process itself. Its fields are | |
195 | explained in Table 1-4. | |
1da177e4 | 196 | |
34e55232 KH |
197 | (for SMP CONFIG users) |
198 | For making accounting scalable, RSS related information are handled in | |
199 | asynchronous manner and the vaule may not be very precise. To see a precise | |
200 | snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table. | |
201 | It's slow but very precise. | |
202 | ||
cb2992a6 | 203 | Table 1-2: Contents of the status files (as of 2.6.30-rc7) |
349888ee SS |
204 | .............................................................................. |
205 | Field Content | |
206 | Name filename of the executable | |
207 | State state (R is running, S is sleeping, D is sleeping | |
208 | in an uninterruptible wait, Z is zombie, | |
209 | T is traced or stopped) | |
210 | Tgid thread group ID | |
211 | Pid process id | |
212 | PPid process id of the parent process | |
213 | TracerPid PID of process tracing this process (0 if not) | |
214 | Uid Real, effective, saved set, and file system UIDs | |
215 | Gid Real, effective, saved set, and file system GIDs | |
216 | FDSize number of file descriptor slots currently allocated | |
217 | Groups supplementary group list | |
218 | VmPeak peak virtual memory size | |
219 | VmSize total program size | |
220 | VmLck locked memory size | |
221 | VmHWM peak resident set size ("high water mark") | |
222 | VmRSS size of memory portions | |
223 | VmData size of data, stack, and text segments | |
224 | VmStk size of data, stack, and text segments | |
225 | VmExe size of text segment | |
226 | VmLib size of shared library code | |
227 | VmPTE size of page table entries | |
b084d435 | 228 | VmSwap size of swap usage (the number of referred swapents) |
349888ee SS |
229 | Threads number of threads |
230 | SigQ number of signals queued/max. number for queue | |
231 | SigPnd bitmap of pending signals for the thread | |
232 | ShdPnd bitmap of shared pending signals for the process | |
233 | SigBlk bitmap of blocked signals | |
234 | SigIgn bitmap of ignored signals | |
235 | SigCgt bitmap of catched signals | |
236 | CapInh bitmap of inheritable capabilities | |
237 | CapPrm bitmap of permitted capabilities | |
238 | CapEff bitmap of effective capabilities | |
239 | CapBnd bitmap of capabilities bounding set | |
240 | Cpus_allowed mask of CPUs on which this process may run | |
241 | Cpus_allowed_list Same as previous, but in "list format" | |
242 | Mems_allowed mask of memory nodes allowed to this process | |
243 | Mems_allowed_list Same as previous, but in "list format" | |
244 | voluntary_ctxt_switches number of voluntary context switches | |
245 | nonvoluntary_ctxt_switches number of non voluntary context switches | |
246 | .............................................................................. | |
1da177e4 | 247 | |
349888ee | 248 | Table 1-3: Contents of the statm files (as of 2.6.8-rc3) |
1da177e4 LT |
249 | .............................................................................. |
250 | Field Content | |
251 | size total program size (pages) (same as VmSize in status) | |
252 | resident size of memory portions (pages) (same as VmRSS in status) | |
253 | shared number of pages that are shared (i.e. backed by a file) | |
254 | trs number of pages that are 'code' (not including libs; broken, | |
255 | includes data segment) | |
256 | lrs number of pages of library (always 0 on 2.6) | |
257 | drs number of pages of data/stack (including libs; broken, | |
258 | includes library text) | |
259 | dt number of dirty pages (always 0 on 2.6) | |
260 | .............................................................................. | |
261 | ||
18d96779 | 262 | |
349888ee | 263 | Table 1-4: Contents of the stat files (as of 2.6.30-rc7) |
18d96779 KC |
264 | .............................................................................. |
265 | Field Content | |
266 | pid process id | |
267 | tcomm filename of the executable | |
268 | state state (R is running, S is sleeping, D is sleeping in an | |
269 | uninterruptible wait, Z is zombie, T is traced or stopped) | |
270 | ppid process id of the parent process | |
271 | pgrp pgrp of the process | |
272 | sid session id | |
273 | tty_nr tty the process uses | |
274 | tty_pgrp pgrp of the tty | |
275 | flags task flags | |
276 | min_flt number of minor faults | |
277 | cmin_flt number of minor faults with child's | |
278 | maj_flt number of major faults | |
279 | cmaj_flt number of major faults with child's | |
280 | utime user mode jiffies | |
281 | stime kernel mode jiffies | |
282 | cutime user mode jiffies with child's | |
283 | cstime kernel mode jiffies with child's | |
284 | priority priority level | |
285 | nice nice level | |
286 | num_threads number of threads | |
2e01e00e | 287 | it_real_value (obsolete, always 0) |
18d96779 KC |
288 | start_time time the process started after system boot |
289 | vsize virtual memory size | |
290 | rss resident set memory size | |
291 | rsslim current limit in bytes on the rss | |
292 | start_code address above which program text can run | |
293 | end_code address below which program text can run | |
b7643757 | 294 | start_stack address of the start of the main process stack |
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295 | esp current value of ESP |
296 | eip current value of EIP | |
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297 | pending bitmap of pending signals |
298 | blocked bitmap of blocked signals | |
299 | sigign bitmap of ignored signals | |
300 | sigcatch bitmap of catched signals | |
18d96779 KC |
301 | wchan address where process went to sleep |
302 | 0 (place holder) | |
303 | 0 (place holder) | |
304 | exit_signal signal to send to parent thread on exit | |
305 | task_cpu which CPU the task is scheduled on | |
306 | rt_priority realtime priority | |
307 | policy scheduling policy (man sched_setscheduler) | |
308 | blkio_ticks time spent waiting for block IO | |
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309 | gtime guest time of the task in jiffies |
310 | cgtime guest time of the task children in jiffies | |
b3f7f573 CG |
311 | start_data address above which program data+bss is placed |
312 | end_data address below which program data+bss is placed | |
313 | start_brk address above which program heap can be expanded with brk() | |
5b172087 CG |
314 | arg_start address above which program command line is placed |
315 | arg_end address below which program command line is placed | |
316 | env_start address above which program environment is placed | |
317 | env_end address below which program environment is placed | |
318 | exit_code the thread's exit_code in the form reported by the waitpid system call | |
18d96779 KC |
319 | .............................................................................. |
320 | ||
32e688b8 | 321 | The /proc/PID/maps file containing the currently mapped memory regions and |
349888ee SS |
322 | their access permissions. |
323 | ||
324 | The format is: | |
325 | ||
326 | address perms offset dev inode pathname | |
327 | ||
328 | 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test | |
329 | 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test | |
330 | 0804a000-0806b000 rw-p 00000000 00:00 0 [heap] | |
331 | a7cb1000-a7cb2000 ---p 00000000 00:00 0 | |
34441427 | 332 | a7cb2000-a7eb2000 rw-p 00000000 00:00 0 |
349888ee | 333 | a7eb2000-a7eb3000 ---p 00000000 00:00 0 |
b7643757 | 334 | a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack:1001] |
349888ee SS |
335 | a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6 |
336 | a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6 | |
337 | a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6 | |
338 | a800b000-a800e000 rw-p 00000000 00:00 0 | |
339 | a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0 | |
340 | a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0 | |
341 | a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0 | |
342 | a8024000-a8027000 rw-p 00000000 00:00 0 | |
343 | a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2 | |
344 | a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2 | |
345 | a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2 | |
346 | aff35000-aff4a000 rw-p 00000000 00:00 0 [stack] | |
347 | ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso] | |
348 | ||
349 | where "address" is the address space in the process that it occupies, "perms" | |
350 | is a set of permissions: | |
351 | ||
352 | r = read | |
353 | w = write | |
354 | x = execute | |
355 | s = shared | |
356 | p = private (copy on write) | |
357 | ||
358 | "offset" is the offset into the mapping, "dev" is the device (major:minor), and | |
359 | "inode" is the inode on that device. 0 indicates that no inode is associated | |
360 | with the memory region, as the case would be with BSS (uninitialized data). | |
361 | The "pathname" shows the name associated file for this mapping. If the mapping | |
362 | is not associated with a file: | |
363 | ||
364 | [heap] = the heap of the program | |
365 | [stack] = the stack of the main process | |
b7643757 | 366 | [stack:1001] = the stack of the thread with tid 1001 |
349888ee SS |
367 | [vdso] = the "virtual dynamic shared object", |
368 | the kernel system call handler | |
369 | ||
370 | or if empty, the mapping is anonymous. | |
371 | ||
b7643757 SP |
372 | The /proc/PID/task/TID/maps is a view of the virtual memory from the viewpoint |
373 | of the individual tasks of a process. In this file you will see a mapping marked | |
374 | as [stack] if that task sees it as a stack. This is a key difference from the | |
375 | content of /proc/PID/maps, where you will see all mappings that are being used | |
376 | as stack by all of those tasks. Hence, for the example above, the task-level | |
377 | map, i.e. /proc/PID/task/TID/maps for thread 1001 will look like this: | |
378 | ||
379 | 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test | |
380 | 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test | |
381 | 0804a000-0806b000 rw-p 00000000 00:00 0 [heap] | |
382 | a7cb1000-a7cb2000 ---p 00000000 00:00 0 | |
383 | a7cb2000-a7eb2000 rw-p 00000000 00:00 0 | |
384 | a7eb2000-a7eb3000 ---p 00000000 00:00 0 | |
385 | a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack] | |
386 | a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6 | |
387 | a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6 | |
388 | a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6 | |
389 | a800b000-a800e000 rw-p 00000000 00:00 0 | |
390 | a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0 | |
391 | a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0 | |
392 | a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0 | |
393 | a8024000-a8027000 rw-p 00000000 00:00 0 | |
394 | a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2 | |
395 | a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2 | |
396 | a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2 | |
397 | aff35000-aff4a000 rw-p 00000000 00:00 0 | |
398 | ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso] | |
349888ee SS |
399 | |
400 | The /proc/PID/smaps is an extension based on maps, showing the memory | |
401 | consumption for each of the process's mappings. For each of mappings there | |
402 | is a series of lines such as the following: | |
403 | ||
404 | 08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash | |
405 | Size: 1084 kB | |
406 | Rss: 892 kB | |
407 | Pss: 374 kB | |
408 | Shared_Clean: 892 kB | |
409 | Shared_Dirty: 0 kB | |
410 | Private_Clean: 0 kB | |
411 | Private_Dirty: 0 kB | |
412 | Referenced: 892 kB | |
b40d4f84 | 413 | Anonymous: 0 kB |
349888ee SS |
414 | Swap: 0 kB |
415 | KernelPageSize: 4 kB | |
416 | MMUPageSize: 4 kB | |
2d90508f | 417 | Locked: 374 kB |
349888ee | 418 | |
0f4d208f MM |
419 | The first of these lines shows the same information as is displayed for the |
420 | mapping in /proc/PID/maps. The remaining lines show the size of the mapping | |
421 | (size), the amount of the mapping that is currently resident in RAM (RSS), the | |
422 | process' proportional share of this mapping (PSS), the number of clean and | |
b40d4f84 NK |
423 | dirty private pages in the mapping. Note that even a page which is part of a |
424 | MAP_SHARED mapping, but has only a single pte mapped, i.e. is currently used | |
425 | by only one process, is accounted as private and not as shared. "Referenced" | |
426 | indicates the amount of memory currently marked as referenced or accessed. | |
427 | "Anonymous" shows the amount of memory that does not belong to any file. Even | |
428 | a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE | |
429 | and a page is modified, the file page is replaced by a private anonymous copy. | |
430 | "Swap" shows how much would-be-anonymous memory is also used, but out on | |
431 | swap. | |
349888ee SS |
432 | |
433 | This file is only present if the CONFIG_MMU kernel configuration option is | |
434 | enabled. | |
18d96779 | 435 | |
398499d5 MB |
436 | The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG |
437 | bits on both physical and virtual pages associated with a process. | |
438 | To clear the bits for all the pages associated with the process | |
439 | > echo 1 > /proc/PID/clear_refs | |
440 | ||
441 | To clear the bits for the anonymous pages associated with the process | |
442 | > echo 2 > /proc/PID/clear_refs | |
443 | ||
444 | To clear the bits for the file mapped pages associated with the process | |
445 | > echo 3 > /proc/PID/clear_refs | |
446 | Any other value written to /proc/PID/clear_refs will have no effect. | |
447 | ||
03f890f8 NK |
448 | The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags |
449 | using /proc/kpageflags and number of times a page is mapped using | |
450 | /proc/kpagecount. For detailed explanation, see Documentation/vm/pagemap.txt. | |
398499d5 | 451 | |
1da177e4 LT |
452 | 1.2 Kernel data |
453 | --------------- | |
454 | ||
455 | Similar to the process entries, the kernel data files give information about | |
456 | the running kernel. The files used to obtain this information are contained in | |
349888ee | 457 | /proc and are listed in Table 1-5. Not all of these will be present in your |
1da177e4 LT |
458 | system. It depends on the kernel configuration and the loaded modules, which |
459 | files are there, and which are missing. | |
460 | ||
349888ee | 461 | Table 1-5: Kernel info in /proc |
1da177e4 LT |
462 | .............................................................................. |
463 | File Content | |
464 | apm Advanced power management info | |
465 | buddyinfo Kernel memory allocator information (see text) (2.5) | |
466 | bus Directory containing bus specific information | |
467 | cmdline Kernel command line | |
468 | cpuinfo Info about the CPU | |
469 | devices Available devices (block and character) | |
470 | dma Used DMS channels | |
471 | filesystems Supported filesystems | |
472 | driver Various drivers grouped here, currently rtc (2.4) | |
473 | execdomains Execdomains, related to security (2.4) | |
474 | fb Frame Buffer devices (2.4) | |
475 | fs File system parameters, currently nfs/exports (2.4) | |
476 | ide Directory containing info about the IDE subsystem | |
477 | interrupts Interrupt usage | |
478 | iomem Memory map (2.4) | |
479 | ioports I/O port usage | |
480 | irq Masks for irq to cpu affinity (2.4)(smp?) | |
481 | isapnp ISA PnP (Plug&Play) Info (2.4) | |
482 | kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4)) | |
483 | kmsg Kernel messages | |
484 | ksyms Kernel symbol table | |
485 | loadavg Load average of last 1, 5 & 15 minutes | |
486 | locks Kernel locks | |
487 | meminfo Memory info | |
488 | misc Miscellaneous | |
489 | modules List of loaded modules | |
490 | mounts Mounted filesystems | |
491 | net Networking info (see text) | |
a1b57ac0 | 492 | pagetypeinfo Additional page allocator information (see text) (2.5) |
1da177e4 | 493 | partitions Table of partitions known to the system |
8b60756a | 494 | pci Deprecated info of PCI bus (new way -> /proc/bus/pci/, |
1da177e4 LT |
495 | decoupled by lspci (2.4) |
496 | rtc Real time clock | |
497 | scsi SCSI info (see text) | |
498 | slabinfo Slab pool info | |
d3d64df2 | 499 | softirqs softirq usage |
1da177e4 LT |
500 | stat Overall statistics |
501 | swaps Swap space utilization | |
502 | sys See chapter 2 | |
503 | sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4) | |
504 | tty Info of tty drivers | |
505 | uptime System uptime | |
506 | version Kernel version | |
507 | video bttv info of video resources (2.4) | |
a47a126a | 508 | vmallocinfo Show vmalloced areas |
1da177e4 LT |
509 | .............................................................................. |
510 | ||
511 | You can, for example, check which interrupts are currently in use and what | |
512 | they are used for by looking in the file /proc/interrupts: | |
513 | ||
514 | > cat /proc/interrupts | |
515 | CPU0 | |
516 | 0: 8728810 XT-PIC timer | |
517 | 1: 895 XT-PIC keyboard | |
518 | 2: 0 XT-PIC cascade | |
519 | 3: 531695 XT-PIC aha152x | |
520 | 4: 2014133 XT-PIC serial | |
521 | 5: 44401 XT-PIC pcnet_cs | |
522 | 8: 2 XT-PIC rtc | |
523 | 11: 8 XT-PIC i82365 | |
524 | 12: 182918 XT-PIC PS/2 Mouse | |
525 | 13: 1 XT-PIC fpu | |
526 | 14: 1232265 XT-PIC ide0 | |
527 | 15: 7 XT-PIC ide1 | |
528 | NMI: 0 | |
529 | ||
530 | In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the | |
531 | output of a SMP machine): | |
532 | ||
533 | > cat /proc/interrupts | |
534 | ||
535 | CPU0 CPU1 | |
536 | 0: 1243498 1214548 IO-APIC-edge timer | |
537 | 1: 8949 8958 IO-APIC-edge keyboard | |
538 | 2: 0 0 XT-PIC cascade | |
539 | 5: 11286 10161 IO-APIC-edge soundblaster | |
540 | 8: 1 0 IO-APIC-edge rtc | |
541 | 9: 27422 27407 IO-APIC-edge 3c503 | |
542 | 12: 113645 113873 IO-APIC-edge PS/2 Mouse | |
543 | 13: 0 0 XT-PIC fpu | |
544 | 14: 22491 24012 IO-APIC-edge ide0 | |
545 | 15: 2183 2415 IO-APIC-edge ide1 | |
546 | 17: 30564 30414 IO-APIC-level eth0 | |
547 | 18: 177 164 IO-APIC-level bttv | |
548 | NMI: 2457961 2457959 | |
549 | LOC: 2457882 2457881 | |
550 | ERR: 2155 | |
551 | ||
552 | NMI is incremented in this case because every timer interrupt generates a NMI | |
553 | (Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups. | |
554 | ||
555 | LOC is the local interrupt counter of the internal APIC of every CPU. | |
556 | ||
557 | ERR is incremented in the case of errors in the IO-APIC bus (the bus that | |
558 | connects the CPUs in a SMP system. This means that an error has been detected, | |
559 | the IO-APIC automatically retry the transmission, so it should not be a big | |
560 | problem, but you should read the SMP-FAQ. | |
561 | ||
38e760a1 JK |
562 | In 2.6.2* /proc/interrupts was expanded again. This time the goal was for |
563 | /proc/interrupts to display every IRQ vector in use by the system, not | |
564 | just those considered 'most important'. The new vectors are: | |
565 | ||
566 | THR -- interrupt raised when a machine check threshold counter | |
567 | (typically counting ECC corrected errors of memory or cache) exceeds | |
568 | a configurable threshold. Only available on some systems. | |
569 | ||
570 | TRM -- a thermal event interrupt occurs when a temperature threshold | |
571 | has been exceeded for the CPU. This interrupt may also be generated | |
572 | when the temperature drops back to normal. | |
573 | ||
574 | SPU -- a spurious interrupt is some interrupt that was raised then lowered | |
575 | by some IO device before it could be fully processed by the APIC. Hence | |
576 | the APIC sees the interrupt but does not know what device it came from. | |
577 | For this case the APIC will generate the interrupt with a IRQ vector | |
578 | of 0xff. This might also be generated by chipset bugs. | |
579 | ||
580 | RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are | |
581 | sent from one CPU to another per the needs of the OS. Typically, | |
582 | their statistics are used by kernel developers and interested users to | |
19f59460 | 583 | determine the occurrence of interrupts of the given type. |
38e760a1 | 584 | |
25985edc | 585 | The above IRQ vectors are displayed only when relevant. For example, |
38e760a1 JK |
586 | the threshold vector does not exist on x86_64 platforms. Others are |
587 | suppressed when the system is a uniprocessor. As of this writing, only | |
588 | i386 and x86_64 platforms support the new IRQ vector displays. | |
589 | ||
590 | Of some interest is the introduction of the /proc/irq directory to 2.4. | |
1da177e4 LT |
591 | It could be used to set IRQ to CPU affinity, this means that you can "hook" an |
592 | IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the | |
18404756 MK |
593 | irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and |
594 | prof_cpu_mask. | |
1da177e4 LT |
595 | |
596 | For example | |
597 | > ls /proc/irq/ | |
598 | 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask | |
18404756 | 599 | 1 11 13 15 17 19 3 5 7 9 default_smp_affinity |
1da177e4 LT |
600 | > ls /proc/irq/0/ |
601 | smp_affinity | |
602 | ||
18404756 MK |
603 | smp_affinity is a bitmask, in which you can specify which CPUs can handle the |
604 | IRQ, you can set it by doing: | |
1da177e4 | 605 | |
18404756 MK |
606 | > echo 1 > /proc/irq/10/smp_affinity |
607 | ||
608 | This means that only the first CPU will handle the IRQ, but you can also echo | |
609 | 5 which means that only the first and fourth CPU can handle the IRQ. | |
1da177e4 | 610 | |
18404756 MK |
611 | The contents of each smp_affinity file is the same by default: |
612 | ||
613 | > cat /proc/irq/0/smp_affinity | |
614 | ffffffff | |
1da177e4 | 615 | |
4b060420 MT |
616 | There is an alternate interface, smp_affinity_list which allows specifying |
617 | a cpu range instead of a bitmask: | |
618 | ||
619 | > cat /proc/irq/0/smp_affinity_list | |
620 | 1024-1031 | |
621 | ||
18404756 MK |
622 | The default_smp_affinity mask applies to all non-active IRQs, which are the |
623 | IRQs which have not yet been allocated/activated, and hence which lack a | |
624 | /proc/irq/[0-9]* directory. | |
1da177e4 | 625 | |
92d6b71a DS |
626 | The node file on an SMP system shows the node to which the device using the IRQ |
627 | reports itself as being attached. This hardware locality information does not | |
628 | include information about any possible driver locality preference. | |
629 | ||
18404756 | 630 | prof_cpu_mask specifies which CPUs are to be profiled by the system wide |
4b060420 | 631 | profiler. Default value is ffffffff (all cpus if there are only 32 of them). |
1da177e4 LT |
632 | |
633 | The way IRQs are routed is handled by the IO-APIC, and it's Round Robin | |
634 | between all the CPUs which are allowed to handle it. As usual the kernel has | |
635 | more info than you and does a better job than you, so the defaults are the | |
4b060420 MT |
636 | best choice for almost everyone. [Note this applies only to those IO-APIC's |
637 | that support "Round Robin" interrupt distribution.] | |
1da177e4 LT |
638 | |
639 | There are three more important subdirectories in /proc: net, scsi, and sys. | |
640 | The general rule is that the contents, or even the existence of these | |
641 | directories, depend on your kernel configuration. If SCSI is not enabled, the | |
642 | directory scsi may not exist. The same is true with the net, which is there | |
643 | only when networking support is present in the running kernel. | |
644 | ||
645 | The slabinfo file gives information about memory usage at the slab level. | |
646 | Linux uses slab pools for memory management above page level in version 2.2. | |
647 | Commonly used objects have their own slab pool (such as network buffers, | |
648 | directory cache, and so on). | |
649 | ||
650 | .............................................................................. | |
651 | ||
652 | > cat /proc/buddyinfo | |
653 | ||
654 | Node 0, zone DMA 0 4 5 4 4 3 ... | |
655 | Node 0, zone Normal 1 0 0 1 101 8 ... | |
656 | Node 0, zone HighMem 2 0 0 1 1 0 ... | |
657 | ||
a1b57ac0 | 658 | External fragmentation is a problem under some workloads, and buddyinfo is a |
1da177e4 LT |
659 | useful tool for helping diagnose these problems. Buddyinfo will give you a |
660 | clue as to how big an area you can safely allocate, or why a previous | |
661 | allocation failed. | |
662 | ||
663 | Each column represents the number of pages of a certain order which are | |
664 | available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in | |
665 | ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE | |
666 | available in ZONE_NORMAL, etc... | |
667 | ||
a1b57ac0 MG |
668 | More information relevant to external fragmentation can be found in |
669 | pagetypeinfo. | |
670 | ||
671 | > cat /proc/pagetypeinfo | |
672 | Page block order: 9 | |
673 | Pages per block: 512 | |
674 | ||
675 | Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10 | |
676 | Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0 | |
677 | Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0 | |
678 | Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2 | |
679 | Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0 | |
680 | Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0 | |
681 | Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9 | |
682 | Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0 | |
683 | Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452 | |
684 | Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0 | |
685 | Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0 | |
686 | ||
687 | Number of blocks type Unmovable Reclaimable Movable Reserve Isolate | |
688 | Node 0, zone DMA 2 0 5 1 0 | |
689 | Node 0, zone DMA32 41 6 967 2 0 | |
690 | ||
691 | Fragmentation avoidance in the kernel works by grouping pages of different | |
692 | migrate types into the same contiguous regions of memory called page blocks. | |
693 | A page block is typically the size of the default hugepage size e.g. 2MB on | |
694 | X86-64. By keeping pages grouped based on their ability to move, the kernel | |
695 | can reclaim pages within a page block to satisfy a high-order allocation. | |
696 | ||
697 | The pagetypinfo begins with information on the size of a page block. It | |
698 | then gives the same type of information as buddyinfo except broken down | |
699 | by migrate-type and finishes with details on how many page blocks of each | |
700 | type exist. | |
701 | ||
702 | If min_free_kbytes has been tuned correctly (recommendations made by hugeadm | |
703 | from libhugetlbfs http://sourceforge.net/projects/libhugetlbfs/), one can | |
704 | make an estimate of the likely number of huge pages that can be allocated | |
705 | at a given point in time. All the "Movable" blocks should be allocatable | |
706 | unless memory has been mlock()'d. Some of the Reclaimable blocks should | |
707 | also be allocatable although a lot of filesystem metadata may have to be | |
708 | reclaimed to achieve this. | |
709 | ||
1da177e4 LT |
710 | .............................................................................. |
711 | ||
712 | meminfo: | |
713 | ||
714 | Provides information about distribution and utilization of memory. This | |
715 | varies by architecture and compile options. The following is from a | |
716 | 16GB PIII, which has highmem enabled. You may not have all of these fields. | |
717 | ||
718 | > cat /proc/meminfo | |
719 | ||
2d90508f NK |
720 | The "Locked" indicates whether the mapping is locked in memory or not. |
721 | ||
1da177e4 LT |
722 | |
723 | MemTotal: 16344972 kB | |
724 | MemFree: 13634064 kB | |
725 | Buffers: 3656 kB | |
726 | Cached: 1195708 kB | |
727 | SwapCached: 0 kB | |
728 | Active: 891636 kB | |
729 | Inactive: 1077224 kB | |
730 | HighTotal: 15597528 kB | |
731 | HighFree: 13629632 kB | |
732 | LowTotal: 747444 kB | |
733 | LowFree: 4432 kB | |
734 | SwapTotal: 0 kB | |
735 | SwapFree: 0 kB | |
736 | Dirty: 968 kB | |
737 | Writeback: 0 kB | |
b88473f7 | 738 | AnonPages: 861800 kB |
1da177e4 | 739 | Mapped: 280372 kB |
b88473f7 MS |
740 | Slab: 284364 kB |
741 | SReclaimable: 159856 kB | |
742 | SUnreclaim: 124508 kB | |
743 | PageTables: 24448 kB | |
744 | NFS_Unstable: 0 kB | |
745 | Bounce: 0 kB | |
746 | WritebackTmp: 0 kB | |
1da177e4 LT |
747 | CommitLimit: 7669796 kB |
748 | Committed_AS: 100056 kB | |
1da177e4 LT |
749 | VmallocTotal: 112216 kB |
750 | VmallocUsed: 428 kB | |
751 | VmallocChunk: 111088 kB | |
69256994 | 752 | AnonHugePages: 49152 kB |
1da177e4 LT |
753 | |
754 | MemTotal: Total usable ram (i.e. physical ram minus a few reserved | |
755 | bits and the kernel binary code) | |
756 | MemFree: The sum of LowFree+HighFree | |
757 | Buffers: Relatively temporary storage for raw disk blocks | |
758 | shouldn't get tremendously large (20MB or so) | |
759 | Cached: in-memory cache for files read from the disk (the | |
760 | pagecache). Doesn't include SwapCached | |
761 | SwapCached: Memory that once was swapped out, is swapped back in but | |
762 | still also is in the swapfile (if memory is needed it | |
763 | doesn't need to be swapped out AGAIN because it is already | |
764 | in the swapfile. This saves I/O) | |
765 | Active: Memory that has been used more recently and usually not | |
766 | reclaimed unless absolutely necessary. | |
767 | Inactive: Memory which has been less recently used. It is more | |
768 | eligible to be reclaimed for other purposes | |
769 | HighTotal: | |
770 | HighFree: Highmem is all memory above ~860MB of physical memory | |
771 | Highmem areas are for use by userspace programs, or | |
772 | for the pagecache. The kernel must use tricks to access | |
773 | this memory, making it slower to access than lowmem. | |
774 | LowTotal: | |
775 | LowFree: Lowmem is memory which can be used for everything that | |
3f6dee9b | 776 | highmem can be used for, but it is also available for the |
1da177e4 LT |
777 | kernel's use for its own data structures. Among many |
778 | other things, it is where everything from the Slab is | |
779 | allocated. Bad things happen when you're out of lowmem. | |
780 | SwapTotal: total amount of swap space available | |
781 | SwapFree: Memory which has been evicted from RAM, and is temporarily | |
782 | on the disk | |
783 | Dirty: Memory which is waiting to get written back to the disk | |
784 | Writeback: Memory which is actively being written back to the disk | |
b88473f7 | 785 | AnonPages: Non-file backed pages mapped into userspace page tables |
69256994 | 786 | AnonHugePages: Non-file backed huge pages mapped into userspace page tables |
1da177e4 | 787 | Mapped: files which have been mmaped, such as libraries |
e82443c0 | 788 | Slab: in-kernel data structures cache |
b88473f7 MS |
789 | SReclaimable: Part of Slab, that might be reclaimed, such as caches |
790 | SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure | |
791 | PageTables: amount of memory dedicated to the lowest level of page | |
792 | tables. | |
793 | NFS_Unstable: NFS pages sent to the server, but not yet committed to stable | |
794 | storage | |
795 | Bounce: Memory used for block device "bounce buffers" | |
796 | WritebackTmp: Memory used by FUSE for temporary writeback buffers | |
1da177e4 LT |
797 | CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'), |
798 | this is the total amount of memory currently available to | |
799 | be allocated on the system. This limit is only adhered to | |
800 | if strict overcommit accounting is enabled (mode 2 in | |
801 | 'vm.overcommit_memory'). | |
802 | The CommitLimit is calculated with the following formula: | |
803 | CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap | |
804 | For example, on a system with 1G of physical RAM and 7G | |
805 | of swap with a `vm.overcommit_ratio` of 30 it would | |
806 | yield a CommitLimit of 7.3G. | |
807 | For more details, see the memory overcommit documentation | |
808 | in vm/overcommit-accounting. | |
809 | Committed_AS: The amount of memory presently allocated on the system. | |
810 | The committed memory is a sum of all of the memory which | |
811 | has been allocated by processes, even if it has not been | |
812 | "used" by them as of yet. A process which malloc()'s 1G | |
813 | of memory, but only touches 300M of it will only show up | |
814 | as using 300M of memory even if it has the address space | |
815 | allocated for the entire 1G. This 1G is memory which has | |
816 | been "committed" to by the VM and can be used at any time | |
817 | by the allocating application. With strict overcommit | |
818 | enabled on the system (mode 2 in 'vm.overcommit_memory'), | |
819 | allocations which would exceed the CommitLimit (detailed | |
820 | above) will not be permitted. This is useful if one needs | |
821 | to guarantee that processes will not fail due to lack of | |
822 | memory once that memory has been successfully allocated. | |
1da177e4 LT |
823 | VmallocTotal: total size of vmalloc memory area |
824 | VmallocUsed: amount of vmalloc area which is used | |
19f59460 | 825 | VmallocChunk: largest contiguous block of vmalloc area which is free |
1da177e4 | 826 | |
a47a126a ED |
827 | .............................................................................. |
828 | ||
829 | vmallocinfo: | |
830 | ||
831 | Provides information about vmalloced/vmaped areas. One line per area, | |
832 | containing the virtual address range of the area, size in bytes, | |
833 | caller information of the creator, and optional information depending | |
834 | on the kind of area : | |
835 | ||
836 | pages=nr number of pages | |
837 | phys=addr if a physical address was specified | |
838 | ioremap I/O mapping (ioremap() and friends) | |
839 | vmalloc vmalloc() area | |
840 | vmap vmap()ed pages | |
841 | user VM_USERMAP area | |
842 | vpages buffer for pages pointers was vmalloced (huge area) | |
843 | N<node>=nr (Only on NUMA kernels) | |
844 | Number of pages allocated on memory node <node> | |
845 | ||
846 | > cat /proc/vmallocinfo | |
847 | 0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ... | |
848 | /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128 | |
849 | 0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ... | |
850 | /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64 | |
851 | 0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f... | |
852 | phys=7fee8000 ioremap | |
853 | 0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f... | |
854 | phys=7fee7000 ioremap | |
855 | 0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210 | |
856 | 0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ... | |
857 | /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3 | |
858 | 0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ... | |
859 | pages=2 vmalloc N1=2 | |
860 | 0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ... | |
861 | /0x130 [x_tables] pages=4 vmalloc N0=4 | |
862 | 0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ... | |
863 | pages=14 vmalloc N2=14 | |
864 | 0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ... | |
865 | pages=4 vmalloc N1=4 | |
866 | 0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ... | |
867 | pages=2 vmalloc N1=2 | |
868 | 0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ... | |
869 | pages=10 vmalloc N0=10 | |
1da177e4 | 870 | |
d3d64df2 KK |
871 | .............................................................................. |
872 | ||
873 | softirqs: | |
874 | ||
875 | Provides counts of softirq handlers serviced since boot time, for each cpu. | |
876 | ||
877 | > cat /proc/softirqs | |
878 | CPU0 CPU1 CPU2 CPU3 | |
879 | HI: 0 0 0 0 | |
880 | TIMER: 27166 27120 27097 27034 | |
881 | NET_TX: 0 0 0 17 | |
882 | NET_RX: 42 0 0 39 | |
883 | BLOCK: 0 0 107 1121 | |
884 | TASKLET: 0 0 0 290 | |
885 | SCHED: 27035 26983 26971 26746 | |
886 | HRTIMER: 0 0 0 0 | |
09223371 | 887 | RCU: 1678 1769 2178 2250 |
d3d64df2 KK |
888 | |
889 | ||
1da177e4 LT |
890 | 1.3 IDE devices in /proc/ide |
891 | ---------------------------- | |
892 | ||
893 | The subdirectory /proc/ide contains information about all IDE devices of which | |
894 | the kernel is aware. There is one subdirectory for each IDE controller, the | |
895 | file drivers and a link for each IDE device, pointing to the device directory | |
896 | in the controller specific subtree. | |
897 | ||
898 | The file drivers contains general information about the drivers used for the | |
899 | IDE devices: | |
900 | ||
901 | > cat /proc/ide/drivers | |
902 | ide-cdrom version 4.53 | |
903 | ide-disk version 1.08 | |
904 | ||
905 | More detailed information can be found in the controller specific | |
906 | subdirectories. These are named ide0, ide1 and so on. Each of these | |
349888ee | 907 | directories contains the files shown in table 1-6. |
1da177e4 LT |
908 | |
909 | ||
349888ee | 910 | Table 1-6: IDE controller info in /proc/ide/ide? |
1da177e4 LT |
911 | .............................................................................. |
912 | File Content | |
913 | channel IDE channel (0 or 1) | |
914 | config Configuration (only for PCI/IDE bridge) | |
915 | mate Mate name | |
916 | model Type/Chipset of IDE controller | |
917 | .............................................................................. | |
918 | ||
919 | Each device connected to a controller has a separate subdirectory in the | |
349888ee | 920 | controllers directory. The files listed in table 1-7 are contained in these |
1da177e4 LT |
921 | directories. |
922 | ||
923 | ||
349888ee | 924 | Table 1-7: IDE device information |
1da177e4 LT |
925 | .............................................................................. |
926 | File Content | |
927 | cache The cache | |
928 | capacity Capacity of the medium (in 512Byte blocks) | |
929 | driver driver and version | |
930 | geometry physical and logical geometry | |
931 | identify device identify block | |
932 | media media type | |
933 | model device identifier | |
934 | settings device setup | |
935 | smart_thresholds IDE disk management thresholds | |
936 | smart_values IDE disk management values | |
937 | .............................................................................. | |
938 | ||
939 | The most interesting file is settings. This file contains a nice overview of | |
940 | the drive parameters: | |
941 | ||
942 | # cat /proc/ide/ide0/hda/settings | |
943 | name value min max mode | |
944 | ---- ----- --- --- ---- | |
945 | bios_cyl 526 0 65535 rw | |
946 | bios_head 255 0 255 rw | |
947 | bios_sect 63 0 63 rw | |
948 | breada_readahead 4 0 127 rw | |
949 | bswap 0 0 1 r | |
950 | file_readahead 72 0 2097151 rw | |
951 | io_32bit 0 0 3 rw | |
952 | keepsettings 0 0 1 rw | |
953 | max_kb_per_request 122 1 127 rw | |
954 | multcount 0 0 8 rw | |
955 | nice1 1 0 1 rw | |
956 | nowerr 0 0 1 rw | |
957 | pio_mode write-only 0 255 w | |
958 | slow 0 0 1 rw | |
959 | unmaskirq 0 0 1 rw | |
960 | using_dma 0 0 1 rw | |
961 | ||
962 | ||
963 | 1.4 Networking info in /proc/net | |
964 | -------------------------------- | |
965 | ||
349888ee | 966 | The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the |
1da177e4 | 967 | additional values you get for IP version 6 if you configure the kernel to |
349888ee | 968 | support this. Table 1-9 lists the files and their meaning. |
1da177e4 LT |
969 | |
970 | ||
349888ee | 971 | Table 1-8: IPv6 info in /proc/net |
1da177e4 LT |
972 | .............................................................................. |
973 | File Content | |
974 | udp6 UDP sockets (IPv6) | |
975 | tcp6 TCP sockets (IPv6) | |
976 | raw6 Raw device statistics (IPv6) | |
977 | igmp6 IP multicast addresses, which this host joined (IPv6) | |
978 | if_inet6 List of IPv6 interface addresses | |
979 | ipv6_route Kernel routing table for IPv6 | |
980 | rt6_stats Global IPv6 routing tables statistics | |
981 | sockstat6 Socket statistics (IPv6) | |
982 | snmp6 Snmp data (IPv6) | |
983 | .............................................................................. | |
984 | ||
985 | ||
349888ee | 986 | Table 1-9: Network info in /proc/net |
1da177e4 LT |
987 | .............................................................................. |
988 | File Content | |
989 | arp Kernel ARP table | |
990 | dev network devices with statistics | |
991 | dev_mcast the Layer2 multicast groups a device is listening too | |
992 | (interface index, label, number of references, number of bound | |
993 | addresses). | |
994 | dev_stat network device status | |
995 | ip_fwchains Firewall chain linkage | |
996 | ip_fwnames Firewall chain names | |
997 | ip_masq Directory containing the masquerading tables | |
998 | ip_masquerade Major masquerading table | |
999 | netstat Network statistics | |
1000 | raw raw device statistics | |
1001 | route Kernel routing table | |
1002 | rpc Directory containing rpc info | |
1003 | rt_cache Routing cache | |
1004 | snmp SNMP data | |
1005 | sockstat Socket statistics | |
1006 | tcp TCP sockets | |
1da177e4 LT |
1007 | udp UDP sockets |
1008 | unix UNIX domain sockets | |
1009 | wireless Wireless interface data (Wavelan etc) | |
1010 | igmp IP multicast addresses, which this host joined | |
1011 | psched Global packet scheduler parameters. | |
1012 | netlink List of PF_NETLINK sockets | |
1013 | ip_mr_vifs List of multicast virtual interfaces | |
1014 | ip_mr_cache List of multicast routing cache | |
1015 | .............................................................................. | |
1016 | ||
1017 | You can use this information to see which network devices are available in | |
1018 | your system and how much traffic was routed over those devices: | |
1019 | ||
1020 | > cat /proc/net/dev | |
1021 | Inter-|Receive |[... | |
1022 | face |bytes packets errs drop fifo frame compressed multicast|[... | |
1023 | lo: 908188 5596 0 0 0 0 0 0 [... | |
1024 | ppp0:15475140 20721 410 0 0 410 0 0 [... | |
1025 | eth0: 614530 7085 0 0 0 0 0 1 [... | |
1026 | ||
1027 | ...] Transmit | |
1028 | ...] bytes packets errs drop fifo colls carrier compressed | |
1029 | ...] 908188 5596 0 0 0 0 0 0 | |
1030 | ...] 1375103 17405 0 0 0 0 0 0 | |
1031 | ...] 1703981 5535 0 0 0 3 0 0 | |
1032 | ||
a33f3224 | 1033 | In addition, each Channel Bond interface has its own directory. For |
1da177e4 LT |
1034 | example, the bond0 device will have a directory called /proc/net/bond0/. |
1035 | It will contain information that is specific to that bond, such as the | |
1036 | current slaves of the bond, the link status of the slaves, and how | |
1037 | many times the slaves link has failed. | |
1038 | ||
1039 | 1.5 SCSI info | |
1040 | ------------- | |
1041 | ||
1042 | If you have a SCSI host adapter in your system, you'll find a subdirectory | |
1043 | named after the driver for this adapter in /proc/scsi. You'll also see a list | |
1044 | of all recognized SCSI devices in /proc/scsi: | |
1045 | ||
1046 | >cat /proc/scsi/scsi | |
1047 | Attached devices: | |
1048 | Host: scsi0 Channel: 00 Id: 00 Lun: 00 | |
1049 | Vendor: IBM Model: DGHS09U Rev: 03E0 | |
1050 | Type: Direct-Access ANSI SCSI revision: 03 | |
1051 | Host: scsi0 Channel: 00 Id: 06 Lun: 00 | |
1052 | Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04 | |
1053 | Type: CD-ROM ANSI SCSI revision: 02 | |
1054 | ||
1055 | ||
1056 | The directory named after the driver has one file for each adapter found in | |
1057 | the system. These files contain information about the controller, including | |
1058 | the used IRQ and the IO address range. The amount of information shown is | |
1059 | dependent on the adapter you use. The example shows the output for an Adaptec | |
1060 | AHA-2940 SCSI adapter: | |
1061 | ||
1062 | > cat /proc/scsi/aic7xxx/0 | |
1063 | ||
1064 | Adaptec AIC7xxx driver version: 5.1.19/3.2.4 | |
1065 | Compile Options: | |
1066 | TCQ Enabled By Default : Disabled | |
1067 | AIC7XXX_PROC_STATS : Disabled | |
1068 | AIC7XXX_RESET_DELAY : 5 | |
1069 | Adapter Configuration: | |
1070 | SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter | |
1071 | Ultra Wide Controller | |
1072 | PCI MMAPed I/O Base: 0xeb001000 | |
1073 | Adapter SEEPROM Config: SEEPROM found and used. | |
1074 | Adaptec SCSI BIOS: Enabled | |
1075 | IRQ: 10 | |
1076 | SCBs: Active 0, Max Active 2, | |
1077 | Allocated 15, HW 16, Page 255 | |
1078 | Interrupts: 160328 | |
1079 | BIOS Control Word: 0x18b6 | |
1080 | Adapter Control Word: 0x005b | |
1081 | Extended Translation: Enabled | |
1082 | Disconnect Enable Flags: 0xffff | |
1083 | Ultra Enable Flags: 0x0001 | |
1084 | Tag Queue Enable Flags: 0x0000 | |
1085 | Ordered Queue Tag Flags: 0x0000 | |
1086 | Default Tag Queue Depth: 8 | |
1087 | Tagged Queue By Device array for aic7xxx host instance 0: | |
1088 | {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255} | |
1089 | Actual queue depth per device for aic7xxx host instance 0: | |
1090 | {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1} | |
1091 | Statistics: | |
1092 | (scsi0:0:0:0) | |
1093 | Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8 | |
1094 | Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0) | |
1095 | Total transfers 160151 (74577 reads and 85574 writes) | |
1096 | (scsi0:0:6:0) | |
1097 | Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15 | |
1098 | Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0) | |
1099 | Total transfers 0 (0 reads and 0 writes) | |
1100 | ||
1101 | ||
1102 | 1.6 Parallel port info in /proc/parport | |
1103 | --------------------------------------- | |
1104 | ||
1105 | The directory /proc/parport contains information about the parallel ports of | |
1106 | your system. It has one subdirectory for each port, named after the port | |
1107 | number (0,1,2,...). | |
1108 | ||
349888ee | 1109 | These directories contain the four files shown in Table 1-10. |
1da177e4 LT |
1110 | |
1111 | ||
349888ee | 1112 | Table 1-10: Files in /proc/parport |
1da177e4 LT |
1113 | .............................................................................. |
1114 | File Content | |
1115 | autoprobe Any IEEE-1284 device ID information that has been acquired. | |
1116 | devices list of the device drivers using that port. A + will appear by the | |
1117 | name of the device currently using the port (it might not appear | |
1118 | against any). | |
1119 | hardware Parallel port's base address, IRQ line and DMA channel. | |
1120 | irq IRQ that parport is using for that port. This is in a separate | |
1121 | file to allow you to alter it by writing a new value in (IRQ | |
1122 | number or none). | |
1123 | .............................................................................. | |
1124 | ||
1125 | 1.7 TTY info in /proc/tty | |
1126 | ------------------------- | |
1127 | ||
1128 | Information about the available and actually used tty's can be found in the | |
1129 | directory /proc/tty.You'll find entries for drivers and line disciplines in | |
349888ee | 1130 | this directory, as shown in Table 1-11. |
1da177e4 LT |
1131 | |
1132 | ||
349888ee | 1133 | Table 1-11: Files in /proc/tty |
1da177e4 LT |
1134 | .............................................................................. |
1135 | File Content | |
1136 | drivers list of drivers and their usage | |
1137 | ldiscs registered line disciplines | |
1138 | driver/serial usage statistic and status of single tty lines | |
1139 | .............................................................................. | |
1140 | ||
1141 | To see which tty's are currently in use, you can simply look into the file | |
1142 | /proc/tty/drivers: | |
1143 | ||
1144 | > cat /proc/tty/drivers | |
1145 | pty_slave /dev/pts 136 0-255 pty:slave | |
1146 | pty_master /dev/ptm 128 0-255 pty:master | |
1147 | pty_slave /dev/ttyp 3 0-255 pty:slave | |
1148 | pty_master /dev/pty 2 0-255 pty:master | |
1149 | serial /dev/cua 5 64-67 serial:callout | |
1150 | serial /dev/ttyS 4 64-67 serial | |
1151 | /dev/tty0 /dev/tty0 4 0 system:vtmaster | |
1152 | /dev/ptmx /dev/ptmx 5 2 system | |
1153 | /dev/console /dev/console 5 1 system:console | |
1154 | /dev/tty /dev/tty 5 0 system:/dev/tty | |
1155 | unknown /dev/tty 4 1-63 console | |
1156 | ||
1157 | ||
1158 | 1.8 Miscellaneous kernel statistics in /proc/stat | |
1159 | ------------------------------------------------- | |
1160 | ||
1161 | Various pieces of information about kernel activity are available in the | |
1162 | /proc/stat file. All of the numbers reported in this file are aggregates | |
1163 | since the system first booted. For a quick look, simply cat the file: | |
1164 | ||
1165 | > cat /proc/stat | |
c574358e ED |
1166 | cpu 2255 34 2290 22625563 6290 127 456 0 0 |
1167 | cpu0 1132 34 1441 11311718 3675 127 438 0 0 | |
1168 | cpu1 1123 0 849 11313845 2614 0 18 0 0 | |
1da177e4 LT |
1169 | intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...] |
1170 | ctxt 1990473 | |
1171 | btime 1062191376 | |
1172 | processes 2915 | |
1173 | procs_running 1 | |
1174 | procs_blocked 0 | |
d3d64df2 | 1175 | softirq 183433 0 21755 12 39 1137 231 21459 2263 |
1da177e4 LT |
1176 | |
1177 | The very first "cpu" line aggregates the numbers in all of the other "cpuN" | |
1178 | lines. These numbers identify the amount of time the CPU has spent performing | |
1179 | different kinds of work. Time units are in USER_HZ (typically hundredths of a | |
1180 | second). The meanings of the columns are as follows, from left to right: | |
1181 | ||
1182 | - user: normal processes executing in user mode | |
1183 | - nice: niced processes executing in user mode | |
1184 | - system: processes executing in kernel mode | |
1185 | - idle: twiddling thumbs | |
1186 | - iowait: waiting for I/O to complete | |
1187 | - irq: servicing interrupts | |
1188 | - softirq: servicing softirqs | |
b68f2c3a | 1189 | - steal: involuntary wait |
ce0e7b28 RO |
1190 | - guest: running a normal guest |
1191 | - guest_nice: running a niced guest | |
1da177e4 LT |
1192 | |
1193 | The "intr" line gives counts of interrupts serviced since boot time, for each | |
1194 | of the possible system interrupts. The first column is the total of all | |
1195 | interrupts serviced; each subsequent column is the total for that particular | |
1196 | interrupt. | |
1197 | ||
1198 | The "ctxt" line gives the total number of context switches across all CPUs. | |
1199 | ||
1200 | The "btime" line gives the time at which the system booted, in seconds since | |
1201 | the Unix epoch. | |
1202 | ||
1203 | The "processes" line gives the number of processes and threads created, which | |
1204 | includes (but is not limited to) those created by calls to the fork() and | |
1205 | clone() system calls. | |
1206 | ||
e3cc2226 LGE |
1207 | The "procs_running" line gives the total number of threads that are |
1208 | running or ready to run (i.e., the total number of runnable threads). | |
1da177e4 LT |
1209 | |
1210 | The "procs_blocked" line gives the number of processes currently blocked, | |
1211 | waiting for I/O to complete. | |
1212 | ||
d3d64df2 KK |
1213 | The "softirq" line gives counts of softirqs serviced since boot time, for each |
1214 | of the possible system softirqs. The first column is the total of all | |
1215 | softirqs serviced; each subsequent column is the total for that particular | |
1216 | softirq. | |
1217 | ||
37515fac | 1218 | |
c9de560d AT |
1219 | 1.9 Ext4 file system parameters |
1220 | ------------------------------ | |
37515fac TT |
1221 | |
1222 | Information about mounted ext4 file systems can be found in | |
1223 | /proc/fs/ext4. Each mounted filesystem will have a directory in | |
1224 | /proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or | |
1225 | /proc/fs/ext4/dm-0). The files in each per-device directory are shown | |
349888ee | 1226 | in Table 1-12, below. |
37515fac | 1227 | |
349888ee | 1228 | Table 1-12: Files in /proc/fs/ext4/<devname> |
37515fac TT |
1229 | .............................................................................. |
1230 | File Content | |
1231 | mb_groups details of multiblock allocator buddy cache of free blocks | |
37515fac TT |
1232 | .............................................................................. |
1233 | ||
23308ba5 JS |
1234 | 2.0 /proc/consoles |
1235 | ------------------ | |
1236 | Shows registered system console lines. | |
1237 | ||
1238 | To see which character device lines are currently used for the system console | |
1239 | /dev/console, you may simply look into the file /proc/consoles: | |
1240 | ||
1241 | > cat /proc/consoles | |
1242 | tty0 -WU (ECp) 4:7 | |
1243 | ttyS0 -W- (Ep) 4:64 | |
1244 | ||
1245 | The columns are: | |
1246 | ||
1247 | device name of the device | |
1248 | operations R = can do read operations | |
1249 | W = can do write operations | |
1250 | U = can do unblank | |
1251 | flags E = it is enabled | |
25985edc | 1252 | C = it is preferred console |
23308ba5 JS |
1253 | B = it is primary boot console |
1254 | p = it is used for printk buffer | |
1255 | b = it is not a TTY but a Braille device | |
1256 | a = it is safe to use when cpu is offline | |
1257 | major:minor major and minor number of the device separated by a colon | |
1da177e4 LT |
1258 | |
1259 | ------------------------------------------------------------------------------ | |
1260 | Summary | |
1261 | ------------------------------------------------------------------------------ | |
1262 | The /proc file system serves information about the running system. It not only | |
1263 | allows access to process data but also allows you to request the kernel status | |
1264 | by reading files in the hierarchy. | |
1265 | ||
1266 | The directory structure of /proc reflects the types of information and makes | |
1267 | it easy, if not obvious, where to look for specific data. | |
1268 | ------------------------------------------------------------------------------ | |
1269 | ||
1270 | ------------------------------------------------------------------------------ | |
1271 | CHAPTER 2: MODIFYING SYSTEM PARAMETERS | |
1272 | ------------------------------------------------------------------------------ | |
1273 | ||
1274 | ------------------------------------------------------------------------------ | |
1275 | In This Chapter | |
1276 | ------------------------------------------------------------------------------ | |
1277 | * Modifying kernel parameters by writing into files found in /proc/sys | |
1278 | * Exploring the files which modify certain parameters | |
1279 | * Review of the /proc/sys file tree | |
1280 | ------------------------------------------------------------------------------ | |
1281 | ||
1282 | ||
1283 | A very interesting part of /proc is the directory /proc/sys. This is not only | |
1284 | a source of information, it also allows you to change parameters within the | |
1285 | kernel. Be very careful when attempting this. You can optimize your system, | |
1286 | but you can also cause it to crash. Never alter kernel parameters on a | |
1287 | production system. Set up a development machine and test to make sure that | |
1288 | everything works the way you want it to. You may have no alternative but to | |
1289 | reboot the machine once an error has been made. | |
1290 | ||
1291 | To change a value, simply echo the new value into the file. An example is | |
1292 | given below in the section on the file system data. You need to be root to do | |
1293 | this. You can create your own boot script to perform this every time your | |
1294 | system boots. | |
1295 | ||
1296 | The files in /proc/sys can be used to fine tune and monitor miscellaneous and | |
1297 | general things in the operation of the Linux kernel. Since some of the files | |
1298 | can inadvertently disrupt your system, it is advisable to read both | |
1299 | documentation and source before actually making adjustments. In any case, be | |
1300 | very careful when writing to any of these files. The entries in /proc may | |
1301 | change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt | |
1302 | review the kernel documentation in the directory /usr/src/linux/Documentation. | |
1303 | This chapter is heavily based on the documentation included in the pre 2.2 | |
1304 | kernels, and became part of it in version 2.2.1 of the Linux kernel. | |
1305 | ||
395cf969 | 1306 | Please see: Documentation/sysctl/ directory for descriptions of these |
db0fb184 | 1307 | entries. |
9d0243bc | 1308 | |
760df93e SF |
1309 | ------------------------------------------------------------------------------ |
1310 | Summary | |
1311 | ------------------------------------------------------------------------------ | |
1312 | Certain aspects of kernel behavior can be modified at runtime, without the | |
1313 | need to recompile the kernel, or even to reboot the system. The files in the | |
1314 | /proc/sys tree can not only be read, but also modified. You can use the echo | |
1315 | command to write value into these files, thereby changing the default settings | |
1316 | of the kernel. | |
1317 | ------------------------------------------------------------------------------ | |
9d0243bc | 1318 | |
760df93e SF |
1319 | ------------------------------------------------------------------------------ |
1320 | CHAPTER 3: PER-PROCESS PARAMETERS | |
1321 | ------------------------------------------------------------------------------ | |
1da177e4 | 1322 | |
a63d83f4 DR |
1323 | 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score |
1324 | -------------------------------------------------------------------------------- | |
1325 | ||
1326 | These file can be used to adjust the badness heuristic used to select which | |
1327 | process gets killed in out of memory conditions. | |
1328 | ||
1329 | The badness heuristic assigns a value to each candidate task ranging from 0 | |
1330 | (never kill) to 1000 (always kill) to determine which process is targeted. The | |
1331 | units are roughly a proportion along that range of allowed memory the process | |
1332 | may allocate from based on an estimation of its current memory and swap use. | |
1333 | For example, if a task is using all allowed memory, its badness score will be | |
1334 | 1000. If it is using half of its allowed memory, its score will be 500. | |
1335 | ||
1336 | There is an additional factor included in the badness score: root | |
1337 | processes are given 3% extra memory over other tasks. | |
1338 | ||
1339 | The amount of "allowed" memory depends on the context in which the oom killer | |
1340 | was called. If it is due to the memory assigned to the allocating task's cpuset | |
1341 | being exhausted, the allowed memory represents the set of mems assigned to that | |
1342 | cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed | |
1343 | memory represents the set of mempolicy nodes. If it is due to a memory | |
1344 | limit (or swap limit) being reached, the allowed memory is that configured | |
1345 | limit. Finally, if it is due to the entire system being out of memory, the | |
1346 | allowed memory represents all allocatable resources. | |
1347 | ||
1348 | The value of /proc/<pid>/oom_score_adj is added to the badness score before it | |
1349 | is used to determine which task to kill. Acceptable values range from -1000 | |
1350 | (OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to | |
1351 | polarize the preference for oom killing either by always preferring a certain | |
1352 | task or completely disabling it. The lowest possible value, -1000, is | |
1353 | equivalent to disabling oom killing entirely for that task since it will always | |
1354 | report a badness score of 0. | |
1355 | ||
1356 | Consequently, it is very simple for userspace to define the amount of memory to | |
1357 | consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for | |
1358 | example, is roughly equivalent to allowing the remainder of tasks sharing the | |
1359 | same system, cpuset, mempolicy, or memory controller resources to use at least | |
1360 | 50% more memory. A value of -500, on the other hand, would be roughly | |
1361 | equivalent to discounting 50% of the task's allowed memory from being considered | |
1362 | as scoring against the task. | |
1363 | ||
1364 | For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also | |
1365 | be used to tune the badness score. Its acceptable values range from -16 | |
1366 | (OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17 | |
1367 | (OOM_DISABLE) to disable oom killing entirely for that task. Its value is | |
1368 | scaled linearly with /proc/<pid>/oom_score_adj. | |
1369 | ||
1370 | Writing to /proc/<pid>/oom_score_adj or /proc/<pid>/oom_adj will change the | |
1371 | other with its scaled value. | |
1372 | ||
dabb16f6 MSB |
1373 | The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last |
1374 | value set by a CAP_SYS_RESOURCE process. To reduce the value any lower | |
1375 | requires CAP_SYS_RESOURCE. | |
1376 | ||
51b1bd2a DR |
1377 | NOTICE: /proc/<pid>/oom_adj is deprecated and will be removed, please see |
1378 | Documentation/feature-removal-schedule.txt. | |
1379 | ||
a63d83f4 | 1380 | Caveat: when a parent task is selected, the oom killer will sacrifice any first |
25985edc | 1381 | generation children with separate address spaces instead, if possible. This |
a63d83f4 DR |
1382 | avoids servers and important system daemons from being killed and loses the |
1383 | minimal amount of work. | |
1384 | ||
9e9e3cbc | 1385 | |
760df93e | 1386 | 3.2 /proc/<pid>/oom_score - Display current oom-killer score |
d7ff0dbf JFM |
1387 | ------------------------------------------------------------- |
1388 | ||
d7ff0dbf JFM |
1389 | This file can be used to check the current score used by the oom-killer is for |
1390 | any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which | |
1391 | process should be killed in an out-of-memory situation. | |
1da177e4 | 1392 | |
f9c99463 | 1393 | |
760df93e | 1394 | 3.3 /proc/<pid>/io - Display the IO accounting fields |
f9c99463 RK |
1395 | ------------------------------------------------------- |
1396 | ||
1397 | This file contains IO statistics for each running process | |
1398 | ||
1399 | Example | |
1400 | ------- | |
1401 | ||
1402 | test:/tmp # dd if=/dev/zero of=/tmp/test.dat & | |
1403 | [1] 3828 | |
1404 | ||
1405 | test:/tmp # cat /proc/3828/io | |
1406 | rchar: 323934931 | |
1407 | wchar: 323929600 | |
1408 | syscr: 632687 | |
1409 | syscw: 632675 | |
1410 | read_bytes: 0 | |
1411 | write_bytes: 323932160 | |
1412 | cancelled_write_bytes: 0 | |
1413 | ||
1414 | ||
1415 | Description | |
1416 | ----------- | |
1417 | ||
1418 | rchar | |
1419 | ----- | |
1420 | ||
1421 | I/O counter: chars read | |
1422 | The number of bytes which this task has caused to be read from storage. This | |
1423 | is simply the sum of bytes which this process passed to read() and pread(). | |
1424 | It includes things like tty IO and it is unaffected by whether or not actual | |
1425 | physical disk IO was required (the read might have been satisfied from | |
1426 | pagecache) | |
1427 | ||
1428 | ||
1429 | wchar | |
1430 | ----- | |
1431 | ||
1432 | I/O counter: chars written | |
1433 | The number of bytes which this task has caused, or shall cause to be written | |
1434 | to disk. Similar caveats apply here as with rchar. | |
1435 | ||
1436 | ||
1437 | syscr | |
1438 | ----- | |
1439 | ||
1440 | I/O counter: read syscalls | |
1441 | Attempt to count the number of read I/O operations, i.e. syscalls like read() | |
1442 | and pread(). | |
1443 | ||
1444 | ||
1445 | syscw | |
1446 | ----- | |
1447 | ||
1448 | I/O counter: write syscalls | |
1449 | Attempt to count the number of write I/O operations, i.e. syscalls like | |
1450 | write() and pwrite(). | |
1451 | ||
1452 | ||
1453 | read_bytes | |
1454 | ---------- | |
1455 | ||
1456 | I/O counter: bytes read | |
1457 | Attempt to count the number of bytes which this process really did cause to | |
1458 | be fetched from the storage layer. Done at the submit_bio() level, so it is | |
1459 | accurate for block-backed filesystems. <please add status regarding NFS and | |
1460 | CIFS at a later time> | |
1461 | ||
1462 | ||
1463 | write_bytes | |
1464 | ----------- | |
1465 | ||
1466 | I/O counter: bytes written | |
1467 | Attempt to count the number of bytes which this process caused to be sent to | |
1468 | the storage layer. This is done at page-dirtying time. | |
1469 | ||
1470 | ||
1471 | cancelled_write_bytes | |
1472 | --------------------- | |
1473 | ||
1474 | The big inaccuracy here is truncate. If a process writes 1MB to a file and | |
1475 | then deletes the file, it will in fact perform no writeout. But it will have | |
1476 | been accounted as having caused 1MB of write. | |
1477 | In other words: The number of bytes which this process caused to not happen, | |
1478 | by truncating pagecache. A task can cause "negative" IO too. If this task | |
1479 | truncates some dirty pagecache, some IO which another task has been accounted | |
a33f3224 | 1480 | for (in its write_bytes) will not be happening. We _could_ just subtract that |
f9c99463 RK |
1481 | from the truncating task's write_bytes, but there is information loss in doing |
1482 | that. | |
1483 | ||
1484 | ||
1485 | Note | |
1486 | ---- | |
1487 | ||
1488 | At its current implementation state, this is a bit racy on 32-bit machines: if | |
1489 | process A reads process B's /proc/pid/io while process B is updating one of | |
1490 | those 64-bit counters, process A could see an intermediate result. | |
1491 | ||
1492 | ||
1493 | More information about this can be found within the taskstats documentation in | |
1494 | Documentation/accounting. | |
1495 | ||
760df93e | 1496 | 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings |
bb90110d KH |
1497 | --------------------------------------------------------------- |
1498 | When a process is dumped, all anonymous memory is written to a core file as | |
1499 | long as the size of the core file isn't limited. But sometimes we don't want | |
1500 | to dump some memory segments, for example, huge shared memory. Conversely, | |
1501 | sometimes we want to save file-backed memory segments into a core file, not | |
1502 | only the individual files. | |
1503 | ||
1504 | /proc/<pid>/coredump_filter allows you to customize which memory segments | |
1505 | will be dumped when the <pid> process is dumped. coredump_filter is a bitmask | |
1506 | of memory types. If a bit of the bitmask is set, memory segments of the | |
1507 | corresponding memory type are dumped, otherwise they are not dumped. | |
1508 | ||
e575f111 | 1509 | The following 7 memory types are supported: |
bb90110d KH |
1510 | - (bit 0) anonymous private memory |
1511 | - (bit 1) anonymous shared memory | |
1512 | - (bit 2) file-backed private memory | |
1513 | - (bit 3) file-backed shared memory | |
b261dfea HK |
1514 | - (bit 4) ELF header pages in file-backed private memory areas (it is |
1515 | effective only if the bit 2 is cleared) | |
e575f111 KM |
1516 | - (bit 5) hugetlb private memory |
1517 | - (bit 6) hugetlb shared memory | |
bb90110d KH |
1518 | |
1519 | Note that MMIO pages such as frame buffer are never dumped and vDSO pages | |
1520 | are always dumped regardless of the bitmask status. | |
1521 | ||
e575f111 KM |
1522 | Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only |
1523 | effected by bit 5-6. | |
1524 | ||
1525 | Default value of coredump_filter is 0x23; this means all anonymous memory | |
1526 | segments and hugetlb private memory are dumped. | |
bb90110d KH |
1527 | |
1528 | If you don't want to dump all shared memory segments attached to pid 1234, | |
e575f111 | 1529 | write 0x21 to the process's proc file. |
bb90110d | 1530 | |
e575f111 | 1531 | $ echo 0x21 > /proc/1234/coredump_filter |
bb90110d KH |
1532 | |
1533 | When a new process is created, the process inherits the bitmask status from its | |
1534 | parent. It is useful to set up coredump_filter before the program runs. | |
1535 | For example: | |
1536 | ||
1537 | $ echo 0x7 > /proc/self/coredump_filter | |
1538 | $ ./some_program | |
1539 | ||
760df93e | 1540 | 3.5 /proc/<pid>/mountinfo - Information about mounts |
2d4d4864 RP |
1541 | -------------------------------------------------------- |
1542 | ||
1543 | This file contains lines of the form: | |
1544 | ||
1545 | 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue | |
1546 | (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) | |
1547 | ||
1548 | (1) mount ID: unique identifier of the mount (may be reused after umount) | |
1549 | (2) parent ID: ID of parent (or of self for the top of the mount tree) | |
1550 | (3) major:minor: value of st_dev for files on filesystem | |
1551 | (4) root: root of the mount within the filesystem | |
1552 | (5) mount point: mount point relative to the process's root | |
1553 | (6) mount options: per mount options | |
1554 | (7) optional fields: zero or more fields of the form "tag[:value]" | |
1555 | (8) separator: marks the end of the optional fields | |
1556 | (9) filesystem type: name of filesystem of the form "type[.subtype]" | |
1557 | (10) mount source: filesystem specific information or "none" | |
1558 | (11) super options: per super block options | |
1559 | ||
1560 | Parsers should ignore all unrecognised optional fields. Currently the | |
1561 | possible optional fields are: | |
1562 | ||
1563 | shared:X mount is shared in peer group X | |
1564 | master:X mount is slave to peer group X | |
97e7e0f7 | 1565 | propagate_from:X mount is slave and receives propagation from peer group X (*) |
2d4d4864 RP |
1566 | unbindable mount is unbindable |
1567 | ||
97e7e0f7 MS |
1568 | (*) X is the closest dominant peer group under the process's root. If |
1569 | X is the immediate master of the mount, or if there's no dominant peer | |
1570 | group under the same root, then only the "master:X" field is present | |
1571 | and not the "propagate_from:X" field. | |
1572 | ||
2d4d4864 RP |
1573 | For more information on mount propagation see: |
1574 | ||
1575 | Documentation/filesystems/sharedsubtree.txt | |
1576 | ||
4614a696 | 1577 | |
1578 | 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm | |
1579 | -------------------------------------------------------- | |
1580 | These files provide a method to access a tasks comm value. It also allows for | |
1581 | a task to set its own or one of its thread siblings comm value. The comm value | |
1582 | is limited in size compared to the cmdline value, so writing anything longer | |
1583 | then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated | |
1584 | comm value. | |
0499680a VK |
1585 | |
1586 | ||
81841161 CG |
1587 | 3.7 /proc/<pid>/task/<tid>/children - Information about task children |
1588 | ------------------------------------------------------------------------- | |
1589 | This file provides a fast way to retrieve first level children pids | |
1590 | of a task pointed by <pid>/<tid> pair. The format is a space separated | |
1591 | stream of pids. | |
1592 | ||
1593 | Note the "first level" here -- if a child has own children they will | |
1594 | not be listed here, one needs to read /proc/<children-pid>/task/<tid>/children | |
1595 | to obtain the descendants. | |
1596 | ||
1597 | Since this interface is intended to be fast and cheap it doesn't | |
1598 | guarantee to provide precise results and some children might be | |
1599 | skipped, especially if they've exited right after we printed their | |
1600 | pids, so one need to either stop or freeze processes being inspected | |
1601 | if precise results are needed. | |
1602 | ||
1603 | ||
0499680a VK |
1604 | ------------------------------------------------------------------------------ |
1605 | Configuring procfs | |
1606 | ------------------------------------------------------------------------------ | |
1607 | ||
1608 | 4.1 Mount options | |
1609 | --------------------- | |
1610 | ||
1611 | The following mount options are supported: | |
1612 | ||
1613 | hidepid= Set /proc/<pid>/ access mode. | |
1614 | gid= Set the group authorized to learn processes information. | |
1615 | ||
1616 | hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories | |
1617 | (default). | |
1618 | ||
1619 | hidepid=1 means users may not access any /proc/<pid>/ directories but their | |
1620 | own. Sensitive files like cmdline, sched*, status are now protected against | |
1621 | other users. This makes it impossible to learn whether any user runs | |
1622 | specific program (given the program doesn't reveal itself by its behaviour). | |
1623 | As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users, | |
1624 | poorly written programs passing sensitive information via program arguments are | |
1625 | now protected against local eavesdroppers. | |
1626 | ||
1627 | hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other | |
1628 | users. It doesn't mean that it hides a fact whether a process with a specific | |
1629 | pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"), | |
1630 | but it hides process' uid and gid, which may be learned by stat()'ing | |
1631 | /proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering | |
1632 | information about running processes, whether some daemon runs with elevated | |
1633 | privileges, whether other user runs some sensitive program, whether other users | |
1634 | run any program at all, etc. | |
1635 | ||
1636 | gid= defines a group authorized to learn processes information otherwise | |
1637 | prohibited by hidepid=. If you use some daemon like identd which needs to learn | |
1638 | information about processes information, just add identd to this group. |