1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 ==================== 3 ====================
4 The /proc Filesystem 4 The /proc Filesystem
5 ==================== 5 ====================
6 6
7 ===================== ======================= 7 ===================== ======================================= ================
8 /proc/sys Terrehon Bowden <terreho 8 /proc/sys Terrehon Bowden <terrehon@pacbell.net>, October 7 1999
9 Bodo Bauer <bb@ricochet. 9 Bodo Bauer <bb@ricochet.net>
10 2.4.x update Jorge Nerin <comandante@ 10 2.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000
11 move /proc/sys Shen Feng <shen@cn.fujit 11 move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
12 fixes/update part 1.1 Stefani Seibold <stefani 12 fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009
13 ===================== ======================= 13 ===================== ======================================= ================
14 14
15 15
16 16
17 .. Table of Contents 17 .. Table of Contents
18 18
19 0 Preface 19 0 Preface
20 0.1 Introduction/Credits 20 0.1 Introduction/Credits
21 0.2 Legal Stuff 21 0.2 Legal Stuff
22 22
23 1 Collecting System Information 23 1 Collecting System Information
24 1.1 Process-Specific Subdirectories 24 1.1 Process-Specific Subdirectories
25 1.2 Kernel data 25 1.2 Kernel data
26 1.3 IDE devices in /proc/ide 26 1.3 IDE devices in /proc/ide
27 1.4 Networking info in /proc/net 27 1.4 Networking info in /proc/net
28 1.5 SCSI info 28 1.5 SCSI info
29 1.6 Parallel port info in /proc/parport 29 1.6 Parallel port info in /proc/parport
30 1.7 TTY info in /proc/tty 30 1.7 TTY info in /proc/tty
31 1.8 Miscellaneous kernel statistics in /pr 31 1.8 Miscellaneous kernel statistics in /proc/stat
32 1.9 Ext4 file system parameters 32 1.9 Ext4 file system parameters
33 33
34 2 Modifying System Parameters 34 2 Modifying System Parameters
35 35
36 3 Per-Process Parameters 36 3 Per-Process Parameters
37 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_ 37 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer
38 38 score
39 3.2 /proc/<pid>/oom_score - Display curren 39 3.2 /proc/<pid>/oom_score - Display current oom-killer score
40 3.3 /proc/<pid>/io - Display the IO accoun 40 3.3 /proc/<pid>/io - Display the IO accounting fields
41 3.4 /proc/<pid>/coredump_filter - Core dum 41 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
42 3.5 /proc/<pid>/mountinfo - Information ab 42 3.5 /proc/<pid>/mountinfo - Information about mounts
43 3.6 /proc/<pid>/comm & /proc/<pid>/task/< 43 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
44 3.7 /proc/<pid>/task/<tid>/children - Info 44 3.7 /proc/<pid>/task/<tid>/children - Information about task children
45 3.8 /proc/<pid>/fdinfo/<fd> - Information 45 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
46 3.9 /proc/<pid>/map_files - Information ab 46 3.9 /proc/<pid>/map_files - Information about memory mapped files
47 3.10 /proc/<pid>/timerslack_ns - Task timer 47 3.10 /proc/<pid>/timerslack_ns - Task timerslack value
48 3.11 /proc/<pid>/patch_state - Livepatch pa 48 3.11 /proc/<pid>/patch_state - Livepatch patch operation state
49 3.12 /proc/<pid>/arch_status - Task archite 49 3.12 /proc/<pid>/arch_status - Task architecture specific information
50 3.13 /proc/<pid>/fd - List of symlinks to o <<
51 50
52 4 Configuring procfs 51 4 Configuring procfs
53 4.1 Mount options 52 4.1 Mount options
54 53
55 5 Filesystem behavior 54 5 Filesystem behavior
56 55
57 Preface 56 Preface
58 ======= 57 =======
59 58
60 0.1 Introduction/Credits 59 0.1 Introduction/Credits
61 ------------------------ 60 ------------------------
62 61
63 This documentation is part of a soon (or so 62 This documentation is part of a soon (or so we hope) to be released book on
64 the SuSE Linux distribution. As there is no 63 the SuSE Linux distribution. As there is no complete documentation for the
65 /proc file system and we've used many freely 64 /proc file system and we've used many freely available sources to write these
66 chapters, it seems only fair to give the wor 65 chapters, it seems only fair to give the work back to the Linux community.
67 This work is based on the 2.2.* kernel versi 66 This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm
68 afraid it's still far from complete, but we h 67 afraid it's still far from complete, but we hope it will be useful. As far as
69 we know, it is the first 'all-in-one' document 68 we know, it is the first 'all-in-one' document about the /proc file system. It
70 is focused on the Intel x86 hardware, so if 69 is focused on the Intel x86 hardware, so if you are looking for PPC, ARM,
71 SPARC, AXP, etc., features, you probably won' 70 SPARC, AXP, etc., features, you probably won't find what you are looking for.
72 It also only covers IPv4 networking, not IPv6 71 It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
73 additions and patches are welcome and will b 72 additions and patches are welcome and will be added to this document if you
74 mail them to Bodo. 73 mail them to Bodo.
75 74
76 We'd like to thank Alan Cox, Rik van Riel, a 75 We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of
77 other people for help compiling this documenta 76 other people for help compiling this documentation. We'd also like to extend a
78 special thank you to Andi Kleen for documenta 77 special thank you to Andi Kleen for documentation, which we relied on heavily
79 to create this document, as well as the add 78 to create this document, as well as the additional information he provided.
80 Thanks to everybody else who contributed so 79 Thanks to everybody else who contributed source or docs to the Linux kernel
81 and helped create a great piece of software... 80 and helped create a great piece of software... :)
82 81
83 If you have any comments, corrections or add 82 If you have any comments, corrections or additions, please don't hesitate to
84 contact Bodo Bauer at bb@ricochet.net. We' 83 contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this
85 document. 84 document.
86 85
87 The latest version of this document 86 The latest version of this document is available online at
88 https://www.kernel.org/doc/html/latest/filesys !! 87 http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html
89 88
90 If the above direction does not works for 89 If the above direction does not works for you, you could try the kernel
91 mailing list at linux-kernel@vger.kernel.or 90 mailing list at linux-kernel@vger.kernel.org and/or try to reach me at
92 comandante@zaralinux.com. 91 comandante@zaralinux.com.
93 92
94 0.2 Legal Stuff 93 0.2 Legal Stuff
95 --------------- 94 ---------------
96 95
97 We don't guarantee the correctness of this 96 We don't guarantee the correctness of this document, and if you come to us
98 complaining about how you screwed up your 97 complaining about how you screwed up your system because of incorrect
99 documentation, we won't feel responsible... 98 documentation, we won't feel responsible...
100 99
101 Chapter 1: Collecting System Information 100 Chapter 1: Collecting System Information
102 ======================================== 101 ========================================
103 102
104 In This Chapter 103 In This Chapter
105 --------------- 104 ---------------
106 * Investigating the properties of the pse 105 * Investigating the properties of the pseudo file system /proc and its
107 ability to provide information on the runnin 106 ability to provide information on the running Linux system
108 * Examining /proc's structure 107 * Examining /proc's structure
109 * Uncovering various information about the 108 * Uncovering various information about the kernel and the processes running
110 on the system 109 on the system
111 110
112 ---------------------------------------------- 111 ------------------------------------------------------------------------------
113 112
114 The proc file system acts as an interface to 113 The proc file system acts as an interface to internal data structures in the
115 kernel. It can be used to obtain informatio 114 kernel. It can be used to obtain information about the system and to change
116 certain kernel parameters at runtime (sysctl). 115 certain kernel parameters at runtime (sysctl).
117 116
118 First, we'll take a look at the read-only 117 First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
119 show you how you can use /proc/sys to change s 118 show you how you can use /proc/sys to change settings.
120 119
121 1.1 Process-Specific Subdirectories 120 1.1 Process-Specific Subdirectories
122 ----------------------------------- 121 -----------------------------------
123 122
124 The directory /proc contains (among other t 123 The directory /proc contains (among other things) one subdirectory for each
125 process running on the system, which is named 124 process running on the system, which is named after the process ID (PID).
126 125
127 The link 'self' points to the process readi 126 The link 'self' points to the process reading the file system. Each process
128 subdirectory has the entries listed in Table 1 127 subdirectory has the entries listed in Table 1-1.
129 128
130 Note that an open file descriptor to /proc/<pi 129 Note that an open file descriptor to /proc/<pid> or to any of its
131 contained files or subdirectories does not pre 130 contained files or subdirectories does not prevent <pid> being reused
132 for some other process in the event that <pid> 131 for some other process in the event that <pid> exits. Operations on
133 open /proc/<pid> file descriptors correspondin 132 open /proc/<pid> file descriptors corresponding to dead processes
134 never act on any new process that the kernel m 133 never act on any new process that the kernel may, through chance, have
135 also assigned the process ID <pid>. Instead, o 134 also assigned the process ID <pid>. Instead, operations on these FDs
136 usually fail with ESRCH. 135 usually fail with ESRCH.
137 136
138 .. table:: Table 1-1: Process specific entries 137 .. table:: Table 1-1: Process specific entries in /proc
139 138
140 ============= ============================== 139 ============= ===============================================================
141 File Content 140 File Content
142 ============= ============================== 141 ============= ===============================================================
143 clear_refs Clears page referenced bits sh 142 clear_refs Clears page referenced bits shown in smaps output
144 cmdline Command line arguments 143 cmdline Command line arguments
145 cpu Current and last cpu in which 144 cpu Current and last cpu in which it was executed (2.4)(smp)
146 cwd Link to the current working di 145 cwd Link to the current working directory
147 environ Values of environment variable 146 environ Values of environment variables
148 exe Link to the executable of this 147 exe Link to the executable of this process
149 fd Directory, which contains all 148 fd Directory, which contains all file descriptors
150 maps Memory maps to executables and 149 maps Memory maps to executables and library files (2.4)
151 mem Memory held by this process 150 mem Memory held by this process
152 root Link to the root directory of 151 root Link to the root directory of this process
153 stat Process status 152 stat Process status
154 statm Process memory status informat 153 statm Process memory status information
155 status Process status in human readab 154 status Process status in human readable form
156 wchan Present with CONFIG_KALLSYMS=y 155 wchan Present with CONFIG_KALLSYMS=y: it shows the kernel function
157 symbol the task is blocked in 156 symbol the task is blocked in - or "0" if not blocked.
158 pagemap Page table 157 pagemap Page table
159 stack Report full stack trace, enabl 158 stack Report full stack trace, enable via CONFIG_STACKTRACE
160 smaps An extension based on maps, sh 159 smaps An extension based on maps, showing the memory consumption of
161 each mapping and flags associa 160 each mapping and flags associated with it
162 smaps_rollup Accumulated smaps stats for al 161 smaps_rollup Accumulated smaps stats for all mappings of the process. This
163 can be derived from smaps, but 162 can be derived from smaps, but is faster and more convenient
164 numa_maps An extension based on maps, sh 163 numa_maps An extension based on maps, showing the memory locality and
165 binding policy as well as mem 164 binding policy as well as mem usage (in pages) of each mapping.
166 ============= ============================== 165 ============= ===============================================================
167 166
168 For example, to get the status information of 167 For example, to get the status information of a process, all you have to do is
169 read the file /proc/PID/status:: 168 read the file /proc/PID/status::
170 169
171 >cat /proc/self/status 170 >cat /proc/self/status
172 Name: cat 171 Name: cat
173 State: R (running) 172 State: R (running)
174 Tgid: 5452 173 Tgid: 5452
175 Pid: 5452 174 Pid: 5452
176 PPid: 743 175 PPid: 743
177 TracerPid: 0 176 TracerPid: 0 (2.4)
178 Uid: 501 501 501 501 177 Uid: 501 501 501 501
179 Gid: 100 100 100 100 178 Gid: 100 100 100 100
180 FDSize: 256 179 FDSize: 256
181 Groups: 100 14 16 180 Groups: 100 14 16
182 Kthread: 0 <<
183 VmPeak: 5004 kB 181 VmPeak: 5004 kB
184 VmSize: 5004 kB 182 VmSize: 5004 kB
185 VmLck: 0 kB 183 VmLck: 0 kB
186 VmHWM: 476 kB 184 VmHWM: 476 kB
187 VmRSS: 476 kB 185 VmRSS: 476 kB
188 RssAnon: 352 kB 186 RssAnon: 352 kB
189 RssFile: 120 kB 187 RssFile: 120 kB
190 RssShmem: 4 kB 188 RssShmem: 4 kB
191 VmData: 156 kB 189 VmData: 156 kB
192 VmStk: 88 kB 190 VmStk: 88 kB
193 VmExe: 68 kB 191 VmExe: 68 kB
194 VmLib: 1412 kB 192 VmLib: 1412 kB
195 VmPTE: 20 kb 193 VmPTE: 20 kb
196 VmSwap: 0 kB 194 VmSwap: 0 kB
197 HugetlbPages: 0 kB 195 HugetlbPages: 0 kB
198 CoreDumping: 0 196 CoreDumping: 0
199 THP_enabled: 1 197 THP_enabled: 1
200 Threads: 1 198 Threads: 1
201 SigQ: 0/28578 199 SigQ: 0/28578
202 SigPnd: 0000000000000000 200 SigPnd: 0000000000000000
203 ShdPnd: 0000000000000000 201 ShdPnd: 0000000000000000
204 SigBlk: 0000000000000000 202 SigBlk: 0000000000000000
205 SigIgn: 0000000000000000 203 SigIgn: 0000000000000000
206 SigCgt: 0000000000000000 204 SigCgt: 0000000000000000
207 CapInh: 00000000fffffeff 205 CapInh: 00000000fffffeff
208 CapPrm: 0000000000000000 206 CapPrm: 0000000000000000
209 CapEff: 0000000000000000 207 CapEff: 0000000000000000
210 CapBnd: ffffffffffffffff 208 CapBnd: ffffffffffffffff
211 CapAmb: 0000000000000000 209 CapAmb: 0000000000000000
212 NoNewPrivs: 0 210 NoNewPrivs: 0
213 Seccomp: 0 211 Seccomp: 0
214 Speculation_Store_Bypass: thread vulne 212 Speculation_Store_Bypass: thread vulnerable
215 SpeculationIndirectBranch: conditional 213 SpeculationIndirectBranch: conditional enabled
216 voluntary_ctxt_switches: 0 214 voluntary_ctxt_switches: 0
217 nonvoluntary_ctxt_switches: 1 215 nonvoluntary_ctxt_switches: 1
218 216
219 This shows you nearly the same information you 217 This shows you nearly the same information you would get if you viewed it with
220 the ps command. In fact, ps uses the pr 218 the ps command. In fact, ps uses the proc file system to obtain its
221 information. But you get a more detailed vie 219 information. But you get a more detailed view of the process by reading the
222 file /proc/PID/status. It fields are described 220 file /proc/PID/status. It fields are described in table 1-2.
223 221
224 The statm file contains more detailed in 222 The statm file contains more detailed information about the process
225 memory usage. Its seven fields are explained i 223 memory usage. Its seven fields are explained in Table 1-3. The stat file
226 contains detailed information about the proces 224 contains detailed information about the process itself. Its fields are
227 explained in Table 1-4. 225 explained in Table 1-4.
228 226
229 (for SMP CONFIG users) 227 (for SMP CONFIG users)
230 228
231 For making accounting scalable, RSS related in 229 For making accounting scalable, RSS related information are handled in an
232 asynchronous manner and the value may not be v 230 asynchronous manner and the value may not be very precise. To see a precise
233 snapshot of a moment, you can see /proc/<pid>/ 231 snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
234 It's slow but very precise. 232 It's slow but very precise.
235 233
236 .. table:: Table 1-2: Contents of the status f !! 234 .. table:: Table 1-2: Contents of the status files (as of 4.19)
237 235
238 ========================== ================= 236 ========================== ===================================================
239 Field Content 237 Field Content
240 ========================== ================= 238 ========================== ===================================================
241 Name filename of the e 239 Name filename of the executable
242 Umask file mode creatio 240 Umask file mode creation mask
243 State state (R is runni 241 State state (R is running, S is sleeping, D is sleeping
244 in an uninterrupt 242 in an uninterruptible wait, Z is zombie,
245 T is traced or st 243 T is traced or stopped)
246 Tgid thread group ID 244 Tgid thread group ID
247 Ngid NUMA group ID (0 245 Ngid NUMA group ID (0 if none)
248 Pid process id 246 Pid process id
249 PPid process id of the 247 PPid process id of the parent process
250 TracerPid PID of process tr !! 248 TracerPid PID of process tracing this process (0 if not)
251 the tracer is out <<
252 Uid Real, effective, 249 Uid Real, effective, saved set, and file system UIDs
253 Gid Real, effective, 250 Gid Real, effective, saved set, and file system GIDs
254 FDSize number of file de 251 FDSize number of file descriptor slots currently allocated
255 Groups supplementary gro 252 Groups supplementary group list
256 NStgid descendant namesp 253 NStgid descendant namespace thread group ID hierarchy
257 NSpid descendant namesp 254 NSpid descendant namespace process ID hierarchy
258 NSpgid descendant namesp 255 NSpgid descendant namespace process group ID hierarchy
259 NSsid descendant namesp 256 NSsid descendant namespace session ID hierarchy
260 Kthread kernel thread fla <<
261 VmPeak peak virtual memo 257 VmPeak peak virtual memory size
262 VmSize total program siz 258 VmSize total program size
263 VmLck locked memory siz 259 VmLck locked memory size
264 VmPin pinned memory siz 260 VmPin pinned memory size
265 VmHWM peak resident set 261 VmHWM peak resident set size ("high water mark")
266 VmRSS size of memory po 262 VmRSS size of memory portions. It contains the three
267 following parts 263 following parts
268 (VmRSS = RssAnon 264 (VmRSS = RssAnon + RssFile + RssShmem)
269 RssAnon size of resident 265 RssAnon size of resident anonymous memory
270 RssFile size of resident 266 RssFile size of resident file mappings
271 RssShmem size of resident 267 RssShmem size of resident shmem memory (includes SysV shm,
272 mapping of tmpfs 268 mapping of tmpfs and shared anonymous mappings)
273 VmData size of private d 269 VmData size of private data segments
274 VmStk size of stack seg 270 VmStk size of stack segments
275 VmExe size of text segm 271 VmExe size of text segment
276 VmLib size of shared li 272 VmLib size of shared library code
277 VmPTE size of page tabl 273 VmPTE size of page table entries
278 VmSwap amount of swap us 274 VmSwap amount of swap used by anonymous private data
279 (shmem swap usage 275 (shmem swap usage is not included)
280 HugetlbPages size of hugetlb m 276 HugetlbPages size of hugetlb memory portions
281 CoreDumping process's memory 277 CoreDumping process's memory is currently being dumped
282 (killing the proc 278 (killing the process may lead to a corrupted core)
283 THP_enabled process is allowe 279 THP_enabled process is allowed to use THP (returns 0 when
284 PR_SET_THP_DISABL 280 PR_SET_THP_DISABLE is set on the process
285 Threads number of threads 281 Threads number of threads
286 SigQ number of signals 282 SigQ number of signals queued/max. number for queue
287 SigPnd bitmap of pending 283 SigPnd bitmap of pending signals for the thread
288 ShdPnd bitmap of shared 284 ShdPnd bitmap of shared pending signals for the process
289 SigBlk bitmap of blocked 285 SigBlk bitmap of blocked signals
290 SigIgn bitmap of ignored 286 SigIgn bitmap of ignored signals
291 SigCgt bitmap of caught 287 SigCgt bitmap of caught signals
292 CapInh bitmap of inherit 288 CapInh bitmap of inheritable capabilities
293 CapPrm bitmap of permitt 289 CapPrm bitmap of permitted capabilities
294 CapEff bitmap of effecti 290 CapEff bitmap of effective capabilities
295 CapBnd bitmap of capabil 291 CapBnd bitmap of capabilities bounding set
296 CapAmb bitmap of ambient 292 CapAmb bitmap of ambient capabilities
297 NoNewPrivs no_new_privs, lik 293 NoNewPrivs no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...)
298 Seccomp seccomp mode, lik 294 Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...)
299 Speculation_Store_Bypass speculative store 295 Speculation_Store_Bypass speculative store bypass mitigation status
300 SpeculationIndirectBranch indirect branch s 296 SpeculationIndirectBranch indirect branch speculation mode
301 Cpus_allowed mask of CPUs on w 297 Cpus_allowed mask of CPUs on which this process may run
302 Cpus_allowed_list Same as previous, 298 Cpus_allowed_list Same as previous, but in "list format"
303 Mems_allowed mask of memory no 299 Mems_allowed mask of memory nodes allowed to this process
304 Mems_allowed_list Same as previous, 300 Mems_allowed_list Same as previous, but in "list format"
305 voluntary_ctxt_switches number of volunta 301 voluntary_ctxt_switches number of voluntary context switches
306 nonvoluntary_ctxt_switches number of non vol 302 nonvoluntary_ctxt_switches number of non voluntary context switches
307 ========================== ================= 303 ========================== ===================================================
308 304
309 305
310 .. table:: Table 1-3: Contents of the statm fi !! 306 .. table:: Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
311 307
312 ======== =============================== 308 ======== =============================== ==============================
313 Field Content 309 Field Content
314 ======== =============================== 310 ======== =============================== ==============================
315 size total program size (pages) 311 size total program size (pages) (same as VmSize in status)
316 resident size of memory portions (pages) 312 resident size of memory portions (pages) (same as VmRSS in status)
317 shared number of pages that are shared 313 shared number of pages that are shared (i.e. backed by a file, same
318 314 as RssFile+RssShmem in status)
319 trs number of pages that are 'code' 315 trs number of pages that are 'code' (not including libs; broken,
320 316 includes data segment)
321 lrs number of pages of library 317 lrs number of pages of library (always 0 on 2.6)
322 drs number of pages of data/stack 318 drs number of pages of data/stack (including libs; broken,
323 319 includes library text)
324 dt number of dirty pages 320 dt number of dirty pages (always 0 on 2.6)
325 ======== =============================== 321 ======== =============================== ==============================
326 322
327 323
328 .. table:: Table 1-4: Contents of the stat fie !! 324 .. table:: Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
329 325
330 ============= ============================== 326 ============= ===============================================================
331 Field Content 327 Field Content
332 ============= ============================== 328 ============= ===============================================================
333 pid process id 329 pid process id
334 tcomm filename of the executable 330 tcomm filename of the executable
335 state state (R is running, S is slee 331 state state (R is running, S is sleeping, D is sleeping in an
336 uninterruptible wait, Z is zom 332 uninterruptible wait, Z is zombie, T is traced or stopped)
337 ppid process id of the parent proce 333 ppid process id of the parent process
338 pgrp pgrp of the process 334 pgrp pgrp of the process
339 sid session id 335 sid session id
340 tty_nr tty the process uses 336 tty_nr tty the process uses
341 tty_pgrp pgrp of the tty 337 tty_pgrp pgrp of the tty
342 flags task flags 338 flags task flags
343 min_flt number of minor faults 339 min_flt number of minor faults
344 cmin_flt number of minor faults with ch 340 cmin_flt number of minor faults with child's
345 maj_flt number of major faults 341 maj_flt number of major faults
346 cmaj_flt number of major faults with ch 342 cmaj_flt number of major faults with child's
347 utime user mode jiffies 343 utime user mode jiffies
348 stime kernel mode jiffies 344 stime kernel mode jiffies
349 cutime user mode jiffies with child's 345 cutime user mode jiffies with child's
350 cstime kernel mode jiffies with child 346 cstime kernel mode jiffies with child's
351 priority priority level 347 priority priority level
352 nice nice level 348 nice nice level
353 num_threads number of threads 349 num_threads number of threads
354 it_real_value (obsolete, always 0) 350 it_real_value (obsolete, always 0)
355 start_time time the process started after 351 start_time time the process started after system boot
356 vsize virtual memory size 352 vsize virtual memory size
357 rss resident set memory size 353 rss resident set memory size
358 rsslim current limit in bytes on the 354 rsslim current limit in bytes on the rss
359 start_code address above which program te 355 start_code address above which program text can run
360 end_code address below which program te 356 end_code address below which program text can run
361 start_stack address of the start of the ma 357 start_stack address of the start of the main process stack
362 esp current value of ESP 358 esp current value of ESP
363 eip current value of EIP 359 eip current value of EIP
364 pending bitmap of pending signals 360 pending bitmap of pending signals
365 blocked bitmap of blocked signals 361 blocked bitmap of blocked signals
366 sigign bitmap of ignored signals 362 sigign bitmap of ignored signals
367 sigcatch bitmap of caught signals 363 sigcatch bitmap of caught signals
368 0 (place holder, used to be the 364 0 (place holder, used to be the wchan address,
369 use /proc/PID/wchan instead) 365 use /proc/PID/wchan instead)
370 0 (place holder) 366 0 (place holder)
371 0 (place holder) 367 0 (place holder)
372 exit_signal signal to send to parent threa 368 exit_signal signal to send to parent thread on exit
373 task_cpu which CPU the task is schedule 369 task_cpu which CPU the task is scheduled on
374 rt_priority realtime priority 370 rt_priority realtime priority
375 policy scheduling policy (man sched_s 371 policy scheduling policy (man sched_setscheduler)
376 blkio_ticks time spent waiting for block I 372 blkio_ticks time spent waiting for block IO
377 gtime guest time of the task in jiff 373 gtime guest time of the task in jiffies
378 cgtime guest time of the task childre 374 cgtime guest time of the task children in jiffies
379 start_data address above which program da 375 start_data address above which program data+bss is placed
380 end_data address below which program da 376 end_data address below which program data+bss is placed
381 start_brk address above which program he 377 start_brk address above which program heap can be expanded with brk()
382 arg_start address above which program co 378 arg_start address above which program command line is placed
383 arg_end address below which program co 379 arg_end address below which program command line is placed
384 env_start address above which program en 380 env_start address above which program environment is placed
385 env_end address below which program en 381 env_end address below which program environment is placed
386 exit_code the thread's exit_code in the 382 exit_code the thread's exit_code in the form reported by the waitpid
387 system call 383 system call
388 ============= ============================== 384 ============= ===============================================================
389 385
390 The /proc/PID/maps file contains the currently 386 The /proc/PID/maps file contains the currently mapped memory regions and
391 their access permissions. 387 their access permissions.
392 388
393 The format is:: 389 The format is::
394 390
395 address perms offset dev inod 391 address perms offset dev inode pathname
396 392
397 08048000-08049000 r-xp 00000000 03:00 8312 393 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test
398 08049000-0804a000 rw-p 00001000 03:00 8312 394 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
399 0804a000-0806b000 rw-p 00000000 00:00 0 395 0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
400 a7cb1000-a7cb2000 ---p 00000000 00:00 0 396 a7cb1000-a7cb2000 ---p 00000000 00:00 0
401 a7cb2000-a7eb2000 rw-p 00000000 00:00 0 397 a7cb2000-a7eb2000 rw-p 00000000 00:00 0
402 a7eb2000-a7eb3000 ---p 00000000 00:00 0 398 a7eb2000-a7eb3000 ---p 00000000 00:00 0
403 a7eb3000-a7ed5000 rw-p 00000000 00:00 0 399 a7eb3000-a7ed5000 rw-p 00000000 00:00 0
404 a7ed5000-a8008000 r-xp 00000000 03:00 4222 400 a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
405 a8008000-a800a000 r--p 00133000 03:00 4222 401 a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
406 a800a000-a800b000 rw-p 00135000 03:00 4222 402 a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
407 a800b000-a800e000 rw-p 00000000 00:00 0 403 a800b000-a800e000 rw-p 00000000 00:00 0
408 a800e000-a8022000 r-xp 00000000 03:00 1446 404 a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
409 a8022000-a8023000 r--p 00013000 03:00 1446 405 a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
410 a8023000-a8024000 rw-p 00014000 03:00 1446 406 a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
411 a8024000-a8027000 rw-p 00000000 00:00 0 407 a8024000-a8027000 rw-p 00000000 00:00 0
412 a8027000-a8043000 r-xp 00000000 03:00 8317 408 a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
413 a8043000-a8044000 r--p 0001b000 03:00 8317 409 a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
414 a8044000-a8045000 rw-p 0001c000 03:00 8317 410 a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
415 aff35000-aff4a000 rw-p 00000000 00:00 0 411 aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
416 ffffe000-fffff000 r-xp 00000000 00:00 0 412 ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
417 413
418 where "address" is the address space in the pr 414 where "address" is the address space in the process that it occupies, "perms"
419 is a set of permissions:: 415 is a set of permissions::
420 416
421 r = read 417 r = read
422 w = write 418 w = write
423 x = execute 419 x = execute
424 s = shared 420 s = shared
425 p = private (copy on write) 421 p = private (copy on write)
426 422
427 "offset" is the offset into the mapping, "dev" 423 "offset" is the offset into the mapping, "dev" is the device (major:minor), and
428 "inode" is the inode on that device. 0 indic 424 "inode" is the inode on that device. 0 indicates that no inode is associated
429 with the memory region, as the case would be w 425 with the memory region, as the case would be with BSS (uninitialized data).
430 The "pathname" shows the name associated file 426 The "pathname" shows the name associated file for this mapping. If the mapping
431 is not associated with a file: 427 is not associated with a file:
432 428
433 =================== ================== !! 429 ============= ====================================
434 [heap] the heap of the pr 430 [heap] the heap of the program
435 [stack] the stack of the m 431 [stack] the stack of the main process
436 [vdso] the "virtual dynam 432 [vdso] the "virtual dynamic shared object",
437 the kernel system 433 the kernel system call handler
438 [anon:<name>] a private anonymou !! 434 [anon:<name>] an anonymous mapping that has been
439 named by userspace 435 named by userspace
440 [anon_shmem:<name>] an anonymous share !! 436 ============= ====================================
441 been named by user <<
442 =================== ================== <<
443 437
444 or if empty, the mapping is anonymous. 438 or if empty, the mapping is anonymous.
445 439
446 Starting with 6.11 kernel, /proc/PID/maps prov <<
447 ioctl()-based API that gives ability to flexib <<
448 filter individual VMAs. This interface is bina <<
449 efficient and easy programmatic use. `struct p <<
450 linux/fs.h UAPI header, serves as an input/out <<
451 `PROCMAP_QUERY` ioctl() command. See comments <<
452 details on query semantics, supported flags, d <<
453 usage information. <<
454 <<
455 The /proc/PID/smaps is an extension based on m 440 The /proc/PID/smaps is an extension based on maps, showing the memory
456 consumption for each of the process's mappings 441 consumption for each of the process's mappings. For each mapping (aka Virtual
457 Memory Area, or VMA) there is a series of line 442 Memory Area, or VMA) there is a series of lines such as the following::
458 443
459 08048000-080bc000 r-xp 00000000 03:02 1313 444 08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
460 445
461 Size: 1084 kB 446 Size: 1084 kB
462 KernelPageSize: 4 kB 447 KernelPageSize: 4 kB
463 MMUPageSize: 4 kB 448 MMUPageSize: 4 kB
464 Rss: 892 kB 449 Rss: 892 kB
465 Pss: 374 kB 450 Pss: 374 kB
466 Pss_Dirty: 0 kB <<
467 Shared_Clean: 892 kB 451 Shared_Clean: 892 kB
468 Shared_Dirty: 0 kB 452 Shared_Dirty: 0 kB
469 Private_Clean: 0 kB 453 Private_Clean: 0 kB
470 Private_Dirty: 0 kB 454 Private_Dirty: 0 kB
471 Referenced: 892 kB 455 Referenced: 892 kB
472 Anonymous: 0 kB 456 Anonymous: 0 kB
473 KSM: 0 kB <<
474 LazyFree: 0 kB 457 LazyFree: 0 kB
475 AnonHugePages: 0 kB 458 AnonHugePages: 0 kB
476 ShmemPmdMapped: 0 kB 459 ShmemPmdMapped: 0 kB
477 Shared_Hugetlb: 0 kB 460 Shared_Hugetlb: 0 kB
478 Private_Hugetlb: 0 kB 461 Private_Hugetlb: 0 kB
479 Swap: 0 kB 462 Swap: 0 kB
480 SwapPss: 0 kB 463 SwapPss: 0 kB
481 KernelPageSize: 4 kB 464 KernelPageSize: 4 kB
482 MMUPageSize: 4 kB 465 MMUPageSize: 4 kB
483 Locked: 0 kB 466 Locked: 0 kB
484 THPeligible: 0 467 THPeligible: 0
485 VmFlags: rd ex mr mw me dw 468 VmFlags: rd ex mr mw me dw
486 469
487 The first of these lines shows the same inform 470 The first of these lines shows the same information as is displayed for the
488 mapping in /proc/PID/maps. Following lines sh 471 mapping in /proc/PID/maps. Following lines show the size of the mapping
489 (size); the size of each page allocated when b 472 (size); the size of each page allocated when backing a VMA (KernelPageSize),
490 which is usually the same as the size in the p 473 which is usually the same as the size in the page table entries; the page size
491 used by the MMU when backing a VMA (in most ca 474 used by the MMU when backing a VMA (in most cases, the same as KernelPageSize);
492 the amount of the mapping that is currently re 475 the amount of the mapping that is currently resident in RAM (RSS); the
493 process' proportional share of this mapping (P 476 process' proportional share of this mapping (PSS); and the number of clean and
494 dirty shared and private pages in the mapping. 477 dirty shared and private pages in the mapping.
495 478
496 The "proportional set size" (PSS) of a process 479 The "proportional set size" (PSS) of a process is the count of pages it has
497 in memory, where each page is divided by the n 480 in memory, where each page is divided by the number of processes sharing it.
498 So if a process has 1000 pages all to itself, 481 So if a process has 1000 pages all to itself, and 1000 shared with one other
499 process, its PSS will be 1500. "Pss_Dirty" is !! 482 process, its PSS will be 1500.
500 consists of dirty pages. ("Pss_Clean" is not <<
501 calculated by subtracting "Pss_Dirty" from "Ps <<
502 483
503 Note that even a page which is part of a MAP_S 484 Note that even a page which is part of a MAP_SHARED mapping, but has only
504 a single pte mapped, i.e. is currently used b 485 a single pte mapped, i.e. is currently used by only one process, is accounted
505 as private and not as shared. 486 as private and not as shared.
506 487
507 "Referenced" indicates the amount of memory cu 488 "Referenced" indicates the amount of memory currently marked as referenced or
508 accessed. 489 accessed.
509 490
510 "Anonymous" shows the amount of memory that do 491 "Anonymous" shows the amount of memory that does not belong to any file. Even
511 a mapping associated with a file may contain a 492 a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
512 and a page is modified, the file page is repla 493 and a page is modified, the file page is replaced by a private anonymous copy.
513 494
514 "KSM" reports how many of the pages are KSM pa <<
515 are not included, only actual KSM pages. <<
516 <<
517 "LazyFree" shows the amount of memory which is 495 "LazyFree" shows the amount of memory which is marked by madvise(MADV_FREE).
518 The memory isn't freed immediately with madvis 496 The memory isn't freed immediately with madvise(). It's freed in memory
519 pressure if the memory is clean. Please note t 497 pressure if the memory is clean. Please note that the printed value might
520 be lower than the real value due to optimizati 498 be lower than the real value due to optimizations used in the current
521 implementation. If this is not desirable pleas 499 implementation. If this is not desirable please file a bug report.
522 500
523 "AnonHugePages" shows the amount of memory bac !! 501 "AnonHugePages" shows the ammount of memory backed by transparent hugepage.
524 502
525 "ShmemPmdMapped" shows the amount of shared (s !! 503 "ShmemPmdMapped" shows the ammount of shared (shmem/tmpfs) memory backed by
526 huge pages. 504 huge pages.
527 505
528 "Shared_Hugetlb" and "Private_Hugetlb" show th !! 506 "Shared_Hugetlb" and "Private_Hugetlb" show the ammounts of memory backed by
529 hugetlbfs page which is *not* counted in "RSS" 507 hugetlbfs page which is *not* counted in "RSS" or "PSS" field for historical
530 reasons. And these are not included in {Shared 508 reasons. And these are not included in {Shared,Private}_{Clean,Dirty} field.
531 509
532 "Swap" shows how much would-be-anonymous memor 510 "Swap" shows how much would-be-anonymous memory is also used, but out on swap.
533 511
534 For shmem mappings, "Swap" includes also the s 512 For shmem mappings, "Swap" includes also the size of the mapped (and not
535 replaced by copy-on-write) part of the underly 513 replaced by copy-on-write) part of the underlying shmem object out on swap.
536 "SwapPss" shows proportional swap share of thi 514 "SwapPss" shows proportional swap share of this mapping. Unlike "Swap", this
537 does not take into account swapped out page of 515 does not take into account swapped out page of underlying shmem objects.
538 "Locked" indicates whether the mapping is lock 516 "Locked" indicates whether the mapping is locked in memory or not.
539 !! 517 "THPeligible" indicates whether the mapping is eligible for allocating THP
540 "THPeligible" indicates whether the mapping is !! 518 pages - 1 if true, 0 otherwise. It just shows the current status.
541 naturally aligned THP pages of any currently e <<
542 otherwise. <<
543 519
544 "VmFlags" field deserves a separate descriptio 520 "VmFlags" field deserves a separate description. This member represents the
545 kernel flags associated with the particular vi 521 kernel flags associated with the particular virtual memory area in two letter
546 encoded manner. The codes are the following: 522 encoded manner. The codes are the following:
547 523
548 == ==================================== 524 == =======================================
549 rd readable 525 rd readable
550 wr writeable 526 wr writeable
551 ex executable 527 ex executable
552 sh shared 528 sh shared
553 mr may read 529 mr may read
554 mw may write 530 mw may write
555 me may execute 531 me may execute
556 ms may share 532 ms may share
557 gd stack segment growns down 533 gd stack segment growns down
558 pf pure PFN range 534 pf pure PFN range
559 dw disabled write to the mapped file 535 dw disabled write to the mapped file
560 lo pages are locked in memory 536 lo pages are locked in memory
561 io memory mapped I/O area 537 io memory mapped I/O area
562 sr sequential read advise provided 538 sr sequential read advise provided
563 rr random read advise provided 539 rr random read advise provided
564 dc do not copy area on fork 540 dc do not copy area on fork
565 de do not expand area on remapping 541 de do not expand area on remapping
566 ac area is accountable 542 ac area is accountable
567 nr swap space is not reserved for the a 543 nr swap space is not reserved for the area
568 ht area uses huge tlb pages 544 ht area uses huge tlb pages
569 sf synchronous page fault 545 sf synchronous page fault
570 ar architecture specific flag 546 ar architecture specific flag
571 wf wipe on fork 547 wf wipe on fork
572 dd do not include area into core dump 548 dd do not include area into core dump
573 sd soft dirty flag 549 sd soft dirty flag
574 mm mixed map area 550 mm mixed map area
575 hg huge page advise flag 551 hg huge page advise flag
576 nh no huge page advise flag 552 nh no huge page advise flag
577 mg mergeable advise flag !! 553 mg mergable advise flag
578 bt arm64 BTI guarded page 554 bt arm64 BTI guarded page
579 mt arm64 MTE allocation tags are enable 555 mt arm64 MTE allocation tags are enabled
580 um userfaultfd missing tracking 556 um userfaultfd missing tracking
581 uw userfaultfd wr-protect tracking 557 uw userfaultfd wr-protect tracking
582 ss shadow stack page <<
583 sl sealed <<
584 == ==================================== 558 == =======================================
585 559
586 Note that there is no guarantee that every fla 560 Note that there is no guarantee that every flag and associated mnemonic will
587 be present in all further kernel releases. Thi 561 be present in all further kernel releases. Things get changed, the flags may
588 be vanished or the reverse -- new added. Inter 562 be vanished or the reverse -- new added. Interpretation of their meaning
589 might change in future as well. So each consum 563 might change in future as well. So each consumer of these flags has to
590 follow each specific kernel version for the ex 564 follow each specific kernel version for the exact semantic.
591 565
592 This file is only present if the CONFIG_MMU ke 566 This file is only present if the CONFIG_MMU kernel configuration option is
593 enabled. 567 enabled.
594 568
595 Note: reading /proc/PID/maps or /proc/PID/smap 569 Note: reading /proc/PID/maps or /proc/PID/smaps is inherently racy (consistent
596 output can be achieved only in the single read 570 output can be achieved only in the single read call).
597 571
598 This typically manifests when doing partial re 572 This typically manifests when doing partial reads of these files while the
599 memory map is being modified. Despite the rac 573 memory map is being modified. Despite the races, we do provide the following
600 guarantees: 574 guarantees:
601 575
602 1) The mapped addresses never go backwards, wh 576 1) The mapped addresses never go backwards, which implies no two
603 regions will ever overlap. 577 regions will ever overlap.
604 2) If there is something at a given vaddr duri 578 2) If there is something at a given vaddr during the entirety of the
605 life of the smaps/maps walk, there will be 579 life of the smaps/maps walk, there will be some output for it.
606 580
607 The /proc/PID/smaps_rollup file includes the s 581 The /proc/PID/smaps_rollup file includes the same fields as /proc/PID/smaps,
608 but their values are the sums of the correspon 582 but their values are the sums of the corresponding values for all mappings of
609 the process. Additionally, it contains these 583 the process. Additionally, it contains these fields:
610 584
611 - Pss_Anon 585 - Pss_Anon
612 - Pss_File 586 - Pss_File
613 - Pss_Shmem 587 - Pss_Shmem
614 588
615 They represent the proportional shares of anon 589 They represent the proportional shares of anonymous, file, and shmem pages, as
616 described for smaps above. These fields are o 590 described for smaps above. These fields are omitted in smaps since each
617 mapping identifies the type (anon, file, or sh 591 mapping identifies the type (anon, file, or shmem) of all pages it contains.
618 Thus all information in smaps_rollup can be de 592 Thus all information in smaps_rollup can be derived from smaps, but at a
619 significantly higher cost. 593 significantly higher cost.
620 594
621 The /proc/PID/clear_refs is used to reset the 595 The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
622 bits on both physical and virtual pages associ 596 bits on both physical and virtual pages associated with a process, and the
623 soft-dirty bit on pte (see Documentation/admin 597 soft-dirty bit on pte (see Documentation/admin-guide/mm/soft-dirty.rst
624 for details). 598 for details).
625 To clear the bits for all the pages associated 599 To clear the bits for all the pages associated with the process::
626 600
627 > echo 1 > /proc/PID/clear_refs 601 > echo 1 > /proc/PID/clear_refs
628 602
629 To clear the bits for the anonymous pages asso 603 To clear the bits for the anonymous pages associated with the process::
630 604
631 > echo 2 > /proc/PID/clear_refs 605 > echo 2 > /proc/PID/clear_refs
632 606
633 To clear the bits for the file mapped pages as 607 To clear the bits for the file mapped pages associated with the process::
634 608
635 > echo 3 > /proc/PID/clear_refs 609 > echo 3 > /proc/PID/clear_refs
636 610
637 To clear the soft-dirty bit:: 611 To clear the soft-dirty bit::
638 612
639 > echo 4 > /proc/PID/clear_refs 613 > echo 4 > /proc/PID/clear_refs
640 614
641 To reset the peak resident set size ("high wat 615 To reset the peak resident set size ("high water mark") to the process's
642 current value:: 616 current value::
643 617
644 > echo 5 > /proc/PID/clear_refs 618 > echo 5 > /proc/PID/clear_refs
645 619
646 Any other value written to /proc/PID/clear_ref 620 Any other value written to /proc/PID/clear_refs will have no effect.
647 621
648 The /proc/pid/pagemap gives the PFN, which can 622 The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
649 using /proc/kpageflags and number of times a p 623 using /proc/kpageflags and number of times a page is mapped using
650 /proc/kpagecount. For detailed explanation, se 624 /proc/kpagecount. For detailed explanation, see
651 Documentation/admin-guide/mm/pagemap.rst. 625 Documentation/admin-guide/mm/pagemap.rst.
652 626
653 The /proc/pid/numa_maps is an extension based 627 The /proc/pid/numa_maps is an extension based on maps, showing the memory
654 locality and binding policy, as well as the me 628 locality and binding policy, as well as the memory usage (in pages) of
655 each mapping. The output follows a general for 629 each mapping. The output follows a general format where mapping details get
656 summarized separated by blank spaces, one mapp 630 summarized separated by blank spaces, one mapping per each file line::
657 631
658 address policy mapping details 632 address policy mapping details
659 633
660 00400000 default file=/usr/local/bin/app m 634 00400000 default file=/usr/local/bin/app mapped=1 active=0 N3=1 kernelpagesize_kB=4
661 00600000 default file=/usr/local/bin/app a 635 00600000 default file=/usr/local/bin/app anon=1 dirty=1 N3=1 kernelpagesize_kB=4
662 3206000000 default file=/lib64/ld-2.12.so 636 3206000000 default file=/lib64/ld-2.12.so mapped=26 mapmax=6 N0=24 N3=2 kernelpagesize_kB=4
663 320621f000 default file=/lib64/ld-2.12.so 637 320621f000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
664 3206220000 default file=/lib64/ld-2.12.so 638 3206220000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
665 3206221000 default anon=1 dirty=1 N3=1 ker 639 3206221000 default anon=1 dirty=1 N3=1 kernelpagesize_kB=4
666 3206800000 default file=/lib64/libc-2.12.s 640 3206800000 default file=/lib64/libc-2.12.so mapped=59 mapmax=21 active=55 N0=41 N3=18 kernelpagesize_kB=4
667 320698b000 default file=/lib64/libc-2.12.s 641 320698b000 default file=/lib64/libc-2.12.so
668 3206b8a000 default file=/lib64/libc-2.12.s 642 3206b8a000 default file=/lib64/libc-2.12.so anon=2 dirty=2 N3=2 kernelpagesize_kB=4
669 3206b8e000 default file=/lib64/libc-2.12.s 643 3206b8e000 default file=/lib64/libc-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
670 3206b8f000 default anon=3 dirty=3 active=1 644 3206b8f000 default anon=3 dirty=3 active=1 N3=3 kernelpagesize_kB=4
671 7f4dc10a2000 default anon=3 dirty=3 N3=3 k 645 7f4dc10a2000 default anon=3 dirty=3 N3=3 kernelpagesize_kB=4
672 7f4dc10b4000 default anon=2 dirty=2 active 646 7f4dc10b4000 default anon=2 dirty=2 active=1 N3=2 kernelpagesize_kB=4
673 7f4dc1200000 default file=/anon_hugepage\0 647 7f4dc1200000 default file=/anon_hugepage\040(deleted) huge anon=1 dirty=1 N3=1 kernelpagesize_kB=2048
674 7fff335f0000 default stack anon=3 dirty=3 648 7fff335f0000 default stack anon=3 dirty=3 N3=3 kernelpagesize_kB=4
675 7fff3369d000 default mapped=1 mapmax=35 ac 649 7fff3369d000 default mapped=1 mapmax=35 active=0 N3=1 kernelpagesize_kB=4
676 650
677 Where: 651 Where:
678 652
679 "address" is the starting address for the mapp 653 "address" is the starting address for the mapping;
680 654
681 "policy" reports the NUMA memory policy set fo 655 "policy" reports the NUMA memory policy set for the mapping (see Documentation/admin-guide/mm/numa_memory_policy.rst);
682 656
683 "mapping details" summarizes mapping data such 657 "mapping details" summarizes mapping data such as mapping type, page usage counters,
684 node locality page counters (N0 == node0, N1 = 658 node locality page counters (N0 == node0, N1 == node1, ...) and the kernel page
685 size, in KB, that is backing the mapping up. 659 size, in KB, that is backing the mapping up.
686 660
687 1.2 Kernel data 661 1.2 Kernel data
688 --------------- 662 ---------------
689 663
690 Similar to the process entries, the kernel d 664 Similar to the process entries, the kernel data files give information about
691 the running kernel. The files used to obtain t 665 the running kernel. The files used to obtain this information are contained in
692 /proc and are listed in Table 1-5. Not all 666 /proc and are listed in Table 1-5. Not all of these will be present in your
693 system. It depends on the kernel configurati 667 system. It depends on the kernel configuration and the loaded modules, which
694 files are there, and which are missing. 668 files are there, and which are missing.
695 669
696 .. table:: Table 1-5: Kernel info in /proc 670 .. table:: Table 1-5: Kernel info in /proc
697 671
698 ============ ================================ 672 ============ ===============================================================
699 File Content 673 File Content
700 ============ ================================ 674 ============ ===============================================================
701 allocinfo Memory allocations profiling inf <<
702 apm Advanced power management info 675 apm Advanced power management info
703 bootconfig Kernel command line obtained fro <<
704 and, if there were kernel parame <<
705 boot loader, a "# Parameters fro <<
706 line followed by a line containi <<
707 parameters prefixed by "# ". <<
708 buddyinfo Kernel memory allocator informat 676 buddyinfo Kernel memory allocator information (see text) (2.5)
709 bus Directory containing bus specifi 677 bus Directory containing bus specific information
710 cmdline Kernel command line, both from b !! 678 cmdline Kernel command line
711 in the kernel image <<
712 cpuinfo Info about the CPU 679 cpuinfo Info about the CPU
713 devices Available devices (block and cha 680 devices Available devices (block and character)
714 dma Used DMS channels 681 dma Used DMS channels
715 filesystems Supported filesystems 682 filesystems Supported filesystems
716 driver Various drivers grouped here, cu 683 driver Various drivers grouped here, currently rtc (2.4)
717 execdomains Execdomains, related to security 684 execdomains Execdomains, related to security (2.4)
718 fb Frame Buffer devices 685 fb Frame Buffer devices (2.4)
719 fs File system parameters, currentl 686 fs File system parameters, currently nfs/exports (2.4)
720 ide Directory containing info about 687 ide Directory containing info about the IDE subsystem
721 interrupts Interrupt usage 688 interrupts Interrupt usage
722 iomem Memory map 689 iomem Memory map (2.4)
723 ioports I/O port usage 690 ioports I/O port usage
724 irq Masks for irq to cpu affinity 691 irq Masks for irq to cpu affinity (2.4)(smp?)
725 isapnp ISA PnP (Plug&Play) Info 692 isapnp ISA PnP (Plug&Play) Info (2.4)
726 kcore Kernel core image (can be ELF or 693 kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
727 kmsg Kernel messages 694 kmsg Kernel messages
728 ksyms Kernel symbol table 695 ksyms Kernel symbol table
729 loadavg Load average of last 1, 5 & 15 m 696 loadavg Load average of last 1, 5 & 15 minutes;
730 number of processes currently 697 number of processes currently runnable (running or on ready queue);
731 total number of processes in s 698 total number of processes in system;
732 last pid created. 699 last pid created.
733 All fields are separated by on 700 All fields are separated by one space except "number of
734 processes currently runnable" 701 processes currently runnable" and "total number of processes
735 in system", which are separate 702 in system", which are separated by a slash ('/'). Example:
736 0.61 0.61 0.55 3/828 22084 703 0.61 0.61 0.55 3/828 22084
737 locks Kernel locks 704 locks Kernel locks
738 meminfo Memory info 705 meminfo Memory info
739 misc Miscellaneous 706 misc Miscellaneous
740 modules List of loaded modules 707 modules List of loaded modules
741 mounts Mounted filesystems 708 mounts Mounted filesystems
742 net Networking info (see text) 709 net Networking info (see text)
743 pagetypeinfo Additional page allocator inform 710 pagetypeinfo Additional page allocator information (see text) (2.5)
744 partitions Table of partitions known to the 711 partitions Table of partitions known to the system
745 pci Deprecated info of PCI bus (new 712 pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
746 decoupled by lspci 713 decoupled by lspci (2.4)
747 rtc Real time clock 714 rtc Real time clock
748 scsi SCSI info (see text) 715 scsi SCSI info (see text)
749 slabinfo Slab pool info 716 slabinfo Slab pool info
750 softirqs softirq usage 717 softirqs softirq usage
751 stat Overall statistics 718 stat Overall statistics
752 swaps Swap space utilization 719 swaps Swap space utilization
753 sys See chapter 2 720 sys See chapter 2
754 sysvipc Info of SysVIPC Resources (msg, 721 sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
755 tty Info of tty drivers 722 tty Info of tty drivers
756 uptime Wall clock since boot, combined 723 uptime Wall clock since boot, combined idle time of all cpus
757 version Kernel version 724 version Kernel version
758 video bttv info of video resources 725 video bttv info of video resources (2.4)
759 vmallocinfo Show vmalloced areas 726 vmallocinfo Show vmalloced areas
760 ============ ================================ 727 ============ ===============================================================
761 728
762 You can, for example, check which interrup 729 You can, for example, check which interrupts are currently in use and what
763 they are used for by looking in the file /proc 730 they are used for by looking in the file /proc/interrupts::
764 731
765 > cat /proc/interrupts 732 > cat /proc/interrupts
766 CPU0 733 CPU0
767 0: 8728810 XT-PIC timer 734 0: 8728810 XT-PIC timer
768 1: 895 XT-PIC keyboard 735 1: 895 XT-PIC keyboard
769 2: 0 XT-PIC cascade 736 2: 0 XT-PIC cascade
770 3: 531695 XT-PIC aha152x 737 3: 531695 XT-PIC aha152x
771 4: 2014133 XT-PIC serial 738 4: 2014133 XT-PIC serial
772 5: 44401 XT-PIC pcnet_cs 739 5: 44401 XT-PIC pcnet_cs
773 8: 2 XT-PIC rtc 740 8: 2 XT-PIC rtc
774 11: 8 XT-PIC i82365 741 11: 8 XT-PIC i82365
775 12: 182918 XT-PIC PS/2 Mouse 742 12: 182918 XT-PIC PS/2 Mouse
776 13: 1 XT-PIC fpu 743 13: 1 XT-PIC fpu
777 14: 1232265 XT-PIC ide0 744 14: 1232265 XT-PIC ide0
778 15: 7 XT-PIC ide1 745 15: 7 XT-PIC ide1
779 NMI: 0 746 NMI: 0
780 747
781 In 2.4.* a couple of lines where added to this 748 In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
782 output of a SMP machine):: 749 output of a SMP machine)::
783 750
784 > cat /proc/interrupts 751 > cat /proc/interrupts
785 752
786 CPU0 CPU1 753 CPU0 CPU1
787 0: 1243498 1214548 IO-APIC-edge 754 0: 1243498 1214548 IO-APIC-edge timer
788 1: 8949 8958 IO-APIC-edge 755 1: 8949 8958 IO-APIC-edge keyboard
789 2: 0 0 XT-PIC 756 2: 0 0 XT-PIC cascade
790 5: 11286 10161 IO-APIC-edge 757 5: 11286 10161 IO-APIC-edge soundblaster
791 8: 1 0 IO-APIC-edge 758 8: 1 0 IO-APIC-edge rtc
792 9: 27422 27407 IO-APIC-edge 759 9: 27422 27407 IO-APIC-edge 3c503
793 12: 113645 113873 IO-APIC-edge 760 12: 113645 113873 IO-APIC-edge PS/2 Mouse
794 13: 0 0 XT-PIC 761 13: 0 0 XT-PIC fpu
795 14: 22491 24012 IO-APIC-edge 762 14: 22491 24012 IO-APIC-edge ide0
796 15: 2183 2415 IO-APIC-edge 763 15: 2183 2415 IO-APIC-edge ide1
797 17: 30564 30414 IO-APIC-level 764 17: 30564 30414 IO-APIC-level eth0
798 18: 177 164 IO-APIC-level 765 18: 177 164 IO-APIC-level bttv
799 NMI: 2457961 2457959 766 NMI: 2457961 2457959
800 LOC: 2457882 2457881 767 LOC: 2457882 2457881
801 ERR: 2155 768 ERR: 2155
802 769
803 NMI is incremented in this case because every 770 NMI is incremented in this case because every timer interrupt generates a NMI
804 (Non Maskable Interrupt) which is used by the 771 (Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups.
805 772
806 LOC is the local interrupt counter of the inte 773 LOC is the local interrupt counter of the internal APIC of every CPU.
807 774
808 ERR is incremented in the case of errors in th 775 ERR is incremented in the case of errors in the IO-APIC bus (the bus that
809 connects the CPUs in a SMP system. This means 776 connects the CPUs in a SMP system. This means that an error has been detected,
810 the IO-APIC automatically retry the transmissi 777 the IO-APIC automatically retry the transmission, so it should not be a big
811 problem, but you should read the SMP-FAQ. 778 problem, but you should read the SMP-FAQ.
812 779
813 In 2.6.2* /proc/interrupts was expanded again. 780 In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
814 /proc/interrupts to display every IRQ vector i 781 /proc/interrupts to display every IRQ vector in use by the system, not
815 just those considered 'most important'. The n 782 just those considered 'most important'. The new vectors are:
816 783
817 THR 784 THR
818 interrupt raised when a machine check thresh 785 interrupt raised when a machine check threshold counter
819 (typically counting ECC corrected errors of 786 (typically counting ECC corrected errors of memory or cache) exceeds
820 a configurable threshold. Only available on 787 a configurable threshold. Only available on some systems.
821 788
822 TRM 789 TRM
823 a thermal event interrupt occurs when a temp 790 a thermal event interrupt occurs when a temperature threshold
824 has been exceeded for the CPU. This interru 791 has been exceeded for the CPU. This interrupt may also be generated
825 when the temperature drops back to normal. 792 when the temperature drops back to normal.
826 793
827 SPU 794 SPU
828 a spurious interrupt is some interrupt that 795 a spurious interrupt is some interrupt that was raised then lowered
829 by some IO device before it could be fully p 796 by some IO device before it could be fully processed by the APIC. Hence
830 the APIC sees the interrupt but does not kno 797 the APIC sees the interrupt but does not know what device it came from.
831 For this case the APIC will generate the int 798 For this case the APIC will generate the interrupt with a IRQ vector
832 of 0xff. This might also be generated by chi 799 of 0xff. This might also be generated by chipset bugs.
833 800
834 RES, CAL, TLB 801 RES, CAL, TLB
835 rescheduling, call and TLB flush interrupts 802 rescheduling, call and TLB flush interrupts are
836 sent from one CPU to another per the needs o 803 sent from one CPU to another per the needs of the OS. Typically,
837 their statistics are used by kernel develope 804 their statistics are used by kernel developers and interested users to
838 determine the occurrence of interrupts of th 805 determine the occurrence of interrupts of the given type.
839 806
840 The above IRQ vectors are displayed only when 807 The above IRQ vectors are displayed only when relevant. For example,
841 the threshold vector does not exist on x86_64 808 the threshold vector does not exist on x86_64 platforms. Others are
842 suppressed when the system is a uniprocessor. 809 suppressed when the system is a uniprocessor. As of this writing, only
843 i386 and x86_64 platforms support the new IRQ 810 i386 and x86_64 platforms support the new IRQ vector displays.
844 811
845 Of some interest is the introduction of the /p 812 Of some interest is the introduction of the /proc/irq directory to 2.4.
846 It could be used to set IRQ to CPU affinity. T 813 It could be used to set IRQ to CPU affinity. This means that you can "hook" an
847 IRQ to only one CPU, or to exclude a CPU of ha 814 IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
848 irq subdir is one subdir for each IRQ, and two 815 irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and
849 prof_cpu_mask. 816 prof_cpu_mask.
850 817
851 For example:: 818 For example::
852 819
853 > ls /proc/irq/ 820 > ls /proc/irq/
854 0 10 12 14 16 18 2 4 6 8 prof_cpu_ 821 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
855 1 11 13 15 17 19 3 5 7 9 default_s 822 1 11 13 15 17 19 3 5 7 9 default_smp_affinity
856 > ls /proc/irq/0/ 823 > ls /proc/irq/0/
857 smp_affinity 824 smp_affinity
858 825
859 smp_affinity is a bitmask, in which you can sp 826 smp_affinity is a bitmask, in which you can specify which CPUs can handle the
860 IRQ. You can set it by doing:: 827 IRQ. You can set it by doing::
861 828
862 > echo 1 > /proc/irq/10/smp_affinity 829 > echo 1 > /proc/irq/10/smp_affinity
863 830
864 This means that only the first CPU will handle 831 This means that only the first CPU will handle the IRQ, but you can also echo
865 5 which means that only the first and third CP 832 5 which means that only the first and third CPU can handle the IRQ.
866 833
867 The contents of each smp_affinity file is the 834 The contents of each smp_affinity file is the same by default::
868 835
869 > cat /proc/irq/0/smp_affinity 836 > cat /proc/irq/0/smp_affinity
870 ffffffff 837 ffffffff
871 838
872 There is an alternate interface, smp_affinity_ 839 There is an alternate interface, smp_affinity_list which allows specifying
873 a CPU range instead of a bitmask:: 840 a CPU range instead of a bitmask::
874 841
875 > cat /proc/irq/0/smp_affinity_list 842 > cat /proc/irq/0/smp_affinity_list
876 1024-1031 843 1024-1031
877 844
878 The default_smp_affinity mask applies to all n 845 The default_smp_affinity mask applies to all non-active IRQs, which are the
879 IRQs which have not yet been allocated/activat 846 IRQs which have not yet been allocated/activated, and hence which lack a
880 /proc/irq/[0-9]* directory. 847 /proc/irq/[0-9]* directory.
881 848
882 The node file on an SMP system shows the node 849 The node file on an SMP system shows the node to which the device using the IRQ
883 reports itself as being attached. This hardwar 850 reports itself as being attached. This hardware locality information does not
884 include information about any possible driver 851 include information about any possible driver locality preference.
885 852
886 prof_cpu_mask specifies which CPUs are to be p 853 prof_cpu_mask specifies which CPUs are to be profiled by the system wide
887 profiler. Default value is ffffffff (all CPUs 854 profiler. Default value is ffffffff (all CPUs if there are only 32 of them).
888 855
889 The way IRQs are routed is handled by the IO-A 856 The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
890 between all the CPUs which are allowed to hand 857 between all the CPUs which are allowed to handle it. As usual the kernel has
891 more info than you and does a better job than 858 more info than you and does a better job than you, so the defaults are the
892 best choice for almost everyone. [Note this a 859 best choice for almost everyone. [Note this applies only to those IO-APIC's
893 that support "Round Robin" interrupt distribut 860 that support "Round Robin" interrupt distribution.]
894 861
895 There are three more important subdirectori 862 There are three more important subdirectories in /proc: net, scsi, and sys.
896 The general rule is that the contents, o 863 The general rule is that the contents, or even the existence of these
897 directories, depend on your kernel configurat 864 directories, depend on your kernel configuration. If SCSI is not enabled, the
898 directory scsi may not exist. The same is t 865 directory scsi may not exist. The same is true with the net, which is there
899 only when networking support is present in the 866 only when networking support is present in the running kernel.
900 867
901 The slabinfo file gives information about 868 The slabinfo file gives information about memory usage at the slab level.
902 Linux uses slab pools for memory management 869 Linux uses slab pools for memory management above page level in version 2.2.
903 Commonly used objects have their own slab 870 Commonly used objects have their own slab pool (such as network buffers,
904 directory cache, and so on). 871 directory cache, and so on).
905 872
906 :: 873 ::
907 874
908 > cat /proc/buddyinfo 875 > cat /proc/buddyinfo
909 876
910 Node 0, zone DMA 0 4 5 877 Node 0, zone DMA 0 4 5 4 4 3 ...
911 Node 0, zone Normal 1 0 0 878 Node 0, zone Normal 1 0 0 1 101 8 ...
912 Node 0, zone HighMem 2 0 0 879 Node 0, zone HighMem 2 0 0 1 1 0 ...
913 880
914 External fragmentation is a problem under some 881 External fragmentation is a problem under some workloads, and buddyinfo is a
915 useful tool for helping diagnose these problem 882 useful tool for helping diagnose these problems. Buddyinfo will give you a
916 clue as to how big an area you can safely allo 883 clue as to how big an area you can safely allocate, or why a previous
917 allocation failed. 884 allocation failed.
918 885
919 Each column represents the number of pages of 886 Each column represents the number of pages of a certain order which are
920 available. In this case, there are 0 chunks o 887 available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in
921 ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DM 888 ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
922 available in ZONE_NORMAL, etc... 889 available in ZONE_NORMAL, etc...
923 890
924 More information relevant to external fragment 891 More information relevant to external fragmentation can be found in
925 pagetypeinfo:: 892 pagetypeinfo::
926 893
927 > cat /proc/pagetypeinfo 894 > cat /proc/pagetypeinfo
928 Page block order: 9 895 Page block order: 9
929 Pages per block: 512 896 Pages per block: 512
930 897
931 Free pages count per migrate type at order 898 Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
932 Node 0, zone DMA, type Unmovabl 899 Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
933 Node 0, zone DMA, type Reclaimabl 900 Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
934 Node 0, zone DMA, type Movabl 901 Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
935 Node 0, zone DMA, type Reserv 902 Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
936 Node 0, zone DMA, type Isolat 903 Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
937 Node 0, zone DMA32, type Unmovabl 904 Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
938 Node 0, zone DMA32, type Reclaimabl 905 Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
939 Node 0, zone DMA32, type Movabl 906 Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
940 Node 0, zone DMA32, type Reserv 907 Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
941 Node 0, zone DMA32, type Isolat 908 Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
942 909
943 Number of blocks type Unmovable Recla 910 Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
944 Node 0, zone DMA 2 911 Node 0, zone DMA 2 0 5 1 0
945 Node 0, zone DMA32 41 912 Node 0, zone DMA32 41 6 967 2 0
946 913
947 Fragmentation avoidance in the kernel works by 914 Fragmentation avoidance in the kernel works by grouping pages of different
948 migrate types into the same contiguous regions 915 migrate types into the same contiguous regions of memory called page blocks.
949 A page block is typically the size of the defa 916 A page block is typically the size of the default hugepage size, e.g. 2MB on
950 X86-64. By keeping pages grouped based on thei 917 X86-64. By keeping pages grouped based on their ability to move, the kernel
951 can reclaim pages within a page block to satis 918 can reclaim pages within a page block to satisfy a high-order allocation.
952 919
953 The pagetypinfo begins with information on the 920 The pagetypinfo begins with information on the size of a page block. It
954 then gives the same type of information as bud 921 then gives the same type of information as buddyinfo except broken down
955 by migrate-type and finishes with details on h 922 by migrate-type and finishes with details on how many page blocks of each
956 type exist. 923 type exist.
957 924
958 If min_free_kbytes has been tuned correctly (r 925 If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
959 from libhugetlbfs https://github.com/libhugetl 926 from libhugetlbfs https://github.com/libhugetlbfs/libhugetlbfs/), one can
960 make an estimate of the likely number of huge 927 make an estimate of the likely number of huge pages that can be allocated
961 at a given point in time. All the "Movable" bl 928 at a given point in time. All the "Movable" blocks should be allocatable
962 unless memory has been mlock()'d. Some of the 929 unless memory has been mlock()'d. Some of the Reclaimable blocks should
963 also be allocatable although a lot of filesyst 930 also be allocatable although a lot of filesystem metadata may have to be
964 reclaimed to achieve this. 931 reclaimed to achieve this.
965 932
966 933
967 allocinfo <<
968 ~~~~~~~~~ <<
969 <<
970 Provides information about memory allocations <<
971 base. Each allocation in the code is identifie <<
972 number, module (if originates from a loadable <<
973 the allocation. The number of bytes allocated <<
974 location are reported. The first line indicate <<
975 second line is the header listing fields in th <<
976 <<
977 Example output. <<
978 <<
979 :: <<
980 <<
981 > tail -n +3 /proc/allocinfo | sort -rn <<
982 127664128 31168 mm/page_ext.c:270 func:a <<
983 56373248 4737 mm/slub.c:2259 func:allo <<
984 14880768 3633 mm/readahead.c:247 func: <<
985 14417920 3520 mm/mm_init.c:2530 func:a <<
986 13377536 234 block/blk-mq.c:3421 func <<
987 11718656 2861 mm/filemap.c:1919 func:_ <<
988 9192960 2800 kernel/fork.c:307 func:a <<
989 4206592 4 net/netfilter/nf_conntra <<
990 4136960 1010 drivers/staging/ctagmod/ <<
991 3940352 962 mm/memory.c:4214 func:al <<
992 2894464 22613 fs/kernfs/dir.c:615 func <<
993 ... <<
994 <<
995 <<
996 meminfo 934 meminfo
997 ~~~~~~~ 935 ~~~~~~~
998 936
999 Provides information about distribution and ut 937 Provides information about distribution and utilization of memory. This
1000 varies by architecture and compile options. 938 varies by architecture and compile options. Some of the counters reported
1001 here overlap. The memory reported by the non 939 here overlap. The memory reported by the non overlapping counters may not
1002 add up to the overall memory usage and the di 940 add up to the overall memory usage and the difference for some workloads
1003 can be substantial. In many cases there are 941 can be substantial. In many cases there are other means to find out
1004 additional memory using subsystem specific in 942 additional memory using subsystem specific interfaces, for instance
1005 /proc/net/sockstat for TCP memory allocations 943 /proc/net/sockstat for TCP memory allocations.
1006 944
1007 Example output. You may not have all of these !! 945 The following is from a 16GB PIII, which has highmem enabled.
>> 946 You may not have all of these fields.
1008 947
1009 :: 948 ::
1010 949
1011 > cat /proc/meminfo 950 > cat /proc/meminfo
1012 951
1013 MemTotal: 32858820 kB !! 952 MemTotal: 16344972 kB
1014 MemFree: 21001236 kB !! 953 MemFree: 13634064 kB
1015 MemAvailable: 27214312 kB !! 954 MemAvailable: 14836172 kB
1016 Buffers: 581092 kB !! 955 Buffers: 3656 kB
1017 Cached: 5587612 kB !! 956 Cached: 1195708 kB
1018 SwapCached: 0 kB !! 957 SwapCached: 0 kB
1019 Active: 3237152 kB !! 958 Active: 891636 kB
1020 Inactive: 7586256 kB !! 959 Inactive: 1077224 kB
1021 Active(anon): 94064 kB !! 960 HighTotal: 15597528 kB
1022 Inactive(anon): 4570616 kB !! 961 HighFree: 13629632 kB
1023 Active(file): 3143088 kB !! 962 LowTotal: 747444 kB
1024 Inactive(file): 3015640 kB !! 963 LowFree: 4432 kB
1025 Unevictable: 0 kB !! 964 SwapTotal: 0 kB
1026 Mlocked: 0 kB !! 965 SwapFree: 0 kB
1027 SwapTotal: 0 kB !! 966 Dirty: 968 kB
1028 SwapFree: 0 kB !! 967 Writeback: 0 kB
1029 Zswap: 1904 kB !! 968 AnonPages: 861800 kB
1030 Zswapped: 7792 kB !! 969 Mapped: 280372 kB
1031 Dirty: 12 kB !! 970 Shmem: 644 kB
1032 Writeback: 0 kB !! 971 KReclaimable: 168048 kB
1033 AnonPages: 4654780 kB !! 972 Slab: 284364 kB
1034 Mapped: 266244 kB !! 973 SReclaimable: 159856 kB
1035 Shmem: 9976 kB !! 974 SUnreclaim: 124508 kB
1036 KReclaimable: 517708 kB !! 975 PageTables: 24448 kB
1037 Slab: 660044 kB !! 976 NFS_Unstable: 0 kB
1038 SReclaimable: 517708 kB !! 977 Bounce: 0 kB
1039 SUnreclaim: 142336 kB !! 978 WritebackTmp: 0 kB
1040 KernelStack: 11168 kB !! 979 CommitLimit: 7669796 kB
1041 PageTables: 20540 kB !! 980 Committed_AS: 100056 kB
1042 SecPageTables: 0 kB !! 981 VmallocTotal: 112216 kB
1043 NFS_Unstable: 0 kB !! 982 VmallocUsed: 428 kB
1044 Bounce: 0 kB !! 983 VmallocChunk: 111088 kB
1045 WritebackTmp: 0 kB !! 984 Percpu: 62080 kB
1046 CommitLimit: 16429408 kB !! 985 HardwareCorrupted: 0 kB
1047 Committed_AS: 7715148 kB !! 986 AnonHugePages: 49152 kB
1048 VmallocTotal: 34359738367 kB !! 987 ShmemHugePages: 0 kB
1049 VmallocUsed: 40444 kB !! 988 ShmemPmdMapped: 0 kB
1050 VmallocChunk: 0 kB <<
1051 Percpu: 29312 kB <<
1052 EarlyMemtestBad: 0 kB <<
1053 HardwareCorrupted: 0 kB <<
1054 AnonHugePages: 4149248 kB <<
1055 ShmemHugePages: 0 kB <<
1056 ShmemPmdMapped: 0 kB <<
1057 FileHugePages: 0 kB <<
1058 FilePmdMapped: 0 kB <<
1059 CmaTotal: 0 kB <<
1060 CmaFree: 0 kB <<
1061 HugePages_Total: 0 <<
1062 HugePages_Free: 0 <<
1063 HugePages_Rsvd: 0 <<
1064 HugePages_Surp: 0 <<
1065 Hugepagesize: 2048 kB <<
1066 Hugetlb: 0 kB <<
1067 DirectMap4k: 401152 kB <<
1068 DirectMap2M: 10008576 kB <<
1069 DirectMap1G: 24117248 kB <<
1070 989
1071 MemTotal 990 MemTotal
1072 Total usable RAM (i.e. physical 991 Total usable RAM (i.e. physical RAM minus a few reserved
1073 bits and the kernel binary code 992 bits and the kernel binary code)
1074 MemFree 993 MemFree
1075 Total free RAM. On highmem syst !! 994 The sum of LowFree+HighFree
1076 MemAvailable 995 MemAvailable
1077 An estimate of how much memory 996 An estimate of how much memory is available for starting new
1078 applications, without swapping. 997 applications, without swapping. Calculated from MemFree,
1079 SReclaimable, the size of the f 998 SReclaimable, the size of the file LRU lists, and the low
1080 watermarks in each zone. 999 watermarks in each zone.
1081 The estimate takes into account 1000 The estimate takes into account that the system needs some
1082 page cache to function well, an 1001 page cache to function well, and that not all reclaimable
1083 slab will be reclaimable, due t 1002 slab will be reclaimable, due to items being in use. The
1084 impact of those factors will va 1003 impact of those factors will vary from system to system.
1085 Buffers 1004 Buffers
1086 Relatively temporary storage fo 1005 Relatively temporary storage for raw disk blocks
1087 shouldn't get tremendously larg 1006 shouldn't get tremendously large (20MB or so)
1088 Cached 1007 Cached
1089 In-memory cache for files read !! 1008 in-memory cache for files read from the disk (the
1090 pagecache) as well as tmpfs & s !! 1009 pagecache). Doesn't include SwapCached
1091 Doesn't include SwapCached. <<
1092 SwapCached 1010 SwapCached
1093 Memory that once was swapped ou 1011 Memory that once was swapped out, is swapped back in but
1094 still also is in the swapfile ( 1012 still also is in the swapfile (if memory is needed it
1095 doesn't need to be swapped out 1013 doesn't need to be swapped out AGAIN because it is already
1096 in the swapfile. This saves I/O 1014 in the swapfile. This saves I/O)
1097 Active 1015 Active
1098 Memory that has been used more 1016 Memory that has been used more recently and usually not
1099 reclaimed unless absolutely nec 1017 reclaimed unless absolutely necessary.
1100 Inactive 1018 Inactive
1101 Memory which has been less rece 1019 Memory which has been less recently used. It is more
1102 eligible to be reclaimed for ot 1020 eligible to be reclaimed for other purposes
1103 Unevictable <<
1104 Memory allocated for userspace <<
1105 as mlocked pages, ramfs backing <<
1106 Mlocked <<
1107 Memory locked with mlock(). <<
1108 HighTotal, HighFree 1021 HighTotal, HighFree
1109 Highmem is all memory above ~86 1022 Highmem is all memory above ~860MB of physical memory.
1110 Highmem areas are for use by us 1023 Highmem areas are for use by userspace programs, or
1111 for the pagecache. The kernel 1024 for the pagecache. The kernel must use tricks to access
1112 this memory, making it slower t 1025 this memory, making it slower to access than lowmem.
1113 LowTotal, LowFree 1026 LowTotal, LowFree
1114 Lowmem is memory which can be u 1027 Lowmem is memory which can be used for everything that
1115 highmem can be used for, but it 1028 highmem can be used for, but it is also available for the
1116 kernel's use for its own data s 1029 kernel's use for its own data structures. Among many
1117 other things, it is where every 1030 other things, it is where everything from the Slab is
1118 allocated. Bad things happen w 1031 allocated. Bad things happen when you're out of lowmem.
1119 SwapTotal 1032 SwapTotal
1120 total amount of swap space avai 1033 total amount of swap space available
1121 SwapFree 1034 SwapFree
1122 Memory which has been evicted f 1035 Memory which has been evicted from RAM, and is temporarily
1123 on the disk 1036 on the disk
1124 Zswap <<
1125 Memory consumed by the zswap ba <<
1126 Zswapped <<
1127 Amount of anonymous memory stor <<
1128 Dirty 1037 Dirty
1129 Memory which is waiting to get 1038 Memory which is waiting to get written back to the disk
1130 Writeback 1039 Writeback
1131 Memory which is actively being 1040 Memory which is actively being written back to the disk
1132 AnonPages 1041 AnonPages
1133 Non-file backed pages mapped in 1042 Non-file backed pages mapped into userspace page tables
>> 1043 HardwareCorrupted
>> 1044 The amount of RAM/memory in KB, the kernel identifies as
>> 1045 corrupted.
>> 1046 AnonHugePages
>> 1047 Non-file backed huge pages mapped into userspace page tables
1134 Mapped 1048 Mapped
1135 files which have been mmapped, !! 1049 files which have been mmaped, such as libraries
1136 Shmem 1050 Shmem
1137 Total memory used by shared mem 1051 Total memory used by shared memory (shmem) and tmpfs
>> 1052 ShmemHugePages
>> 1053 Memory used by shared memory (shmem) and tmpfs allocated
>> 1054 with huge pages
>> 1055 ShmemPmdMapped
>> 1056 Shared memory mapped into userspace with huge pages
1138 KReclaimable 1057 KReclaimable
1139 Kernel allocations that the ker 1058 Kernel allocations that the kernel will attempt to reclaim
1140 under memory pressure. Includes 1059 under memory pressure. Includes SReclaimable (below), and other
1141 direct allocations with a shrin 1060 direct allocations with a shrinker.
1142 Slab 1061 Slab
1143 in-kernel data structures cache 1062 in-kernel data structures cache
1144 SReclaimable 1063 SReclaimable
1145 Part of Slab, that might be rec 1064 Part of Slab, that might be reclaimed, such as caches
1146 SUnreclaim 1065 SUnreclaim
1147 Part of Slab, that cannot be re 1066 Part of Slab, that cannot be reclaimed on memory pressure
1148 KernelStack <<
1149 Memory consumed by the kernel s <<
1150 PageTables 1067 PageTables
1151 Memory consumed by userspace pa !! 1068 amount of memory dedicated to the lowest level of page
1152 SecPageTables !! 1069 tables.
1153 Memory consumed by secondary pa <<
1154 KVM mmu and IOMMU allocations o <<
1155 NFS_Unstable 1070 NFS_Unstable
1156 Always zero. Previous counted p 1071 Always zero. Previous counted pages which had been written to
1157 the server, but has not been co 1072 the server, but has not been committed to stable storage.
1158 Bounce 1073 Bounce
1159 Memory used for block device "b 1074 Memory used for block device "bounce buffers"
1160 WritebackTmp 1075 WritebackTmp
1161 Memory used by FUSE for tempora 1076 Memory used by FUSE for temporary writeback buffers
1162 CommitLimit 1077 CommitLimit
1163 Based on the overcommit ratio ( 1078 Based on the overcommit ratio ('vm.overcommit_ratio'),
1164 this is the total amount of me 1079 this is the total amount of memory currently available to
1165 be allocated on the system. Thi 1080 be allocated on the system. This limit is only adhered to
1166 if strict overcommit accounting 1081 if strict overcommit accounting is enabled (mode 2 in
1167 'vm.overcommit_memory'). 1082 'vm.overcommit_memory').
1168 1083
1169 The CommitLimit is calculated w 1084 The CommitLimit is calculated with the following formula::
1170 1085
1171 CommitLimit = ([total RAM pag 1086 CommitLimit = ([total RAM pages] - [total huge TLB pages]) *
1172 overcommit_rat 1087 overcommit_ratio / 100 + [total swap pages]
1173 1088
1174 For example, on a system with 1 1089 For example, on a system with 1G of physical RAM and 7G
1175 of swap with a `vm.overcommit_r 1090 of swap with a `vm.overcommit_ratio` of 30 it would
1176 yield a CommitLimit of 7.3G. 1091 yield a CommitLimit of 7.3G.
1177 1092
1178 For more details, see the memor 1093 For more details, see the memory overcommit documentation
1179 in mm/overcommit-accounting. !! 1094 in vm/overcommit-accounting.
1180 Committed_AS 1095 Committed_AS
1181 The amount of memory presently 1096 The amount of memory presently allocated on the system.
1182 The committed memory is a sum o 1097 The committed memory is a sum of all of the memory which
1183 has been allocated by processes 1098 has been allocated by processes, even if it has not been
1184 "used" by them as of yet. A pro 1099 "used" by them as of yet. A process which malloc()'s 1G
1185 of memory, but only touches 300 1100 of memory, but only touches 300M of it will show up as
1186 using 1G. This 1G is memory whi !! 1101 using 1G. This 1G is memory which has been "committed" to
1187 by the VM and can be used at an 1102 by the VM and can be used at any time by the allocating
1188 application. With strict overco 1103 application. With strict overcommit enabled on the system
1189 (mode 2 in 'vm.overcommit_memor 1104 (mode 2 in 'vm.overcommit_memory'), allocations which would
1190 exceed the CommitLimit (detaile 1105 exceed the CommitLimit (detailed above) will not be permitted.
1191 This is useful if one needs to 1106 This is useful if one needs to guarantee that processes will
1192 not fail due to lack of memory 1107 not fail due to lack of memory once that memory has been
1193 successfully allocated. 1108 successfully allocated.
1194 VmallocTotal 1109 VmallocTotal
1195 total size of vmalloc virtual a !! 1110 total size of vmalloc memory area
1196 VmallocUsed 1111 VmallocUsed
1197 amount of vmalloc area which is 1112 amount of vmalloc area which is used
1198 VmallocChunk 1113 VmallocChunk
1199 largest contiguous block of vma 1114 largest contiguous block of vmalloc area which is free
1200 Percpu 1115 Percpu
1201 Memory allocated to the percpu 1116 Memory allocated to the percpu allocator used to back percpu
1202 allocations. This stat excludes 1117 allocations. This stat excludes the cost of metadata.
1203 EarlyMemtestBad <<
1204 The amount of RAM/memory in kB, <<
1205 by early memtest. If memtest wa <<
1206 be displayed at all. Size is ne <<
1207 That means if 0 kB is reported, <<
1208 there was at least one pass of <<
1209 found a single faulty byte of R <<
1210 HardwareCorrupted <<
1211 The amount of RAM/memory in KB, <<
1212 corrupted. <<
1213 AnonHugePages <<
1214 Non-file backed huge pages mapp <<
1215 ShmemHugePages <<
1216 Memory used by shared memory (s <<
1217 with huge pages <<
1218 ShmemPmdMapped <<
1219 Shared memory mapped into users <<
1220 FileHugePages <<
1221 Memory used for filesystem data <<
1222 with huge pages <<
1223 FilePmdMapped <<
1224 Page cache mapped into userspac <<
1225 CmaTotal <<
1226 Memory reserved for the Contigu <<
1227 CmaFree <<
1228 Free remaining memory in the CM <<
1229 HugePages_Total, HugePages_Free, HugePages_Rs <<
1230 See Documentation/admin-guide/m <<
1231 DirectMap4k, DirectMap2M, DirectMap1G <<
1232 Breakdown of page table sizes u <<
1233 identity mapping of RAM <<
1234 1118
1235 vmallocinfo 1119 vmallocinfo
1236 ~~~~~~~~~~~ 1120 ~~~~~~~~~~~
1237 1121
1238 Provides information about vmalloced/vmaped a 1122 Provides information about vmalloced/vmaped areas. One line per area,
1239 containing the virtual address range of the a 1123 containing the virtual address range of the area, size in bytes,
1240 caller information of the creator, and option 1124 caller information of the creator, and optional information depending
1241 on the kind of area: 1125 on the kind of area:
1242 1126
1243 ========== ================================ 1127 ========== ===================================================
1244 pages=nr number of pages 1128 pages=nr number of pages
1245 phys=addr if a physical address was specif 1129 phys=addr if a physical address was specified
1246 ioremap I/O mapping (ioremap() and frien 1130 ioremap I/O mapping (ioremap() and friends)
1247 vmalloc vmalloc() area 1131 vmalloc vmalloc() area
1248 vmap vmap()ed pages 1132 vmap vmap()ed pages
1249 user VM_USERMAP area 1133 user VM_USERMAP area
1250 vpages buffer for pages pointers was vm 1134 vpages buffer for pages pointers was vmalloced (huge area)
1251 N<node>=nr (Only on NUMA kernels) 1135 N<node>=nr (Only on NUMA kernels)
1252 Number of pages allocated on mem 1136 Number of pages allocated on memory node <node>
1253 ========== ================================ 1137 ========== ===================================================
1254 1138
1255 :: 1139 ::
1256 1140
1257 > cat /proc/vmallocinfo 1141 > cat /proc/vmallocinfo
1258 0xffffc20000000000-0xffffc20000201000 210 1142 0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
1259 /0x2c0 pages=512 vmalloc N0=128 N1=128 N2 1143 /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
1260 0xffffc20000201000-0xffffc20000302000 105 1144 0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
1261 /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=6 1145 /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
1262 0xffffc20000302000-0xffffc20000304000 1146 0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
1263 phys=7fee8000 ioremap 1147 phys=7fee8000 ioremap
1264 0xffffc20000304000-0xffffc20000307000 1 1148 0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
1265 phys=7fee7000 ioremap 1149 phys=7fee7000 ioremap
1266 0xffffc2000031d000-0xffffc2000031f000 1150 0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
1267 0xffffc2000031f000-0xffffc2000032b000 4 1151 0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
1268 /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3= 1152 /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
1269 0xffffc2000033a000-0xffffc2000033d000 1 1153 0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
1270 pages=2 vmalloc N1=2 1154 pages=2 vmalloc N1=2
1271 0xffffc20000347000-0xffffc2000034c000 2 1155 0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
1272 /0x130 [x_tables] pages=4 vmalloc N0=4 1156 /0x130 [x_tables] pages=4 vmalloc N0=4
1273 0xffffffffa0000000-0xffffffffa000f000 6 1157 0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
1274 pages=14 vmalloc N2=14 1158 pages=14 vmalloc N2=14
1275 0xffffffffa000f000-0xffffffffa0014000 2 1159 0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
1276 pages=4 vmalloc N1=4 1160 pages=4 vmalloc N1=4
1277 0xffffffffa0014000-0xffffffffa0017000 1 1161 0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
1278 pages=2 vmalloc N1=2 1162 pages=2 vmalloc N1=2
1279 0xffffffffa0017000-0xffffffffa0022000 4 1163 0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
1280 pages=10 vmalloc N0=10 1164 pages=10 vmalloc N0=10
1281 1165
1282 1166
1283 softirqs 1167 softirqs
1284 ~~~~~~~~ 1168 ~~~~~~~~
1285 1169
1286 Provides counts of softirq handlers serviced 1170 Provides counts of softirq handlers serviced since boot time, for each CPU.
1287 1171
1288 :: 1172 ::
1289 1173
1290 > cat /proc/softirqs 1174 > cat /proc/softirqs
1291 CPU0 CPU1 CPU2 1175 CPU0 CPU1 CPU2 CPU3
1292 HI: 0 0 0 1176 HI: 0 0 0 0
1293 TIMER: 27166 27120 27097 1177 TIMER: 27166 27120 27097 27034
1294 NET_TX: 0 0 0 1178 NET_TX: 0 0 0 17
1295 NET_RX: 42 0 0 1179 NET_RX: 42 0 0 39
1296 BLOCK: 0 0 107 1180 BLOCK: 0 0 107 1121
1297 TASKLET: 0 0 0 1181 TASKLET: 0 0 0 290
1298 SCHED: 27035 26983 26971 1182 SCHED: 27035 26983 26971 26746
1299 HRTIMER: 0 0 0 1183 HRTIMER: 0 0 0 0
1300 RCU: 1678 1769 2178 1184 RCU: 1678 1769 2178 2250
1301 1185
1302 1.3 Networking info in /proc/net !! 1186
>> 1187 1.3 IDE devices in /proc/ide
>> 1188 ----------------------------
>> 1189
>> 1190 The subdirectory /proc/ide contains information about all IDE devices of which
>> 1191 the kernel is aware. There is one subdirectory for each IDE controller, the
>> 1192 file drivers and a link for each IDE device, pointing to the device directory
>> 1193 in the controller specific subtree.
>> 1194
>> 1195 The file 'drivers' contains general information about the drivers used for the
>> 1196 IDE devices::
>> 1197
>> 1198 > cat /proc/ide/drivers
>> 1199 ide-cdrom version 4.53
>> 1200 ide-disk version 1.08
>> 1201
>> 1202 More detailed information can be found in the controller specific
>> 1203 subdirectories. These are named ide0, ide1 and so on. Each of these
>> 1204 directories contains the files shown in table 1-6.
>> 1205
>> 1206
>> 1207 .. table:: Table 1-6: IDE controller info in /proc/ide/ide?
>> 1208
>> 1209 ======= =======================================
>> 1210 File Content
>> 1211 ======= =======================================
>> 1212 channel IDE channel (0 or 1)
>> 1213 config Configuration (only for PCI/IDE bridge)
>> 1214 mate Mate name
>> 1215 model Type/Chipset of IDE controller
>> 1216 ======= =======================================
>> 1217
>> 1218 Each device connected to a controller has a separate subdirectory in the
>> 1219 controllers directory. The files listed in table 1-7 are contained in these
>> 1220 directories.
>> 1221
>> 1222
>> 1223 .. table:: Table 1-7: IDE device information
>> 1224
>> 1225 ================ ==========================================
>> 1226 File Content
>> 1227 ================ ==========================================
>> 1228 cache The cache
>> 1229 capacity Capacity of the medium (in 512Byte blocks)
>> 1230 driver driver and version
>> 1231 geometry physical and logical geometry
>> 1232 identify device identify block
>> 1233 media media type
>> 1234 model device identifier
>> 1235 settings device setup
>> 1236 smart_thresholds IDE disk management thresholds
>> 1237 smart_values IDE disk management values
>> 1238 ================ ==========================================
>> 1239
>> 1240 The most interesting file is ``settings``. This file contains a nice
>> 1241 overview of the drive parameters::
>> 1242
>> 1243 # cat /proc/ide/ide0/hda/settings
>> 1244 name value min max mode
>> 1245 ---- ----- --- --- ----
>> 1246 bios_cyl 526 0 65535 rw
>> 1247 bios_head 255 0 255 rw
>> 1248 bios_sect 63 0 63 rw
>> 1249 breada_readahead 4 0 127 rw
>> 1250 bswap 0 0 1 r
>> 1251 file_readahead 72 0 2097151 rw
>> 1252 io_32bit 0 0 3 rw
>> 1253 keepsettings 0 0 1 rw
>> 1254 max_kb_per_request 122 1 127 rw
>> 1255 multcount 0 0 8 rw
>> 1256 nice1 1 0 1 rw
>> 1257 nowerr 0 0 1 rw
>> 1258 pio_mode write-only 0 255 w
>> 1259 slow 0 0 1 rw
>> 1260 unmaskirq 0 0 1 rw
>> 1261 using_dma 0 0 1 rw
>> 1262
>> 1263
>> 1264 1.4 Networking info in /proc/net
1303 -------------------------------- 1265 --------------------------------
1304 1266
1305 The subdirectory /proc/net follows the us 1267 The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
1306 additional values you get for IP version 1268 additional values you get for IP version 6 if you configure the kernel to
1307 support this. Table 1-9 lists the files and t 1269 support this. Table 1-9 lists the files and their meaning.
1308 1270
1309 1271
1310 .. table:: Table 1-8: IPv6 info in /proc/net 1272 .. table:: Table 1-8: IPv6 info in /proc/net
1311 1273
1312 ========== ================================= 1274 ========== =====================================================
1313 File Content 1275 File Content
1314 ========== ================================= 1276 ========== =====================================================
1315 udp6 UDP sockets (IPv6) 1277 udp6 UDP sockets (IPv6)
1316 tcp6 TCP sockets (IPv6) 1278 tcp6 TCP sockets (IPv6)
1317 raw6 Raw device statistics (IPv6) 1279 raw6 Raw device statistics (IPv6)
1318 igmp6 IP multicast addresses, which thi 1280 igmp6 IP multicast addresses, which this host joined (IPv6)
1319 if_inet6 List of IPv6 interface addresses 1281 if_inet6 List of IPv6 interface addresses
1320 ipv6_route Kernel routing table for IPv6 1282 ipv6_route Kernel routing table for IPv6
1321 rt6_stats Global IPv6 routing tables statis 1283 rt6_stats Global IPv6 routing tables statistics
1322 sockstat6 Socket statistics (IPv6) 1284 sockstat6 Socket statistics (IPv6)
1323 snmp6 Snmp data (IPv6) 1285 snmp6 Snmp data (IPv6)
1324 ========== ================================= 1286 ========== =====================================================
1325 1287
1326 .. table:: Table 1-9: Network info in /proc/n 1288 .. table:: Table 1-9: Network info in /proc/net
1327 1289
1328 ============= ============================== 1290 ============= ================================================================
1329 File Content 1291 File Content
1330 ============= ============================== 1292 ============= ================================================================
1331 arp Kernel ARP table 1293 arp Kernel ARP table
1332 dev network devices with statistic 1294 dev network devices with statistics
1333 dev_mcast the Layer2 multicast groups a 1295 dev_mcast the Layer2 multicast groups a device is listening too
1334 (interface index, label, numbe 1296 (interface index, label, number of references, number of bound
1335 addresses). 1297 addresses).
1336 dev_stat network device status 1298 dev_stat network device status
1337 ip_fwchains Firewall chain linkage 1299 ip_fwchains Firewall chain linkage
1338 ip_fwnames Firewall chain names 1300 ip_fwnames Firewall chain names
1339 ip_masq Directory containing the masqu 1301 ip_masq Directory containing the masquerading tables
1340 ip_masquerade Major masquerading table 1302 ip_masquerade Major masquerading table
1341 netstat Network statistics 1303 netstat Network statistics
1342 raw raw device statistics 1304 raw raw device statistics
1343 route Kernel routing table 1305 route Kernel routing table
1344 rpc Directory containing rpc info 1306 rpc Directory containing rpc info
1345 rt_cache Routing cache 1307 rt_cache Routing cache
1346 snmp SNMP data 1308 snmp SNMP data
1347 sockstat Socket statistics 1309 sockstat Socket statistics
1348 softnet_stat Per-CPU incoming packets queue <<
1349 tcp TCP sockets 1310 tcp TCP sockets
1350 udp UDP sockets 1311 udp UDP sockets
1351 unix UNIX domain sockets 1312 unix UNIX domain sockets
1352 wireless Wireless interface data (Wavel 1313 wireless Wireless interface data (Wavelan etc)
1353 igmp IP multicast addresses, which 1314 igmp IP multicast addresses, which this host joined
1354 psched Global packet scheduler parame 1315 psched Global packet scheduler parameters.
1355 netlink List of PF_NETLINK sockets 1316 netlink List of PF_NETLINK sockets
1356 ip_mr_vifs List of multicast virtual inte 1317 ip_mr_vifs List of multicast virtual interfaces
1357 ip_mr_cache List of multicast routing cach 1318 ip_mr_cache List of multicast routing cache
1358 ============= ============================== 1319 ============= ================================================================
1359 1320
1360 You can use this information to see which 1321 You can use this information to see which network devices are available in
1361 your system and how much traffic was routed o 1322 your system and how much traffic was routed over those devices::
1362 1323
1363 > cat /proc/net/dev 1324 > cat /proc/net/dev
1364 Inter-|Receive 1325 Inter-|Receive |[...
1365 face |bytes packets errs drop fifo fram 1326 face |bytes packets errs drop fifo frame compressed multicast|[...
1366 lo: 908188 5596 0 0 0 1327 lo: 908188 5596 0 0 0 0 0 0 [...
1367 ppp0:15475140 20721 410 0 0 41 1328 ppp0:15475140 20721 410 0 0 410 0 0 [...
1368 eth0: 614530 7085 0 0 0 1329 eth0: 614530 7085 0 0 0 0 0 1 [...
1369 1330
1370 ...] Transmit 1331 ...] Transmit
1371 ...] bytes packets errs drop fifo colls 1332 ...] bytes packets errs drop fifo colls carrier compressed
1372 ...] 908188 5596 0 0 0 0 1333 ...] 908188 5596 0 0 0 0 0 0
1373 ...] 1375103 17405 0 0 0 0 1334 ...] 1375103 17405 0 0 0 0 0 0
1374 ...] 1703981 5535 0 0 0 3 1335 ...] 1703981 5535 0 0 0 3 0 0
1375 1336
1376 In addition, each Channel Bond interface has 1337 In addition, each Channel Bond interface has its own directory. For
1377 example, the bond0 device will have a directo 1338 example, the bond0 device will have a directory called /proc/net/bond0/.
1378 It will contain information that is specific 1339 It will contain information that is specific to that bond, such as the
1379 current slaves of the bond, the link status o 1340 current slaves of the bond, the link status of the slaves, and how
1380 many times the slaves link has failed. 1341 many times the slaves link has failed.
1381 1342
1382 1.4 SCSI info !! 1343 1.5 SCSI info
1383 ------------- 1344 -------------
1384 1345
1385 If you have a SCSI or ATA host adapter in you !! 1346 If you have a SCSI host adapter in your system, you'll find a subdirectory
1386 subdirectory named after the driver for this !! 1347 named after the driver for this adapter in /proc/scsi. You'll also see a list
1387 You'll also see a list of all recognized SCSI !! 1348 of all recognized SCSI devices in /proc/scsi::
1388 1349
1389 >cat /proc/scsi/scsi 1350 >cat /proc/scsi/scsi
1390 Attached devices: 1351 Attached devices:
1391 Host: scsi0 Channel: 00 Id: 00 Lun: 00 1352 Host: scsi0 Channel: 00 Id: 00 Lun: 00
1392 Vendor: IBM Model: DGHS09U 1353 Vendor: IBM Model: DGHS09U Rev: 03E0
1393 Type: Direct-Access 1354 Type: Direct-Access ANSI SCSI revision: 03
1394 Host: scsi0 Channel: 00 Id: 06 Lun: 00 1355 Host: scsi0 Channel: 00 Id: 06 Lun: 00
1395 Vendor: PIONEER Model: CD-ROM DR-U06S 1356 Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
1396 Type: CD-ROM 1357 Type: CD-ROM ANSI SCSI revision: 02
1397 1358
1398 1359
1399 The directory named after the driver has o 1360 The directory named after the driver has one file for each adapter found in
1400 the system. These files contain informatio 1361 the system. These files contain information about the controller, including
1401 the used IRQ and the IO address range. T 1362 the used IRQ and the IO address range. The amount of information shown is
1402 dependent on the adapter you use. The exampl 1363 dependent on the adapter you use. The example shows the output for an Adaptec
1403 AHA-2940 SCSI adapter:: 1364 AHA-2940 SCSI adapter::
1404 1365
1405 > cat /proc/scsi/aic7xxx/0 1366 > cat /proc/scsi/aic7xxx/0
1406 1367
1407 Adaptec AIC7xxx driver version: 5.1.19/3.2. 1368 Adaptec AIC7xxx driver version: 5.1.19/3.2.4
1408 Compile Options: 1369 Compile Options:
1409 TCQ Enabled By Default : Disabled 1370 TCQ Enabled By Default : Disabled
1410 AIC7XXX_PROC_STATS : Disabled 1371 AIC7XXX_PROC_STATS : Disabled
1411 AIC7XXX_RESET_DELAY : 5 1372 AIC7XXX_RESET_DELAY : 5
1412 Adapter Configuration: 1373 Adapter Configuration:
1413 SCSI Adapter: Adaptec AHA-294X U 1374 SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
1414 Ultra Wide Contr 1375 Ultra Wide Controller
1415 PCI MMAPed I/O Base: 0xeb001000 1376 PCI MMAPed I/O Base: 0xeb001000
1416 Adapter SEEPROM Config: SEEPROM found and 1377 Adapter SEEPROM Config: SEEPROM found and used.
1417 Adaptec SCSI BIOS: Enabled 1378 Adaptec SCSI BIOS: Enabled
1418 IRQ: 10 1379 IRQ: 10
1419 SCBs: Active 0, Max Acti 1380 SCBs: Active 0, Max Active 2,
1420 Allocated 15, HW 1 1381 Allocated 15, HW 16, Page 255
1421 Interrupts: 160328 1382 Interrupts: 160328
1422 BIOS Control Word: 0x18b6 1383 BIOS Control Word: 0x18b6
1423 Adapter Control Word: 0x005b 1384 Adapter Control Word: 0x005b
1424 Extended Translation: Enabled 1385 Extended Translation: Enabled
1425 Disconnect Enable Flags: 0xffff 1386 Disconnect Enable Flags: 0xffff
1426 Ultra Enable Flags: 0x0001 1387 Ultra Enable Flags: 0x0001
1427 Tag Queue Enable Flags: 0x0000 1388 Tag Queue Enable Flags: 0x0000
1428 Ordered Queue Tag Flags: 0x0000 1389 Ordered Queue Tag Flags: 0x0000
1429 Default Tag Queue Depth: 8 1390 Default Tag Queue Depth: 8
1430 Tagged Queue By Device array for aic7xx 1391 Tagged Queue By Device array for aic7xxx host instance 0:
1431 {255,255,255,255,255,255,255,255,255, 1392 {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
1432 Actual queue depth per device for aic7x 1393 Actual queue depth per device for aic7xxx host instance 0:
1433 {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1} 1394 {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
1434 Statistics: 1395 Statistics:
1435 (scsi0:0:0:0) 1396 (scsi0:0:0:0)
1436 Device using Wide/Sync transfers at 40.0 1397 Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
1437 Transinfo settings: current(12/8/1/0), go 1398 Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0)
1438 Total transfers 160151 (74577 reads and 8 1399 Total transfers 160151 (74577 reads and 85574 writes)
1439 (scsi0:0:6:0) 1400 (scsi0:0:6:0)
1440 Device using Narrow/Sync transfers at 5.0 1401 Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
1441 Transinfo settings: current(50/15/0/0), g 1402 Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0)
1442 Total transfers 0 (0 reads and 0 writes) 1403 Total transfers 0 (0 reads and 0 writes)
1443 1404
1444 1405
1445 1.5 Parallel port info in /proc/parport !! 1406 1.6 Parallel port info in /proc/parport
1446 --------------------------------------- 1407 ---------------------------------------
1447 1408
1448 The directory /proc/parport contains inform 1409 The directory /proc/parport contains information about the parallel ports of
1449 your system. It has one subdirectory for 1410 your system. It has one subdirectory for each port, named after the port
1450 number (0,1,2,...). 1411 number (0,1,2,...).
1451 1412
1452 These directories contain the four files show 1413 These directories contain the four files shown in Table 1-10.
1453 1414
1454 1415
1455 .. table:: Table 1-10: Files in /proc/parport 1416 .. table:: Table 1-10: Files in /proc/parport
1456 1417
1457 ========= ================================== 1418 ========= ====================================================================
1458 File Content 1419 File Content
1459 ========= ================================== 1420 ========= ====================================================================
1460 autoprobe Any IEEE-1284 device ID informatio 1421 autoprobe Any IEEE-1284 device ID information that has been acquired.
1461 devices list of the device drivers using t 1422 devices list of the device drivers using that port. A + will appear by the
1462 name of the device currently using 1423 name of the device currently using the port (it might not appear
1463 against any). 1424 against any).
1464 hardware Parallel port's base address, IRQ 1425 hardware Parallel port's base address, IRQ line and DMA channel.
1465 irq IRQ that parport is using for that 1426 irq IRQ that parport is using for that port. This is in a separate
1466 file to allow you to alter it by w 1427 file to allow you to alter it by writing a new value in (IRQ
1467 number or none). 1428 number or none).
1468 ========= ================================== 1429 ========= ====================================================================
1469 1430
1470 1.6 TTY info in /proc/tty !! 1431 1.7 TTY info in /proc/tty
1471 ------------------------- 1432 -------------------------
1472 1433
1473 Information about the available and actual 1434 Information about the available and actually used tty's can be found in the
1474 directory /proc/tty. You'll find entries fo 1435 directory /proc/tty. You'll find entries for drivers and line disciplines in
1475 this directory, as shown in Table 1-11. 1436 this directory, as shown in Table 1-11.
1476 1437
1477 1438
1478 .. table:: Table 1-11: Files in /proc/tty 1439 .. table:: Table 1-11: Files in /proc/tty
1479 1440
1480 ============= ============================== 1441 ============= ==============================================
1481 File Content 1442 File Content
1482 ============= ============================== 1443 ============= ==============================================
1483 drivers list of drivers and their usag 1444 drivers list of drivers and their usage
1484 ldiscs registered line disciplines 1445 ldiscs registered line disciplines
1485 driver/serial usage statistic and status of 1446 driver/serial usage statistic and status of single tty lines
1486 ============= ============================== 1447 ============= ==============================================
1487 1448
1488 To see which tty's are currently in use, 1449 To see which tty's are currently in use, you can simply look into the file
1489 /proc/tty/drivers:: 1450 /proc/tty/drivers::
1490 1451
1491 > cat /proc/tty/drivers 1452 > cat /proc/tty/drivers
1492 pty_slave /dev/pts 136 0- 1453 pty_slave /dev/pts 136 0-255 pty:slave
1493 pty_master /dev/ptm 128 0- 1454 pty_master /dev/ptm 128 0-255 pty:master
1494 pty_slave /dev/ttyp 3 0- 1455 pty_slave /dev/ttyp 3 0-255 pty:slave
1495 pty_master /dev/pty 2 0- 1456 pty_master /dev/pty 2 0-255 pty:master
1496 serial /dev/cua 5 64 1457 serial /dev/cua 5 64-67 serial:callout
1497 serial /dev/ttyS 4 64 1458 serial /dev/ttyS 4 64-67 serial
1498 /dev/tty0 /dev/tty0 4 1459 /dev/tty0 /dev/tty0 4 0 system:vtmaster
1499 /dev/ptmx /dev/ptmx 5 1460 /dev/ptmx /dev/ptmx 5 2 system
1500 /dev/console /dev/console 5 1461 /dev/console /dev/console 5 1 system:console
1501 /dev/tty /dev/tty 5 1462 /dev/tty /dev/tty 5 0 system:/dev/tty
1502 unknown /dev/tty 4 1 1463 unknown /dev/tty 4 1-63 console
1503 1464
1504 1465
1505 1.7 Miscellaneous kernel statistics in /proc/ !! 1466 1.8 Miscellaneous kernel statistics in /proc/stat
1506 --------------------------------------------- 1467 -------------------------------------------------
1507 1468
1508 Various pieces of information about kerne 1469 Various pieces of information about kernel activity are available in the
1509 /proc/stat file. All of the numbers report 1470 /proc/stat file. All of the numbers reported in this file are aggregates
1510 since the system first booted. For a quick l 1471 since the system first booted. For a quick look, simply cat the file::
1511 1472
1512 > cat /proc/stat 1473 > cat /proc/stat
1513 cpu 237902850 368826709 106375398 18735175 !! 1474 cpu 2255 34 2290 22625563 6290 127 456 0 0 0
1514 cpu0 60045249 91891769 26331539 468411416 4 !! 1475 cpu0 1132 34 1441 11311718 3675 127 438 0 0 0
1515 cpu1 59746288 91759249 26609887 468860630 3 !! 1476 cpu1 1123 0 849 11313845 2614 0 18 0 0 0
1516 cpu2 59489247 92985423 26904446 467808813 1 !! 1477 intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
1517 cpu3 58622065 92190267 26529524 468436680 1 !! 1478 ctxt 1990473
1518 intr 8688370575 8 3373 0 0 0 0 0 0 1 40791 !! 1479 btime 1062191376
1519 ctxt 22848221062 !! 1480 processes 2915
1520 btime 1605316999 !! 1481 procs_running 1
1521 processes 746787147 <<
1522 procs_running 2 <<
1523 procs_blocked 0 1482 procs_blocked 0
1524 softirq 12121874454 100099120 3938138295 12 !! 1483 softirq 183433 0 21755 12 39 1137 231 21459 2263
1525 1484
1526 The very first "cpu" line aggregates the nu 1485 The very first "cpu" line aggregates the numbers in all of the other "cpuN"
1527 lines. These numbers identify the amount of 1486 lines. These numbers identify the amount of time the CPU has spent performing
1528 different kinds of work. Time units are in U 1487 different kinds of work. Time units are in USER_HZ (typically hundredths of a
1529 second). The meanings of the columns are as 1488 second). The meanings of the columns are as follows, from left to right:
1530 1489
1531 - user: normal processes executing in user mo 1490 - user: normal processes executing in user mode
1532 - nice: niced processes executing in user mod 1491 - nice: niced processes executing in user mode
1533 - system: processes executing in kernel mode 1492 - system: processes executing in kernel mode
1534 - idle: twiddling thumbs 1493 - idle: twiddling thumbs
1535 - iowait: In a word, iowait stands for waitin 1494 - iowait: In a word, iowait stands for waiting for I/O to complete. But there
1536 are several problems: 1495 are several problems:
1537 1496
1538 1. CPU will not wait for I/O to complete, i 1497 1. CPU will not wait for I/O to complete, iowait is the time that a task is
1539 waiting for I/O to complete. When CPU go 1498 waiting for I/O to complete. When CPU goes into idle state for
1540 outstanding task I/O, another task will 1499 outstanding task I/O, another task will be scheduled on this CPU.
1541 2. In a multi-core CPU, the task waiting fo 1500 2. In a multi-core CPU, the task waiting for I/O to complete is not running
1542 on any CPU, so the iowait of each CPU is 1501 on any CPU, so the iowait of each CPU is difficult to calculate.
1543 3. The value of iowait field in /proc/stat 1502 3. The value of iowait field in /proc/stat will decrease in certain
1544 conditions. 1503 conditions.
1545 1504
1546 So, the iowait is not reliable by reading f 1505 So, the iowait is not reliable by reading from /proc/stat.
1547 - irq: servicing interrupts 1506 - irq: servicing interrupts
1548 - softirq: servicing softirqs 1507 - softirq: servicing softirqs
1549 - steal: involuntary wait 1508 - steal: involuntary wait
1550 - guest: running a normal guest 1509 - guest: running a normal guest
1551 - guest_nice: running a niced guest 1510 - guest_nice: running a niced guest
1552 1511
1553 The "intr" line gives counts of interrupts s 1512 The "intr" line gives counts of interrupts serviced since boot time, for each
1554 of the possible system interrupts. The fir 1513 of the possible system interrupts. The first column is the total of all
1555 interrupts serviced including unnumbered a 1514 interrupts serviced including unnumbered architecture specific interrupts;
1556 each subsequent column is the total for tha 1515 each subsequent column is the total for that particular numbered interrupt.
1557 Unnumbered interrupts are not shown, only sum 1516 Unnumbered interrupts are not shown, only summed into the total.
1558 1517
1559 The "ctxt" line gives the total number of con 1518 The "ctxt" line gives the total number of context switches across all CPUs.
1560 1519
1561 The "btime" line gives the time at which the 1520 The "btime" line gives the time at which the system booted, in seconds since
1562 the Unix epoch. 1521 the Unix epoch.
1563 1522
1564 The "processes" line gives the number of pro 1523 The "processes" line gives the number of processes and threads created, which
1565 includes (but is not limited to) those cre 1524 includes (but is not limited to) those created by calls to the fork() and
1566 clone() system calls. 1525 clone() system calls.
1567 1526
1568 The "procs_running" line gives the total numb 1527 The "procs_running" line gives the total number of threads that are
1569 running or ready to run (i.e., the total numb 1528 running or ready to run (i.e., the total number of runnable threads).
1570 1529
1571 The "procs_blocked" line gives the number 1530 The "procs_blocked" line gives the number of processes currently blocked,
1572 waiting for I/O to complete. 1531 waiting for I/O to complete.
1573 1532
1574 The "softirq" line gives counts of softirqs s 1533 The "softirq" line gives counts of softirqs serviced since boot time, for each
1575 of the possible system softirqs. The first co 1534 of the possible system softirqs. The first column is the total of all
1576 softirqs serviced; each subsequent column is 1535 softirqs serviced; each subsequent column is the total for that particular
1577 softirq. 1536 softirq.
1578 1537
1579 1538
1580 1.8 Ext4 file system parameters !! 1539 1.9 Ext4 file system parameters
1581 ------------------------------- 1540 -------------------------------
1582 1541
1583 Information about mounted ext4 file systems c 1542 Information about mounted ext4 file systems can be found in
1584 /proc/fs/ext4. Each mounted filesystem will 1543 /proc/fs/ext4. Each mounted filesystem will have a directory in
1585 /proc/fs/ext4 based on its device name (i.e., 1544 /proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
1586 /proc/fs/ext4/sda9 or /proc/fs/ext4/dm-0). !! 1545 /proc/fs/ext4/dm-0). The files in each per-device directory are shown
1587 directory are shown in Table 1-12, below. !! 1546 in Table 1-12, below.
1588 1547
1589 .. table:: Table 1-12: Files in /proc/fs/ext4 1548 .. table:: Table 1-12: Files in /proc/fs/ext4/<devname>
1590 1549
1591 ============== ============================ 1550 ============== ==========================================================
1592 File Content 1551 File Content
1593 mb_groups details of multiblock alloca 1552 mb_groups details of multiblock allocator buddy cache of free blocks
1594 ============== ============================ 1553 ============== ==========================================================
1595 1554
1596 1.9 /proc/consoles !! 1555 1.10 /proc/consoles
1597 ------------------- 1556 -------------------
1598 Shows registered system console lines. 1557 Shows registered system console lines.
1599 1558
1600 To see which character device lines are curre 1559 To see which character device lines are currently used for the system console
1601 /dev/console, you may simply look into the fi 1560 /dev/console, you may simply look into the file /proc/consoles::
1602 1561
1603 > cat /proc/consoles 1562 > cat /proc/consoles
1604 tty0 -WU (ECp) 4:7 1563 tty0 -WU (ECp) 4:7
1605 ttyS0 -W- (Ep) 4:64 1564 ttyS0 -W- (Ep) 4:64
1606 1565
1607 The columns are: 1566 The columns are:
1608 1567
1609 +--------------------+----------------------- 1568 +--------------------+-------------------------------------------------------+
1610 | device | name of the device 1569 | device | name of the device |
1611 +====================+======================= 1570 +====================+=======================================================+
1612 | operations | * R = can do read oper 1571 | operations | * R = can do read operations |
1613 | | * W = can do write ope 1572 | | * W = can do write operations |
1614 | | * U = can do unblank 1573 | | * U = can do unblank |
1615 +--------------------+----------------------- 1574 +--------------------+-------------------------------------------------------+
1616 | flags | * E = it is enabled 1575 | flags | * E = it is enabled |
1617 | | * C = it is preferred 1576 | | * C = it is preferred console |
1618 | | * B = it is primary bo 1577 | | * B = it is primary boot console |
1619 | | * p = it is used for p 1578 | | * p = it is used for printk buffer |
1620 | | * b = it is not a TTY 1579 | | * b = it is not a TTY but a Braille device |
1621 | | * a = it is safe to us 1580 | | * a = it is safe to use when cpu is offline |
1622 +--------------------+----------------------- 1581 +--------------------+-------------------------------------------------------+
1623 | major:minor | major and minor number 1582 | major:minor | major and minor number of the device separated by a |
1624 | | colon 1583 | | colon |
1625 +--------------------+----------------------- 1584 +--------------------+-------------------------------------------------------+
1626 1585
1627 Summary 1586 Summary
1628 ------- 1587 -------
1629 1588
1630 The /proc file system serves information abou 1589 The /proc file system serves information about the running system. It not only
1631 allows access to process data but also allows 1590 allows access to process data but also allows you to request the kernel status
1632 by reading files in the hierarchy. 1591 by reading files in the hierarchy.
1633 1592
1634 The directory structure of /proc reflects t 1593 The directory structure of /proc reflects the types of information and makes
1635 it easy, if not obvious, where to look for sp 1594 it easy, if not obvious, where to look for specific data.
1636 1595
1637 Chapter 2: Modifying System Parameters 1596 Chapter 2: Modifying System Parameters
1638 ====================================== 1597 ======================================
1639 1598
1640 In This Chapter 1599 In This Chapter
1641 --------------- 1600 ---------------
1642 1601
1643 * Modifying kernel parameters by writing into 1602 * Modifying kernel parameters by writing into files found in /proc/sys
1644 * Exploring the files which modify certain pa 1603 * Exploring the files which modify certain parameters
1645 * Review of the /proc/sys file tree 1604 * Review of the /proc/sys file tree
1646 1605
1647 --------------------------------------------- 1606 ------------------------------------------------------------------------------
1648 1607
1649 A very interesting part of /proc is the dire 1608 A very interesting part of /proc is the directory /proc/sys. This is not only
1650 a source of information, it also allows yo 1609 a source of information, it also allows you to change parameters within the
1651 kernel. Be very careful when attempting th 1610 kernel. Be very careful when attempting this. You can optimize your system,
1652 but you can also cause it to crash. Ne 1611 but you can also cause it to crash. Never alter kernel parameters on a
1653 production system. Set up a development m 1612 production system. Set up a development machine and test to make sure that
1654 everything works the way you want it to. Y 1613 everything works the way you want it to. You may have no alternative but to
1655 reboot the machine once an error has been mad 1614 reboot the machine once an error has been made.
1656 1615
1657 To change a value, simply echo the new v 1616 To change a value, simply echo the new value into the file.
1658 You need to be root to do this. You can cre 1617 You need to be root to do this. You can create your own boot script
1659 to perform this every time your system boots. 1618 to perform this every time your system boots.
1660 1619
1661 The files in /proc/sys can be used to fine t 1620 The files in /proc/sys can be used to fine tune and monitor miscellaneous and
1662 general things in the operation of the Linu 1621 general things in the operation of the Linux kernel. Since some of the files
1663 can inadvertently disrupt your system, it 1622 can inadvertently disrupt your system, it is advisable to read both
1664 documentation and source before actually ma 1623 documentation and source before actually making adjustments. In any case, be
1665 very careful when writing to any of thes 1624 very careful when writing to any of these files. The entries in /proc may
1666 change slightly between the 2.1.* and the 2.2 1625 change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
1667 review the kernel documentation in the direct !! 1626 review the kernel documentation in the directory /usr/src/linux/Documentation.
1668 This chapter is heavily based on the docu 1627 This chapter is heavily based on the documentation included in the pre 2.2
1669 kernels, and became part of it in version 2.2 1628 kernels, and became part of it in version 2.2.1 of the Linux kernel.
1670 1629
1671 Please see: Documentation/admin-guide/sysctl/ !! 1630 Please see: Documentation/admin-guide/sysctl/ directory for descriptions of these
1672 these entries. !! 1631 entries.
1673 1632
1674 Summary 1633 Summary
1675 ------- 1634 -------
1676 1635
1677 Certain aspects of kernel behavior can be 1636 Certain aspects of kernel behavior can be modified at runtime, without the
1678 need to recompile the kernel, or even to re 1637 need to recompile the kernel, or even to reboot the system. The files in the
1679 /proc/sys tree can not only be read, but al 1638 /proc/sys tree can not only be read, but also modified. You can use the echo
1680 command to write value into these files, ther 1639 command to write value into these files, thereby changing the default settings
1681 of the kernel. 1640 of the kernel.
1682 1641
1683 1642
1684 Chapter 3: Per-process Parameters 1643 Chapter 3: Per-process Parameters
1685 ================================= 1644 =================================
1686 1645
1687 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_sco 1646 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
1688 --------------------------------------------- 1647 --------------------------------------------------------------------------------
1689 1648
1690 These files can be used to adjust the badness 1649 These files can be used to adjust the badness heuristic used to select which
1691 process gets killed in out of memory (oom) co 1650 process gets killed in out of memory (oom) conditions.
1692 1651
1693 The badness heuristic assigns a value to each 1652 The badness heuristic assigns a value to each candidate task ranging from 0
1694 (never kill) to 1000 (always kill) to determi 1653 (never kill) to 1000 (always kill) to determine which process is targeted. The
1695 units are roughly a proportion along that ran 1654 units are roughly a proportion along that range of allowed memory the process
1696 may allocate from based on an estimation of i 1655 may allocate from based on an estimation of its current memory and swap use.
1697 For example, if a task is using all allowed m 1656 For example, if a task is using all allowed memory, its badness score will be
1698 1000. If it is using half of its allowed mem 1657 1000. If it is using half of its allowed memory, its score will be 500.
1699 1658
1700 The amount of "allowed" memory depends on the 1659 The amount of "allowed" memory depends on the context in which the oom killer
1701 was called. If it is due to the memory assig 1660 was called. If it is due to the memory assigned to the allocating task's cpuset
1702 being exhausted, the allowed memory represent 1661 being exhausted, the allowed memory represents the set of mems assigned to that
1703 cpuset. If it is due to a mempolicy's node(s 1662 cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed
1704 memory represents the set of mempolicy nodes. 1663 memory represents the set of mempolicy nodes. If it is due to a memory
1705 limit (or swap limit) being reached, the allo 1664 limit (or swap limit) being reached, the allowed memory is that configured
1706 limit. Finally, if it is due to the entire s 1665 limit. Finally, if it is due to the entire system being out of memory, the
1707 allowed memory represents all allocatable res 1666 allowed memory represents all allocatable resources.
1708 1667
1709 The value of /proc/<pid>/oom_score_adj is add 1668 The value of /proc/<pid>/oom_score_adj is added to the badness score before it
1710 is used to determine which task to kill. Acc 1669 is used to determine which task to kill. Acceptable values range from -1000
1711 (OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_M 1670 (OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to
1712 polarize the preference for oom killing eithe 1671 polarize the preference for oom killing either by always preferring a certain
1713 task or completely disabling it. The lowest 1672 task or completely disabling it. The lowest possible value, -1000, is
1714 equivalent to disabling oom killing entirely 1673 equivalent to disabling oom killing entirely for that task since it will always
1715 report a badness score of 0. 1674 report a badness score of 0.
1716 1675
1717 Consequently, it is very simple for userspace 1676 Consequently, it is very simple for userspace to define the amount of memory to
1718 consider for each task. Setting a /proc/<pid 1677 consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for
1719 example, is roughly equivalent to allowing th 1678 example, is roughly equivalent to allowing the remainder of tasks sharing the
1720 same system, cpuset, mempolicy, or memory con 1679 same system, cpuset, mempolicy, or memory controller resources to use at least
1721 50% more memory. A value of -500, on the oth 1680 50% more memory. A value of -500, on the other hand, would be roughly
1722 equivalent to discounting 50% of the task's a 1681 equivalent to discounting 50% of the task's allowed memory from being considered
1723 as scoring against the task. 1682 as scoring against the task.
1724 1683
1725 For backwards compatibility with previous ker 1684 For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
1726 be used to tune the badness score. Its accep 1685 be used to tune the badness score. Its acceptable values range from -16
1727 (OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and 1686 (OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
1728 (OOM_DISABLE) to disable oom killing entirely 1687 (OOM_DISABLE) to disable oom killing entirely for that task. Its value is
1729 scaled linearly with /proc/<pid>/oom_score_ad 1688 scaled linearly with /proc/<pid>/oom_score_adj.
1730 1689
1731 The value of /proc/<pid>/oom_score_adj may be 1690 The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
1732 value set by a CAP_SYS_RESOURCE process. To r 1691 value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
1733 requires CAP_SYS_RESOURCE. 1692 requires CAP_SYS_RESOURCE.
1734 1693
1735 1694
1736 3.2 /proc/<pid>/oom_score - Display current o 1695 3.2 /proc/<pid>/oom_score - Display current oom-killer score
1737 --------------------------------------------- 1696 -------------------------------------------------------------
1738 1697
1739 This file can be used to check the current sc 1698 This file can be used to check the current score used by the oom-killer for
1740 any given <pid>. Use it together with /proc/< 1699 any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which
1741 process should be killed in an out-of-memory 1700 process should be killed in an out-of-memory situation.
1742 1701
1743 Please note that the exported value includes 1702 Please note that the exported value includes oom_score_adj so it is
1744 effectively in range [0,2000]. 1703 effectively in range [0,2000].
1745 1704
1746 1705
1747 3.3 /proc/<pid>/io - Display the IO accounti 1706 3.3 /proc/<pid>/io - Display the IO accounting fields
1748 --------------------------------------------- 1707 -------------------------------------------------------
1749 1708
1750 This file contains IO statistics for each run 1709 This file contains IO statistics for each running process.
1751 1710
1752 Example 1711 Example
1753 ~~~~~~~ 1712 ~~~~~~~
1754 1713
1755 :: 1714 ::
1756 1715
1757 test:/tmp # dd if=/dev/zero of=/tmp/test. 1716 test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
1758 [1] 3828 1717 [1] 3828
1759 1718
1760 test:/tmp # cat /proc/3828/io 1719 test:/tmp # cat /proc/3828/io
1761 rchar: 323934931 1720 rchar: 323934931
1762 wchar: 323929600 1721 wchar: 323929600
1763 syscr: 632687 1722 syscr: 632687
1764 syscw: 632675 1723 syscw: 632675
1765 read_bytes: 0 1724 read_bytes: 0
1766 write_bytes: 323932160 1725 write_bytes: 323932160
1767 cancelled_write_bytes: 0 1726 cancelled_write_bytes: 0
1768 1727
1769 1728
1770 Description 1729 Description
1771 ~~~~~~~~~~~ 1730 ~~~~~~~~~~~
1772 1731
1773 rchar 1732 rchar
1774 ^^^^^ 1733 ^^^^^
1775 1734
1776 I/O counter: chars read 1735 I/O counter: chars read
1777 The number of bytes which this task has cause 1736 The number of bytes which this task has caused to be read from storage. This
1778 is simply the sum of bytes which this process 1737 is simply the sum of bytes which this process passed to read() and pread().
1779 It includes things like tty IO and it is unaf 1738 It includes things like tty IO and it is unaffected by whether or not actual
1780 physical disk IO was required (the read might 1739 physical disk IO was required (the read might have been satisfied from
1781 pagecache). 1740 pagecache).
1782 1741
1783 1742
1784 wchar 1743 wchar
1785 ^^^^^ 1744 ^^^^^
1786 1745
1787 I/O counter: chars written 1746 I/O counter: chars written
1788 The number of bytes which this task has cause 1747 The number of bytes which this task has caused, or shall cause to be written
1789 to disk. Similar caveats apply here as with r 1748 to disk. Similar caveats apply here as with rchar.
1790 1749
1791 1750
1792 syscr 1751 syscr
1793 ^^^^^ 1752 ^^^^^
1794 1753
1795 I/O counter: read syscalls 1754 I/O counter: read syscalls
1796 Attempt to count the number of read I/O opera 1755 Attempt to count the number of read I/O operations, i.e. syscalls like read()
1797 and pread(). 1756 and pread().
1798 1757
1799 1758
1800 syscw 1759 syscw
1801 ^^^^^ 1760 ^^^^^
1802 1761
1803 I/O counter: write syscalls 1762 I/O counter: write syscalls
1804 Attempt to count the number of write I/O oper 1763 Attempt to count the number of write I/O operations, i.e. syscalls like
1805 write() and pwrite(). 1764 write() and pwrite().
1806 1765
1807 1766
1808 read_bytes 1767 read_bytes
1809 ^^^^^^^^^^ 1768 ^^^^^^^^^^
1810 1769
1811 I/O counter: bytes read 1770 I/O counter: bytes read
1812 Attempt to count the number of bytes which th 1771 Attempt to count the number of bytes which this process really did cause to
1813 be fetched from the storage layer. Done at th 1772 be fetched from the storage layer. Done at the submit_bio() level, so it is
1814 accurate for block-backed filesystems. <pleas 1773 accurate for block-backed filesystems. <please add status regarding NFS and
1815 CIFS at a later time> 1774 CIFS at a later time>
1816 1775
1817 1776
1818 write_bytes 1777 write_bytes
1819 ^^^^^^^^^^^ 1778 ^^^^^^^^^^^
1820 1779
1821 I/O counter: bytes written 1780 I/O counter: bytes written
1822 Attempt to count the number of bytes which th 1781 Attempt to count the number of bytes which this process caused to be sent to
1823 the storage layer. This is done at page-dirty 1782 the storage layer. This is done at page-dirtying time.
1824 1783
1825 1784
1826 cancelled_write_bytes 1785 cancelled_write_bytes
1827 ^^^^^^^^^^^^^^^^^^^^^ 1786 ^^^^^^^^^^^^^^^^^^^^^
1828 1787
1829 The big inaccuracy here is truncate. If a pro 1788 The big inaccuracy here is truncate. If a process writes 1MB to a file and
1830 then deletes the file, it will in fact perfor 1789 then deletes the file, it will in fact perform no writeout. But it will have
1831 been accounted as having caused 1MB of write. 1790 been accounted as having caused 1MB of write.
1832 In other words: The number of bytes which thi 1791 In other words: The number of bytes which this process caused to not happen,
1833 by truncating pagecache. A task can cause "ne 1792 by truncating pagecache. A task can cause "negative" IO too. If this task
1834 truncates some dirty pagecache, some IO which 1793 truncates some dirty pagecache, some IO which another task has been accounted
1835 for (in its write_bytes) will not be happenin 1794 for (in its write_bytes) will not be happening. We _could_ just subtract that
1836 from the truncating task's write_bytes, but t 1795 from the truncating task's write_bytes, but there is information loss in doing
1837 that. 1796 that.
1838 1797
1839 1798
1840 .. Note:: 1799 .. Note::
1841 1800
1842 At its current implementation state, this 1801 At its current implementation state, this is a bit racy on 32-bit machines:
1843 if process A reads process B's /proc/pid/i 1802 if process A reads process B's /proc/pid/io while process B is updating one
1844 of those 64-bit counters, process A could 1803 of those 64-bit counters, process A could see an intermediate result.
1845 1804
1846 1805
1847 More information about this can be found with 1806 More information about this can be found within the taskstats documentation in
1848 Documentation/accounting. 1807 Documentation/accounting.
1849 1808
1850 3.4 /proc/<pid>/coredump_filter - Core dump f 1809 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
1851 --------------------------------------------- 1810 ---------------------------------------------------------------
1852 When a process is dumped, all anonymous memor 1811 When a process is dumped, all anonymous memory is written to a core file as
1853 long as the size of the core file isn't limit 1812 long as the size of the core file isn't limited. But sometimes we don't want
1854 to dump some memory segments, for example, hu 1813 to dump some memory segments, for example, huge shared memory or DAX.
1855 Conversely, sometimes we want to save file-ba 1814 Conversely, sometimes we want to save file-backed memory segments into a core
1856 file, not only the individual files. 1815 file, not only the individual files.
1857 1816
1858 /proc/<pid>/coredump_filter allows you to cus 1817 /proc/<pid>/coredump_filter allows you to customize which memory segments
1859 will be dumped when the <pid> process is dump 1818 will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
1860 of memory types. If a bit of the bitmask is s 1819 of memory types. If a bit of the bitmask is set, memory segments of the
1861 corresponding memory type are dumped, otherwi 1820 corresponding memory type are dumped, otherwise they are not dumped.
1862 1821
1863 The following 9 memory types are supported: 1822 The following 9 memory types are supported:
1864 1823
1865 - (bit 0) anonymous private memory 1824 - (bit 0) anonymous private memory
1866 - (bit 1) anonymous shared memory 1825 - (bit 1) anonymous shared memory
1867 - (bit 2) file-backed private memory 1826 - (bit 2) file-backed private memory
1868 - (bit 3) file-backed shared memory 1827 - (bit 3) file-backed shared memory
1869 - (bit 4) ELF header pages in file-backed p 1828 - (bit 4) ELF header pages in file-backed private memory areas (it is
1870 effective only if the bit 2 is cleared) 1829 effective only if the bit 2 is cleared)
1871 - (bit 5) hugetlb private memory 1830 - (bit 5) hugetlb private memory
1872 - (bit 6) hugetlb shared memory 1831 - (bit 6) hugetlb shared memory
1873 - (bit 7) DAX private memory 1832 - (bit 7) DAX private memory
1874 - (bit 8) DAX shared memory 1833 - (bit 8) DAX shared memory
1875 1834
1876 Note that MMIO pages such as frame buffer a 1835 Note that MMIO pages such as frame buffer are never dumped and vDSO pages
1877 are always dumped regardless of the bitmask 1836 are always dumped regardless of the bitmask status.
1878 1837
1879 Note that bits 0-4 don't affect hugetlb or 1838 Note that bits 0-4 don't affect hugetlb or DAX memory. hugetlb memory is
1880 only affected by bit 5-6, and DAX is only a 1839 only affected by bit 5-6, and DAX is only affected by bits 7-8.
1881 1840
1882 The default value of coredump_filter is 0x33; 1841 The default value of coredump_filter is 0x33; this means all anonymous memory
1883 segments, ELF header pages and hugetlb privat 1842 segments, ELF header pages and hugetlb private memory are dumped.
1884 1843
1885 If you don't want to dump all shared memory s 1844 If you don't want to dump all shared memory segments attached to pid 1234,
1886 write 0x31 to the process's proc file:: 1845 write 0x31 to the process's proc file::
1887 1846
1888 $ echo 0x31 > /proc/1234/coredump_filter 1847 $ echo 0x31 > /proc/1234/coredump_filter
1889 1848
1890 When a new process is created, the process in 1849 When a new process is created, the process inherits the bitmask status from its
1891 parent. It is useful to set up coredump_filte 1850 parent. It is useful to set up coredump_filter before the program runs.
1892 For example:: 1851 For example::
1893 1852
1894 $ echo 0x7 > /proc/self/coredump_filter 1853 $ echo 0x7 > /proc/self/coredump_filter
1895 $ ./some_program 1854 $ ./some_program
1896 1855
1897 3.5 /proc/<pid>/mountinfo - Information a 1856 3.5 /proc/<pid>/mountinfo - Information about mounts
1898 --------------------------------------------- 1857 --------------------------------------------------------
1899 1858
1900 This file contains lines of the form:: 1859 This file contains lines of the form::
1901 1860
1902 36 35 98:0 /mnt1 /mnt2 rw,noatime master: 1861 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
1903 (1)(2)(3) (4) (5) (6) (n…m 1862 (1)(2)(3) (4) (5) (6) (n…m) (m+1)(m+2) (m+3) (m+4)
1904 1863
1905 (1) mount ID: unique identifier 1864 (1) mount ID: unique identifier of the mount (may be reused after umount)
1906 (2) parent ID: ID of parent (or o 1865 (2) parent ID: ID of parent (or of self for the top of the mount tree)
1907 (3) major:minor: value of st_dev fo 1866 (3) major:minor: value of st_dev for files on filesystem
1908 (4) root: root of the mount 1867 (4) root: root of the mount within the filesystem
1909 (5) mount point: mount point relati 1868 (5) mount point: mount point relative to the process's root
1910 (6) mount options: per mount options 1869 (6) mount options: per mount options
1911 (n…m) optional fields: zero or more fie 1870 (n…m) optional fields: zero or more fields of the form "tag[:value]"
1912 (m+1) separator: marks the end of t 1871 (m+1) separator: marks the end of the optional fields
1913 (m+2) filesystem type: name of filesystem 1872 (m+2) filesystem type: name of filesystem of the form "type[.subtype]"
1914 (m+3) mount source: filesystem specifi 1873 (m+3) mount source: filesystem specific information or "none"
1915 (m+4) super options: per super block op 1874 (m+4) super options: per super block options
1916 1875
1917 Parsers should ignore all unrecognised option 1876 Parsers should ignore all unrecognised optional fields. Currently the
1918 possible optional fields are: 1877 possible optional fields are:
1919 1878
1920 ================ =========================== 1879 ================ ==============================================================
1921 shared:X mount is shared in peer gro 1880 shared:X mount is shared in peer group X
1922 master:X mount is slave to peer grou 1881 master:X mount is slave to peer group X
1923 propagate_from:X mount is slave and receives 1882 propagate_from:X mount is slave and receives propagation from peer group X [#]_
1924 unbindable mount is unbindable 1883 unbindable mount is unbindable
1925 ================ =========================== 1884 ================ ==============================================================
1926 1885
1927 .. [#] X is the closest dominant peer group u 1886 .. [#] X is the closest dominant peer group under the process's root. If
1928 X is the immediate master of the mount 1887 X is the immediate master of the mount, or if there's no dominant peer
1929 group under the same root, then only t 1888 group under the same root, then only the "master:X" field is present
1930 and not the "propagate_from:X" field. 1889 and not the "propagate_from:X" field.
1931 1890
1932 For more information on mount propagation see 1891 For more information on mount propagation see:
1933 1892
1934 Documentation/filesystems/sharedsubtree.rst 1893 Documentation/filesystems/sharedsubtree.rst
1935 1894
1936 1895
1937 3.6 /proc/<pid>/comm & /proc/<pid>/task/ 1896 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
1938 --------------------------------------------- 1897 --------------------------------------------------------
1939 These files provide a method to access a task 1898 These files provide a method to access a task's comm value. It also allows for
1940 a task to set its own or one of its thread si 1899 a task to set its own or one of its thread siblings comm value. The comm value
1941 is limited in size compared to the cmdline va 1900 is limited in size compared to the cmdline value, so writing anything longer
1942 then the kernel's TASK_COMM_LEN (currently 16 !! 1901 then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
1943 terminator) will result in a truncated comm v !! 1902 comm value.
1944 1903
1945 1904
1946 3.7 /proc/<pid>/task/<tid>/children - Inf 1905 3.7 /proc/<pid>/task/<tid>/children - Information about task children
1947 --------------------------------------------- 1906 -------------------------------------------------------------------------
1948 This file provides a fast way to retrieve fir 1907 This file provides a fast way to retrieve first level children pids
1949 of a task pointed by <pid>/<tid> pair. The fo 1908 of a task pointed by <pid>/<tid> pair. The format is a space separated
1950 stream of pids. 1909 stream of pids.
1951 1910
1952 Note the "first level" here -- if a child has 1911 Note the "first level" here -- if a child has its own children they will
1953 not be listed here; one needs to read /proc/< 1912 not be listed here; one needs to read /proc/<children-pid>/task/<tid>/children
1954 to obtain the descendants. 1913 to obtain the descendants.
1955 1914
1956 Since this interface is intended to be fast a 1915 Since this interface is intended to be fast and cheap it doesn't
1957 guarantee to provide precise results and some 1916 guarantee to provide precise results and some children might be
1958 skipped, especially if they've exited right a 1917 skipped, especially if they've exited right after we printed their
1959 pids, so one needs to either stop or freeze p 1918 pids, so one needs to either stop or freeze processes being inspected
1960 if precise results are needed. 1919 if precise results are needed.
1961 1920
1962 1921
1963 3.8 /proc/<pid>/fdinfo/<fd> - Information 1922 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
1964 --------------------------------------------- 1923 ---------------------------------------------------------------
1965 This file provides information associated wit 1924 This file provides information associated with an opened file. The regular
1966 files have at least four fields -- 'pos', 'fl 1925 files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'.
1967 The 'pos' represents the current offset of th 1926 The 'pos' represents the current offset of the opened file in decimal
1968 form [see lseek(2) for details], 'flags' deno 1927 form [see lseek(2) for details], 'flags' denotes the octal O_xxx mask the
1969 file has been created with [see open(2) for d 1928 file has been created with [see open(2) for details] and 'mnt_id' represents
1970 mount ID of the file system containing the op 1929 mount ID of the file system containing the opened file [see 3.5
1971 /proc/<pid>/mountinfo for details]. 'ino' rep 1930 /proc/<pid>/mountinfo for details]. 'ino' represents the inode number of
1972 the file. 1931 the file.
1973 1932
1974 A typical output is:: 1933 A typical output is::
1975 1934
1976 pos: 0 1935 pos: 0
1977 flags: 0100002 1936 flags: 0100002
1978 mnt_id: 19 1937 mnt_id: 19
1979 ino: 63107 1938 ino: 63107
1980 1939
1981 All locks associated with a file descriptor a 1940 All locks associated with a file descriptor are shown in its fdinfo too::
1982 1941
1983 lock: 1: FLOCK ADVISORY WRITE 359 1942 lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF
1984 1943
1985 The files such as eventfd, fsnotify, signalfd 1944 The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags
1986 pair provide additional information particula 1945 pair provide additional information particular to the objects they represent.
1987 1946
1988 Eventfd files 1947 Eventfd files
1989 ~~~~~~~~~~~~~ 1948 ~~~~~~~~~~~~~
1990 1949
1991 :: 1950 ::
1992 1951
1993 pos: 0 1952 pos: 0
1994 flags: 04002 1953 flags: 04002
1995 mnt_id: 9 1954 mnt_id: 9
1996 ino: 63107 1955 ino: 63107
1997 eventfd-count: 5a 1956 eventfd-count: 5a
1998 1957
1999 where 'eventfd-count' is hex value of a count 1958 where 'eventfd-count' is hex value of a counter.
2000 1959
2001 Signalfd files 1960 Signalfd files
2002 ~~~~~~~~~~~~~~ 1961 ~~~~~~~~~~~~~~
2003 1962
2004 :: 1963 ::
2005 1964
2006 pos: 0 1965 pos: 0
2007 flags: 04002 1966 flags: 04002
2008 mnt_id: 9 1967 mnt_id: 9
2009 ino: 63107 1968 ino: 63107
2010 sigmask: 0000000000000200 1969 sigmask: 0000000000000200
2011 1970
2012 where 'sigmask' is hex value of the signal ma 1971 where 'sigmask' is hex value of the signal mask associated
2013 with a file. 1972 with a file.
2014 1973
2015 Epoll files 1974 Epoll files
2016 ~~~~~~~~~~~ 1975 ~~~~~~~~~~~
2017 1976
2018 :: 1977 ::
2019 1978
2020 pos: 0 1979 pos: 0
2021 flags: 02 1980 flags: 02
2022 mnt_id: 9 1981 mnt_id: 9
2023 ino: 63107 1982 ino: 63107
2024 tfd: 5 events: 1d data: 1983 tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7
2025 1984
2026 where 'tfd' is a target file descriptor numbe 1985 where 'tfd' is a target file descriptor number in decimal form,
2027 'events' is events mask being watched and the 1986 'events' is events mask being watched and the 'data' is data
2028 associated with a target [see epoll(7) for mo 1987 associated with a target [see epoll(7) for more details].
2029 1988
2030 The 'pos' is current offset of the target fil 1989 The 'pos' is current offset of the target file in decimal form
2031 [see lseek(2)], 'ino' and 'sdev' are inode an 1990 [see lseek(2)], 'ino' and 'sdev' are inode and device numbers
2032 where target file resides, all in hex format. 1991 where target file resides, all in hex format.
2033 1992
2034 Fsnotify files 1993 Fsnotify files
2035 ~~~~~~~~~~~~~~ 1994 ~~~~~~~~~~~~~~
2036 For inotify files the format is the following 1995 For inotify files the format is the following::
2037 1996
2038 pos: 0 1997 pos: 0
2039 flags: 02000000 1998 flags: 02000000
2040 mnt_id: 9 1999 mnt_id: 9
2041 ino: 63107 2000 ino: 63107
2042 inotify wd:3 ino:9e7e sdev:800013 mas 2001 inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d
2043 2002
2044 where 'wd' is a watch descriptor in decimal f 2003 where 'wd' is a watch descriptor in decimal form, i.e. a target file
2045 descriptor number, 'ino' and 'sdev' are inode 2004 descriptor number, 'ino' and 'sdev' are inode and device where the
2046 target file resides and the 'mask' is the mas 2005 target file resides and the 'mask' is the mask of events, all in hex
2047 form [see inotify(7) for more details]. 2006 form [see inotify(7) for more details].
2048 2007
2049 If the kernel was built with exportfs support 2008 If the kernel was built with exportfs support, the path to the target
2050 file is encoded as a file handle. The file h 2009 file is encoded as a file handle. The file handle is provided by three
2051 fields 'fhandle-bytes', 'fhandle-type' and 'f 2010 fields 'fhandle-bytes', 'fhandle-type' and 'f_handle', all in hex
2052 format. 2011 format.
2053 2012
2054 If the kernel is built without exportfs suppo 2013 If the kernel is built without exportfs support the file handle won't be
2055 printed out. 2014 printed out.
2056 2015
2057 If there is no inotify mark attached yet the 2016 If there is no inotify mark attached yet the 'inotify' line will be omitted.
2058 2017
2059 For fanotify files the format is:: 2018 For fanotify files the format is::
2060 2019
2061 pos: 0 2020 pos: 0
2062 flags: 02 2021 flags: 02
2063 mnt_id: 9 2022 mnt_id: 9
2064 ino: 63107 2023 ino: 63107
2065 fanotify flags:10 event-flags:0 2024 fanotify flags:10 event-flags:0
2066 fanotify mnt_id:12 mflags:40 mask:38 2025 fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003
2067 fanotify ino:4f969 sdev:800013 mflags 2026 fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4
2068 2027
2069 where fanotify 'flags' and 'event-flags' are 2028 where fanotify 'flags' and 'event-flags' are values used in fanotify_init
2070 call, 'mnt_id' is the mount point identifier, 2029 call, 'mnt_id' is the mount point identifier, 'mflags' is the value of
2071 flags associated with mark which are tracked 2030 flags associated with mark which are tracked separately from events
2072 mask. 'ino' and 'sdev' are target inode and d 2031 mask. 'ino' and 'sdev' are target inode and device, 'mask' is the events
2073 mask and 'ignored_mask' is the mask of events 2032 mask and 'ignored_mask' is the mask of events which are to be ignored.
2074 All are in hex format. Incorporation of 'mfla 2033 All are in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask'
2075 provide information about flags and mask used 2034 provide information about flags and mask used in fanotify_mark
2076 call [see fsnotify manpage for details]. 2035 call [see fsnotify manpage for details].
2077 2036
2078 While the first three lines are mandatory and 2037 While the first three lines are mandatory and always printed, the rest is
2079 optional and may be omitted if no marks creat 2038 optional and may be omitted if no marks created yet.
2080 2039
2081 Timerfd files 2040 Timerfd files
2082 ~~~~~~~~~~~~~ 2041 ~~~~~~~~~~~~~
2083 2042
2084 :: 2043 ::
2085 2044
2086 pos: 0 2045 pos: 0
2087 flags: 02 2046 flags: 02
2088 mnt_id: 9 2047 mnt_id: 9
2089 ino: 63107 2048 ino: 63107
2090 clockid: 0 2049 clockid: 0
2091 ticks: 0 2050 ticks: 0
2092 settime flags: 01 2051 settime flags: 01
2093 it_value: (0, 49406829) 2052 it_value: (0, 49406829)
2094 it_interval: (1, 0) 2053 it_interval: (1, 0)
2095 2054
2096 where 'clockid' is the clock type and 'ticks' 2055 where 'clockid' is the clock type and 'ticks' is the number of the timer expirations
2097 that have occurred [see timerfd_create(2) for 2056 that have occurred [see timerfd_create(2) for details]. 'settime flags' are
2098 flags in octal form been used to setup the ti 2057 flags in octal form been used to setup the timer [see timerfd_settime(2) for
2099 details]. 'it_value' is remaining time until 2058 details]. 'it_value' is remaining time until the timer expiration.
2100 'it_interval' is the interval for the timer. 2059 'it_interval' is the interval for the timer. Note the timer might be set up
2101 with TIMER_ABSTIME option which will be shown 2060 with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value'
2102 still exhibits timer's remaining time. 2061 still exhibits timer's remaining time.
2103 2062
2104 DMA Buffer files 2063 DMA Buffer files
2105 ~~~~~~~~~~~~~~~~ 2064 ~~~~~~~~~~~~~~~~
2106 2065
2107 :: 2066 ::
2108 2067
2109 pos: 0 2068 pos: 0
2110 flags: 04002 2069 flags: 04002
2111 mnt_id: 9 2070 mnt_id: 9
2112 ino: 63107 2071 ino: 63107
2113 size: 32768 2072 size: 32768
2114 count: 2 2073 count: 2
2115 exp_name: system-heap 2074 exp_name: system-heap
2116 2075
2117 where 'size' is the size of the DMA buffer in 2076 where 'size' is the size of the DMA buffer in bytes. 'count' is the file count of
2118 the DMA buffer file. 'exp_name' is the name o 2077 the DMA buffer file. 'exp_name' is the name of the DMA buffer exporter.
2119 2078
2120 3.9 /proc/<pid>/map_files - Information a 2079 3.9 /proc/<pid>/map_files - Information about memory mapped files
2121 --------------------------------------------- 2080 ---------------------------------------------------------------------
2122 This directory contains symbolic links which 2081 This directory contains symbolic links which represent memory mapped files
2123 the process is maintaining. Example output:: 2082 the process is maintaining. Example output::
2124 2083
2125 | lr-------- 1 root root 64 Jan 27 11:24 2084 | lr-------- 1 root root 64 Jan 27 11:24 333c600000-333c620000 -> /usr/lib64/ld-2.18.so
2126 | lr-------- 1 root root 64 Jan 27 11:24 2085 | lr-------- 1 root root 64 Jan 27 11:24 333c81f000-333c820000 -> /usr/lib64/ld-2.18.so
2127 | lr-------- 1 root root 64 Jan 27 11:24 2086 | lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so
2128 | ... 2087 | ...
2129 | lr-------- 1 root root 64 Jan 27 11:24 2088 | lr-------- 1 root root 64 Jan 27 11:24 35d0421000-35d0422000 -> /usr/lib64/libselinux.so.1
2130 | lr-------- 1 root root 64 Jan 27 11:24 2089 | lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls
2131 2090
2132 The name of a link represents the virtual mem 2091 The name of a link represents the virtual memory bounds of a mapping, i.e.
2133 vm_area_struct::vm_start-vm_area_struct::vm_e 2092 vm_area_struct::vm_start-vm_area_struct::vm_end.
2134 2093
2135 The main purpose of the map_files is to retri 2094 The main purpose of the map_files is to retrieve a set of memory mapped
2136 files in a fast way instead of parsing /proc/ 2095 files in a fast way instead of parsing /proc/<pid>/maps or
2137 /proc/<pid>/smaps, both of which contain many 2096 /proc/<pid>/smaps, both of which contain many more records. At the same
2138 time one can open(2) mappings from the listin 2097 time one can open(2) mappings from the listings of two processes and
2139 comparing their inode numbers to figure out w 2098 comparing their inode numbers to figure out which anonymous memory areas
2140 are actually shared. 2099 are actually shared.
2141 2100
2142 3.10 /proc/<pid>/timerslack_ns - Task time 2101 3.10 /proc/<pid>/timerslack_ns - Task timerslack value
2143 --------------------------------------------- 2102 ---------------------------------------------------------
2144 This file provides the value of the task's ti 2103 This file provides the value of the task's timerslack value in nanoseconds.
2145 This value specifies an amount of time that n 2104 This value specifies an amount of time that normal timers may be deferred
2146 in order to coalesce timers and avoid unneces 2105 in order to coalesce timers and avoid unnecessary wakeups.
2147 2106
2148 This allows a task's interactivity vs power c 2107 This allows a task's interactivity vs power consumption tradeoff to be
2149 adjusted. 2108 adjusted.
2150 2109
2151 Writing 0 to the file will set the task's tim 2110 Writing 0 to the file will set the task's timerslack to the default value.
2152 2111
2153 Valid values are from 0 - ULLONG_MAX 2112 Valid values are from 0 - ULLONG_MAX
2154 2113
2155 An application setting the value must have PT 2114 An application setting the value must have PTRACE_MODE_ATTACH_FSCREDS level
2156 permissions on the task specified to change i 2115 permissions on the task specified to change its timerslack_ns value.
2157 2116
2158 3.11 /proc/<pid>/patch_state - Livepatch p 2117 3.11 /proc/<pid>/patch_state - Livepatch patch operation state
2159 --------------------------------------------- 2118 -----------------------------------------------------------------
2160 When CONFIG_LIVEPATCH is enabled, this file d 2119 When CONFIG_LIVEPATCH is enabled, this file displays the value of the
2161 patch state for the task. 2120 patch state for the task.
2162 2121
2163 A value of '-1' indicates that no patch is in 2122 A value of '-1' indicates that no patch is in transition.
2164 2123
2165 A value of '0' indicates that a patch is in t 2124 A value of '0' indicates that a patch is in transition and the task is
2166 unpatched. If the patch is being enabled, th 2125 unpatched. If the patch is being enabled, then the task hasn't been
2167 patched yet. If the patch is being disabled, 2126 patched yet. If the patch is being disabled, then the task has already
2168 been unpatched. 2127 been unpatched.
2169 2128
2170 A value of '1' indicates that a patch is in t 2129 A value of '1' indicates that a patch is in transition and the task is
2171 patched. If the patch is being enabled, then 2130 patched. If the patch is being enabled, then the task has already been
2172 patched. If the patch is being disabled, the 2131 patched. If the patch is being disabled, then the task hasn't been
2173 unpatched yet. 2132 unpatched yet.
2174 2133
2175 3.12 /proc/<pid>/arch_status - task architect 2134 3.12 /proc/<pid>/arch_status - task architecture specific status
2176 --------------------------------------------- 2135 -------------------------------------------------------------------
2177 When CONFIG_PROC_PID_ARCH_STATUS is enabled, 2136 When CONFIG_PROC_PID_ARCH_STATUS is enabled, this file displays the
2178 architecture specific status of the task. 2137 architecture specific status of the task.
2179 2138
2180 Example 2139 Example
2181 ~~~~~~~ 2140 ~~~~~~~
2182 2141
2183 :: 2142 ::
2184 2143
2185 $ cat /proc/6753/arch_status 2144 $ cat /proc/6753/arch_status
2186 AVX512_elapsed_ms: 8 2145 AVX512_elapsed_ms: 8
2187 2146
2188 Description 2147 Description
2189 ~~~~~~~~~~~ 2148 ~~~~~~~~~~~
2190 2149
2191 x86 specific entries 2150 x86 specific entries
2192 ~~~~~~~~~~~~~~~~~~~~~ 2151 ~~~~~~~~~~~~~~~~~~~~~
2193 2152
2194 AVX512_elapsed_ms 2153 AVX512_elapsed_ms
2195 ^^^^^^^^^^^^^^^^^^ 2154 ^^^^^^^^^^^^^^^^^^
2196 2155
2197 If AVX512 is supported on the machine, this 2156 If AVX512 is supported on the machine, this entry shows the milliseconds
2198 elapsed since the last time AVX512 usage wa 2157 elapsed since the last time AVX512 usage was recorded. The recording
2199 happens on a best effort basis when a task 2158 happens on a best effort basis when a task is scheduled out. This means
2200 that the value depends on two factors: 2159 that the value depends on two factors:
2201 2160
2202 1) The time which the task spent on the C 2161 1) The time which the task spent on the CPU without being scheduled
2203 out. With CPU isolation and a single r 2162 out. With CPU isolation and a single runnable task this can take
2204 several seconds. 2163 several seconds.
2205 2164
2206 2) The time since the task was scheduled 2165 2) The time since the task was scheduled out last. Depending on the
2207 reason for being scheduled out (time s 2166 reason for being scheduled out (time slice exhausted, syscall ...)
2208 this can be arbitrary long time. 2167 this can be arbitrary long time.
2209 2168
2210 As a consequence the value cannot be consid 2169 As a consequence the value cannot be considered precise and authoritative
2211 information. The application which uses thi 2170 information. The application which uses this information has to be aware
2212 of the overall scenario on the system in or 2171 of the overall scenario on the system in order to determine whether a
2213 task is a real AVX512 user or not. Precise 2172 task is a real AVX512 user or not. Precise information can be obtained
2214 with performance counters. 2173 with performance counters.
2215 2174
2216 A special value of '-1' indicates that no A 2175 A special value of '-1' indicates that no AVX512 usage was recorded, thus
2217 the task is unlikely an AVX512 user, but de 2176 the task is unlikely an AVX512 user, but depends on the workload and the
2218 scheduling scenario, it also could be a fal 2177 scheduling scenario, it also could be a false negative mentioned above.
2219 2178
2220 3.13 /proc/<pid>/fd - List of symlinks to ope <<
2221 --------------------------------------------- <<
2222 This directory contains symbolic links which <<
2223 the process is maintaining. Example output:: <<
2224 <<
2225 lr-x------ 1 root root 64 Sep 20 17:53 0 -> <<
2226 l-wx------ 1 root root 64 Sep 20 17:53 1 -> <<
2227 lrwx------ 1 root root 64 Sep 20 17:53 10 - <<
2228 lrwx------ 1 root root 64 Sep 20 17:53 11 - <<
2229 lrwx------ 1 root root 64 Sep 20 17:53 12 - <<
2230 <<
2231 The number of open files for the process is s <<
2232 of stat() output for /proc/<pid>/fd for fast <<
2233 --------------------------------------------- <<
2234 <<
2235 <<
2236 Chapter 4: Configuring procfs 2179 Chapter 4: Configuring procfs
2237 ============================= 2180 =============================
2238 2181
2239 4.1 Mount options 2182 4.1 Mount options
2240 --------------------- 2183 ---------------------
2241 2184
2242 The following mount options are supported: 2185 The following mount options are supported:
2243 2186
2244 ========= ===================== 2187 ========= ========================================================
2245 hidepid= Set /proc/<pid>/ acce 2188 hidepid= Set /proc/<pid>/ access mode.
2246 gid= Set the group authori 2189 gid= Set the group authorized to learn processes information.
2247 subset= Show only the specifi 2190 subset= Show only the specified subset of procfs.
2248 ========= ===================== 2191 ========= ========================================================
2249 2192
2250 hidepid=off or hidepid=0 means classic mode - 2193 hidepid=off or hidepid=0 means classic mode - everybody may access all
2251 /proc/<pid>/ directories (default). 2194 /proc/<pid>/ directories (default).
2252 2195
2253 hidepid=noaccess or hidepid=1 means users may 2196 hidepid=noaccess or hidepid=1 means users may not access any /proc/<pid>/
2254 directories but their own. Sensitive files l 2197 directories but their own. Sensitive files like cmdline, sched*, status are now
2255 protected against other users. This makes it 2198 protected against other users. This makes it impossible to learn whether any
2256 user runs specific program (given the program 2199 user runs specific program (given the program doesn't reveal itself by its
2257 behaviour). As an additional bonus, as /proc 2200 behaviour). As an additional bonus, as /proc/<pid>/cmdline is unaccessible for
2258 other users, poorly written programs passing 2201 other users, poorly written programs passing sensitive information via program
2259 arguments are now protected against local eav 2202 arguments are now protected against local eavesdroppers.
2260 2203
2261 hidepid=invisible or hidepid=2 means hidepid= 2204 hidepid=invisible or hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be
2262 fully invisible to other users. It doesn't m 2205 fully invisible to other users. It doesn't mean that it hides a fact whether a
2263 process with a specific pid value exists (it 2206 process with a specific pid value exists (it can be learned by other means, e.g.
2264 by "kill -0 $PID"), but it hides process' uid 2207 by "kill -0 $PID"), but it hides process' uid and gid, which may be learned by
2265 stat()'ing /proc/<pid>/ otherwise. It greatl 2208 stat()'ing /proc/<pid>/ otherwise. It greatly complicates an intruder's task of
2266 gathering information about running processes 2209 gathering information about running processes, whether some daemon runs with
2267 elevated privileges, whether other user runs 2210 elevated privileges, whether other user runs some sensitive program, whether
2268 other users run any program at all, etc. 2211 other users run any program at all, etc.
2269 2212
2270 hidepid=ptraceable or hidepid=4 means that pr 2213 hidepid=ptraceable or hidepid=4 means that procfs should only contain
2271 /proc/<pid>/ directories that the caller can 2214 /proc/<pid>/ directories that the caller can ptrace.
2272 2215
2273 gid= defines a group authorized to learn proc 2216 gid= defines a group authorized to learn processes information otherwise
2274 prohibited by hidepid=. If you use some daem 2217 prohibited by hidepid=. If you use some daemon like identd which needs to learn
2275 information about processes information, just 2218 information about processes information, just add identd to this group.
2276 2219
2277 subset=pid hides all top level files and dire 2220 subset=pid hides all top level files and directories in the procfs that
2278 are not related to tasks. 2221 are not related to tasks.
2279 2222
2280 Chapter 5: Filesystem behavior 2223 Chapter 5: Filesystem behavior
2281 ============================== 2224 ==============================
2282 2225
2283 Originally, before the advent of pid namespac !! 2226 Originally, before the advent of pid namepsace, procfs was a global file
2284 system. It means that there was only one proc 2227 system. It means that there was only one procfs instance in the system.
2285 2228
2286 When pid namespace was added, a separate proc 2229 When pid namespace was added, a separate procfs instance was mounted in
2287 each pid namespace. So, procfs mount options 2230 each pid namespace. So, procfs mount options are global among all
2288 mountpoints within the same namespace:: 2231 mountpoints within the same namespace::
2289 2232
2290 # grep ^proc /proc/mounts 2233 # grep ^proc /proc/mounts
2291 proc /proc proc rw,relatime,hidepid=2 2234 proc /proc proc rw,relatime,hidepid=2 0 0
2292 2235
2293 # strace -e mount mount -o hidepid=1 2236 # strace -e mount mount -o hidepid=1 -t proc proc /tmp/proc
2294 mount("proc", "/tmp/proc", "proc", 0, 2237 mount("proc", "/tmp/proc", "proc", 0, "hidepid=1") = 0
2295 +++ exited with 0 +++ 2238 +++ exited with 0 +++
2296 2239
2297 # grep ^proc /proc/mounts 2240 # grep ^proc /proc/mounts
2298 proc /proc proc rw,relatime,hidepid=2 2241 proc /proc proc rw,relatime,hidepid=2 0 0
2299 proc /tmp/proc proc rw,relatime,hidep 2242 proc /tmp/proc proc rw,relatime,hidepid=2 0 0
2300 2243
2301 and only after remounting procfs mount option 2244 and only after remounting procfs mount options will change at all
2302 mountpoints:: 2245 mountpoints::
2303 2246
2304 # mount -o remount,hidepid=1 -t proc 2247 # mount -o remount,hidepid=1 -t proc proc /tmp/proc
2305 2248
2306 # grep ^proc /proc/mounts 2249 # grep ^proc /proc/mounts
2307 proc /proc proc rw,relatime,hidepid=1 2250 proc /proc proc rw,relatime,hidepid=1 0 0
2308 proc /tmp/proc proc rw,relatime,hidep 2251 proc /tmp/proc proc rw,relatime,hidepid=1 0 0
2309 2252
2310 This behavior is different from the behavior 2253 This behavior is different from the behavior of other filesystems.
2311 2254
2312 The new procfs behavior is more like other fi 2255 The new procfs behavior is more like other filesystems. Each procfs mount
2313 creates a new procfs instance. Mount options 2256 creates a new procfs instance. Mount options affect own procfs instance.
2314 It means that it became possible to have seve 2257 It means that it became possible to have several procfs instances
2315 displaying tasks with different filtering opt 2258 displaying tasks with different filtering options in one pid namespace::
2316 2259
2317 # mount -o hidepid=invisible -t proc 2260 # mount -o hidepid=invisible -t proc proc /proc
2318 # mount -o hidepid=noaccess -t proc p 2261 # mount -o hidepid=noaccess -t proc proc /tmp/proc
2319 # grep ^proc /proc/mounts 2262 # grep ^proc /proc/mounts
2320 proc /proc proc rw,relatime,hidepid=i 2263 proc /proc proc rw,relatime,hidepid=invisible 0 0
2321 proc /tmp/proc proc rw,relatime,hidep 2264 proc /tmp/proc proc rw,relatime,hidepid=noaccess 0 0
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