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1da177e4 LT |
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 |
1da177e4 LT |
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 | |
ae96b348 | 31 | 1.9 Ext4 file system parameters |
1da177e4 LT |
32 | |
33 | 2 Modifying System Parameters | |
760df93e SF |
34 | |
35 | 3 Per-Process Parameters | |
fa0cbbf1 | 36 | 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer |
a63d83f4 | 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 |
f1d8c162 | 44 | 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file |
740a5ddb | 45 | 3.9 /proc/<pid>/map_files - Information about memory mapped files |
5de23d43 | 46 | 3.10 /proc/<pid>/timerslack_ns - Task timerslack value |
7c23b330 | 47 | 3.11 /proc/<pid>/patch_state - Livepatch patch operation state |
711486fd | 48 | 3.12 /proc/<pid>/arch_status - Task architecture specific information |
760df93e | 49 | |
0499680a VK |
50 | 4 Configuring procfs |
51 | 4.1 Mount options | |
1da177e4 LT |
52 | |
53 | ------------------------------------------------------------------------------ | |
54 | Preface | |
55 | ------------------------------------------------------------------------------ | |
56 | ||
57 | 0.1 Introduction/Credits | |
58 | ------------------------ | |
59 | ||
60 | This documentation is part of a soon (or so we hope) to be released book on | |
61 | the SuSE Linux distribution. As there is no complete documentation for the | |
62 | /proc file system and we've used many freely available sources to write these | |
63 | chapters, it seems only fair to give the work back to the Linux community. | |
64 | This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm | |
65 | afraid it's still far from complete, but we hope it will be useful. As far as | |
66 | we know, it is the first 'all-in-one' document about the /proc file system. It | |
67 | is focused on the Intel x86 hardware, so if you are looking for PPC, ARM, | |
68 | SPARC, AXP, etc., features, you probably won't find what you are looking for. | |
69 | It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But | |
70 | additions and patches are welcome and will be added to this document if you | |
71 | mail them to Bodo. | |
72 | ||
73 | We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of | |
74 | other people for help compiling this documentation. We'd also like to extend a | |
75 | special thank you to Andi Kleen for documentation, which we relied on heavily | |
76 | to create this document, as well as the additional information he provided. | |
77 | Thanks to everybody else who contributed source or docs to the Linux kernel | |
78 | and helped create a great piece of software... :) | |
79 | ||
80 | If you have any comments, corrections or additions, please don't hesitate to | |
81 | contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this | |
82 | document. | |
83 | ||
84 | The latest version of this document is available online at | |
0ea6e611 | 85 | http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html |
1da177e4 | 86 | |
0ea6e611 | 87 | If the above direction does not works for you, you could try the kernel |
1da177e4 LT |
88 | mailing list at linux-kernel@vger.kernel.org and/or try to reach me at |
89 | comandante@zaralinux.com. | |
90 | ||
91 | 0.2 Legal Stuff | |
92 | --------------- | |
93 | ||
94 | We don't guarantee the correctness of this document, and if you come to us | |
95 | complaining about how you screwed up your system because of incorrect | |
96 | documentation, we won't feel responsible... | |
97 | ||
98 | ------------------------------------------------------------------------------ | |
99 | CHAPTER 1: COLLECTING SYSTEM INFORMATION | |
100 | ------------------------------------------------------------------------------ | |
101 | ||
102 | ------------------------------------------------------------------------------ | |
103 | In This Chapter | |
104 | ------------------------------------------------------------------------------ | |
105 | * Investigating the properties of the pseudo file system /proc and its | |
106 | ability to provide information on the running Linux system | |
107 | * Examining /proc's structure | |
108 | * Uncovering various information about the kernel and the processes running | |
109 | on the system | |
110 | ------------------------------------------------------------------------------ | |
111 | ||
112 | ||
113 | The proc file system acts as an interface to internal data structures in the | |
114 | kernel. It can be used to obtain information about the system and to change | |
115 | certain kernel parameters at runtime (sysctl). | |
116 | ||
117 | First, we'll take a look at the read-only parts of /proc. In Chapter 2, we | |
118 | show you how you can use /proc/sys to change settings. | |
119 | ||
120 | 1.1 Process-Specific Subdirectories | |
121 | ----------------------------------- | |
122 | ||
123 | The directory /proc contains (among other things) one subdirectory for each | |
124 | process running on the system, which is named after the process ID (PID). | |
125 | ||
126 | The link self points to the process reading the file system. Each process | |
127 | subdirectory has the entries listed in Table 1-1. | |
128 | ||
c969eb83 DC |
129 | Note that an open a file descriptor to /proc/<pid> or to any of its |
130 | contained files or subdirectories does not prevent <pid> being reused | |
131 | for some other process in the event that <pid> exits. Operations on | |
132 | open /proc/<pid> file descriptors corresponding to dead processes | |
133 | never act on any new process that the kernel may, through chance, have | |
134 | also assigned the process ID <pid>. Instead, operations on these FDs | |
135 | usually fail with ESRCH. | |
1da177e4 | 136 | |
349888ee | 137 | Table 1-1: Process specific entries in /proc |
1da177e4 | 138 | .............................................................................. |
b813e931 DR |
139 | File Content |
140 | clear_refs Clears page referenced bits shown in smaps output | |
141 | cmdline Command line arguments | |
142 | cpu Current and last cpu in which it was executed (2.4)(smp) | |
143 | cwd Link to the current working directory | |
144 | environ Values of environment variables | |
145 | exe Link to the executable of this process | |
146 | fd Directory, which contains all file descriptors | |
147 | maps Memory maps to executables and library files (2.4) | |
148 | mem Memory held by this process | |
149 | root Link to the root directory of this process | |
150 | stat Process status | |
151 | statm Process memory status information | |
152 | status Process status in human readable form | |
b2f73922 IM |
153 | wchan Present with CONFIG_KALLSYMS=y: it shows the kernel function |
154 | symbol the task is blocked in - or "0" if not blocked. | |
03f890f8 | 155 | pagemap Page table |
2ec220e2 | 156 | stack Report full stack trace, enable via CONFIG_STACKTRACE |
ee2ad71b | 157 | smaps An extension based on maps, showing the memory consumption of |
834f82e2 | 158 | each mapping and flags associated with it |
ee2ad71b LS |
159 | smaps_rollup Accumulated smaps stats for all mappings of the process. This |
160 | can be derived from smaps, but is faster and more convenient | |
161 | numa_maps An extension based on maps, showing the memory locality and | |
0c369711 | 162 | binding policy as well as mem usage (in pages) of each mapping. |
1da177e4 LT |
163 | .............................................................................. |
164 | ||
165 | For example, to get the status information of a process, all you have to do is | |
166 | read the file /proc/PID/status: | |
167 | ||
349888ee SS |
168 | >cat /proc/self/status |
169 | Name: cat | |
170 | State: R (running) | |
171 | Tgid: 5452 | |
172 | Pid: 5452 | |
173 | PPid: 743 | |
1da177e4 | 174 | TracerPid: 0 (2.4) |
349888ee SS |
175 | Uid: 501 501 501 501 |
176 | Gid: 100 100 100 100 | |
177 | FDSize: 256 | |
178 | Groups: 100 14 16 | |
179 | VmPeak: 5004 kB | |
180 | VmSize: 5004 kB | |
181 | VmLck: 0 kB | |
182 | VmHWM: 476 kB | |
183 | VmRSS: 476 kB | |
8cee852e JM |
184 | RssAnon: 352 kB |
185 | RssFile: 120 kB | |
186 | RssShmem: 4 kB | |
349888ee SS |
187 | VmData: 156 kB |
188 | VmStk: 88 kB | |
189 | VmExe: 68 kB | |
190 | VmLib: 1412 kB | |
191 | VmPTE: 20 kb | |
b084d435 | 192 | VmSwap: 0 kB |
5d317b2b | 193 | HugetlbPages: 0 kB |
c6434012 | 194 | CoreDumping: 0 |
a1400af7 | 195 | THP_enabled: 1 |
349888ee SS |
196 | Threads: 1 |
197 | SigQ: 0/28578 | |
198 | SigPnd: 0000000000000000 | |
199 | ShdPnd: 0000000000000000 | |
200 | SigBlk: 0000000000000000 | |
201 | SigIgn: 0000000000000000 | |
202 | SigCgt: 0000000000000000 | |
203 | CapInh: 00000000fffffeff | |
204 | CapPrm: 0000000000000000 | |
205 | CapEff: 0000000000000000 | |
206 | CapBnd: ffffffffffffffff | |
f8d0dc21 | 207 | CapAmb: 0000000000000000 |
af884cd4 | 208 | NoNewPrivs: 0 |
2f4b3bf6 | 209 | Seccomp: 0 |
f8d0dc21 | 210 | Speculation_Store_Bypass: thread vulnerable |
349888ee SS |
211 | voluntary_ctxt_switches: 0 |
212 | nonvoluntary_ctxt_switches: 1 | |
1da177e4 LT |
213 | |
214 | This shows you nearly the same information you would get if you viewed it with | |
215 | the ps command. In fact, ps uses the proc file system to obtain its | |
349888ee SS |
216 | information. But you get a more detailed view of the process by reading the |
217 | file /proc/PID/status. It fields are described in table 1-2. | |
218 | ||
219 | The statm file contains more detailed information about the process | |
220 | memory usage. Its seven fields are explained in Table 1-3. The stat file | |
221 | contains details information about the process itself. Its fields are | |
222 | explained in Table 1-4. | |
1da177e4 | 223 | |
34e55232 | 224 | (for SMP CONFIG users) |
15eb42d6 NS |
225 | For making accounting scalable, RSS related information are handled in an |
226 | asynchronous manner and the value may not be very precise. To see a precise | |
34e55232 KH |
227 | snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table. |
228 | It's slow but very precise. | |
229 | ||
f8d0dc21 | 230 | Table 1-2: Contents of the status files (as of 4.19) |
349888ee SS |
231 | .............................................................................. |
232 | Field Content | |
233 | Name filename of the executable | |
bbd88e1d | 234 | Umask file mode creation mask |
349888ee SS |
235 | State state (R is running, S is sleeping, D is sleeping |
236 | in an uninterruptible wait, Z is zombie, | |
237 | T is traced or stopped) | |
238 | Tgid thread group ID | |
15eb42d6 | 239 | Ngid NUMA group ID (0 if none) |
349888ee SS |
240 | Pid process id |
241 | PPid process id of the parent process | |
242 | TracerPid PID of process tracing this process (0 if not) | |
243 | Uid Real, effective, saved set, and file system UIDs | |
244 | Gid Real, effective, saved set, and file system GIDs | |
245 | FDSize number of file descriptor slots currently allocated | |
246 | Groups supplementary group list | |
15eb42d6 NS |
247 | NStgid descendant namespace thread group ID hierarchy |
248 | NSpid descendant namespace process ID hierarchy | |
249 | NSpgid descendant namespace process group ID hierarchy | |
250 | NSsid descendant namespace session ID hierarchy | |
349888ee SS |
251 | VmPeak peak virtual memory size |
252 | VmSize total program size | |
253 | VmLck locked memory size | |
bbd88e1d | 254 | VmPin pinned memory size |
349888ee | 255 | VmHWM peak resident set size ("high water mark") |
8cee852e JM |
256 | VmRSS size of memory portions. It contains the three |
257 | following parts (VmRSS = RssAnon + RssFile + RssShmem) | |
258 | RssAnon size of resident anonymous memory | |
259 | RssFile size of resident file mappings | |
260 | RssShmem size of resident shmem memory (includes SysV shm, | |
261 | mapping of tmpfs and shared anonymous mappings) | |
30bdbb78 KK |
262 | VmData size of private data segments |
263 | VmStk size of stack segments | |
349888ee SS |
264 | VmExe size of text segment |
265 | VmLib size of shared library code | |
266 | VmPTE size of page table entries | |
bf9683d6 VB |
267 | VmSwap amount of swap used by anonymous private data |
268 | (shmem swap usage is not included) | |
5d317b2b | 269 | HugetlbPages size of hugetlb memory portions |
c6434012 RG |
270 | CoreDumping process's memory is currently being dumped |
271 | (killing the process may lead to a corrupted core) | |
a1400af7 MH |
272 | THP_enabled process is allowed to use THP (returns 0 when |
273 | PR_SET_THP_DISABLE is set on the process | |
349888ee SS |
274 | Threads number of threads |
275 | SigQ number of signals queued/max. number for queue | |
276 | SigPnd bitmap of pending signals for the thread | |
277 | ShdPnd bitmap of shared pending signals for the process | |
278 | SigBlk bitmap of blocked signals | |
279 | SigIgn bitmap of ignored signals | |
c98be0c9 | 280 | SigCgt bitmap of caught signals |
349888ee SS |
281 | CapInh bitmap of inheritable capabilities |
282 | CapPrm bitmap of permitted capabilities | |
283 | CapEff bitmap of effective capabilities | |
284 | CapBnd bitmap of capabilities bounding set | |
f8d0dc21 | 285 | CapAmb bitmap of ambient capabilities |
af884cd4 | 286 | NoNewPrivs no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...) |
2f4b3bf6 | 287 | Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...) |
f8d0dc21 | 288 | Speculation_Store_Bypass speculative store bypass mitigation status |
349888ee SS |
289 | Cpus_allowed mask of CPUs on which this process may run |
290 | Cpus_allowed_list Same as previous, but in "list format" | |
291 | Mems_allowed mask of memory nodes allowed to this process | |
292 | Mems_allowed_list Same as previous, but in "list format" | |
293 | voluntary_ctxt_switches number of voluntary context switches | |
294 | nonvoluntary_ctxt_switches number of non voluntary context switches | |
295 | .............................................................................. | |
1da177e4 | 296 | |
349888ee | 297 | Table 1-3: Contents of the statm files (as of 2.6.8-rc3) |
1da177e4 LT |
298 | .............................................................................. |
299 | Field Content | |
300 | size total program size (pages) (same as VmSize in status) | |
301 | resident size of memory portions (pages) (same as VmRSS in status) | |
8cee852e JM |
302 | shared number of pages that are shared (i.e. backed by a file, same |
303 | as RssFile+RssShmem in status) | |
1da177e4 LT |
304 | trs number of pages that are 'code' (not including libs; broken, |
305 | includes data segment) | |
306 | lrs number of pages of library (always 0 on 2.6) | |
307 | drs number of pages of data/stack (including libs; broken, | |
308 | includes library text) | |
309 | dt number of dirty pages (always 0 on 2.6) | |
310 | .............................................................................. | |
311 | ||
18d96779 | 312 | |
349888ee | 313 | Table 1-4: Contents of the stat files (as of 2.6.30-rc7) |
18d96779 KC |
314 | .............................................................................. |
315 | Field Content | |
316 | pid process id | |
317 | tcomm filename of the executable | |
318 | state state (R is running, S is sleeping, D is sleeping in an | |
319 | uninterruptible wait, Z is zombie, T is traced or stopped) | |
320 | ppid process id of the parent process | |
321 | pgrp pgrp of the process | |
322 | sid session id | |
323 | tty_nr tty the process uses | |
324 | tty_pgrp pgrp of the tty | |
325 | flags task flags | |
326 | min_flt number of minor faults | |
327 | cmin_flt number of minor faults with child's | |
328 | maj_flt number of major faults | |
329 | cmaj_flt number of major faults with child's | |
330 | utime user mode jiffies | |
331 | stime kernel mode jiffies | |
332 | cutime user mode jiffies with child's | |
333 | cstime kernel mode jiffies with child's | |
334 | priority priority level | |
335 | nice nice level | |
336 | num_threads number of threads | |
2e01e00e | 337 | it_real_value (obsolete, always 0) |
18d96779 KC |
338 | start_time time the process started after system boot |
339 | vsize virtual memory size | |
340 | rss resident set memory size | |
341 | rsslim current limit in bytes on the rss | |
342 | start_code address above which program text can run | |
343 | end_code address below which program text can run | |
b7643757 | 344 | start_stack address of the start of the main process stack |
18d96779 KC |
345 | esp current value of ESP |
346 | eip current value of EIP | |
349888ee SS |
347 | pending bitmap of pending signals |
348 | blocked bitmap of blocked signals | |
349 | sigign bitmap of ignored signals | |
c98be0c9 | 350 | sigcatch bitmap of caught signals |
b2f73922 | 351 | 0 (place holder, used to be the wchan address, use /proc/PID/wchan instead) |
18d96779 KC |
352 | 0 (place holder) |
353 | 0 (place holder) | |
354 | exit_signal signal to send to parent thread on exit | |
355 | task_cpu which CPU the task is scheduled on | |
356 | rt_priority realtime priority | |
357 | policy scheduling policy (man sched_setscheduler) | |
358 | blkio_ticks time spent waiting for block IO | |
349888ee SS |
359 | gtime guest time of the task in jiffies |
360 | cgtime guest time of the task children in jiffies | |
b3f7f573 CG |
361 | start_data address above which program data+bss is placed |
362 | end_data address below which program data+bss is placed | |
363 | start_brk address above which program heap can be expanded with brk() | |
5b172087 CG |
364 | arg_start address above which program command line is placed |
365 | arg_end address below which program command line is placed | |
366 | env_start address above which program environment is placed | |
367 | env_end address below which program environment is placed | |
368 | exit_code the thread's exit_code in the form reported by the waitpid system call | |
18d96779 KC |
369 | .............................................................................. |
370 | ||
ee2ad71b | 371 | The /proc/PID/maps file contains the currently mapped memory regions and |
349888ee SS |
372 | their access permissions. |
373 | ||
374 | The format is: | |
375 | ||
376 | address perms offset dev inode pathname | |
377 | ||
378 | 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test | |
379 | 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test | |
380 | 0804a000-0806b000 rw-p 00000000 00:00 0 [heap] | |
381 | a7cb1000-a7cb2000 ---p 00000000 00:00 0 | |
34441427 | 382 | a7cb2000-a7eb2000 rw-p 00000000 00:00 0 |
349888ee | 383 | a7eb2000-a7eb3000 ---p 00000000 00:00 0 |
65376df5 | 384 | a7eb3000-a7ed5000 rw-p 00000000 00:00 0 |
349888ee SS |
385 | a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6 |
386 | a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6 | |
387 | a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6 | |
388 | a800b000-a800e000 rw-p 00000000 00:00 0 | |
389 | a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0 | |
390 | a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0 | |
391 | a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0 | |
392 | a8024000-a8027000 rw-p 00000000 00:00 0 | |
393 | a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2 | |
394 | a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2 | |
395 | a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2 | |
396 | aff35000-aff4a000 rw-p 00000000 00:00 0 [stack] | |
397 | ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso] | |
398 | ||
399 | where "address" is the address space in the process that it occupies, "perms" | |
400 | is a set of permissions: | |
401 | ||
402 | r = read | |
403 | w = write | |
404 | x = execute | |
405 | s = shared | |
406 | p = private (copy on write) | |
407 | ||
408 | "offset" is the offset into the mapping, "dev" is the device (major:minor), and | |
409 | "inode" is the inode on that device. 0 indicates that no inode is associated | |
410 | with the memory region, as the case would be with BSS (uninitialized data). | |
411 | The "pathname" shows the name associated file for this mapping. If the mapping | |
412 | is not associated with a file: | |
413 | ||
414 | [heap] = the heap of the program | |
415 | [stack] = the stack of the main process | |
416 | [vdso] = the "virtual dynamic shared object", | |
417 | the kernel system call handler | |
418 | ||
419 | or if empty, the mapping is anonymous. | |
420 | ||
349888ee | 421 | The /proc/PID/smaps is an extension based on maps, showing the memory |
ee2ad71b LS |
422 | consumption for each of the process's mappings. For each mapping (aka Virtual |
423 | Memory Area, or VMA) there is a series of lines such as the following: | |
349888ee SS |
424 | |
425 | 08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash | |
ee2ad71b | 426 | |
349888ee | 427 | Size: 1084 kB |
ee2ad71b LS |
428 | KernelPageSize: 4 kB |
429 | MMUPageSize: 4 kB | |
349888ee SS |
430 | Rss: 892 kB |
431 | Pss: 374 kB | |
432 | Shared_Clean: 892 kB | |
433 | Shared_Dirty: 0 kB | |
434 | Private_Clean: 0 kB | |
435 | Private_Dirty: 0 kB | |
436 | Referenced: 892 kB | |
b40d4f84 | 437 | Anonymous: 0 kB |
cf8496ea | 438 | LazyFree: 0 kB |
25ee01a2 | 439 | AnonHugePages: 0 kB |
1b5946a8 | 440 | ShmemPmdMapped: 0 kB |
25ee01a2 NH |
441 | Shared_Hugetlb: 0 kB |
442 | Private_Hugetlb: 0 kB | |
349888ee | 443 | Swap: 0 kB |
8334b962 | 444 | SwapPss: 0 kB |
349888ee SS |
445 | KernelPageSize: 4 kB |
446 | MMUPageSize: 4 kB | |
a5be3563 | 447 | Locked: 0 kB |
7635d9cb | 448 | THPeligible: 0 |
a5be3563 | 449 | VmFlags: rd ex mr mw me dw |
349888ee | 450 | |
ee2ad71b LS |
451 | The first of these lines shows the same information as is displayed for the |
452 | mapping in /proc/PID/maps. Following lines show the size of the mapping | |
453 | (size); the size of each page allocated when backing a VMA (KernelPageSize), | |
454 | which is usually the same as the size in the page table entries; the page size | |
455 | used by the MMU when backing a VMA (in most cases, the same as KernelPageSize); | |
456 | the amount of the mapping that is currently resident in RAM (RSS); the | |
457 | process' proportional share of this mapping (PSS); and the number of clean and | |
458 | dirty shared and private pages in the mapping. | |
8334b962 MK |
459 | |
460 | The "proportional set size" (PSS) of a process is the count of pages it has | |
461 | in memory, where each page is divided by the number of processes sharing it. | |
462 | So if a process has 1000 pages all to itself, and 1000 shared with one other | |
463 | process, its PSS will be 1500. | |
464 | Note that even a page which is part of a MAP_SHARED mapping, but has only | |
465 | a single pte mapped, i.e. is currently used by only one process, is accounted | |
466 | as private and not as shared. | |
467 | "Referenced" indicates the amount of memory currently marked as referenced or | |
468 | accessed. | |
b40d4f84 NK |
469 | "Anonymous" shows the amount of memory that does not belong to any file. Even |
470 | a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE | |
471 | and a page is modified, the file page is replaced by a private anonymous copy. | |
cf8496ea SL |
472 | "LazyFree" shows the amount of memory which is marked by madvise(MADV_FREE). |
473 | The memory isn't freed immediately with madvise(). It's freed in memory | |
474 | pressure if the memory is clean. Please note that the printed value might | |
475 | be lower than the real value due to optimizations used in the current | |
476 | implementation. If this is not desirable please file a bug report. | |
25ee01a2 | 477 | "AnonHugePages" shows the ammount of memory backed by transparent hugepage. |
1b5946a8 KS |
478 | "ShmemPmdMapped" shows the ammount of shared (shmem/tmpfs) memory backed by |
479 | huge pages. | |
25ee01a2 NH |
480 | "Shared_Hugetlb" and "Private_Hugetlb" show the ammounts of memory backed by |
481 | hugetlbfs page which is *not* counted in "RSS" or "PSS" field for historical | |
482 | reasons. And these are not included in {Shared,Private}_{Clean,Dirty} field. | |
a5be3563 | 483 | "Swap" shows how much would-be-anonymous memory is also used, but out on swap. |
c261e7d9 VB |
484 | For shmem mappings, "Swap" includes also the size of the mapped (and not |
485 | replaced by copy-on-write) part of the underlying shmem object out on swap. | |
486 | "SwapPss" shows proportional swap share of this mapping. Unlike "Swap", this | |
487 | does not take into account swapped out page of underlying shmem objects. | |
a5be3563 | 488 | "Locked" indicates whether the mapping is locked in memory or not. |
c0630669 YS |
489 | "THPeligible" indicates whether the mapping is eligible for allocating THP |
490 | pages - 1 if true, 0 otherwise. It just shows the current status. | |
25ee01a2 | 491 | |
834f82e2 CG |
492 | "VmFlags" field deserves a separate description. This member represents the kernel |
493 | flags associated with the particular virtual memory area in two letter encoded | |
494 | manner. The codes are the following: | |
495 | rd - readable | |
496 | wr - writeable | |
497 | ex - executable | |
498 | sh - shared | |
499 | mr - may read | |
500 | mw - may write | |
501 | me - may execute | |
502 | ms - may share | |
503 | gd - stack segment growns down | |
504 | pf - pure PFN range | |
505 | dw - disabled write to the mapped file | |
506 | lo - pages are locked in memory | |
507 | io - memory mapped I/O area | |
508 | sr - sequential read advise provided | |
509 | rr - random read advise provided | |
510 | dc - do not copy area on fork | |
511 | de - do not expand area on remapping | |
512 | ac - area is accountable | |
513 | nr - swap space is not reserved for the area | |
514 | ht - area uses huge tlb pages | |
834f82e2 CG |
515 | ar - architecture specific flag |
516 | dd - do not include area into core dump | |
ec8e41ae | 517 | sd - soft-dirty flag |
834f82e2 CG |
518 | mm - mixed map area |
519 | hg - huge page advise flag | |
520 | nh - no-huge page advise flag | |
521 | mg - mergable advise flag | |
522 | ||
523 | Note that there is no guarantee that every flag and associated mnemonic will | |
524 | be present in all further kernel releases. Things get changed, the flags may | |
7550c607 MH |
525 | be vanished or the reverse -- new added. Interpretation of their meaning |
526 | might change in future as well. So each consumer of these flags has to | |
527 | follow each specific kernel version for the exact semantic. | |
834f82e2 | 528 | |
349888ee SS |
529 | This file is only present if the CONFIG_MMU kernel configuration option is |
530 | enabled. | |
18d96779 | 531 | |
53aeee7a RH |
532 | Note: reading /proc/PID/maps or /proc/PID/smaps is inherently racy (consistent |
533 | output can be achieved only in the single read call). | |
534 | This typically manifests when doing partial reads of these files while the | |
535 | memory map is being modified. Despite the races, we do provide the following | |
536 | guarantees: | |
537 | ||
538 | 1) The mapped addresses never go backwards, which implies no two | |
539 | regions will ever overlap. | |
540 | 2) If there is something at a given vaddr during the entirety of the | |
541 | life of the smaps/maps walk, there will be some output for it. | |
542 | ||
ee2ad71b LS |
543 | The /proc/PID/smaps_rollup file includes the same fields as /proc/PID/smaps, |
544 | but their values are the sums of the corresponding values for all mappings of | |
545 | the process. Additionally, it contains these fields: | |
546 | ||
547 | Pss_Anon | |
548 | Pss_File | |
549 | Pss_Shmem | |
550 | ||
551 | They represent the proportional shares of anonymous, file, and shmem pages, as | |
552 | described for smaps above. These fields are omitted in smaps since each | |
553 | mapping identifies the type (anon, file, or shmem) of all pages it contains. | |
554 | Thus all information in smaps_rollup can be derived from smaps, but at a | |
555 | significantly higher cost. | |
53aeee7a | 556 | |
398499d5 | 557 | The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG |
0f8975ec | 558 | bits on both physical and virtual pages associated with a process, and the |
1ad1335d MR |
559 | soft-dirty bit on pte (see Documentation/admin-guide/mm/soft-dirty.rst |
560 | for details). | |
398499d5 MB |
561 | To clear the bits for all the pages associated with the process |
562 | > echo 1 > /proc/PID/clear_refs | |
563 | ||
564 | To clear the bits for the anonymous pages associated with the process | |
565 | > echo 2 > /proc/PID/clear_refs | |
566 | ||
567 | To clear the bits for the file mapped pages associated with the process | |
568 | > echo 3 > /proc/PID/clear_refs | |
0f8975ec PE |
569 | |
570 | To clear the soft-dirty bit | |
571 | > echo 4 > /proc/PID/clear_refs | |
572 | ||
695f0559 PC |
573 | To reset the peak resident set size ("high water mark") to the process's |
574 | current value: | |
575 | > echo 5 > /proc/PID/clear_refs | |
576 | ||
398499d5 MB |
577 | Any other value written to /proc/PID/clear_refs will have no effect. |
578 | ||
03f890f8 NK |
579 | The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags |
580 | using /proc/kpageflags and number of times a page is mapped using | |
1ad1335d MR |
581 | /proc/kpagecount. For detailed explanation, see |
582 | Documentation/admin-guide/mm/pagemap.rst. | |
398499d5 | 583 | |
0c369711 RA |
584 | The /proc/pid/numa_maps is an extension based on maps, showing the memory |
585 | locality and binding policy, as well as the memory usage (in pages) of | |
586 | each mapping. The output follows a general format where mapping details get | |
587 | summarized separated by blank spaces, one mapping per each file line: | |
588 | ||
589 | address policy mapping details | |
590 | ||
198d1597 RA |
591 | 00400000 default file=/usr/local/bin/app mapped=1 active=0 N3=1 kernelpagesize_kB=4 |
592 | 00600000 default file=/usr/local/bin/app anon=1 dirty=1 N3=1 kernelpagesize_kB=4 | |
593 | 3206000000 default file=/lib64/ld-2.12.so mapped=26 mapmax=6 N0=24 N3=2 kernelpagesize_kB=4 | |
594 | 320621f000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4 | |
595 | 3206220000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4 | |
596 | 3206221000 default anon=1 dirty=1 N3=1 kernelpagesize_kB=4 | |
597 | 3206800000 default file=/lib64/libc-2.12.so mapped=59 mapmax=21 active=55 N0=41 N3=18 kernelpagesize_kB=4 | |
0c369711 | 598 | 320698b000 default file=/lib64/libc-2.12.so |
198d1597 RA |
599 | 3206b8a000 default file=/lib64/libc-2.12.so anon=2 dirty=2 N3=2 kernelpagesize_kB=4 |
600 | 3206b8e000 default file=/lib64/libc-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4 | |
601 | 3206b8f000 default anon=3 dirty=3 active=1 N3=3 kernelpagesize_kB=4 | |
602 | 7f4dc10a2000 default anon=3 dirty=3 N3=3 kernelpagesize_kB=4 | |
603 | 7f4dc10b4000 default anon=2 dirty=2 active=1 N3=2 kernelpagesize_kB=4 | |
604 | 7f4dc1200000 default file=/anon_hugepage\040(deleted) huge anon=1 dirty=1 N3=1 kernelpagesize_kB=2048 | |
605 | 7fff335f0000 default stack anon=3 dirty=3 N3=3 kernelpagesize_kB=4 | |
606 | 7fff3369d000 default mapped=1 mapmax=35 active=0 N3=1 kernelpagesize_kB=4 | |
0c369711 RA |
607 | |
608 | Where: | |
609 | "address" is the starting address for the mapping; | |
3ecf53e4 | 610 | "policy" reports the NUMA memory policy set for the mapping (see Documentation/admin-guide/mm/numa_memory_policy.rst); |
0c369711 RA |
611 | "mapping details" summarizes mapping data such as mapping type, page usage counters, |
612 | node locality page counters (N0 == node0, N1 == node1, ...) and the kernel page | |
613 | size, in KB, that is backing the mapping up. | |
614 | ||
1da177e4 LT |
615 | 1.2 Kernel data |
616 | --------------- | |
617 | ||
618 | Similar to the process entries, the kernel data files give information about | |
619 | the running kernel. The files used to obtain this information are contained in | |
349888ee | 620 | /proc and are listed in Table 1-5. Not all of these will be present in your |
1da177e4 LT |
621 | system. It depends on the kernel configuration and the loaded modules, which |
622 | files are there, and which are missing. | |
623 | ||
349888ee | 624 | Table 1-5: Kernel info in /proc |
1da177e4 LT |
625 | .............................................................................. |
626 | File Content | |
627 | apm Advanced power management info | |
628 | buddyinfo Kernel memory allocator information (see text) (2.5) | |
629 | bus Directory containing bus specific information | |
630 | cmdline Kernel command line | |
631 | cpuinfo Info about the CPU | |
632 | devices Available devices (block and character) | |
633 | dma Used DMS channels | |
634 | filesystems Supported filesystems | |
635 | driver Various drivers grouped here, currently rtc (2.4) | |
636 | execdomains Execdomains, related to security (2.4) | |
637 | fb Frame Buffer devices (2.4) | |
638 | fs File system parameters, currently nfs/exports (2.4) | |
639 | ide Directory containing info about the IDE subsystem | |
640 | interrupts Interrupt usage | |
641 | iomem Memory map (2.4) | |
642 | ioports I/O port usage | |
643 | irq Masks for irq to cpu affinity (2.4)(smp?) | |
644 | isapnp ISA PnP (Plug&Play) Info (2.4) | |
645 | kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4)) | |
646 | kmsg Kernel messages | |
647 | ksyms Kernel symbol table | |
648 | loadavg Load average of last 1, 5 & 15 minutes | |
649 | locks Kernel locks | |
650 | meminfo Memory info | |
651 | misc Miscellaneous | |
652 | modules List of loaded modules | |
653 | mounts Mounted filesystems | |
654 | net Networking info (see text) | |
a1b57ac0 | 655 | pagetypeinfo Additional page allocator information (see text) (2.5) |
1da177e4 | 656 | partitions Table of partitions known to the system |
8b60756a | 657 | pci Deprecated info of PCI bus (new way -> /proc/bus/pci/, |
1da177e4 LT |
658 | decoupled by lspci (2.4) |
659 | rtc Real time clock | |
660 | scsi SCSI info (see text) | |
661 | slabinfo Slab pool info | |
d3d64df2 | 662 | softirqs softirq usage |
1da177e4 LT |
663 | stat Overall statistics |
664 | swaps Swap space utilization | |
665 | sys See chapter 2 | |
666 | sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4) | |
667 | tty Info of tty drivers | |
49457896 | 668 | uptime Wall clock since boot, combined idle time of all cpus |
1da177e4 LT |
669 | version Kernel version |
670 | video bttv info of video resources (2.4) | |
a47a126a | 671 | vmallocinfo Show vmalloced areas |
1da177e4 LT |
672 | .............................................................................. |
673 | ||
674 | You can, for example, check which interrupts are currently in use and what | |
675 | they are used for by looking in the file /proc/interrupts: | |
676 | ||
677 | > cat /proc/interrupts | |
678 | CPU0 | |
679 | 0: 8728810 XT-PIC timer | |
680 | 1: 895 XT-PIC keyboard | |
681 | 2: 0 XT-PIC cascade | |
682 | 3: 531695 XT-PIC aha152x | |
683 | 4: 2014133 XT-PIC serial | |
684 | 5: 44401 XT-PIC pcnet_cs | |
685 | 8: 2 XT-PIC rtc | |
686 | 11: 8 XT-PIC i82365 | |
687 | 12: 182918 XT-PIC PS/2 Mouse | |
688 | 13: 1 XT-PIC fpu | |
689 | 14: 1232265 XT-PIC ide0 | |
690 | 15: 7 XT-PIC ide1 | |
691 | NMI: 0 | |
692 | ||
693 | In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the | |
694 | output of a SMP machine): | |
695 | ||
696 | > cat /proc/interrupts | |
697 | ||
698 | CPU0 CPU1 | |
699 | 0: 1243498 1214548 IO-APIC-edge timer | |
700 | 1: 8949 8958 IO-APIC-edge keyboard | |
701 | 2: 0 0 XT-PIC cascade | |
702 | 5: 11286 10161 IO-APIC-edge soundblaster | |
703 | 8: 1 0 IO-APIC-edge rtc | |
704 | 9: 27422 27407 IO-APIC-edge 3c503 | |
705 | 12: 113645 113873 IO-APIC-edge PS/2 Mouse | |
706 | 13: 0 0 XT-PIC fpu | |
707 | 14: 22491 24012 IO-APIC-edge ide0 | |
708 | 15: 2183 2415 IO-APIC-edge ide1 | |
709 | 17: 30564 30414 IO-APIC-level eth0 | |
710 | 18: 177 164 IO-APIC-level bttv | |
711 | NMI: 2457961 2457959 | |
712 | LOC: 2457882 2457881 | |
713 | ERR: 2155 | |
714 | ||
715 | NMI is incremented in this case because every timer interrupt generates a NMI | |
716 | (Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups. | |
717 | ||
718 | LOC is the local interrupt counter of the internal APIC of every CPU. | |
719 | ||
720 | ERR is incremented in the case of errors in the IO-APIC bus (the bus that | |
721 | connects the CPUs in a SMP system. This means that an error has been detected, | |
722 | the IO-APIC automatically retry the transmission, so it should not be a big | |
723 | problem, but you should read the SMP-FAQ. | |
724 | ||
38e760a1 JK |
725 | In 2.6.2* /proc/interrupts was expanded again. This time the goal was for |
726 | /proc/interrupts to display every IRQ vector in use by the system, not | |
727 | just those considered 'most important'. The new vectors are: | |
728 | ||
729 | THR -- interrupt raised when a machine check threshold counter | |
730 | (typically counting ECC corrected errors of memory or cache) exceeds | |
731 | a configurable threshold. Only available on some systems. | |
732 | ||
733 | TRM -- a thermal event interrupt occurs when a temperature threshold | |
734 | has been exceeded for the CPU. This interrupt may also be generated | |
735 | when the temperature drops back to normal. | |
736 | ||
737 | SPU -- a spurious interrupt is some interrupt that was raised then lowered | |
738 | by some IO device before it could be fully processed by the APIC. Hence | |
739 | the APIC sees the interrupt but does not know what device it came from. | |
740 | For this case the APIC will generate the interrupt with a IRQ vector | |
741 | of 0xff. This might also be generated by chipset bugs. | |
742 | ||
743 | RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are | |
744 | sent from one CPU to another per the needs of the OS. Typically, | |
745 | their statistics are used by kernel developers and interested users to | |
19f59460 | 746 | determine the occurrence of interrupts of the given type. |
38e760a1 | 747 | |
25985edc | 748 | The above IRQ vectors are displayed only when relevant. For example, |
38e760a1 JK |
749 | the threshold vector does not exist on x86_64 platforms. Others are |
750 | suppressed when the system is a uniprocessor. As of this writing, only | |
751 | i386 and x86_64 platforms support the new IRQ vector displays. | |
752 | ||
753 | Of some interest is the introduction of the /proc/irq directory to 2.4. | |
1da177e4 LT |
754 | It could be used to set IRQ to CPU affinity, this means that you can "hook" an |
755 | IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the | |
18404756 MK |
756 | irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and |
757 | prof_cpu_mask. | |
1da177e4 LT |
758 | |
759 | For example | |
760 | > ls /proc/irq/ | |
761 | 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask | |
18404756 | 762 | 1 11 13 15 17 19 3 5 7 9 default_smp_affinity |
1da177e4 LT |
763 | > ls /proc/irq/0/ |
764 | smp_affinity | |
765 | ||
18404756 MK |
766 | smp_affinity is a bitmask, in which you can specify which CPUs can handle the |
767 | IRQ, you can set it by doing: | |
1da177e4 | 768 | |
18404756 MK |
769 | > echo 1 > /proc/irq/10/smp_affinity |
770 | ||
771 | This means that only the first CPU will handle the IRQ, but you can also echo | |
99e9d958 | 772 | 5 which means that only the first and third CPU can handle the IRQ. |
1da177e4 | 773 | |
18404756 MK |
774 | The contents of each smp_affinity file is the same by default: |
775 | ||
776 | > cat /proc/irq/0/smp_affinity | |
777 | ffffffff | |
1da177e4 | 778 | |
4b060420 MT |
779 | There is an alternate interface, smp_affinity_list which allows specifying |
780 | a cpu range instead of a bitmask: | |
781 | ||
782 | > cat /proc/irq/0/smp_affinity_list | |
783 | 1024-1031 | |
784 | ||
18404756 MK |
785 | The default_smp_affinity mask applies to all non-active IRQs, which are the |
786 | IRQs which have not yet been allocated/activated, and hence which lack a | |
787 | /proc/irq/[0-9]* directory. | |
1da177e4 | 788 | |
92d6b71a DS |
789 | The node file on an SMP system shows the node to which the device using the IRQ |
790 | reports itself as being attached. This hardware locality information does not | |
791 | include information about any possible driver locality preference. | |
792 | ||
18404756 | 793 | prof_cpu_mask specifies which CPUs are to be profiled by the system wide |
4b060420 | 794 | profiler. Default value is ffffffff (all cpus if there are only 32 of them). |
1da177e4 LT |
795 | |
796 | The way IRQs are routed is handled by the IO-APIC, and it's Round Robin | |
797 | between all the CPUs which are allowed to handle it. As usual the kernel has | |
798 | more info than you and does a better job than you, so the defaults are the | |
4b060420 MT |
799 | best choice for almost everyone. [Note this applies only to those IO-APIC's |
800 | that support "Round Robin" interrupt distribution.] | |
1da177e4 LT |
801 | |
802 | There are three more important subdirectories in /proc: net, scsi, and sys. | |
803 | The general rule is that the contents, or even the existence of these | |
804 | directories, depend on your kernel configuration. If SCSI is not enabled, the | |
805 | directory scsi may not exist. The same is true with the net, which is there | |
806 | only when networking support is present in the running kernel. | |
807 | ||
808 | The slabinfo file gives information about memory usage at the slab level. | |
809 | Linux uses slab pools for memory management above page level in version 2.2. | |
810 | Commonly used objects have their own slab pool (such as network buffers, | |
811 | directory cache, and so on). | |
812 | ||
813 | .............................................................................. | |
814 | ||
815 | > cat /proc/buddyinfo | |
816 | ||
817 | Node 0, zone DMA 0 4 5 4 4 3 ... | |
818 | Node 0, zone Normal 1 0 0 1 101 8 ... | |
819 | Node 0, zone HighMem 2 0 0 1 1 0 ... | |
820 | ||
a1b57ac0 | 821 | External fragmentation is a problem under some workloads, and buddyinfo is a |
1da177e4 LT |
822 | useful tool for helping diagnose these problems. Buddyinfo will give you a |
823 | clue as to how big an area you can safely allocate, or why a previous | |
824 | allocation failed. | |
825 | ||
826 | Each column represents the number of pages of a certain order which are | |
827 | available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in | |
828 | ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE | |
829 | available in ZONE_NORMAL, etc... | |
830 | ||
a1b57ac0 MG |
831 | More information relevant to external fragmentation can be found in |
832 | pagetypeinfo. | |
833 | ||
834 | > cat /proc/pagetypeinfo | |
835 | Page block order: 9 | |
836 | Pages per block: 512 | |
837 | ||
838 | Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10 | |
839 | Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0 | |
840 | Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0 | |
841 | Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2 | |
842 | Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0 | |
843 | Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0 | |
844 | Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9 | |
845 | Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0 | |
846 | Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452 | |
847 | Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0 | |
848 | Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0 | |
849 | ||
850 | Number of blocks type Unmovable Reclaimable Movable Reserve Isolate | |
851 | Node 0, zone DMA 2 0 5 1 0 | |
852 | Node 0, zone DMA32 41 6 967 2 0 | |
853 | ||
854 | Fragmentation avoidance in the kernel works by grouping pages of different | |
855 | migrate types into the same contiguous regions of memory called page blocks. | |
856 | A page block is typically the size of the default hugepage size e.g. 2MB on | |
857 | X86-64. By keeping pages grouped based on their ability to move, the kernel | |
858 | can reclaim pages within a page block to satisfy a high-order allocation. | |
859 | ||
860 | The pagetypinfo begins with information on the size of a page block. It | |
861 | then gives the same type of information as buddyinfo except broken down | |
862 | by migrate-type and finishes with details on how many page blocks of each | |
863 | type exist. | |
864 | ||
865 | If min_free_kbytes has been tuned correctly (recommendations made by hugeadm | |
ceec86ec | 866 | from libhugetlbfs https://github.com/libhugetlbfs/libhugetlbfs/), one can |
a1b57ac0 MG |
867 | make an estimate of the likely number of huge pages that can be allocated |
868 | at a given point in time. All the "Movable" blocks should be allocatable | |
869 | unless memory has been mlock()'d. Some of the Reclaimable blocks should | |
870 | also be allocatable although a lot of filesystem metadata may have to be | |
871 | reclaimed to achieve this. | |
872 | ||
1da177e4 LT |
873 | .............................................................................. |
874 | ||
875 | meminfo: | |
876 | ||
877 | Provides information about distribution and utilization of memory. This | |
878 | varies by architecture and compile options. The following is from a | |
879 | 16GB PIII, which has highmem enabled. You may not have all of these fields. | |
880 | ||
881 | > cat /proc/meminfo | |
882 | ||
1da177e4 LT |
883 | MemTotal: 16344972 kB |
884 | MemFree: 13634064 kB | |
34e431b0 | 885 | MemAvailable: 14836172 kB |
1da177e4 LT |
886 | Buffers: 3656 kB |
887 | Cached: 1195708 kB | |
888 | SwapCached: 0 kB | |
889 | Active: 891636 kB | |
890 | Inactive: 1077224 kB | |
891 | HighTotal: 15597528 kB | |
892 | HighFree: 13629632 kB | |
893 | LowTotal: 747444 kB | |
894 | LowFree: 4432 kB | |
895 | SwapTotal: 0 kB | |
896 | SwapFree: 0 kB | |
897 | Dirty: 968 kB | |
898 | Writeback: 0 kB | |
b88473f7 | 899 | AnonPages: 861800 kB |
1da177e4 | 900 | Mapped: 280372 kB |
0bc126d4 | 901 | Shmem: 644 kB |
61f94e18 | 902 | KReclaimable: 168048 kB |
b88473f7 MS |
903 | Slab: 284364 kB |
904 | SReclaimable: 159856 kB | |
905 | SUnreclaim: 124508 kB | |
906 | PageTables: 24448 kB | |
907 | NFS_Unstable: 0 kB | |
908 | Bounce: 0 kB | |
909 | WritebackTmp: 0 kB | |
1da177e4 LT |
910 | CommitLimit: 7669796 kB |
911 | Committed_AS: 100056 kB | |
1da177e4 LT |
912 | VmallocTotal: 112216 kB |
913 | VmallocUsed: 428 kB | |
914 | VmallocChunk: 111088 kB | |
7e8a6304 | 915 | Percpu: 62080 kB |
655c75a2 | 916 | HardwareCorrupted: 0 kB |
69256994 | 917 | AnonHugePages: 49152 kB |
1b5946a8 KS |
918 | ShmemHugePages: 0 kB |
919 | ShmemPmdMapped: 0 kB | |
920 | ||
1da177e4 LT |
921 | |
922 | MemTotal: Total usable ram (i.e. physical ram minus a few reserved | |
923 | bits and the kernel binary code) | |
924 | MemFree: The sum of LowFree+HighFree | |
34e431b0 RR |
925 | MemAvailable: An estimate of how much memory is available for starting new |
926 | applications, without swapping. Calculated from MemFree, | |
927 | SReclaimable, the size of the file LRU lists, and the low | |
928 | watermarks in each zone. | |
929 | The estimate takes into account that the system needs some | |
930 | page cache to function well, and that not all reclaimable | |
931 | slab will be reclaimable, due to items being in use. The | |
932 | impact of those factors will vary from system to system. | |
1da177e4 LT |
933 | Buffers: Relatively temporary storage for raw disk blocks |
934 | shouldn't get tremendously large (20MB or so) | |
935 | Cached: in-memory cache for files read from the disk (the | |
936 | pagecache). Doesn't include SwapCached | |
937 | SwapCached: Memory that once was swapped out, is swapped back in but | |
938 | still also is in the swapfile (if memory is needed it | |
939 | doesn't need to be swapped out AGAIN because it is already | |
940 | in the swapfile. This saves I/O) | |
941 | Active: Memory that has been used more recently and usually not | |
942 | reclaimed unless absolutely necessary. | |
943 | Inactive: Memory which has been less recently used. It is more | |
944 | eligible to be reclaimed for other purposes | |
945 | HighTotal: | |
946 | HighFree: Highmem is all memory above ~860MB of physical memory | |
947 | Highmem areas are for use by userspace programs, or | |
948 | for the pagecache. The kernel must use tricks to access | |
949 | this memory, making it slower to access than lowmem. | |
950 | LowTotal: | |
951 | LowFree: Lowmem is memory which can be used for everything that | |
3f6dee9b | 952 | highmem can be used for, but it is also available for the |
1da177e4 LT |
953 | kernel's use for its own data structures. Among many |
954 | other things, it is where everything from the Slab is | |
955 | allocated. Bad things happen when you're out of lowmem. | |
956 | SwapTotal: total amount of swap space available | |
957 | SwapFree: Memory which has been evicted from RAM, and is temporarily | |
958 | on the disk | |
959 | Dirty: Memory which is waiting to get written back to the disk | |
960 | Writeback: Memory which is actively being written back to the disk | |
b88473f7 | 961 | AnonPages: Non-file backed pages mapped into userspace page tables |
655c75a2 PD |
962 | HardwareCorrupted: The amount of RAM/memory in KB, the kernel identifies as |
963 | corrupted. | |
69256994 | 964 | AnonHugePages: Non-file backed huge pages mapped into userspace page tables |
1da177e4 | 965 | Mapped: files which have been mmaped, such as libraries |
0bc126d4 | 966 | Shmem: Total memory used by shared memory (shmem) and tmpfs |
1b5946a8 KS |
967 | ShmemHugePages: Memory used by shared memory (shmem) and tmpfs allocated |
968 | with huge pages | |
969 | ShmemPmdMapped: Shared memory mapped into userspace with huge pages | |
61f94e18 VB |
970 | KReclaimable: Kernel allocations that the kernel will attempt to reclaim |
971 | under memory pressure. Includes SReclaimable (below), and other | |
972 | direct allocations with a shrinker. | |
e82443c0 | 973 | Slab: in-kernel data structures cache |
b88473f7 MS |
974 | SReclaimable: Part of Slab, that might be reclaimed, such as caches |
975 | SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure | |
976 | PageTables: amount of memory dedicated to the lowest level of page | |
977 | tables. | |
978 | NFS_Unstable: NFS pages sent to the server, but not yet committed to stable | |
979 | storage | |
980 | Bounce: Memory used for block device "bounce buffers" | |
981 | WritebackTmp: Memory used by FUSE for temporary writeback buffers | |
1da177e4 LT |
982 | CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'), |
983 | this is the total amount of memory currently available to | |
984 | be allocated on the system. This limit is only adhered to | |
985 | if strict overcommit accounting is enabled (mode 2 in | |
986 | 'vm.overcommit_memory'). | |
987 | The CommitLimit is calculated with the following formula: | |
7a9e6da1 PO |
988 | CommitLimit = ([total RAM pages] - [total huge TLB pages]) * |
989 | overcommit_ratio / 100 + [total swap pages] | |
1da177e4 LT |
990 | For example, on a system with 1G of physical RAM and 7G |
991 | of swap with a `vm.overcommit_ratio` of 30 it would | |
992 | yield a CommitLimit of 7.3G. | |
993 | For more details, see the memory overcommit documentation | |
994 | in vm/overcommit-accounting. | |
995 | Committed_AS: The amount of memory presently allocated on the system. | |
996 | The committed memory is a sum of all of the memory which | |
997 | has been allocated by processes, even if it has not been | |
998 | "used" by them as of yet. A process which malloc()'s 1G | |
46496022 MJ |
999 | of memory, but only touches 300M of it will show up as |
1000 | using 1G. This 1G is memory which has been "committed" to | |
1001 | by the VM and can be used at any time by the allocating | |
1002 | application. With strict overcommit enabled on the system | |
1003 | (mode 2 in 'vm.overcommit_memory'),allocations which would | |
1004 | exceed the CommitLimit (detailed above) will not be permitted. | |
1005 | This is useful if one needs to guarantee that processes will | |
1006 | not fail due to lack of memory once that memory has been | |
1007 | successfully allocated. | |
1da177e4 LT |
1008 | VmallocTotal: total size of vmalloc memory area |
1009 | VmallocUsed: amount of vmalloc area which is used | |
19f59460 | 1010 | VmallocChunk: largest contiguous block of vmalloc area which is free |
7e8a6304 DZF |
1011 | Percpu: Memory allocated to the percpu allocator used to back percpu |
1012 | allocations. This stat excludes the cost of metadata. | |
1da177e4 | 1013 | |
a47a126a ED |
1014 | .............................................................................. |
1015 | ||
1016 | vmallocinfo: | |
1017 | ||
1018 | Provides information about vmalloced/vmaped areas. One line per area, | |
1019 | containing the virtual address range of the area, size in bytes, | |
1020 | caller information of the creator, and optional information depending | |
1021 | on the kind of area : | |
1022 | ||
1023 | pages=nr number of pages | |
1024 | phys=addr if a physical address was specified | |
1025 | ioremap I/O mapping (ioremap() and friends) | |
1026 | vmalloc vmalloc() area | |
1027 | vmap vmap()ed pages | |
1028 | user VM_USERMAP area | |
1029 | vpages buffer for pages pointers was vmalloced (huge area) | |
1030 | N<node>=nr (Only on NUMA kernels) | |
1031 | Number of pages allocated on memory node <node> | |
1032 | ||
1033 | > cat /proc/vmallocinfo | |
1034 | 0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ... | |
1035 | /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128 | |
1036 | 0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ... | |
1037 | /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64 | |
1038 | 0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f... | |
1039 | phys=7fee8000 ioremap | |
1040 | 0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f... | |
1041 | phys=7fee7000 ioremap | |
1042 | 0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210 | |
1043 | 0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ... | |
1044 | /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3 | |
1045 | 0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ... | |
1046 | pages=2 vmalloc N1=2 | |
1047 | 0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ... | |
1048 | /0x130 [x_tables] pages=4 vmalloc N0=4 | |
1049 | 0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ... | |
1050 | pages=14 vmalloc N2=14 | |
1051 | 0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ... | |
1052 | pages=4 vmalloc N1=4 | |
1053 | 0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ... | |
1054 | pages=2 vmalloc N1=2 | |
1055 | 0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ... | |
1056 | pages=10 vmalloc N0=10 | |
1da177e4 | 1057 | |
d3d64df2 KK |
1058 | .............................................................................. |
1059 | ||
1060 | softirqs: | |
1061 | ||
1062 | Provides counts of softirq handlers serviced since boot time, for each cpu. | |
1063 | ||
1064 | > cat /proc/softirqs | |
1065 | CPU0 CPU1 CPU2 CPU3 | |
1066 | HI: 0 0 0 0 | |
1067 | TIMER: 27166 27120 27097 27034 | |
1068 | NET_TX: 0 0 0 17 | |
1069 | NET_RX: 42 0 0 39 | |
1070 | BLOCK: 0 0 107 1121 | |
1071 | TASKLET: 0 0 0 290 | |
1072 | SCHED: 27035 26983 26971 26746 | |
1073 | HRTIMER: 0 0 0 0 | |
09223371 | 1074 | RCU: 1678 1769 2178 2250 |
d3d64df2 KK |
1075 | |
1076 | ||
1da177e4 LT |
1077 | 1.3 IDE devices in /proc/ide |
1078 | ---------------------------- | |
1079 | ||
1080 | The subdirectory /proc/ide contains information about all IDE devices of which | |
1081 | the kernel is aware. There is one subdirectory for each IDE controller, the | |
1082 | file drivers and a link for each IDE device, pointing to the device directory | |
1083 | in the controller specific subtree. | |
1084 | ||
1085 | The file drivers contains general information about the drivers used for the | |
1086 | IDE devices: | |
1087 | ||
1088 | > cat /proc/ide/drivers | |
1089 | ide-cdrom version 4.53 | |
1090 | ide-disk version 1.08 | |
1091 | ||
1092 | More detailed information can be found in the controller specific | |
1093 | subdirectories. These are named ide0, ide1 and so on. Each of these | |
349888ee | 1094 | directories contains the files shown in table 1-6. |
1da177e4 LT |
1095 | |
1096 | ||
349888ee | 1097 | Table 1-6: IDE controller info in /proc/ide/ide? |
1da177e4 LT |
1098 | .............................................................................. |
1099 | File Content | |
1100 | channel IDE channel (0 or 1) | |
1101 | config Configuration (only for PCI/IDE bridge) | |
1102 | mate Mate name | |
1103 | model Type/Chipset of IDE controller | |
1104 | .............................................................................. | |
1105 | ||
1106 | Each device connected to a controller has a separate subdirectory in the | |
349888ee | 1107 | controllers directory. The files listed in table 1-7 are contained in these |
1da177e4 LT |
1108 | directories. |
1109 | ||
1110 | ||
349888ee | 1111 | Table 1-7: IDE device information |
1da177e4 LT |
1112 | .............................................................................. |
1113 | File Content | |
1114 | cache The cache | |
1115 | capacity Capacity of the medium (in 512Byte blocks) | |
1116 | driver driver and version | |
1117 | geometry physical and logical geometry | |
1118 | identify device identify block | |
1119 | media media type | |
1120 | model device identifier | |
1121 | settings device setup | |
1122 | smart_thresholds IDE disk management thresholds | |
1123 | smart_values IDE disk management values | |
1124 | .............................................................................. | |
1125 | ||
1126 | The most interesting file is settings. This file contains a nice overview of | |
1127 | the drive parameters: | |
1128 | ||
1129 | # cat /proc/ide/ide0/hda/settings | |
1130 | name value min max mode | |
1131 | ---- ----- --- --- ---- | |
1132 | bios_cyl 526 0 65535 rw | |
1133 | bios_head 255 0 255 rw | |
1134 | bios_sect 63 0 63 rw | |
1135 | breada_readahead 4 0 127 rw | |
1136 | bswap 0 0 1 r | |
1137 | file_readahead 72 0 2097151 rw | |
1138 | io_32bit 0 0 3 rw | |
1139 | keepsettings 0 0 1 rw | |
1140 | max_kb_per_request 122 1 127 rw | |
1141 | multcount 0 0 8 rw | |
1142 | nice1 1 0 1 rw | |
1143 | nowerr 0 0 1 rw | |
1144 | pio_mode write-only 0 255 w | |
1145 | slow 0 0 1 rw | |
1146 | unmaskirq 0 0 1 rw | |
1147 | using_dma 0 0 1 rw | |
1148 | ||
1149 | ||
1150 | 1.4 Networking info in /proc/net | |
1151 | -------------------------------- | |
1152 | ||
349888ee | 1153 | The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the |
1da177e4 | 1154 | additional values you get for IP version 6 if you configure the kernel to |
349888ee | 1155 | support this. Table 1-9 lists the files and their meaning. |
1da177e4 LT |
1156 | |
1157 | ||
349888ee | 1158 | Table 1-8: IPv6 info in /proc/net |
1da177e4 LT |
1159 | .............................................................................. |
1160 | File Content | |
1161 | udp6 UDP sockets (IPv6) | |
1162 | tcp6 TCP sockets (IPv6) | |
1163 | raw6 Raw device statistics (IPv6) | |
1164 | igmp6 IP multicast addresses, which this host joined (IPv6) | |
1165 | if_inet6 List of IPv6 interface addresses | |
1166 | ipv6_route Kernel routing table for IPv6 | |
1167 | rt6_stats Global IPv6 routing tables statistics | |
1168 | sockstat6 Socket statistics (IPv6) | |
1169 | snmp6 Snmp data (IPv6) | |
1170 | .............................................................................. | |
1171 | ||
1172 | ||
349888ee | 1173 | Table 1-9: Network info in /proc/net |
1da177e4 LT |
1174 | .............................................................................. |
1175 | File Content | |
1176 | arp Kernel ARP table | |
1177 | dev network devices with statistics | |
1178 | dev_mcast the Layer2 multicast groups a device is listening too | |
1179 | (interface index, label, number of references, number of bound | |
1180 | addresses). | |
1181 | dev_stat network device status | |
1182 | ip_fwchains Firewall chain linkage | |
1183 | ip_fwnames Firewall chain names | |
1184 | ip_masq Directory containing the masquerading tables | |
1185 | ip_masquerade Major masquerading table | |
1186 | netstat Network statistics | |
1187 | raw raw device statistics | |
1188 | route Kernel routing table | |
1189 | rpc Directory containing rpc info | |
1190 | rt_cache Routing cache | |
1191 | snmp SNMP data | |
1192 | sockstat Socket statistics | |
1193 | tcp TCP sockets | |
1da177e4 LT |
1194 | udp UDP sockets |
1195 | unix UNIX domain sockets | |
1196 | wireless Wireless interface data (Wavelan etc) | |
1197 | igmp IP multicast addresses, which this host joined | |
1198 | psched Global packet scheduler parameters. | |
1199 | netlink List of PF_NETLINK sockets | |
1200 | ip_mr_vifs List of multicast virtual interfaces | |
1201 | ip_mr_cache List of multicast routing cache | |
1202 | .............................................................................. | |
1203 | ||
1204 | You can use this information to see which network devices are available in | |
1205 | your system and how much traffic was routed over those devices: | |
1206 | ||
1207 | > cat /proc/net/dev | |
1208 | Inter-|Receive |[... | |
1209 | face |bytes packets errs drop fifo frame compressed multicast|[... | |
1210 | lo: 908188 5596 0 0 0 0 0 0 [... | |
1211 | ppp0:15475140 20721 410 0 0 410 0 0 [... | |
1212 | eth0: 614530 7085 0 0 0 0 0 1 [... | |
1213 | ||
1214 | ...] Transmit | |
1215 | ...] bytes packets errs drop fifo colls carrier compressed | |
1216 | ...] 908188 5596 0 0 0 0 0 0 | |
1217 | ...] 1375103 17405 0 0 0 0 0 0 | |
1218 | ...] 1703981 5535 0 0 0 3 0 0 | |
1219 | ||
a33f3224 | 1220 | In addition, each Channel Bond interface has its own directory. For |
1da177e4 LT |
1221 | example, the bond0 device will have a directory called /proc/net/bond0/. |
1222 | It will contain information that is specific to that bond, such as the | |
1223 | current slaves of the bond, the link status of the slaves, and how | |
1224 | many times the slaves link has failed. | |
1225 | ||
1226 | 1.5 SCSI info | |
1227 | ------------- | |
1228 | ||
1229 | If you have a SCSI host adapter in your system, you'll find a subdirectory | |
1230 | named after the driver for this adapter in /proc/scsi. You'll also see a list | |
1231 | of all recognized SCSI devices in /proc/scsi: | |
1232 | ||
1233 | >cat /proc/scsi/scsi | |
1234 | Attached devices: | |
1235 | Host: scsi0 Channel: 00 Id: 00 Lun: 00 | |
1236 | Vendor: IBM Model: DGHS09U Rev: 03E0 | |
1237 | Type: Direct-Access ANSI SCSI revision: 03 | |
1238 | Host: scsi0 Channel: 00 Id: 06 Lun: 00 | |
1239 | Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04 | |
1240 | Type: CD-ROM ANSI SCSI revision: 02 | |
1241 | ||
1242 | ||
1243 | The directory named after the driver has one file for each adapter found in | |
1244 | the system. These files contain information about the controller, including | |
1245 | the used IRQ and the IO address range. The amount of information shown is | |
1246 | dependent on the adapter you use. The example shows the output for an Adaptec | |
1247 | AHA-2940 SCSI adapter: | |
1248 | ||
1249 | > cat /proc/scsi/aic7xxx/0 | |
1250 | ||
1251 | Adaptec AIC7xxx driver version: 5.1.19/3.2.4 | |
1252 | Compile Options: | |
1253 | TCQ Enabled By Default : Disabled | |
1254 | AIC7XXX_PROC_STATS : Disabled | |
1255 | AIC7XXX_RESET_DELAY : 5 | |
1256 | Adapter Configuration: | |
1257 | SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter | |
1258 | Ultra Wide Controller | |
1259 | PCI MMAPed I/O Base: 0xeb001000 | |
1260 | Adapter SEEPROM Config: SEEPROM found and used. | |
1261 | Adaptec SCSI BIOS: Enabled | |
1262 | IRQ: 10 | |
1263 | SCBs: Active 0, Max Active 2, | |
1264 | Allocated 15, HW 16, Page 255 | |
1265 | Interrupts: 160328 | |
1266 | BIOS Control Word: 0x18b6 | |
1267 | Adapter Control Word: 0x005b | |
1268 | Extended Translation: Enabled | |
1269 | Disconnect Enable Flags: 0xffff | |
1270 | Ultra Enable Flags: 0x0001 | |
1271 | Tag Queue Enable Flags: 0x0000 | |
1272 | Ordered Queue Tag Flags: 0x0000 | |
1273 | Default Tag Queue Depth: 8 | |
1274 | Tagged Queue By Device array for aic7xxx host instance 0: | |
1275 | {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255} | |
1276 | Actual queue depth per device for aic7xxx host instance 0: | |
1277 | {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1} | |
1278 | Statistics: | |
1279 | (scsi0:0:0:0) | |
1280 | Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8 | |
1281 | Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0) | |
1282 | Total transfers 160151 (74577 reads and 85574 writes) | |
1283 | (scsi0:0:6:0) | |
1284 | Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15 | |
1285 | Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0) | |
1286 | Total transfers 0 (0 reads and 0 writes) | |
1287 | ||
1288 | ||
1289 | 1.6 Parallel port info in /proc/parport | |
1290 | --------------------------------------- | |
1291 | ||
1292 | The directory /proc/parport contains information about the parallel ports of | |
1293 | your system. It has one subdirectory for each port, named after the port | |
1294 | number (0,1,2,...). | |
1295 | ||
349888ee | 1296 | These directories contain the four files shown in Table 1-10. |
1da177e4 LT |
1297 | |
1298 | ||
349888ee | 1299 | Table 1-10: Files in /proc/parport |
1da177e4 LT |
1300 | .............................................................................. |
1301 | File Content | |
1302 | autoprobe Any IEEE-1284 device ID information that has been acquired. | |
1303 | devices list of the device drivers using that port. A + will appear by the | |
1304 | name of the device currently using the port (it might not appear | |
1305 | against any). | |
1306 | hardware Parallel port's base address, IRQ line and DMA channel. | |
1307 | irq IRQ that parport is using for that port. This is in a separate | |
1308 | file to allow you to alter it by writing a new value in (IRQ | |
1309 | number or none). | |
1310 | .............................................................................. | |
1311 | ||
1312 | 1.7 TTY info in /proc/tty | |
1313 | ------------------------- | |
1314 | ||
1315 | Information about the available and actually used tty's can be found in the | |
1316 | directory /proc/tty.You'll find entries for drivers and line disciplines in | |
349888ee | 1317 | this directory, as shown in Table 1-11. |
1da177e4 LT |
1318 | |
1319 | ||
349888ee | 1320 | Table 1-11: Files in /proc/tty |
1da177e4 LT |
1321 | .............................................................................. |
1322 | File Content | |
1323 | drivers list of drivers and their usage | |
1324 | ldiscs registered line disciplines | |
1325 | driver/serial usage statistic and status of single tty lines | |
1326 | .............................................................................. | |
1327 | ||
1328 | To see which tty's are currently in use, you can simply look into the file | |
1329 | /proc/tty/drivers: | |
1330 | ||
1331 | > cat /proc/tty/drivers | |
1332 | pty_slave /dev/pts 136 0-255 pty:slave | |
1333 | pty_master /dev/ptm 128 0-255 pty:master | |
1334 | pty_slave /dev/ttyp 3 0-255 pty:slave | |
1335 | pty_master /dev/pty 2 0-255 pty:master | |
1336 | serial /dev/cua 5 64-67 serial:callout | |
1337 | serial /dev/ttyS 4 64-67 serial | |
1338 | /dev/tty0 /dev/tty0 4 0 system:vtmaster | |
1339 | /dev/ptmx /dev/ptmx 5 2 system | |
1340 | /dev/console /dev/console 5 1 system:console | |
1341 | /dev/tty /dev/tty 5 0 system:/dev/tty | |
1342 | unknown /dev/tty 4 1-63 console | |
1343 | ||
1344 | ||
1345 | 1.8 Miscellaneous kernel statistics in /proc/stat | |
1346 | ------------------------------------------------- | |
1347 | ||
1348 | Various pieces of information about kernel activity are available in the | |
1349 | /proc/stat file. All of the numbers reported in this file are aggregates | |
1350 | since the system first booted. For a quick look, simply cat the file: | |
1351 | ||
1352 | > cat /proc/stat | |
c8a329c7 TK |
1353 | cpu 2255 34 2290 22625563 6290 127 456 0 0 0 |
1354 | cpu0 1132 34 1441 11311718 3675 127 438 0 0 0 | |
1355 | cpu1 1123 0 849 11313845 2614 0 18 0 0 0 | |
1da177e4 LT |
1356 | intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...] |
1357 | ctxt 1990473 | |
1358 | btime 1062191376 | |
1359 | processes 2915 | |
1360 | procs_running 1 | |
1361 | procs_blocked 0 | |
d3d64df2 | 1362 | softirq 183433 0 21755 12 39 1137 231 21459 2263 |
1da177e4 LT |
1363 | |
1364 | The very first "cpu" line aggregates the numbers in all of the other "cpuN" | |
1365 | lines. These numbers identify the amount of time the CPU has spent performing | |
1366 | different kinds of work. Time units are in USER_HZ (typically hundredths of a | |
1367 | second). The meanings of the columns are as follows, from left to right: | |
1368 | ||
1369 | - user: normal processes executing in user mode | |
1370 | - nice: niced processes executing in user mode | |
1371 | - system: processes executing in kernel mode | |
1372 | - idle: twiddling thumbs | |
9c240d75 CF |
1373 | - iowait: In a word, iowait stands for waiting for I/O to complete. But there |
1374 | are several problems: | |
1375 | 1. Cpu will not wait for I/O to complete, iowait is the time that a task is | |
1376 | waiting for I/O to complete. When cpu goes into idle state for | |
1377 | outstanding task io, another task will be scheduled on this CPU. | |
1378 | 2. In a multi-core CPU, the task waiting for I/O to complete is not running | |
1379 | on any CPU, so the iowait of each CPU is difficult to calculate. | |
1380 | 3. The value of iowait field in /proc/stat will decrease in certain | |
1381 | conditions. | |
1382 | So, the iowait is not reliable by reading from /proc/stat. | |
1da177e4 LT |
1383 | - irq: servicing interrupts |
1384 | - softirq: servicing softirqs | |
b68f2c3a | 1385 | - steal: involuntary wait |
ce0e7b28 RO |
1386 | - guest: running a normal guest |
1387 | - guest_nice: running a niced guest | |
1da177e4 LT |
1388 | |
1389 | The "intr" line gives counts of interrupts serviced since boot time, for each | |
1390 | of the possible system interrupts. The first column is the total of all | |
3568a1db JMM |
1391 | interrupts serviced including unnumbered architecture specific interrupts; |
1392 | each subsequent column is the total for that particular numbered interrupt. | |
1393 | Unnumbered interrupts are not shown, only summed into the total. | |
1da177e4 LT |
1394 | |
1395 | The "ctxt" line gives the total number of context switches across all CPUs. | |
1396 | ||
1397 | The "btime" line gives the time at which the system booted, in seconds since | |
1398 | the Unix epoch. | |
1399 | ||
1400 | The "processes" line gives the number of processes and threads created, which | |
1401 | includes (but is not limited to) those created by calls to the fork() and | |
1402 | clone() system calls. | |
1403 | ||
e3cc2226 LGE |
1404 | The "procs_running" line gives the total number of threads that are |
1405 | running or ready to run (i.e., the total number of runnable threads). | |
1da177e4 LT |
1406 | |
1407 | The "procs_blocked" line gives the number of processes currently blocked, | |
1408 | waiting for I/O to complete. | |
1409 | ||
d3d64df2 KK |
1410 | The "softirq" line gives counts of softirqs serviced since boot time, for each |
1411 | of the possible system softirqs. The first column is the total of all | |
1412 | softirqs serviced; each subsequent column is the total for that particular | |
1413 | softirq. | |
1414 | ||
37515fac | 1415 | |
c9de560d | 1416 | 1.9 Ext4 file system parameters |
690b0543 | 1417 | ------------------------------- |
37515fac TT |
1418 | |
1419 | Information about mounted ext4 file systems can be found in | |
1420 | /proc/fs/ext4. Each mounted filesystem will have a directory in | |
1421 | /proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or | |
1422 | /proc/fs/ext4/dm-0). The files in each per-device directory are shown | |
349888ee | 1423 | in Table 1-12, below. |
37515fac | 1424 | |
349888ee | 1425 | Table 1-12: Files in /proc/fs/ext4/<devname> |
37515fac TT |
1426 | .............................................................................. |
1427 | File Content | |
1428 | mb_groups details of multiblock allocator buddy cache of free blocks | |
37515fac TT |
1429 | .............................................................................. |
1430 | ||
23308ba5 JS |
1431 | 2.0 /proc/consoles |
1432 | ------------------ | |
1433 | Shows registered system console lines. | |
1434 | ||
1435 | To see which character device lines are currently used for the system console | |
1436 | /dev/console, you may simply look into the file /proc/consoles: | |
1437 | ||
1438 | > cat /proc/consoles | |
1439 | tty0 -WU (ECp) 4:7 | |
1440 | ttyS0 -W- (Ep) 4:64 | |
1441 | ||
1442 | The columns are: | |
1443 | ||
1444 | device name of the device | |
1445 | operations R = can do read operations | |
1446 | W = can do write operations | |
1447 | U = can do unblank | |
1448 | flags E = it is enabled | |
25985edc | 1449 | C = it is preferred console |
23308ba5 JS |
1450 | B = it is primary boot console |
1451 | p = it is used for printk buffer | |
1452 | b = it is not a TTY but a Braille device | |
1453 | a = it is safe to use when cpu is offline | |
1454 | major:minor major and minor number of the device separated by a colon | |
1da177e4 LT |
1455 | |
1456 | ------------------------------------------------------------------------------ | |
1457 | Summary | |
1458 | ------------------------------------------------------------------------------ | |
1459 | The /proc file system serves information about the running system. It not only | |
1460 | allows access to process data but also allows you to request the kernel status | |
1461 | by reading files in the hierarchy. | |
1462 | ||
1463 | The directory structure of /proc reflects the types of information and makes | |
1464 | it easy, if not obvious, where to look for specific data. | |
1465 | ------------------------------------------------------------------------------ | |
1466 | ||
1467 | ------------------------------------------------------------------------------ | |
1468 | CHAPTER 2: MODIFYING SYSTEM PARAMETERS | |
1469 | ------------------------------------------------------------------------------ | |
1470 | ||
1471 | ------------------------------------------------------------------------------ | |
1472 | In This Chapter | |
1473 | ------------------------------------------------------------------------------ | |
1474 | * Modifying kernel parameters by writing into files found in /proc/sys | |
1475 | * Exploring the files which modify certain parameters | |
1476 | * Review of the /proc/sys file tree | |
1477 | ------------------------------------------------------------------------------ | |
1478 | ||
1479 | ||
1480 | A very interesting part of /proc is the directory /proc/sys. This is not only | |
1481 | a source of information, it also allows you to change parameters within the | |
1482 | kernel. Be very careful when attempting this. You can optimize your system, | |
1483 | but you can also cause it to crash. Never alter kernel parameters on a | |
1484 | production system. Set up a development machine and test to make sure that | |
1485 | everything works the way you want it to. You may have no alternative but to | |
1486 | reboot the machine once an error has been made. | |
1487 | ||
1488 | To change a value, simply echo the new value into the file. An example is | |
1489 | given below in the section on the file system data. You need to be root to do | |
1490 | this. You can create your own boot script to perform this every time your | |
1491 | system boots. | |
1492 | ||
1493 | The files in /proc/sys can be used to fine tune and monitor miscellaneous and | |
1494 | general things in the operation of the Linux kernel. Since some of the files | |
1495 | can inadvertently disrupt your system, it is advisable to read both | |
1496 | documentation and source before actually making adjustments. In any case, be | |
1497 | very careful when writing to any of these files. The entries in /proc may | |
1498 | change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt | |
1499 | review the kernel documentation in the directory /usr/src/linux/Documentation. | |
1500 | This chapter is heavily based on the documentation included in the pre 2.2 | |
1501 | kernels, and became part of it in version 2.2.1 of the Linux kernel. | |
1502 | ||
57043247 | 1503 | Please see: Documentation/admin-guide/sysctl/ directory for descriptions of these |
db0fb184 | 1504 | entries. |
9d0243bc | 1505 | |
760df93e SF |
1506 | ------------------------------------------------------------------------------ |
1507 | Summary | |
1508 | ------------------------------------------------------------------------------ | |
1509 | Certain aspects of kernel behavior can be modified at runtime, without the | |
1510 | need to recompile the kernel, or even to reboot the system. The files in the | |
1511 | /proc/sys tree can not only be read, but also modified. You can use the echo | |
1512 | command to write value into these files, thereby changing the default settings | |
1513 | of the kernel. | |
1514 | ------------------------------------------------------------------------------ | |
9d0243bc | 1515 | |
760df93e SF |
1516 | ------------------------------------------------------------------------------ |
1517 | CHAPTER 3: PER-PROCESS PARAMETERS | |
1518 | ------------------------------------------------------------------------------ | |
1da177e4 | 1519 | |
fa0cbbf1 | 1520 | 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score |
a63d83f4 DR |
1521 | -------------------------------------------------------------------------------- |
1522 | ||
fa0cbbf1 | 1523 | These file can be used to adjust the badness heuristic used to select which |
a63d83f4 DR |
1524 | process gets killed in out of memory conditions. |
1525 | ||
1526 | The badness heuristic assigns a value to each candidate task ranging from 0 | |
1527 | (never kill) to 1000 (always kill) to determine which process is targeted. The | |
1528 | units are roughly a proportion along that range of allowed memory the process | |
1529 | may allocate from based on an estimation of its current memory and swap use. | |
1530 | For example, if a task is using all allowed memory, its badness score will be | |
1531 | 1000. If it is using half of its allowed memory, its score will be 500. | |
1532 | ||
778c14af DR |
1533 | There is an additional factor included in the badness score: the current memory |
1534 | and swap usage is discounted by 3% for root processes. | |
a63d83f4 DR |
1535 | |
1536 | The amount of "allowed" memory depends on the context in which the oom killer | |
1537 | was called. If it is due to the memory assigned to the allocating task's cpuset | |
1538 | being exhausted, the allowed memory represents the set of mems assigned to that | |
1539 | cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed | |
1540 | memory represents the set of mempolicy nodes. If it is due to a memory | |
1541 | limit (or swap limit) being reached, the allowed memory is that configured | |
1542 | limit. Finally, if it is due to the entire system being out of memory, the | |
1543 | allowed memory represents all allocatable resources. | |
1544 | ||
1545 | The value of /proc/<pid>/oom_score_adj is added to the badness score before it | |
1546 | is used to determine which task to kill. Acceptable values range from -1000 | |
1547 | (OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to | |
1548 | polarize the preference for oom killing either by always preferring a certain | |
1549 | task or completely disabling it. The lowest possible value, -1000, is | |
1550 | equivalent to disabling oom killing entirely for that task since it will always | |
1551 | report a badness score of 0. | |
1552 | ||
1553 | Consequently, it is very simple for userspace to define the amount of memory to | |
1554 | consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for | |
1555 | example, is roughly equivalent to allowing the remainder of tasks sharing the | |
1556 | same system, cpuset, mempolicy, or memory controller resources to use at least | |
1557 | 50% more memory. A value of -500, on the other hand, would be roughly | |
1558 | equivalent to discounting 50% of the task's allowed memory from being considered | |
1559 | as scoring against the task. | |
1560 | ||
fa0cbbf1 DR |
1561 | For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also |
1562 | be used to tune the badness score. Its acceptable values range from -16 | |
1563 | (OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17 | |
1564 | (OOM_DISABLE) to disable oom killing entirely for that task. Its value is | |
1565 | scaled linearly with /proc/<pid>/oom_score_adj. | |
1566 | ||
dabb16f6 MSB |
1567 | The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last |
1568 | value set by a CAP_SYS_RESOURCE process. To reduce the value any lower | |
1569 | requires CAP_SYS_RESOURCE. | |
1570 | ||
a63d83f4 | 1571 | Caveat: when a parent task is selected, the oom killer will sacrifice any first |
25985edc | 1572 | generation children with separate address spaces instead, if possible. This |
a63d83f4 DR |
1573 | avoids servers and important system daemons from being killed and loses the |
1574 | minimal amount of work. | |
1575 | ||
9e9e3cbc | 1576 | |
760df93e | 1577 | 3.2 /proc/<pid>/oom_score - Display current oom-killer score |
d7ff0dbf JFM |
1578 | ------------------------------------------------------------- |
1579 | ||
d7ff0dbf | 1580 | This file can be used to check the current score used by the oom-killer is for |
fa0cbbf1 DR |
1581 | any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which |
1582 | process should be killed in an out-of-memory situation. | |
1583 | ||
f9c99463 | 1584 | |
760df93e | 1585 | 3.3 /proc/<pid>/io - Display the IO accounting fields |
f9c99463 RK |
1586 | ------------------------------------------------------- |
1587 | ||
1588 | This file contains IO statistics for each running process | |
1589 | ||
1590 | Example | |
1591 | ------- | |
1592 | ||
1593 | test:/tmp # dd if=/dev/zero of=/tmp/test.dat & | |
1594 | [1] 3828 | |
1595 | ||
1596 | test:/tmp # cat /proc/3828/io | |
1597 | rchar: 323934931 | |
1598 | wchar: 323929600 | |
1599 | syscr: 632687 | |
1600 | syscw: 632675 | |
1601 | read_bytes: 0 | |
1602 | write_bytes: 323932160 | |
1603 | cancelled_write_bytes: 0 | |
1604 | ||
1605 | ||
1606 | Description | |
1607 | ----------- | |
1608 | ||
1609 | rchar | |
1610 | ----- | |
1611 | ||
1612 | I/O counter: chars read | |
1613 | The number of bytes which this task has caused to be read from storage. This | |
1614 | is simply the sum of bytes which this process passed to read() and pread(). | |
1615 | It includes things like tty IO and it is unaffected by whether or not actual | |
1616 | physical disk IO was required (the read might have been satisfied from | |
1617 | pagecache) | |
1618 | ||
1619 | ||
1620 | wchar | |
1621 | ----- | |
1622 | ||
1623 | I/O counter: chars written | |
1624 | The number of bytes which this task has caused, or shall cause to be written | |
1625 | to disk. Similar caveats apply here as with rchar. | |
1626 | ||
1627 | ||
1628 | syscr | |
1629 | ----- | |
1630 | ||
1631 | I/O counter: read syscalls | |
1632 | Attempt to count the number of read I/O operations, i.e. syscalls like read() | |
1633 | and pread(). | |
1634 | ||
1635 | ||
1636 | syscw | |
1637 | ----- | |
1638 | ||
1639 | I/O counter: write syscalls | |
1640 | Attempt to count the number of write I/O operations, i.e. syscalls like | |
1641 | write() and pwrite(). | |
1642 | ||
1643 | ||
1644 | read_bytes | |
1645 | ---------- | |
1646 | ||
1647 | I/O counter: bytes read | |
1648 | Attempt to count the number of bytes which this process really did cause to | |
1649 | be fetched from the storage layer. Done at the submit_bio() level, so it is | |
1650 | accurate for block-backed filesystems. <please add status regarding NFS and | |
1651 | CIFS at a later time> | |
1652 | ||
1653 | ||
1654 | write_bytes | |
1655 | ----------- | |
1656 | ||
1657 | I/O counter: bytes written | |
1658 | Attempt to count the number of bytes which this process caused to be sent to | |
1659 | the storage layer. This is done at page-dirtying time. | |
1660 | ||
1661 | ||
1662 | cancelled_write_bytes | |
1663 | --------------------- | |
1664 | ||
1665 | The big inaccuracy here is truncate. If a process writes 1MB to a file and | |
1666 | then deletes the file, it will in fact perform no writeout. But it will have | |
1667 | been accounted as having caused 1MB of write. | |
1668 | In other words: The number of bytes which this process caused to not happen, | |
1669 | by truncating pagecache. A task can cause "negative" IO too. If this task | |
1670 | truncates some dirty pagecache, some IO which another task has been accounted | |
a33f3224 | 1671 | for (in its write_bytes) will not be happening. We _could_ just subtract that |
f9c99463 RK |
1672 | from the truncating task's write_bytes, but there is information loss in doing |
1673 | that. | |
1674 | ||
1675 | ||
1676 | Note | |
1677 | ---- | |
1678 | ||
1679 | At its current implementation state, this is a bit racy on 32-bit machines: if | |
1680 | process A reads process B's /proc/pid/io while process B is updating one of | |
1681 | those 64-bit counters, process A could see an intermediate result. | |
1682 | ||
1683 | ||
1684 | More information about this can be found within the taskstats documentation in | |
1685 | Documentation/accounting. | |
1686 | ||
760df93e | 1687 | 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings |
bb90110d KH |
1688 | --------------------------------------------------------------- |
1689 | When a process is dumped, all anonymous memory is written to a core file as | |
1690 | long as the size of the core file isn't limited. But sometimes we don't want | |
5037835c RZ |
1691 | to dump some memory segments, for example, huge shared memory or DAX. |
1692 | Conversely, sometimes we want to save file-backed memory segments into a core | |
1693 | file, not only the individual files. | |
bb90110d KH |
1694 | |
1695 | /proc/<pid>/coredump_filter allows you to customize which memory segments | |
1696 | will be dumped when the <pid> process is dumped. coredump_filter is a bitmask | |
1697 | of memory types. If a bit of the bitmask is set, memory segments of the | |
1698 | corresponding memory type are dumped, otherwise they are not dumped. | |
1699 | ||
5037835c | 1700 | The following 9 memory types are supported: |
bb90110d KH |
1701 | - (bit 0) anonymous private memory |
1702 | - (bit 1) anonymous shared memory | |
1703 | - (bit 2) file-backed private memory | |
1704 | - (bit 3) file-backed shared memory | |
b261dfea HK |
1705 | - (bit 4) ELF header pages in file-backed private memory areas (it is |
1706 | effective only if the bit 2 is cleared) | |
e575f111 KM |
1707 | - (bit 5) hugetlb private memory |
1708 | - (bit 6) hugetlb shared memory | |
5037835c RZ |
1709 | - (bit 7) DAX private memory |
1710 | - (bit 8) DAX shared memory | |
bb90110d KH |
1711 | |
1712 | Note that MMIO pages such as frame buffer are never dumped and vDSO pages | |
1713 | are always dumped regardless of the bitmask status. | |
1714 | ||
5037835c RZ |
1715 | Note that bits 0-4 don't affect hugetlb or DAX memory. hugetlb memory is |
1716 | only affected by bit 5-6, and DAX is only affected by bits 7-8. | |
e575f111 | 1717 | |
5037835c RZ |
1718 | The default value of coredump_filter is 0x33; this means all anonymous memory |
1719 | segments, ELF header pages and hugetlb private memory are dumped. | |
bb90110d KH |
1720 | |
1721 | If you don't want to dump all shared memory segments attached to pid 1234, | |
5037835c | 1722 | write 0x31 to the process's proc file. |
bb90110d | 1723 | |
5037835c | 1724 | $ echo 0x31 > /proc/1234/coredump_filter |
bb90110d KH |
1725 | |
1726 | When a new process is created, the process inherits the bitmask status from its | |
1727 | parent. It is useful to set up coredump_filter before the program runs. | |
1728 | For example: | |
1729 | ||
1730 | $ echo 0x7 > /proc/self/coredump_filter | |
1731 | $ ./some_program | |
1732 | ||
760df93e | 1733 | 3.5 /proc/<pid>/mountinfo - Information about mounts |
2d4d4864 RP |
1734 | -------------------------------------------------------- |
1735 | ||
1736 | This file contains lines of the form: | |
1737 | ||
1738 | 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue | |
1739 | (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) | |
1740 | ||
1741 | (1) mount ID: unique identifier of the mount (may be reused after umount) | |
1742 | (2) parent ID: ID of parent (or of self for the top of the mount tree) | |
1743 | (3) major:minor: value of st_dev for files on filesystem | |
1744 | (4) root: root of the mount within the filesystem | |
1745 | (5) mount point: mount point relative to the process's root | |
1746 | (6) mount options: per mount options | |
1747 | (7) optional fields: zero or more fields of the form "tag[:value]" | |
1748 | (8) separator: marks the end of the optional fields | |
1749 | (9) filesystem type: name of filesystem of the form "type[.subtype]" | |
1750 | (10) mount source: filesystem specific information or "none" | |
1751 | (11) super options: per super block options | |
1752 | ||
1753 | Parsers should ignore all unrecognised optional fields. Currently the | |
1754 | possible optional fields are: | |
1755 | ||
1756 | shared:X mount is shared in peer group X | |
1757 | master:X mount is slave to peer group X | |
97e7e0f7 | 1758 | propagate_from:X mount is slave and receives propagation from peer group X (*) |
2d4d4864 RP |
1759 | unbindable mount is unbindable |
1760 | ||
97e7e0f7 MS |
1761 | (*) X is the closest dominant peer group under the process's root. If |
1762 | X is the immediate master of the mount, or if there's no dominant peer | |
1763 | group under the same root, then only the "master:X" field is present | |
1764 | and not the "propagate_from:X" field. | |
1765 | ||
2d4d4864 RP |
1766 | For more information on mount propagation see: |
1767 | ||
1768 | Documentation/filesystems/sharedsubtree.txt | |
1769 | ||
4614a696 JS |
1770 | |
1771 | 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm | |
1772 | -------------------------------------------------------- | |
1773 | These files provide a method to access a tasks comm value. It also allows for | |
1774 | a task to set its own or one of its thread siblings comm value. The comm value | |
1775 | is limited in size compared to the cmdline value, so writing anything longer | |
1776 | then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated | |
1777 | comm value. | |
0499680a VK |
1778 | |
1779 | ||
81841161 CG |
1780 | 3.7 /proc/<pid>/task/<tid>/children - Information about task children |
1781 | ------------------------------------------------------------------------- | |
1782 | This file provides a fast way to retrieve first level children pids | |
1783 | of a task pointed by <pid>/<tid> pair. The format is a space separated | |
1784 | stream of pids. | |
1785 | ||
1786 | Note the "first level" here -- if a child has own children they will | |
1787 | not be listed here, one needs to read /proc/<children-pid>/task/<tid>/children | |
1788 | to obtain the descendants. | |
1789 | ||
1790 | Since this interface is intended to be fast and cheap it doesn't | |
1791 | guarantee to provide precise results and some children might be | |
1792 | skipped, especially if they've exited right after we printed their | |
1793 | pids, so one need to either stop or freeze processes being inspected | |
1794 | if precise results are needed. | |
1795 | ||
1796 | ||
49d063cb | 1797 | 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file |
f1d8c162 CG |
1798 | --------------------------------------------------------------- |
1799 | This file provides information associated with an opened file. The regular | |
49d063cb AV |
1800 | files have at least three fields -- 'pos', 'flags' and mnt_id. The 'pos' |
1801 | represents the current offset of the opened file in decimal form [see lseek(2) | |
1802 | for details], 'flags' denotes the octal O_xxx mask the file has been | |
1803 | created with [see open(2) for details] and 'mnt_id' represents mount ID of | |
1804 | the file system containing the opened file [see 3.5 /proc/<pid>/mountinfo | |
1805 | for details]. | |
f1d8c162 CG |
1806 | |
1807 | A typical output is | |
1808 | ||
1809 | pos: 0 | |
1810 | flags: 0100002 | |
49d063cb | 1811 | mnt_id: 19 |
f1d8c162 | 1812 | |
6c8c9031 AV |
1813 | All locks associated with a file descriptor are shown in its fdinfo too. |
1814 | ||
1815 | lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF | |
1816 | ||
f1d8c162 CG |
1817 | The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags |
1818 | pair provide additional information particular to the objects they represent. | |
1819 | ||
1820 | Eventfd files | |
1821 | ~~~~~~~~~~~~~ | |
1822 | pos: 0 | |
1823 | flags: 04002 | |
49d063cb | 1824 | mnt_id: 9 |
f1d8c162 CG |
1825 | eventfd-count: 5a |
1826 | ||
1827 | where 'eventfd-count' is hex value of a counter. | |
1828 | ||
1829 | Signalfd files | |
1830 | ~~~~~~~~~~~~~~ | |
1831 | pos: 0 | |
1832 | flags: 04002 | |
49d063cb | 1833 | mnt_id: 9 |
f1d8c162 CG |
1834 | sigmask: 0000000000000200 |
1835 | ||
1836 | where 'sigmask' is hex value of the signal mask associated | |
1837 | with a file. | |
1838 | ||
1839 | Epoll files | |
1840 | ~~~~~~~~~~~ | |
1841 | pos: 0 | |
1842 | flags: 02 | |
49d063cb | 1843 | mnt_id: 9 |
77493f04 | 1844 | tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7 |
f1d8c162 CG |
1845 | |
1846 | where 'tfd' is a target file descriptor number in decimal form, | |
1847 | 'events' is events mask being watched and the 'data' is data | |
1848 | associated with a target [see epoll(7) for more details]. | |
1849 | ||
77493f04 CG |
1850 | The 'pos' is current offset of the target file in decimal form |
1851 | [see lseek(2)], 'ino' and 'sdev' are inode and device numbers | |
1852 | where target file resides, all in hex format. | |
1853 | ||
f1d8c162 CG |
1854 | Fsnotify files |
1855 | ~~~~~~~~~~~~~~ | |
1856 | For inotify files the format is the following | |
1857 | ||
1858 | pos: 0 | |
1859 | flags: 02000000 | |
1860 | inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d | |
1861 | ||
1862 | where 'wd' is a watch descriptor in decimal form, ie a target file | |
1863 | descriptor number, 'ino' and 'sdev' are inode and device where the | |
1864 | target file resides and the 'mask' is the mask of events, all in hex | |
1865 | form [see inotify(7) for more details]. | |
1866 | ||
1867 | If the kernel was built with exportfs support, the path to the target | |
1868 | file is encoded as a file handle. The file handle is provided by three | |
1869 | fields 'fhandle-bytes', 'fhandle-type' and 'f_handle', all in hex | |
1870 | format. | |
1871 | ||
1872 | If the kernel is built without exportfs support the file handle won't be | |
1873 | printed out. | |
1874 | ||
e71ec593 | 1875 | If there is no inotify mark attached yet the 'inotify' line will be omitted. |
f1d8c162 | 1876 | |
e71ec593 | 1877 | For fanotify files the format is |
f1d8c162 CG |
1878 | |
1879 | pos: 0 | |
1880 | flags: 02 | |
49d063cb | 1881 | mnt_id: 9 |
e71ec593 CG |
1882 | fanotify flags:10 event-flags:0 |
1883 | fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003 | |
1884 | fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4 | |
1885 | ||
1886 | where fanotify 'flags' and 'event-flags' are values used in fanotify_init | |
1887 | call, 'mnt_id' is the mount point identifier, 'mflags' is the value of | |
1888 | flags associated with mark which are tracked separately from events | |
1889 | mask. 'ino', 'sdev' are target inode and device, 'mask' is the events | |
1890 | mask and 'ignored_mask' is the mask of events which are to be ignored. | |
1891 | All in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask' | |
1892 | does provide information about flags and mask used in fanotify_mark | |
1893 | call [see fsnotify manpage for details]. | |
1894 | ||
1895 | While the first three lines are mandatory and always printed, the rest is | |
1896 | optional and may be omitted if no marks created yet. | |
f1d8c162 | 1897 | |
854d06d9 CG |
1898 | Timerfd files |
1899 | ~~~~~~~~~~~~~ | |
1900 | ||
1901 | pos: 0 | |
1902 | flags: 02 | |
1903 | mnt_id: 9 | |
1904 | clockid: 0 | |
1905 | ticks: 0 | |
1906 | settime flags: 01 | |
1907 | it_value: (0, 49406829) | |
1908 | it_interval: (1, 0) | |
1909 | ||
1910 | where 'clockid' is the clock type and 'ticks' is the number of the timer expirations | |
1911 | that have occurred [see timerfd_create(2) for details]. 'settime flags' are | |
1912 | flags in octal form been used to setup the timer [see timerfd_settime(2) for | |
1913 | details]. 'it_value' is remaining time until the timer exiration. | |
1914 | 'it_interval' is the interval for the timer. Note the timer might be set up | |
1915 | with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value' | |
1916 | still exhibits timer's remaining time. | |
f1d8c162 | 1917 | |
740a5ddb CG |
1918 | 3.9 /proc/<pid>/map_files - Information about memory mapped files |
1919 | --------------------------------------------------------------------- | |
1920 | This directory contains symbolic links which represent memory mapped files | |
1921 | the process is maintaining. Example output: | |
1922 | ||
1923 | | lr-------- 1 root root 64 Jan 27 11:24 333c600000-333c620000 -> /usr/lib64/ld-2.18.so | |
1924 | | lr-------- 1 root root 64 Jan 27 11:24 333c81f000-333c820000 -> /usr/lib64/ld-2.18.so | |
1925 | | lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so | |
1926 | | ... | |
1927 | | lr-------- 1 root root 64 Jan 27 11:24 35d0421000-35d0422000 -> /usr/lib64/libselinux.so.1 | |
1928 | | lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls | |
1929 | ||
1930 | The name of a link represents the virtual memory bounds of a mapping, i.e. | |
1931 | vm_area_struct::vm_start-vm_area_struct::vm_end. | |
1932 | ||
1933 | The main purpose of the map_files is to retrieve a set of memory mapped | |
1934 | files in a fast way instead of parsing /proc/<pid>/maps or | |
1935 | /proc/<pid>/smaps, both of which contain many more records. At the same | |
1936 | time one can open(2) mappings from the listings of two processes and | |
1937 | comparing their inode numbers to figure out which anonymous memory areas | |
1938 | are actually shared. | |
1939 | ||
5de23d43 JS |
1940 | 3.10 /proc/<pid>/timerslack_ns - Task timerslack value |
1941 | --------------------------------------------------------- | |
1942 | This file provides the value of the task's timerslack value in nanoseconds. | |
1943 | This value specifies a amount of time that normal timers may be deferred | |
1944 | in order to coalesce timers and avoid unnecessary wakeups. | |
1945 | ||
1946 | This allows a task's interactivity vs power consumption trade off to be | |
1947 | adjusted. | |
1948 | ||
1949 | Writing 0 to the file will set the tasks timerslack to the default value. | |
1950 | ||
1951 | Valid values are from 0 - ULLONG_MAX | |
1952 | ||
1953 | An application setting the value must have PTRACE_MODE_ATTACH_FSCREDS level | |
1954 | permissions on the task specified to change its timerslack_ns value. | |
1955 | ||
7c23b330 JP |
1956 | 3.11 /proc/<pid>/patch_state - Livepatch patch operation state |
1957 | ----------------------------------------------------------------- | |
1958 | When CONFIG_LIVEPATCH is enabled, this file displays the value of the | |
1959 | patch state for the task. | |
1960 | ||
1961 | A value of '-1' indicates that no patch is in transition. | |
1962 | ||
1963 | A value of '0' indicates that a patch is in transition and the task is | |
1964 | unpatched. If the patch is being enabled, then the task hasn't been | |
1965 | patched yet. If the patch is being disabled, then the task has already | |
1966 | been unpatched. | |
1967 | ||
1968 | A value of '1' indicates that a patch is in transition and the task is | |
1969 | patched. If the patch is being enabled, then the task has already been | |
1970 | patched. If the patch is being disabled, then the task hasn't been | |
1971 | unpatched yet. | |
1972 | ||
711486fd AL |
1973 | 3.12 /proc/<pid>/arch_status - task architecture specific status |
1974 | ------------------------------------------------------------------- | |
1975 | When CONFIG_PROC_PID_ARCH_STATUS is enabled, this file displays the | |
1976 | architecture specific status of the task. | |
1977 | ||
1978 | Example | |
1979 | ------- | |
1980 | $ cat /proc/6753/arch_status | |
1981 | AVX512_elapsed_ms: 8 | |
1982 | ||
1983 | Description | |
1984 | ----------- | |
1985 | ||
1986 | x86 specific entries: | |
1987 | --------------------- | |
1988 | AVX512_elapsed_ms: | |
1989 | ------------------ | |
1990 | If AVX512 is supported on the machine, this entry shows the milliseconds | |
1991 | elapsed since the last time AVX512 usage was recorded. The recording | |
1992 | happens on a best effort basis when a task is scheduled out. This means | |
1993 | that the value depends on two factors: | |
1994 | ||
1995 | 1) The time which the task spent on the CPU without being scheduled | |
1996 | out. With CPU isolation and a single runnable task this can take | |
1997 | several seconds. | |
1998 | ||
1999 | 2) The time since the task was scheduled out last. Depending on the | |
2000 | reason for being scheduled out (time slice exhausted, syscall ...) | |
2001 | this can be arbitrary long time. | |
2002 | ||
2003 | As a consequence the value cannot be considered precise and authoritative | |
2004 | information. The application which uses this information has to be aware | |
2005 | of the overall scenario on the system in order to determine whether a | |
2006 | task is a real AVX512 user or not. Precise information can be obtained | |
2007 | with performance counters. | |
2008 | ||
2009 | A special value of '-1' indicates that no AVX512 usage was recorded, thus | |
2010 | the task is unlikely an AVX512 user, but depends on the workload and the | |
2011 | scheduling scenario, it also could be a false negative mentioned above. | |
5de23d43 | 2012 | |
0499680a VK |
2013 | ------------------------------------------------------------------------------ |
2014 | Configuring procfs | |
2015 | ------------------------------------------------------------------------------ | |
2016 | ||
2017 | 4.1 Mount options | |
2018 | --------------------- | |
2019 | ||
2020 | The following mount options are supported: | |
2021 | ||
2022 | hidepid= Set /proc/<pid>/ access mode. | |
2023 | gid= Set the group authorized to learn processes information. | |
2024 | ||
2025 | hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories | |
2026 | (default). | |
2027 | ||
2028 | hidepid=1 means users may not access any /proc/<pid>/ directories but their | |
2029 | own. Sensitive files like cmdline, sched*, status are now protected against | |
2030 | other users. This makes it impossible to learn whether any user runs | |
2031 | specific program (given the program doesn't reveal itself by its behaviour). | |
2032 | As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users, | |
2033 | poorly written programs passing sensitive information via program arguments are | |
2034 | now protected against local eavesdroppers. | |
2035 | ||
2036 | hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other | |
2037 | users. It doesn't mean that it hides a fact whether a process with a specific | |
2038 | pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"), | |
2039 | but it hides process' uid and gid, which may be learned by stat()'ing | |
2040 | /proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering | |
2041 | information about running processes, whether some daemon runs with elevated | |
2042 | privileges, whether other user runs some sensitive program, whether other users | |
2043 | run any program at all, etc. | |
2044 | ||
2045 | gid= defines a group authorized to learn processes information otherwise | |
2046 | prohibited by hidepid=. If you use some daemon like identd which needs to learn | |
2047 | information about processes information, just add identd to this group. |