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 50 3.13 /proc/<pid>/fd - List of symlinks to open files
51 51
52 4 Configuring procfs 52 4 Configuring procfs
53 4.1 Mount options 53 4.1 Mount options
54 54
55 5 Filesystem behavior 55 5 Filesystem behavior
56 56
57 Preface 57 Preface
58 ======= 58 =======
59 59
60 0.1 Introduction/Credits 60 0.1 Introduction/Credits
61 ------------------------ 61 ------------------------
62 62
63 This documentation is part of a soon (or so 63 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 64 the SuSE Linux distribution. As there is no complete documentation for the
65 /proc file system and we've used many freely 65 /proc file system and we've used many freely available sources to write these
66 chapters, it seems only fair to give the wor 66 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 67 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 68 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 69 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 70 is focused on the Intel x86 hardware, so if you are looking for PPC, ARM,
71 SPARC, AXP, etc., features, you probably won' 71 SPARC, AXP, etc., features, you probably won't find what you are looking for.
72 It also only covers IPv4 networking, not IPv6 72 It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
73 additions and patches are welcome and will b 73 additions and patches are welcome and will be added to this document if you
74 mail them to Bodo. 74 mail them to Bodo.
75 75
76 We'd like to thank Alan Cox, Rik van Riel, a 76 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 77 other people for help compiling this documentation. We'd also like to extend a
78 special thank you to Andi Kleen for documenta 78 special thank you to Andi Kleen for documentation, which we relied on heavily
79 to create this document, as well as the add 79 to create this document, as well as the additional information he provided.
80 Thanks to everybody else who contributed so 80 Thanks to everybody else who contributed source or docs to the Linux kernel
81 and helped create a great piece of software... 81 and helped create a great piece of software... :)
82 82
83 If you have any comments, corrections or add 83 If you have any comments, corrections or additions, please don't hesitate to
84 contact Bodo Bauer at bb@ricochet.net. We' 84 contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this
85 document. 85 document.
86 86
87 The latest version of this document 87 The latest version of this document is available online at
88 https://www.kernel.org/doc/html/latest/filesys !! 88 http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html
89 89
90 If the above direction does not works for 90 If the above direction does not works for you, you could try the kernel
91 mailing list at linux-kernel@vger.kernel.or 91 mailing list at linux-kernel@vger.kernel.org and/or try to reach me at
92 comandante@zaralinux.com. 92 comandante@zaralinux.com.
93 93
94 0.2 Legal Stuff 94 0.2 Legal Stuff
95 --------------- 95 ---------------
96 96
97 We don't guarantee the correctness of this 97 We don't guarantee the correctness of this document, and if you come to us
98 complaining about how you screwed up your 98 complaining about how you screwed up your system because of incorrect
99 documentation, we won't feel responsible... 99 documentation, we won't feel responsible...
100 100
101 Chapter 1: Collecting System Information 101 Chapter 1: Collecting System Information
102 ======================================== 102 ========================================
103 103
104 In This Chapter 104 In This Chapter
105 --------------- 105 ---------------
106 * Investigating the properties of the pse 106 * Investigating the properties of the pseudo file system /proc and its
107 ability to provide information on the runnin 107 ability to provide information on the running Linux system
108 * Examining /proc's structure 108 * Examining /proc's structure
109 * Uncovering various information about the 109 * Uncovering various information about the kernel and the processes running
110 on the system 110 on the system
111 111
112 ---------------------------------------------- 112 ------------------------------------------------------------------------------
113 113
114 The proc file system acts as an interface to 114 The proc file system acts as an interface to internal data structures in the
115 kernel. It can be used to obtain informatio 115 kernel. It can be used to obtain information about the system and to change
116 certain kernel parameters at runtime (sysctl). 116 certain kernel parameters at runtime (sysctl).
117 117
118 First, we'll take a look at the read-only 118 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 119 show you how you can use /proc/sys to change settings.
120 120
121 1.1 Process-Specific Subdirectories 121 1.1 Process-Specific Subdirectories
122 ----------------------------------- 122 -----------------------------------
123 123
124 The directory /proc contains (among other t 124 The directory /proc contains (among other things) one subdirectory for each
125 process running on the system, which is named 125 process running on the system, which is named after the process ID (PID).
126 126
127 The link 'self' points to the process readi 127 The link 'self' points to the process reading the file system. Each process
128 subdirectory has the entries listed in Table 1 128 subdirectory has the entries listed in Table 1-1.
129 129
130 Note that an open file descriptor to /proc/<pi 130 Note that an open file descriptor to /proc/<pid> or to any of its
131 contained files or subdirectories does not pre 131 contained files or subdirectories does not prevent <pid> being reused
132 for some other process in the event that <pid> 132 for some other process in the event that <pid> exits. Operations on
133 open /proc/<pid> file descriptors correspondin 133 open /proc/<pid> file descriptors corresponding to dead processes
134 never act on any new process that the kernel m 134 never act on any new process that the kernel may, through chance, have
135 also assigned the process ID <pid>. Instead, o 135 also assigned the process ID <pid>. Instead, operations on these FDs
136 usually fail with ESRCH. 136 usually fail with ESRCH.
137 137
138 .. table:: Table 1-1: Process specific entries 138 .. table:: Table 1-1: Process specific entries in /proc
139 139
140 ============= ============================== 140 ============= ===============================================================
141 File Content 141 File Content
142 ============= ============================== 142 ============= ===============================================================
143 clear_refs Clears page referenced bits sh 143 clear_refs Clears page referenced bits shown in smaps output
144 cmdline Command line arguments 144 cmdline Command line arguments
145 cpu Current and last cpu in which 145 cpu Current and last cpu in which it was executed (2.4)(smp)
146 cwd Link to the current working di 146 cwd Link to the current working directory
147 environ Values of environment variable 147 environ Values of environment variables
148 exe Link to the executable of this 148 exe Link to the executable of this process
149 fd Directory, which contains all 149 fd Directory, which contains all file descriptors
150 maps Memory maps to executables and 150 maps Memory maps to executables and library files (2.4)
151 mem Memory held by this process 151 mem Memory held by this process
152 root Link to the root directory of 152 root Link to the root directory of this process
153 stat Process status 153 stat Process status
154 statm Process memory status informat 154 statm Process memory status information
155 status Process status in human readab 155 status Process status in human readable form
156 wchan Present with CONFIG_KALLSYMS=y 156 wchan Present with CONFIG_KALLSYMS=y: it shows the kernel function
157 symbol the task is blocked in 157 symbol the task is blocked in - or "0" if not blocked.
158 pagemap Page table 158 pagemap Page table
159 stack Report full stack trace, enabl 159 stack Report full stack trace, enable via CONFIG_STACKTRACE
160 smaps An extension based on maps, sh 160 smaps An extension based on maps, showing the memory consumption of
161 each mapping and flags associa 161 each mapping and flags associated with it
162 smaps_rollup Accumulated smaps stats for al 162 smaps_rollup Accumulated smaps stats for all mappings of the process. This
163 can be derived from smaps, but 163 can be derived from smaps, but is faster and more convenient
164 numa_maps An extension based on maps, sh 164 numa_maps An extension based on maps, showing the memory locality and
165 binding policy as well as mem 165 binding policy as well as mem usage (in pages) of each mapping.
166 ============= ============================== 166 ============= ===============================================================
167 167
168 For example, to get the status information of 168 For example, to get the status information of a process, all you have to do is
169 read the file /proc/PID/status:: 169 read the file /proc/PID/status::
170 170
171 >cat /proc/self/status 171 >cat /proc/self/status
172 Name: cat 172 Name: cat
173 State: R (running) 173 State: R (running)
174 Tgid: 5452 174 Tgid: 5452
175 Pid: 5452 175 Pid: 5452
176 PPid: 743 176 PPid: 743
177 TracerPid: 0 177 TracerPid: 0 (2.4)
178 Uid: 501 501 501 501 178 Uid: 501 501 501 501
179 Gid: 100 100 100 100 179 Gid: 100 100 100 100
180 FDSize: 256 180 FDSize: 256
181 Groups: 100 14 16 181 Groups: 100 14 16
182 Kthread: 0 <<
183 VmPeak: 5004 kB 182 VmPeak: 5004 kB
184 VmSize: 5004 kB 183 VmSize: 5004 kB
185 VmLck: 0 kB 184 VmLck: 0 kB
186 VmHWM: 476 kB 185 VmHWM: 476 kB
187 VmRSS: 476 kB 186 VmRSS: 476 kB
188 RssAnon: 352 kB 187 RssAnon: 352 kB
189 RssFile: 120 kB 188 RssFile: 120 kB
190 RssShmem: 4 kB 189 RssShmem: 4 kB
191 VmData: 156 kB 190 VmData: 156 kB
192 VmStk: 88 kB 191 VmStk: 88 kB
193 VmExe: 68 kB 192 VmExe: 68 kB
194 VmLib: 1412 kB 193 VmLib: 1412 kB
195 VmPTE: 20 kb 194 VmPTE: 20 kb
196 VmSwap: 0 kB 195 VmSwap: 0 kB
197 HugetlbPages: 0 kB 196 HugetlbPages: 0 kB
198 CoreDumping: 0 197 CoreDumping: 0
199 THP_enabled: 1 198 THP_enabled: 1
200 Threads: 1 199 Threads: 1
201 SigQ: 0/28578 200 SigQ: 0/28578
202 SigPnd: 0000000000000000 201 SigPnd: 0000000000000000
203 ShdPnd: 0000000000000000 202 ShdPnd: 0000000000000000
204 SigBlk: 0000000000000000 203 SigBlk: 0000000000000000
205 SigIgn: 0000000000000000 204 SigIgn: 0000000000000000
206 SigCgt: 0000000000000000 205 SigCgt: 0000000000000000
207 CapInh: 00000000fffffeff 206 CapInh: 00000000fffffeff
208 CapPrm: 0000000000000000 207 CapPrm: 0000000000000000
209 CapEff: 0000000000000000 208 CapEff: 0000000000000000
210 CapBnd: ffffffffffffffff 209 CapBnd: ffffffffffffffff
211 CapAmb: 0000000000000000 210 CapAmb: 0000000000000000
212 NoNewPrivs: 0 211 NoNewPrivs: 0
213 Seccomp: 0 212 Seccomp: 0
214 Speculation_Store_Bypass: thread vulne 213 Speculation_Store_Bypass: thread vulnerable
215 SpeculationIndirectBranch: conditional 214 SpeculationIndirectBranch: conditional enabled
216 voluntary_ctxt_switches: 0 215 voluntary_ctxt_switches: 0
217 nonvoluntary_ctxt_switches: 1 216 nonvoluntary_ctxt_switches: 1
218 217
219 This shows you nearly the same information you 218 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 219 the ps command. In fact, ps uses the proc file system to obtain its
221 information. But you get a more detailed vie 220 information. But you get a more detailed view of the process by reading the
222 file /proc/PID/status. It fields are described 221 file /proc/PID/status. It fields are described in table 1-2.
223 222
224 The statm file contains more detailed in 223 The statm file contains more detailed information about the process
225 memory usage. Its seven fields are explained i 224 memory usage. Its seven fields are explained in Table 1-3. The stat file
226 contains detailed information about the proces 225 contains detailed information about the process itself. Its fields are
227 explained in Table 1-4. 226 explained in Table 1-4.
228 227
229 (for SMP CONFIG users) 228 (for SMP CONFIG users)
230 229
231 For making accounting scalable, RSS related in 230 For making accounting scalable, RSS related information are handled in an
232 asynchronous manner and the value may not be v 231 asynchronous manner and the value may not be very precise. To see a precise
233 snapshot of a moment, you can see /proc/<pid>/ 232 snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
234 It's slow but very precise. 233 It's slow but very precise.
235 234
236 .. table:: Table 1-2: Contents of the status f !! 235 .. table:: Table 1-2: Contents of the status files (as of 4.19)
237 236
238 ========================== ================= 237 ========================== ===================================================
239 Field Content 238 Field Content
240 ========================== ================= 239 ========================== ===================================================
241 Name filename of the e 240 Name filename of the executable
242 Umask file mode creatio 241 Umask file mode creation mask
243 State state (R is runni 242 State state (R is running, S is sleeping, D is sleeping
244 in an uninterrupt 243 in an uninterruptible wait, Z is zombie,
245 T is traced or st 244 T is traced or stopped)
246 Tgid thread group ID 245 Tgid thread group ID
247 Ngid NUMA group ID (0 246 Ngid NUMA group ID (0 if none)
248 Pid process id 247 Pid process id
249 PPid process id of the 248 PPid process id of the parent process
250 TracerPid PID of process tr 249 TracerPid PID of process tracing this process (0 if not, or
251 the tracer is out 250 the tracer is outside of the current pid namespace)
252 Uid Real, effective, 251 Uid Real, effective, saved set, and file system UIDs
253 Gid Real, effective, 252 Gid Real, effective, saved set, and file system GIDs
254 FDSize number of file de 253 FDSize number of file descriptor slots currently allocated
255 Groups supplementary gro 254 Groups supplementary group list
256 NStgid descendant namesp 255 NStgid descendant namespace thread group ID hierarchy
257 NSpid descendant namesp 256 NSpid descendant namespace process ID hierarchy
258 NSpgid descendant namesp 257 NSpgid descendant namespace process group ID hierarchy
259 NSsid descendant namesp 258 NSsid descendant namespace session ID hierarchy
260 Kthread kernel thread fla <<
261 VmPeak peak virtual memo 259 VmPeak peak virtual memory size
262 VmSize total program siz 260 VmSize total program size
263 VmLck locked memory siz 261 VmLck locked memory size
264 VmPin pinned memory siz 262 VmPin pinned memory size
265 VmHWM peak resident set 263 VmHWM peak resident set size ("high water mark")
266 VmRSS size of memory po 264 VmRSS size of memory portions. It contains the three
267 following parts 265 following parts
268 (VmRSS = RssAnon 266 (VmRSS = RssAnon + RssFile + RssShmem)
269 RssAnon size of resident 267 RssAnon size of resident anonymous memory
270 RssFile size of resident 268 RssFile size of resident file mappings
271 RssShmem size of resident 269 RssShmem size of resident shmem memory (includes SysV shm,
272 mapping of tmpfs 270 mapping of tmpfs and shared anonymous mappings)
273 VmData size of private d 271 VmData size of private data segments
274 VmStk size of stack seg 272 VmStk size of stack segments
275 VmExe size of text segm 273 VmExe size of text segment
276 VmLib size of shared li 274 VmLib size of shared library code
277 VmPTE size of page tabl 275 VmPTE size of page table entries
278 VmSwap amount of swap us 276 VmSwap amount of swap used by anonymous private data
279 (shmem swap usage 277 (shmem swap usage is not included)
280 HugetlbPages size of hugetlb m 278 HugetlbPages size of hugetlb memory portions
281 CoreDumping process's memory 279 CoreDumping process's memory is currently being dumped
282 (killing the proc 280 (killing the process may lead to a corrupted core)
283 THP_enabled process is allowe 281 THP_enabled process is allowed to use THP (returns 0 when
284 PR_SET_THP_DISABL 282 PR_SET_THP_DISABLE is set on the process
285 Threads number of threads 283 Threads number of threads
286 SigQ number of signals 284 SigQ number of signals queued/max. number for queue
287 SigPnd bitmap of pending 285 SigPnd bitmap of pending signals for the thread
288 ShdPnd bitmap of shared 286 ShdPnd bitmap of shared pending signals for the process
289 SigBlk bitmap of blocked 287 SigBlk bitmap of blocked signals
290 SigIgn bitmap of ignored 288 SigIgn bitmap of ignored signals
291 SigCgt bitmap of caught 289 SigCgt bitmap of caught signals
292 CapInh bitmap of inherit 290 CapInh bitmap of inheritable capabilities
293 CapPrm bitmap of permitt 291 CapPrm bitmap of permitted capabilities
294 CapEff bitmap of effecti 292 CapEff bitmap of effective capabilities
295 CapBnd bitmap of capabil 293 CapBnd bitmap of capabilities bounding set
296 CapAmb bitmap of ambient 294 CapAmb bitmap of ambient capabilities
297 NoNewPrivs no_new_privs, lik 295 NoNewPrivs no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...)
298 Seccomp seccomp mode, lik 296 Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...)
299 Speculation_Store_Bypass speculative store 297 Speculation_Store_Bypass speculative store bypass mitigation status
300 SpeculationIndirectBranch indirect branch s 298 SpeculationIndirectBranch indirect branch speculation mode
301 Cpus_allowed mask of CPUs on w 299 Cpus_allowed mask of CPUs on which this process may run
302 Cpus_allowed_list Same as previous, 300 Cpus_allowed_list Same as previous, but in "list format"
303 Mems_allowed mask of memory no 301 Mems_allowed mask of memory nodes allowed to this process
304 Mems_allowed_list Same as previous, 302 Mems_allowed_list Same as previous, but in "list format"
305 voluntary_ctxt_switches number of volunta 303 voluntary_ctxt_switches number of voluntary context switches
306 nonvoluntary_ctxt_switches number of non vol 304 nonvoluntary_ctxt_switches number of non voluntary context switches
307 ========================== ================= 305 ========================== ===================================================
308 306
309 307
310 .. table:: Table 1-3: Contents of the statm fi !! 308 .. table:: Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
311 309
312 ======== =============================== 310 ======== =============================== ==============================
313 Field Content 311 Field Content
314 ======== =============================== 312 ======== =============================== ==============================
315 size total program size (pages) 313 size total program size (pages) (same as VmSize in status)
316 resident size of memory portions (pages) 314 resident size of memory portions (pages) (same as VmRSS in status)
317 shared number of pages that are shared 315 shared number of pages that are shared (i.e. backed by a file, same
318 316 as RssFile+RssShmem in status)
319 trs number of pages that are 'code' 317 trs number of pages that are 'code' (not including libs; broken,
320 318 includes data segment)
321 lrs number of pages of library 319 lrs number of pages of library (always 0 on 2.6)
322 drs number of pages of data/stack 320 drs number of pages of data/stack (including libs; broken,
323 321 includes library text)
324 dt number of dirty pages 322 dt number of dirty pages (always 0 on 2.6)
325 ======== =============================== 323 ======== =============================== ==============================
326 324
327 325
328 .. table:: Table 1-4: Contents of the stat fie !! 326 .. table:: Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
329 327
330 ============= ============================== 328 ============= ===============================================================
331 Field Content 329 Field Content
332 ============= ============================== 330 ============= ===============================================================
333 pid process id 331 pid process id
334 tcomm filename of the executable 332 tcomm filename of the executable
335 state state (R is running, S is slee 333 state state (R is running, S is sleeping, D is sleeping in an
336 uninterruptible wait, Z is zom 334 uninterruptible wait, Z is zombie, T is traced or stopped)
337 ppid process id of the parent proce 335 ppid process id of the parent process
338 pgrp pgrp of the process 336 pgrp pgrp of the process
339 sid session id 337 sid session id
340 tty_nr tty the process uses 338 tty_nr tty the process uses
341 tty_pgrp pgrp of the tty 339 tty_pgrp pgrp of the tty
342 flags task flags 340 flags task flags
343 min_flt number of minor faults 341 min_flt number of minor faults
344 cmin_flt number of minor faults with ch 342 cmin_flt number of minor faults with child's
345 maj_flt number of major faults 343 maj_flt number of major faults
346 cmaj_flt number of major faults with ch 344 cmaj_flt number of major faults with child's
347 utime user mode jiffies 345 utime user mode jiffies
348 stime kernel mode jiffies 346 stime kernel mode jiffies
349 cutime user mode jiffies with child's 347 cutime user mode jiffies with child's
350 cstime kernel mode jiffies with child 348 cstime kernel mode jiffies with child's
351 priority priority level 349 priority priority level
352 nice nice level 350 nice nice level
353 num_threads number of threads 351 num_threads number of threads
354 it_real_value (obsolete, always 0) 352 it_real_value (obsolete, always 0)
355 start_time time the process started after 353 start_time time the process started after system boot
356 vsize virtual memory size 354 vsize virtual memory size
357 rss resident set memory size 355 rss resident set memory size
358 rsslim current limit in bytes on the 356 rsslim current limit in bytes on the rss
359 start_code address above which program te 357 start_code address above which program text can run
360 end_code address below which program te 358 end_code address below which program text can run
361 start_stack address of the start of the ma 359 start_stack address of the start of the main process stack
362 esp current value of ESP 360 esp current value of ESP
363 eip current value of EIP 361 eip current value of EIP
364 pending bitmap of pending signals 362 pending bitmap of pending signals
365 blocked bitmap of blocked signals 363 blocked bitmap of blocked signals
366 sigign bitmap of ignored signals 364 sigign bitmap of ignored signals
367 sigcatch bitmap of caught signals 365 sigcatch bitmap of caught signals
368 0 (place holder, used to be the 366 0 (place holder, used to be the wchan address,
369 use /proc/PID/wchan instead) 367 use /proc/PID/wchan instead)
370 0 (place holder) 368 0 (place holder)
371 0 (place holder) 369 0 (place holder)
372 exit_signal signal to send to parent threa 370 exit_signal signal to send to parent thread on exit
373 task_cpu which CPU the task is schedule 371 task_cpu which CPU the task is scheduled on
374 rt_priority realtime priority 372 rt_priority realtime priority
375 policy scheduling policy (man sched_s 373 policy scheduling policy (man sched_setscheduler)
376 blkio_ticks time spent waiting for block I 374 blkio_ticks time spent waiting for block IO
377 gtime guest time of the task in jiff 375 gtime guest time of the task in jiffies
378 cgtime guest time of the task childre 376 cgtime guest time of the task children in jiffies
379 start_data address above which program da 377 start_data address above which program data+bss is placed
380 end_data address below which program da 378 end_data address below which program data+bss is placed
381 start_brk address above which program he 379 start_brk address above which program heap can be expanded with brk()
382 arg_start address above which program co 380 arg_start address above which program command line is placed
383 arg_end address below which program co 381 arg_end address below which program command line is placed
384 env_start address above which program en 382 env_start address above which program environment is placed
385 env_end address below which program en 383 env_end address below which program environment is placed
386 exit_code the thread's exit_code in the 384 exit_code the thread's exit_code in the form reported by the waitpid
387 system call 385 system call
388 ============= ============================== 386 ============= ===============================================================
389 387
390 The /proc/PID/maps file contains the currently 388 The /proc/PID/maps file contains the currently mapped memory regions and
391 their access permissions. 389 their access permissions.
392 390
393 The format is:: 391 The format is::
394 392
395 address perms offset dev inod 393 address perms offset dev inode pathname
396 394
397 08048000-08049000 r-xp 00000000 03:00 8312 395 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test
398 08049000-0804a000 rw-p 00001000 03:00 8312 396 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
399 0804a000-0806b000 rw-p 00000000 00:00 0 397 0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
400 a7cb1000-a7cb2000 ---p 00000000 00:00 0 398 a7cb1000-a7cb2000 ---p 00000000 00:00 0
401 a7cb2000-a7eb2000 rw-p 00000000 00:00 0 399 a7cb2000-a7eb2000 rw-p 00000000 00:00 0
402 a7eb2000-a7eb3000 ---p 00000000 00:00 0 400 a7eb2000-a7eb3000 ---p 00000000 00:00 0
403 a7eb3000-a7ed5000 rw-p 00000000 00:00 0 401 a7eb3000-a7ed5000 rw-p 00000000 00:00 0
404 a7ed5000-a8008000 r-xp 00000000 03:00 4222 402 a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
405 a8008000-a800a000 r--p 00133000 03:00 4222 403 a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
406 a800a000-a800b000 rw-p 00135000 03:00 4222 404 a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
407 a800b000-a800e000 rw-p 00000000 00:00 0 405 a800b000-a800e000 rw-p 00000000 00:00 0
408 a800e000-a8022000 r-xp 00000000 03:00 1446 406 a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
409 a8022000-a8023000 r--p 00013000 03:00 1446 407 a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
410 a8023000-a8024000 rw-p 00014000 03:00 1446 408 a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
411 a8024000-a8027000 rw-p 00000000 00:00 0 409 a8024000-a8027000 rw-p 00000000 00:00 0
412 a8027000-a8043000 r-xp 00000000 03:00 8317 410 a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
413 a8043000-a8044000 r--p 0001b000 03:00 8317 411 a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
414 a8044000-a8045000 rw-p 0001c000 03:00 8317 412 a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
415 aff35000-aff4a000 rw-p 00000000 00:00 0 413 aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
416 ffffe000-fffff000 r-xp 00000000 00:00 0 414 ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
417 415
418 where "address" is the address space in the pr 416 where "address" is the address space in the process that it occupies, "perms"
419 is a set of permissions:: 417 is a set of permissions::
420 418
421 r = read 419 r = read
422 w = write 420 w = write
423 x = execute 421 x = execute
424 s = shared 422 s = shared
425 p = private (copy on write) 423 p = private (copy on write)
426 424
427 "offset" is the offset into the mapping, "dev" 425 "offset" is the offset into the mapping, "dev" is the device (major:minor), and
428 "inode" is the inode on that device. 0 indic 426 "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 427 with the memory region, as the case would be with BSS (uninitialized data).
430 The "pathname" shows the name associated file 428 The "pathname" shows the name associated file for this mapping. If the mapping
431 is not associated with a file: 429 is not associated with a file:
432 430
433 =================== ================== 431 =================== ===========================================
434 [heap] the heap of the pr 432 [heap] the heap of the program
435 [stack] the stack of the m 433 [stack] the stack of the main process
436 [vdso] the "virtual dynam 434 [vdso] the "virtual dynamic shared object",
437 the kernel system 435 the kernel system call handler
438 [anon:<name>] a private anonymou 436 [anon:<name>] a private anonymous mapping that has been
439 named by userspace 437 named by userspace
440 [anon_shmem:<name>] an anonymous share 438 [anon_shmem:<name>] an anonymous shared memory mapping that has
441 been named by user 439 been named by userspace
442 =================== ================== 440 =================== ===========================================
443 441
444 or if empty, the mapping is anonymous. 442 or if empty, the mapping is anonymous.
445 443
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 444 The /proc/PID/smaps is an extension based on maps, showing the memory
456 consumption for each of the process's mappings 445 consumption for each of the process's mappings. For each mapping (aka Virtual
457 Memory Area, or VMA) there is a series of line 446 Memory Area, or VMA) there is a series of lines such as the following::
458 447
459 08048000-080bc000 r-xp 00000000 03:02 1313 448 08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
460 449
461 Size: 1084 kB 450 Size: 1084 kB
462 KernelPageSize: 4 kB 451 KernelPageSize: 4 kB
463 MMUPageSize: 4 kB 452 MMUPageSize: 4 kB
464 Rss: 892 kB 453 Rss: 892 kB
465 Pss: 374 kB 454 Pss: 374 kB
466 Pss_Dirty: 0 kB 455 Pss_Dirty: 0 kB
467 Shared_Clean: 892 kB 456 Shared_Clean: 892 kB
468 Shared_Dirty: 0 kB 457 Shared_Dirty: 0 kB
469 Private_Clean: 0 kB 458 Private_Clean: 0 kB
470 Private_Dirty: 0 kB 459 Private_Dirty: 0 kB
471 Referenced: 892 kB 460 Referenced: 892 kB
472 Anonymous: 0 kB 461 Anonymous: 0 kB
473 KSM: 0 kB <<
474 LazyFree: 0 kB 462 LazyFree: 0 kB
475 AnonHugePages: 0 kB 463 AnonHugePages: 0 kB
476 ShmemPmdMapped: 0 kB 464 ShmemPmdMapped: 0 kB
477 Shared_Hugetlb: 0 kB 465 Shared_Hugetlb: 0 kB
478 Private_Hugetlb: 0 kB 466 Private_Hugetlb: 0 kB
479 Swap: 0 kB 467 Swap: 0 kB
480 SwapPss: 0 kB 468 SwapPss: 0 kB
481 KernelPageSize: 4 kB 469 KernelPageSize: 4 kB
482 MMUPageSize: 4 kB 470 MMUPageSize: 4 kB
483 Locked: 0 kB 471 Locked: 0 kB
484 THPeligible: 0 472 THPeligible: 0
485 VmFlags: rd ex mr mw me dw 473 VmFlags: rd ex mr mw me dw
486 474
487 The first of these lines shows the same inform 475 The first of these lines shows the same information as is displayed for the
488 mapping in /proc/PID/maps. Following lines sh 476 mapping in /proc/PID/maps. Following lines show the size of the mapping
489 (size); the size of each page allocated when b 477 (size); the size of each page allocated when backing a VMA (KernelPageSize),
490 which is usually the same as the size in the p 478 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 479 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 480 the amount of the mapping that is currently resident in RAM (RSS); the
493 process' proportional share of this mapping (P 481 process' proportional share of this mapping (PSS); and the number of clean and
494 dirty shared and private pages in the mapping. 482 dirty shared and private pages in the mapping.
495 483
496 The "proportional set size" (PSS) of a process 484 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 485 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, 486 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 487 process, its PSS will be 1500. "Pss_Dirty" is the portion of PSS which
500 consists of dirty pages. ("Pss_Clean" is not 488 consists of dirty pages. ("Pss_Clean" is not included, but it can be
501 calculated by subtracting "Pss_Dirty" from "Ps 489 calculated by subtracting "Pss_Dirty" from "Pss".)
502 490
503 Note that even a page which is part of a MAP_S 491 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 492 a single pte mapped, i.e. is currently used by only one process, is accounted
505 as private and not as shared. 493 as private and not as shared.
506 494
507 "Referenced" indicates the amount of memory cu 495 "Referenced" indicates the amount of memory currently marked as referenced or
508 accessed. 496 accessed.
509 497
510 "Anonymous" shows the amount of memory that do 498 "Anonymous" shows the amount of memory that does not belong to any file. Even
511 a mapping associated with a file may contain a 499 a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
512 and a page is modified, the file page is repla 500 and a page is modified, the file page is replaced by a private anonymous copy.
513 501
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 502 "LazyFree" shows the amount of memory which is marked by madvise(MADV_FREE).
518 The memory isn't freed immediately with madvis 503 The memory isn't freed immediately with madvise(). It's freed in memory
519 pressure if the memory is clean. Please note t 504 pressure if the memory is clean. Please note that the printed value might
520 be lower than the real value due to optimizati 505 be lower than the real value due to optimizations used in the current
521 implementation. If this is not desirable pleas 506 implementation. If this is not desirable please file a bug report.
522 507
523 "AnonHugePages" shows the amount of memory bac !! 508 "AnonHugePages" shows the ammount of memory backed by transparent hugepage.
524 509
525 "ShmemPmdMapped" shows the amount of shared (s !! 510 "ShmemPmdMapped" shows the ammount of shared (shmem/tmpfs) memory backed by
526 huge pages. 511 huge pages.
527 512
528 "Shared_Hugetlb" and "Private_Hugetlb" show th !! 513 "Shared_Hugetlb" and "Private_Hugetlb" show the ammounts of memory backed by
529 hugetlbfs page which is *not* counted in "RSS" 514 hugetlbfs page which is *not* counted in "RSS" or "PSS" field for historical
530 reasons. And these are not included in {Shared 515 reasons. And these are not included in {Shared,Private}_{Clean,Dirty} field.
531 516
532 "Swap" shows how much would-be-anonymous memor 517 "Swap" shows how much would-be-anonymous memory is also used, but out on swap.
533 518
534 For shmem mappings, "Swap" includes also the s 519 For shmem mappings, "Swap" includes also the size of the mapped (and not
535 replaced by copy-on-write) part of the underly 520 replaced by copy-on-write) part of the underlying shmem object out on swap.
536 "SwapPss" shows proportional swap share of thi 521 "SwapPss" shows proportional swap share of this mapping. Unlike "Swap", this
537 does not take into account swapped out page of 522 does not take into account swapped out page of underlying shmem objects.
538 "Locked" indicates whether the mapping is lock 523 "Locked" indicates whether the mapping is locked in memory or not.
539 524
540 "THPeligible" indicates whether the mapping is !! 525 "THPeligible" indicates whether the mapping is eligible for allocating THP
541 naturally aligned THP pages of any currently e !! 526 pages as well as the THP is PMD mappable or not - 1 if true, 0 otherwise.
542 otherwise. !! 527 It just shows the current status.
543 528
544 "VmFlags" field deserves a separate descriptio 529 "VmFlags" field deserves a separate description. This member represents the
545 kernel flags associated with the particular vi 530 kernel flags associated with the particular virtual memory area in two letter
546 encoded manner. The codes are the following: 531 encoded manner. The codes are the following:
547 532
548 == ==================================== 533 == =======================================
549 rd readable 534 rd readable
550 wr writeable 535 wr writeable
551 ex executable 536 ex executable
552 sh shared 537 sh shared
553 mr may read 538 mr may read
554 mw may write 539 mw may write
555 me may execute 540 me may execute
556 ms may share 541 ms may share
557 gd stack segment growns down 542 gd stack segment growns down
558 pf pure PFN range 543 pf pure PFN range
559 dw disabled write to the mapped file 544 dw disabled write to the mapped file
560 lo pages are locked in memory 545 lo pages are locked in memory
561 io memory mapped I/O area 546 io memory mapped I/O area
562 sr sequential read advise provided 547 sr sequential read advise provided
563 rr random read advise provided 548 rr random read advise provided
564 dc do not copy area on fork 549 dc do not copy area on fork
565 de do not expand area on remapping 550 de do not expand area on remapping
566 ac area is accountable 551 ac area is accountable
567 nr swap space is not reserved for the a 552 nr swap space is not reserved for the area
568 ht area uses huge tlb pages 553 ht area uses huge tlb pages
569 sf synchronous page fault 554 sf synchronous page fault
570 ar architecture specific flag 555 ar architecture specific flag
571 wf wipe on fork 556 wf wipe on fork
572 dd do not include area into core dump 557 dd do not include area into core dump
573 sd soft dirty flag 558 sd soft dirty flag
574 mm mixed map area 559 mm mixed map area
575 hg huge page advise flag 560 hg huge page advise flag
576 nh no huge page advise flag 561 nh no huge page advise flag
577 mg mergeable advise flag !! 562 mg mergable advise flag
578 bt arm64 BTI guarded page 563 bt arm64 BTI guarded page
579 mt arm64 MTE allocation tags are enable 564 mt arm64 MTE allocation tags are enabled
580 um userfaultfd missing tracking 565 um userfaultfd missing tracking
581 uw userfaultfd wr-protect tracking 566 uw userfaultfd wr-protect tracking
582 ss shadow stack page <<
583 sl sealed <<
584 == ==================================== 567 == =======================================
585 568
586 Note that there is no guarantee that every fla 569 Note that there is no guarantee that every flag and associated mnemonic will
587 be present in all further kernel releases. Thi 570 be present in all further kernel releases. Things get changed, the flags may
588 be vanished or the reverse -- new added. Inter 571 be vanished or the reverse -- new added. Interpretation of their meaning
589 might change in future as well. So each consum 572 might change in future as well. So each consumer of these flags has to
590 follow each specific kernel version for the ex 573 follow each specific kernel version for the exact semantic.
591 574
592 This file is only present if the CONFIG_MMU ke 575 This file is only present if the CONFIG_MMU kernel configuration option is
593 enabled. 576 enabled.
594 577
595 Note: reading /proc/PID/maps or /proc/PID/smap 578 Note: reading /proc/PID/maps or /proc/PID/smaps is inherently racy (consistent
596 output can be achieved only in the single read 579 output can be achieved only in the single read call).
597 580
598 This typically manifests when doing partial re 581 This typically manifests when doing partial reads of these files while the
599 memory map is being modified. Despite the rac 582 memory map is being modified. Despite the races, we do provide the following
600 guarantees: 583 guarantees:
601 584
602 1) The mapped addresses never go backwards, wh 585 1) The mapped addresses never go backwards, which implies no two
603 regions will ever overlap. 586 regions will ever overlap.
604 2) If there is something at a given vaddr duri 587 2) If there is something at a given vaddr during the entirety of the
605 life of the smaps/maps walk, there will be 588 life of the smaps/maps walk, there will be some output for it.
606 589
607 The /proc/PID/smaps_rollup file includes the s 590 The /proc/PID/smaps_rollup file includes the same fields as /proc/PID/smaps,
608 but their values are the sums of the correspon 591 but their values are the sums of the corresponding values for all mappings of
609 the process. Additionally, it contains these 592 the process. Additionally, it contains these fields:
610 593
611 - Pss_Anon 594 - Pss_Anon
612 - Pss_File 595 - Pss_File
613 - Pss_Shmem 596 - Pss_Shmem
614 597
615 They represent the proportional shares of anon 598 They represent the proportional shares of anonymous, file, and shmem pages, as
616 described for smaps above. These fields are o 599 described for smaps above. These fields are omitted in smaps since each
617 mapping identifies the type (anon, file, or sh 600 mapping identifies the type (anon, file, or shmem) of all pages it contains.
618 Thus all information in smaps_rollup can be de 601 Thus all information in smaps_rollup can be derived from smaps, but at a
619 significantly higher cost. 602 significantly higher cost.
620 603
621 The /proc/PID/clear_refs is used to reset the 604 The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
622 bits on both physical and virtual pages associ 605 bits on both physical and virtual pages associated with a process, and the
623 soft-dirty bit on pte (see Documentation/admin 606 soft-dirty bit on pte (see Documentation/admin-guide/mm/soft-dirty.rst
624 for details). 607 for details).
625 To clear the bits for all the pages associated 608 To clear the bits for all the pages associated with the process::
626 609
627 > echo 1 > /proc/PID/clear_refs 610 > echo 1 > /proc/PID/clear_refs
628 611
629 To clear the bits for the anonymous pages asso 612 To clear the bits for the anonymous pages associated with the process::
630 613
631 > echo 2 > /proc/PID/clear_refs 614 > echo 2 > /proc/PID/clear_refs
632 615
633 To clear the bits for the file mapped pages as 616 To clear the bits for the file mapped pages associated with the process::
634 617
635 > echo 3 > /proc/PID/clear_refs 618 > echo 3 > /proc/PID/clear_refs
636 619
637 To clear the soft-dirty bit:: 620 To clear the soft-dirty bit::
638 621
639 > echo 4 > /proc/PID/clear_refs 622 > echo 4 > /proc/PID/clear_refs
640 623
641 To reset the peak resident set size ("high wat 624 To reset the peak resident set size ("high water mark") to the process's
642 current value:: 625 current value::
643 626
644 > echo 5 > /proc/PID/clear_refs 627 > echo 5 > /proc/PID/clear_refs
645 628
646 Any other value written to /proc/PID/clear_ref 629 Any other value written to /proc/PID/clear_refs will have no effect.
647 630
648 The /proc/pid/pagemap gives the PFN, which can 631 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 632 using /proc/kpageflags and number of times a page is mapped using
650 /proc/kpagecount. For detailed explanation, se 633 /proc/kpagecount. For detailed explanation, see
651 Documentation/admin-guide/mm/pagemap.rst. 634 Documentation/admin-guide/mm/pagemap.rst.
652 635
653 The /proc/pid/numa_maps is an extension based 636 The /proc/pid/numa_maps is an extension based on maps, showing the memory
654 locality and binding policy, as well as the me 637 locality and binding policy, as well as the memory usage (in pages) of
655 each mapping. The output follows a general for 638 each mapping. The output follows a general format where mapping details get
656 summarized separated by blank spaces, one mapp 639 summarized separated by blank spaces, one mapping per each file line::
657 640
658 address policy mapping details 641 address policy mapping details
659 642
660 00400000 default file=/usr/local/bin/app m 643 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 644 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 645 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 646 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 647 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 648 3206221000 default anon=1 dirty=1 N3=1 kernelpagesize_kB=4
666 3206800000 default file=/lib64/libc-2.12.s 649 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 650 320698b000 default file=/lib64/libc-2.12.so
668 3206b8a000 default file=/lib64/libc-2.12.s 651 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 652 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=1 653 3206b8f000 default anon=3 dirty=3 active=1 N3=3 kernelpagesize_kB=4
671 7f4dc10a2000 default anon=3 dirty=3 N3=3 k 654 7f4dc10a2000 default anon=3 dirty=3 N3=3 kernelpagesize_kB=4
672 7f4dc10b4000 default anon=2 dirty=2 active 655 7f4dc10b4000 default anon=2 dirty=2 active=1 N3=2 kernelpagesize_kB=4
673 7f4dc1200000 default file=/anon_hugepage\0 656 7f4dc1200000 default file=/anon_hugepage\040(deleted) huge anon=1 dirty=1 N3=1 kernelpagesize_kB=2048
674 7fff335f0000 default stack anon=3 dirty=3 657 7fff335f0000 default stack anon=3 dirty=3 N3=3 kernelpagesize_kB=4
675 7fff3369d000 default mapped=1 mapmax=35 ac 658 7fff3369d000 default mapped=1 mapmax=35 active=0 N3=1 kernelpagesize_kB=4
676 659
677 Where: 660 Where:
678 661
679 "address" is the starting address for the mapp 662 "address" is the starting address for the mapping;
680 663
681 "policy" reports the NUMA memory policy set fo 664 "policy" reports the NUMA memory policy set for the mapping (see Documentation/admin-guide/mm/numa_memory_policy.rst);
682 665
683 "mapping details" summarizes mapping data such 666 "mapping details" summarizes mapping data such as mapping type, page usage counters,
684 node locality page counters (N0 == node0, N1 = 667 node locality page counters (N0 == node0, N1 == node1, ...) and the kernel page
685 size, in KB, that is backing the mapping up. 668 size, in KB, that is backing the mapping up.
686 669
687 1.2 Kernel data 670 1.2 Kernel data
688 --------------- 671 ---------------
689 672
690 Similar to the process entries, the kernel d 673 Similar to the process entries, the kernel data files give information about
691 the running kernel. The files used to obtain t 674 the running kernel. The files used to obtain this information are contained in
692 /proc and are listed in Table 1-5. Not all 675 /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 676 system. It depends on the kernel configuration and the loaded modules, which
694 files are there, and which are missing. 677 files are there, and which are missing.
695 678
696 .. table:: Table 1-5: Kernel info in /proc 679 .. table:: Table 1-5: Kernel info in /proc
697 680
698 ============ ================================ 681 ============ ===============================================================
699 File Content 682 File Content
700 ============ ================================ 683 ============ ===============================================================
701 allocinfo Memory allocations profiling inf <<
702 apm Advanced power management info 684 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 685 buddyinfo Kernel memory allocator information (see text) (2.5)
709 bus Directory containing bus specifi 686 bus Directory containing bus specific information
710 cmdline Kernel command line, both from b !! 687 cmdline Kernel command line
711 in the kernel image <<
712 cpuinfo Info about the CPU 688 cpuinfo Info about the CPU
713 devices Available devices (block and cha 689 devices Available devices (block and character)
714 dma Used DMS channels 690 dma Used DMS channels
715 filesystems Supported filesystems 691 filesystems Supported filesystems
716 driver Various drivers grouped here, cu 692 driver Various drivers grouped here, currently rtc (2.4)
717 execdomains Execdomains, related to security 693 execdomains Execdomains, related to security (2.4)
718 fb Frame Buffer devices 694 fb Frame Buffer devices (2.4)
719 fs File system parameters, currentl 695 fs File system parameters, currently nfs/exports (2.4)
720 ide Directory containing info about 696 ide Directory containing info about the IDE subsystem
721 interrupts Interrupt usage 697 interrupts Interrupt usage
722 iomem Memory map 698 iomem Memory map (2.4)
723 ioports I/O port usage 699 ioports I/O port usage
724 irq Masks for irq to cpu affinity 700 irq Masks for irq to cpu affinity (2.4)(smp?)
725 isapnp ISA PnP (Plug&Play) Info 701 isapnp ISA PnP (Plug&Play) Info (2.4)
726 kcore Kernel core image (can be ELF or 702 kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
727 kmsg Kernel messages 703 kmsg Kernel messages
728 ksyms Kernel symbol table 704 ksyms Kernel symbol table
729 loadavg Load average of last 1, 5 & 15 m 705 loadavg Load average of last 1, 5 & 15 minutes;
730 number of processes currently 706 number of processes currently runnable (running or on ready queue);
731 total number of processes in s 707 total number of processes in system;
732 last pid created. 708 last pid created.
733 All fields are separated by on 709 All fields are separated by one space except "number of
734 processes currently runnable" 710 processes currently runnable" and "total number of processes
735 in system", which are separate 711 in system", which are separated by a slash ('/'). Example:
736 0.61 0.61 0.55 3/828 22084 712 0.61 0.61 0.55 3/828 22084
737 locks Kernel locks 713 locks Kernel locks
738 meminfo Memory info 714 meminfo Memory info
739 misc Miscellaneous 715 misc Miscellaneous
740 modules List of loaded modules 716 modules List of loaded modules
741 mounts Mounted filesystems 717 mounts Mounted filesystems
742 net Networking info (see text) 718 net Networking info (see text)
743 pagetypeinfo Additional page allocator inform 719 pagetypeinfo Additional page allocator information (see text) (2.5)
744 partitions Table of partitions known to the 720 partitions Table of partitions known to the system
745 pci Deprecated info of PCI bus (new 721 pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
746 decoupled by lspci 722 decoupled by lspci (2.4)
747 rtc Real time clock 723 rtc Real time clock
748 scsi SCSI info (see text) 724 scsi SCSI info (see text)
749 slabinfo Slab pool info 725 slabinfo Slab pool info
750 softirqs softirq usage 726 softirqs softirq usage
751 stat Overall statistics 727 stat Overall statistics
752 swaps Swap space utilization 728 swaps Swap space utilization
753 sys See chapter 2 729 sys See chapter 2
754 sysvipc Info of SysVIPC Resources (msg, 730 sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
755 tty Info of tty drivers 731 tty Info of tty drivers
756 uptime Wall clock since boot, combined 732 uptime Wall clock since boot, combined idle time of all cpus
757 version Kernel version 733 version Kernel version
758 video bttv info of video resources 734 video bttv info of video resources (2.4)
759 vmallocinfo Show vmalloced areas 735 vmallocinfo Show vmalloced areas
760 ============ ================================ 736 ============ ===============================================================
761 737
762 You can, for example, check which interrup 738 You can, for example, check which interrupts are currently in use and what
763 they are used for by looking in the file /proc 739 they are used for by looking in the file /proc/interrupts::
764 740
765 > cat /proc/interrupts 741 > cat /proc/interrupts
766 CPU0 742 CPU0
767 0: 8728810 XT-PIC timer 743 0: 8728810 XT-PIC timer
768 1: 895 XT-PIC keyboard 744 1: 895 XT-PIC keyboard
769 2: 0 XT-PIC cascade 745 2: 0 XT-PIC cascade
770 3: 531695 XT-PIC aha152x 746 3: 531695 XT-PIC aha152x
771 4: 2014133 XT-PIC serial 747 4: 2014133 XT-PIC serial
772 5: 44401 XT-PIC pcnet_cs 748 5: 44401 XT-PIC pcnet_cs
773 8: 2 XT-PIC rtc 749 8: 2 XT-PIC rtc
774 11: 8 XT-PIC i82365 750 11: 8 XT-PIC i82365
775 12: 182918 XT-PIC PS/2 Mouse 751 12: 182918 XT-PIC PS/2 Mouse
776 13: 1 XT-PIC fpu 752 13: 1 XT-PIC fpu
777 14: 1232265 XT-PIC ide0 753 14: 1232265 XT-PIC ide0
778 15: 7 XT-PIC ide1 754 15: 7 XT-PIC ide1
779 NMI: 0 755 NMI: 0
780 756
781 In 2.4.* a couple of lines where added to this 757 In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
782 output of a SMP machine):: 758 output of a SMP machine)::
783 759
784 > cat /proc/interrupts 760 > cat /proc/interrupts
785 761
786 CPU0 CPU1 762 CPU0 CPU1
787 0: 1243498 1214548 IO-APIC-edge 763 0: 1243498 1214548 IO-APIC-edge timer
788 1: 8949 8958 IO-APIC-edge 764 1: 8949 8958 IO-APIC-edge keyboard
789 2: 0 0 XT-PIC 765 2: 0 0 XT-PIC cascade
790 5: 11286 10161 IO-APIC-edge 766 5: 11286 10161 IO-APIC-edge soundblaster
791 8: 1 0 IO-APIC-edge 767 8: 1 0 IO-APIC-edge rtc
792 9: 27422 27407 IO-APIC-edge 768 9: 27422 27407 IO-APIC-edge 3c503
793 12: 113645 113873 IO-APIC-edge 769 12: 113645 113873 IO-APIC-edge PS/2 Mouse
794 13: 0 0 XT-PIC 770 13: 0 0 XT-PIC fpu
795 14: 22491 24012 IO-APIC-edge 771 14: 22491 24012 IO-APIC-edge ide0
796 15: 2183 2415 IO-APIC-edge 772 15: 2183 2415 IO-APIC-edge ide1
797 17: 30564 30414 IO-APIC-level 773 17: 30564 30414 IO-APIC-level eth0
798 18: 177 164 IO-APIC-level 774 18: 177 164 IO-APIC-level bttv
799 NMI: 2457961 2457959 775 NMI: 2457961 2457959
800 LOC: 2457882 2457881 776 LOC: 2457882 2457881
801 ERR: 2155 777 ERR: 2155
802 778
803 NMI is incremented in this case because every 779 NMI is incremented in this case because every timer interrupt generates a NMI
804 (Non Maskable Interrupt) which is used by the 780 (Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups.
805 781
806 LOC is the local interrupt counter of the inte 782 LOC is the local interrupt counter of the internal APIC of every CPU.
807 783
808 ERR is incremented in the case of errors in th 784 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 785 connects the CPUs in a SMP system. This means that an error has been detected,
810 the IO-APIC automatically retry the transmissi 786 the IO-APIC automatically retry the transmission, so it should not be a big
811 problem, but you should read the SMP-FAQ. 787 problem, but you should read the SMP-FAQ.
812 788
813 In 2.6.2* /proc/interrupts was expanded again. 789 In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
814 /proc/interrupts to display every IRQ vector i 790 /proc/interrupts to display every IRQ vector in use by the system, not
815 just those considered 'most important'. The n 791 just those considered 'most important'. The new vectors are:
816 792
817 THR 793 THR
818 interrupt raised when a machine check thresh 794 interrupt raised when a machine check threshold counter
819 (typically counting ECC corrected errors of 795 (typically counting ECC corrected errors of memory or cache) exceeds
820 a configurable threshold. Only available on 796 a configurable threshold. Only available on some systems.
821 797
822 TRM 798 TRM
823 a thermal event interrupt occurs when a temp 799 a thermal event interrupt occurs when a temperature threshold
824 has been exceeded for the CPU. This interru 800 has been exceeded for the CPU. This interrupt may also be generated
825 when the temperature drops back to normal. 801 when the temperature drops back to normal.
826 802
827 SPU 803 SPU
828 a spurious interrupt is some interrupt that 804 a spurious interrupt is some interrupt that was raised then lowered
829 by some IO device before it could be fully p 805 by some IO device before it could be fully processed by the APIC. Hence
830 the APIC sees the interrupt but does not kno 806 the APIC sees the interrupt but does not know what device it came from.
831 For this case the APIC will generate the int 807 For this case the APIC will generate the interrupt with a IRQ vector
832 of 0xff. This might also be generated by chi 808 of 0xff. This might also be generated by chipset bugs.
833 809
834 RES, CAL, TLB 810 RES, CAL, TLB
835 rescheduling, call and TLB flush interrupts 811 rescheduling, call and TLB flush interrupts are
836 sent from one CPU to another per the needs o 812 sent from one CPU to another per the needs of the OS. Typically,
837 their statistics are used by kernel develope 813 their statistics are used by kernel developers and interested users to
838 determine the occurrence of interrupts of th 814 determine the occurrence of interrupts of the given type.
839 815
840 The above IRQ vectors are displayed only when 816 The above IRQ vectors are displayed only when relevant. For example,
841 the threshold vector does not exist on x86_64 817 the threshold vector does not exist on x86_64 platforms. Others are
842 suppressed when the system is a uniprocessor. 818 suppressed when the system is a uniprocessor. As of this writing, only
843 i386 and x86_64 platforms support the new IRQ 819 i386 and x86_64 platforms support the new IRQ vector displays.
844 820
845 Of some interest is the introduction of the /p 821 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 822 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 823 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 824 irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and
849 prof_cpu_mask. 825 prof_cpu_mask.
850 826
851 For example:: 827 For example::
852 828
853 > ls /proc/irq/ 829 > ls /proc/irq/
854 0 10 12 14 16 18 2 4 6 8 prof_cpu_ 830 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 831 1 11 13 15 17 19 3 5 7 9 default_smp_affinity
856 > ls /proc/irq/0/ 832 > ls /proc/irq/0/
857 smp_affinity 833 smp_affinity
858 834
859 smp_affinity is a bitmask, in which you can sp 835 smp_affinity is a bitmask, in which you can specify which CPUs can handle the
860 IRQ. You can set it by doing:: 836 IRQ. You can set it by doing::
861 837
862 > echo 1 > /proc/irq/10/smp_affinity 838 > echo 1 > /proc/irq/10/smp_affinity
863 839
864 This means that only the first CPU will handle 840 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 841 5 which means that only the first and third CPU can handle the IRQ.
866 842
867 The contents of each smp_affinity file is the 843 The contents of each smp_affinity file is the same by default::
868 844
869 > cat /proc/irq/0/smp_affinity 845 > cat /proc/irq/0/smp_affinity
870 ffffffff 846 ffffffff
871 847
872 There is an alternate interface, smp_affinity_ 848 There is an alternate interface, smp_affinity_list which allows specifying
873 a CPU range instead of a bitmask:: 849 a CPU range instead of a bitmask::
874 850
875 > cat /proc/irq/0/smp_affinity_list 851 > cat /proc/irq/0/smp_affinity_list
876 1024-1031 852 1024-1031
877 853
878 The default_smp_affinity mask applies to all n 854 The default_smp_affinity mask applies to all non-active IRQs, which are the
879 IRQs which have not yet been allocated/activat 855 IRQs which have not yet been allocated/activated, and hence which lack a
880 /proc/irq/[0-9]* directory. 856 /proc/irq/[0-9]* directory.
881 857
882 The node file on an SMP system shows the node 858 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 859 reports itself as being attached. This hardware locality information does not
884 include information about any possible driver 860 include information about any possible driver locality preference.
885 861
886 prof_cpu_mask specifies which CPUs are to be p 862 prof_cpu_mask specifies which CPUs are to be profiled by the system wide
887 profiler. Default value is ffffffff (all CPUs 863 profiler. Default value is ffffffff (all CPUs if there are only 32 of them).
888 864
889 The way IRQs are routed is handled by the IO-A 865 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 866 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 867 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 868 best choice for almost everyone. [Note this applies only to those IO-APIC's
893 that support "Round Robin" interrupt distribut 869 that support "Round Robin" interrupt distribution.]
894 870
895 There are three more important subdirectori 871 There are three more important subdirectories in /proc: net, scsi, and sys.
896 The general rule is that the contents, o 872 The general rule is that the contents, or even the existence of these
897 directories, depend on your kernel configurat 873 directories, depend on your kernel configuration. If SCSI is not enabled, the
898 directory scsi may not exist. The same is t 874 directory scsi may not exist. The same is true with the net, which is there
899 only when networking support is present in the 875 only when networking support is present in the running kernel.
900 876
901 The slabinfo file gives information about 877 The slabinfo file gives information about memory usage at the slab level.
902 Linux uses slab pools for memory management 878 Linux uses slab pools for memory management above page level in version 2.2.
903 Commonly used objects have their own slab 879 Commonly used objects have their own slab pool (such as network buffers,
904 directory cache, and so on). 880 directory cache, and so on).
905 881
906 :: 882 ::
907 883
908 > cat /proc/buddyinfo 884 > cat /proc/buddyinfo
909 885
910 Node 0, zone DMA 0 4 5 886 Node 0, zone DMA 0 4 5 4 4 3 ...
911 Node 0, zone Normal 1 0 0 887 Node 0, zone Normal 1 0 0 1 101 8 ...
912 Node 0, zone HighMem 2 0 0 888 Node 0, zone HighMem 2 0 0 1 1 0 ...
913 889
914 External fragmentation is a problem under some 890 External fragmentation is a problem under some workloads, and buddyinfo is a
915 useful tool for helping diagnose these problem 891 useful tool for helping diagnose these problems. Buddyinfo will give you a
916 clue as to how big an area you can safely allo 892 clue as to how big an area you can safely allocate, or why a previous
917 allocation failed. 893 allocation failed.
918 894
919 Each column represents the number of pages of 895 Each column represents the number of pages of a certain order which are
920 available. In this case, there are 0 chunks o 896 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 897 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... 898 available in ZONE_NORMAL, etc...
923 899
924 More information relevant to external fragment 900 More information relevant to external fragmentation can be found in
925 pagetypeinfo:: 901 pagetypeinfo::
926 902
927 > cat /proc/pagetypeinfo 903 > cat /proc/pagetypeinfo
928 Page block order: 9 904 Page block order: 9
929 Pages per block: 512 905 Pages per block: 512
930 906
931 Free pages count per migrate type at order 907 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 908 Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
933 Node 0, zone DMA, type Reclaimabl 909 Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
934 Node 0, zone DMA, type Movabl 910 Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
935 Node 0, zone DMA, type Reserv 911 Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
936 Node 0, zone DMA, type Isolat 912 Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
937 Node 0, zone DMA32, type Unmovabl 913 Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
938 Node 0, zone DMA32, type Reclaimabl 914 Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
939 Node 0, zone DMA32, type Movabl 915 Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
940 Node 0, zone DMA32, type Reserv 916 Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
941 Node 0, zone DMA32, type Isolat 917 Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
942 918
943 Number of blocks type Unmovable Recla 919 Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
944 Node 0, zone DMA 2 920 Node 0, zone DMA 2 0 5 1 0
945 Node 0, zone DMA32 41 921 Node 0, zone DMA32 41 6 967 2 0
946 922
947 Fragmentation avoidance in the kernel works by 923 Fragmentation avoidance in the kernel works by grouping pages of different
948 migrate types into the same contiguous regions 924 migrate types into the same contiguous regions of memory called page blocks.
949 A page block is typically the size of the defa 925 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 926 X86-64. By keeping pages grouped based on their ability to move, the kernel
951 can reclaim pages within a page block to satis 927 can reclaim pages within a page block to satisfy a high-order allocation.
952 928
953 The pagetypinfo begins with information on the 929 The pagetypinfo begins with information on the size of a page block. It
954 then gives the same type of information as bud 930 then gives the same type of information as buddyinfo except broken down
955 by migrate-type and finishes with details on h 931 by migrate-type and finishes with details on how many page blocks of each
956 type exist. 932 type exist.
957 933
958 If min_free_kbytes has been tuned correctly (r 934 If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
959 from libhugetlbfs https://github.com/libhugetl 935 from libhugetlbfs https://github.com/libhugetlbfs/libhugetlbfs/), one can
960 make an estimate of the likely number of huge 936 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 937 at a given point in time. All the "Movable" blocks should be allocatable
962 unless memory has been mlock()'d. Some of the 938 unless memory has been mlock()'d. Some of the Reclaimable blocks should
963 also be allocatable although a lot of filesyst 939 also be allocatable although a lot of filesystem metadata may have to be
964 reclaimed to achieve this. 940 reclaimed to achieve this.
965 941
966 942
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 943 meminfo
997 ~~~~~~~ 944 ~~~~~~~
998 945
999 Provides information about distribution and ut 946 Provides information about distribution and utilization of memory. This
1000 varies by architecture and compile options. 947 varies by architecture and compile options. Some of the counters reported
1001 here overlap. The memory reported by the non 948 here overlap. The memory reported by the non overlapping counters may not
1002 add up to the overall memory usage and the di 949 add up to the overall memory usage and the difference for some workloads
1003 can be substantial. In many cases there are 950 can be substantial. In many cases there are other means to find out
1004 additional memory using subsystem specific in 951 additional memory using subsystem specific interfaces, for instance
1005 /proc/net/sockstat for TCP memory allocations 952 /proc/net/sockstat for TCP memory allocations.
1006 953
1007 Example output. You may not have all of these 954 Example output. You may not have all of these fields.
1008 955
1009 :: 956 ::
1010 957
1011 > cat /proc/meminfo 958 > cat /proc/meminfo
1012 959
1013 MemTotal: 32858820 kB 960 MemTotal: 32858820 kB
1014 MemFree: 21001236 kB 961 MemFree: 21001236 kB
1015 MemAvailable: 27214312 kB 962 MemAvailable: 27214312 kB
1016 Buffers: 581092 kB 963 Buffers: 581092 kB
1017 Cached: 5587612 kB 964 Cached: 5587612 kB
1018 SwapCached: 0 kB 965 SwapCached: 0 kB
1019 Active: 3237152 kB 966 Active: 3237152 kB
1020 Inactive: 7586256 kB 967 Inactive: 7586256 kB
1021 Active(anon): 94064 kB 968 Active(anon): 94064 kB
1022 Inactive(anon): 4570616 kB 969 Inactive(anon): 4570616 kB
1023 Active(file): 3143088 kB 970 Active(file): 3143088 kB
1024 Inactive(file): 3015640 kB 971 Inactive(file): 3015640 kB
1025 Unevictable: 0 kB 972 Unevictable: 0 kB
1026 Mlocked: 0 kB 973 Mlocked: 0 kB
1027 SwapTotal: 0 kB 974 SwapTotal: 0 kB
1028 SwapFree: 0 kB 975 SwapFree: 0 kB
1029 Zswap: 1904 kB 976 Zswap: 1904 kB
1030 Zswapped: 7792 kB 977 Zswapped: 7792 kB
1031 Dirty: 12 kB 978 Dirty: 12 kB
1032 Writeback: 0 kB 979 Writeback: 0 kB
1033 AnonPages: 4654780 kB 980 AnonPages: 4654780 kB
1034 Mapped: 266244 kB 981 Mapped: 266244 kB
1035 Shmem: 9976 kB 982 Shmem: 9976 kB
1036 KReclaimable: 517708 kB 983 KReclaimable: 517708 kB
1037 Slab: 660044 kB 984 Slab: 660044 kB
1038 SReclaimable: 517708 kB 985 SReclaimable: 517708 kB
1039 SUnreclaim: 142336 kB 986 SUnreclaim: 142336 kB
1040 KernelStack: 11168 kB 987 KernelStack: 11168 kB
1041 PageTables: 20540 kB 988 PageTables: 20540 kB
1042 SecPageTables: 0 kB 989 SecPageTables: 0 kB
1043 NFS_Unstable: 0 kB 990 NFS_Unstable: 0 kB
1044 Bounce: 0 kB 991 Bounce: 0 kB
1045 WritebackTmp: 0 kB 992 WritebackTmp: 0 kB
1046 CommitLimit: 16429408 kB 993 CommitLimit: 16429408 kB
1047 Committed_AS: 7715148 kB 994 Committed_AS: 7715148 kB
1048 VmallocTotal: 34359738367 kB 995 VmallocTotal: 34359738367 kB
1049 VmallocUsed: 40444 kB 996 VmallocUsed: 40444 kB
1050 VmallocChunk: 0 kB 997 VmallocChunk: 0 kB
1051 Percpu: 29312 kB 998 Percpu: 29312 kB
1052 EarlyMemtestBad: 0 kB <<
1053 HardwareCorrupted: 0 kB 999 HardwareCorrupted: 0 kB
1054 AnonHugePages: 4149248 kB 1000 AnonHugePages: 4149248 kB
1055 ShmemHugePages: 0 kB 1001 ShmemHugePages: 0 kB
1056 ShmemPmdMapped: 0 kB 1002 ShmemPmdMapped: 0 kB
1057 FileHugePages: 0 kB 1003 FileHugePages: 0 kB
1058 FilePmdMapped: 0 kB 1004 FilePmdMapped: 0 kB
1059 CmaTotal: 0 kB 1005 CmaTotal: 0 kB
1060 CmaFree: 0 kB 1006 CmaFree: 0 kB
1061 HugePages_Total: 0 1007 HugePages_Total: 0
1062 HugePages_Free: 0 1008 HugePages_Free: 0
1063 HugePages_Rsvd: 0 1009 HugePages_Rsvd: 0
1064 HugePages_Surp: 0 1010 HugePages_Surp: 0
1065 Hugepagesize: 2048 kB 1011 Hugepagesize: 2048 kB
1066 Hugetlb: 0 kB 1012 Hugetlb: 0 kB
1067 DirectMap4k: 401152 kB 1013 DirectMap4k: 401152 kB
1068 DirectMap2M: 10008576 kB 1014 DirectMap2M: 10008576 kB
1069 DirectMap1G: 24117248 kB 1015 DirectMap1G: 24117248 kB
1070 1016
1071 MemTotal 1017 MemTotal
1072 Total usable RAM (i.e. physical 1018 Total usable RAM (i.e. physical RAM minus a few reserved
1073 bits and the kernel binary code 1019 bits and the kernel binary code)
1074 MemFree 1020 MemFree
1075 Total free RAM. On highmem syst 1021 Total free RAM. On highmem systems, the sum of LowFree+HighFree
1076 MemAvailable 1022 MemAvailable
1077 An estimate of how much memory 1023 An estimate of how much memory is available for starting new
1078 applications, without swapping. 1024 applications, without swapping. Calculated from MemFree,
1079 SReclaimable, the size of the f 1025 SReclaimable, the size of the file LRU lists, and the low
1080 watermarks in each zone. 1026 watermarks in each zone.
1081 The estimate takes into account 1027 The estimate takes into account that the system needs some
1082 page cache to function well, an 1028 page cache to function well, and that not all reclaimable
1083 slab will be reclaimable, due t 1029 slab will be reclaimable, due to items being in use. The
1084 impact of those factors will va 1030 impact of those factors will vary from system to system.
1085 Buffers 1031 Buffers
1086 Relatively temporary storage fo 1032 Relatively temporary storage for raw disk blocks
1087 shouldn't get tremendously larg 1033 shouldn't get tremendously large (20MB or so)
1088 Cached 1034 Cached
1089 In-memory cache for files read 1035 In-memory cache for files read from the disk (the
1090 pagecache) as well as tmpfs & s 1036 pagecache) as well as tmpfs & shmem.
1091 Doesn't include SwapCached. 1037 Doesn't include SwapCached.
1092 SwapCached 1038 SwapCached
1093 Memory that once was swapped ou 1039 Memory that once was swapped out, is swapped back in but
1094 still also is in the swapfile ( 1040 still also is in the swapfile (if memory is needed it
1095 doesn't need to be swapped out 1041 doesn't need to be swapped out AGAIN because it is already
1096 in the swapfile. This saves I/O 1042 in the swapfile. This saves I/O)
1097 Active 1043 Active
1098 Memory that has been used more 1044 Memory that has been used more recently and usually not
1099 reclaimed unless absolutely nec 1045 reclaimed unless absolutely necessary.
1100 Inactive 1046 Inactive
1101 Memory which has been less rece 1047 Memory which has been less recently used. It is more
1102 eligible to be reclaimed for ot 1048 eligible to be reclaimed for other purposes
1103 Unevictable 1049 Unevictable
1104 Memory allocated for userspace 1050 Memory allocated for userspace which cannot be reclaimed, such
1105 as mlocked pages, ramfs backing 1051 as mlocked pages, ramfs backing pages, secret memfd pages etc.
1106 Mlocked 1052 Mlocked
1107 Memory locked with mlock(). 1053 Memory locked with mlock().
1108 HighTotal, HighFree 1054 HighTotal, HighFree
1109 Highmem is all memory above ~86 1055 Highmem is all memory above ~860MB of physical memory.
1110 Highmem areas are for use by us 1056 Highmem areas are for use by userspace programs, or
1111 for the pagecache. The kernel 1057 for the pagecache. The kernel must use tricks to access
1112 this memory, making it slower t 1058 this memory, making it slower to access than lowmem.
1113 LowTotal, LowFree 1059 LowTotal, LowFree
1114 Lowmem is memory which can be u 1060 Lowmem is memory which can be used for everything that
1115 highmem can be used for, but it 1061 highmem can be used for, but it is also available for the
1116 kernel's use for its own data s 1062 kernel's use for its own data structures. Among many
1117 other things, it is where every 1063 other things, it is where everything from the Slab is
1118 allocated. Bad things happen w 1064 allocated. Bad things happen when you're out of lowmem.
1119 SwapTotal 1065 SwapTotal
1120 total amount of swap space avai 1066 total amount of swap space available
1121 SwapFree 1067 SwapFree
1122 Memory which has been evicted f 1068 Memory which has been evicted from RAM, and is temporarily
1123 on the disk 1069 on the disk
1124 Zswap 1070 Zswap
1125 Memory consumed by the zswap ba 1071 Memory consumed by the zswap backend (compressed size)
1126 Zswapped 1072 Zswapped
1127 Amount of anonymous memory stor 1073 Amount of anonymous memory stored in zswap (original size)
1128 Dirty 1074 Dirty
1129 Memory which is waiting to get 1075 Memory which is waiting to get written back to the disk
1130 Writeback 1076 Writeback
1131 Memory which is actively being 1077 Memory which is actively being written back to the disk
1132 AnonPages 1078 AnonPages
1133 Non-file backed pages mapped in 1079 Non-file backed pages mapped into userspace page tables
1134 Mapped 1080 Mapped
1135 files which have been mmapped, !! 1081 files which have been mmaped, such as libraries
1136 Shmem 1082 Shmem
1137 Total memory used by shared mem 1083 Total memory used by shared memory (shmem) and tmpfs
1138 KReclaimable 1084 KReclaimable
1139 Kernel allocations that the ker 1085 Kernel allocations that the kernel will attempt to reclaim
1140 under memory pressure. Includes 1086 under memory pressure. Includes SReclaimable (below), and other
1141 direct allocations with a shrin 1087 direct allocations with a shrinker.
1142 Slab 1088 Slab
1143 in-kernel data structures cache 1089 in-kernel data structures cache
1144 SReclaimable 1090 SReclaimable
1145 Part of Slab, that might be rec 1091 Part of Slab, that might be reclaimed, such as caches
1146 SUnreclaim 1092 SUnreclaim
1147 Part of Slab, that cannot be re 1093 Part of Slab, that cannot be reclaimed on memory pressure
1148 KernelStack 1094 KernelStack
1149 Memory consumed by the kernel s 1095 Memory consumed by the kernel stacks of all tasks
1150 PageTables 1096 PageTables
1151 Memory consumed by userspace pa 1097 Memory consumed by userspace page tables
1152 SecPageTables 1098 SecPageTables
1153 Memory consumed by secondary pa !! 1099 Memory consumed by secondary page tables, this currently
1154 KVM mmu and IOMMU allocations o !! 1100 currently includes KVM mmu allocations on x86 and arm64.
1155 NFS_Unstable 1101 NFS_Unstable
1156 Always zero. Previous counted p 1102 Always zero. Previous counted pages which had been written to
1157 the server, but has not been co 1103 the server, but has not been committed to stable storage.
1158 Bounce 1104 Bounce
1159 Memory used for block device "b 1105 Memory used for block device "bounce buffers"
1160 WritebackTmp 1106 WritebackTmp
1161 Memory used by FUSE for tempora 1107 Memory used by FUSE for temporary writeback buffers
1162 CommitLimit 1108 CommitLimit
1163 Based on the overcommit ratio ( 1109 Based on the overcommit ratio ('vm.overcommit_ratio'),
1164 this is the total amount of me 1110 this is the total amount of memory currently available to
1165 be allocated on the system. Thi 1111 be allocated on the system. This limit is only adhered to
1166 if strict overcommit accounting 1112 if strict overcommit accounting is enabled (mode 2 in
1167 'vm.overcommit_memory'). 1113 'vm.overcommit_memory').
1168 1114
1169 The CommitLimit is calculated w 1115 The CommitLimit is calculated with the following formula::
1170 1116
1171 CommitLimit = ([total RAM pag 1117 CommitLimit = ([total RAM pages] - [total huge TLB pages]) *
1172 overcommit_rat 1118 overcommit_ratio / 100 + [total swap pages]
1173 1119
1174 For example, on a system with 1 1120 For example, on a system with 1G of physical RAM and 7G
1175 of swap with a `vm.overcommit_r 1121 of swap with a `vm.overcommit_ratio` of 30 it would
1176 yield a CommitLimit of 7.3G. 1122 yield a CommitLimit of 7.3G.
1177 1123
1178 For more details, see the memor 1124 For more details, see the memory overcommit documentation
1179 in mm/overcommit-accounting. 1125 in mm/overcommit-accounting.
1180 Committed_AS 1126 Committed_AS
1181 The amount of memory presently 1127 The amount of memory presently allocated on the system.
1182 The committed memory is a sum o 1128 The committed memory is a sum of all of the memory which
1183 has been allocated by processes 1129 has been allocated by processes, even if it has not been
1184 "used" by them as of yet. A pro 1130 "used" by them as of yet. A process which malloc()'s 1G
1185 of memory, but only touches 300 1131 of memory, but only touches 300M of it will show up as
1186 using 1G. This 1G is memory whi 1132 using 1G. This 1G is memory which has been "committed" to
1187 by the VM and can be used at an 1133 by the VM and can be used at any time by the allocating
1188 application. With strict overco 1134 application. With strict overcommit enabled on the system
1189 (mode 2 in 'vm.overcommit_memor 1135 (mode 2 in 'vm.overcommit_memory'), allocations which would
1190 exceed the CommitLimit (detaile 1136 exceed the CommitLimit (detailed above) will not be permitted.
1191 This is useful if one needs to 1137 This is useful if one needs to guarantee that processes will
1192 not fail due to lack of memory 1138 not fail due to lack of memory once that memory has been
1193 successfully allocated. 1139 successfully allocated.
1194 VmallocTotal 1140 VmallocTotal
1195 total size of vmalloc virtual a 1141 total size of vmalloc virtual address space
1196 VmallocUsed 1142 VmallocUsed
1197 amount of vmalloc area which is 1143 amount of vmalloc area which is used
1198 VmallocChunk 1144 VmallocChunk
1199 largest contiguous block of vma 1145 largest contiguous block of vmalloc area which is free
1200 Percpu 1146 Percpu
1201 Memory allocated to the percpu 1147 Memory allocated to the percpu allocator used to back percpu
1202 allocations. This stat excludes 1148 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 1149 HardwareCorrupted
1211 The amount of RAM/memory in KB, 1150 The amount of RAM/memory in KB, the kernel identifies as
1212 corrupted. 1151 corrupted.
1213 AnonHugePages 1152 AnonHugePages
1214 Non-file backed huge pages mapp 1153 Non-file backed huge pages mapped into userspace page tables
1215 ShmemHugePages 1154 ShmemHugePages
1216 Memory used by shared memory (s 1155 Memory used by shared memory (shmem) and tmpfs allocated
1217 with huge pages 1156 with huge pages
1218 ShmemPmdMapped 1157 ShmemPmdMapped
1219 Shared memory mapped into users 1158 Shared memory mapped into userspace with huge pages
1220 FileHugePages 1159 FileHugePages
1221 Memory used for filesystem data 1160 Memory used for filesystem data (page cache) allocated
1222 with huge pages 1161 with huge pages
1223 FilePmdMapped 1162 FilePmdMapped
1224 Page cache mapped into userspac 1163 Page cache mapped into userspace with huge pages
1225 CmaTotal 1164 CmaTotal
1226 Memory reserved for the Contigu 1165 Memory reserved for the Contiguous Memory Allocator (CMA)
1227 CmaFree 1166 CmaFree
1228 Free remaining memory in the CM 1167 Free remaining memory in the CMA reserves
1229 HugePages_Total, HugePages_Free, HugePages_Rs 1168 HugePages_Total, HugePages_Free, HugePages_Rsvd, HugePages_Surp, Hugepagesize, Hugetlb
1230 See Documentation/admin-guide/m 1169 See Documentation/admin-guide/mm/hugetlbpage.rst.
1231 DirectMap4k, DirectMap2M, DirectMap1G 1170 DirectMap4k, DirectMap2M, DirectMap1G
1232 Breakdown of page table sizes u 1171 Breakdown of page table sizes used in the kernel's
1233 identity mapping of RAM 1172 identity mapping of RAM
1234 1173
1235 vmallocinfo 1174 vmallocinfo
1236 ~~~~~~~~~~~ 1175 ~~~~~~~~~~~
1237 1176
1238 Provides information about vmalloced/vmaped a 1177 Provides information about vmalloced/vmaped areas. One line per area,
1239 containing the virtual address range of the a 1178 containing the virtual address range of the area, size in bytes,
1240 caller information of the creator, and option 1179 caller information of the creator, and optional information depending
1241 on the kind of area: 1180 on the kind of area:
1242 1181
1243 ========== ================================ 1182 ========== ===================================================
1244 pages=nr number of pages 1183 pages=nr number of pages
1245 phys=addr if a physical address was specif 1184 phys=addr if a physical address was specified
1246 ioremap I/O mapping (ioremap() and frien 1185 ioremap I/O mapping (ioremap() and friends)
1247 vmalloc vmalloc() area 1186 vmalloc vmalloc() area
1248 vmap vmap()ed pages 1187 vmap vmap()ed pages
1249 user VM_USERMAP area 1188 user VM_USERMAP area
1250 vpages buffer for pages pointers was vm 1189 vpages buffer for pages pointers was vmalloced (huge area)
1251 N<node>=nr (Only on NUMA kernels) 1190 N<node>=nr (Only on NUMA kernels)
1252 Number of pages allocated on mem 1191 Number of pages allocated on memory node <node>
1253 ========== ================================ 1192 ========== ===================================================
1254 1193
1255 :: 1194 ::
1256 1195
1257 > cat /proc/vmallocinfo 1196 > cat /proc/vmallocinfo
1258 0xffffc20000000000-0xffffc20000201000 210 1197 0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
1259 /0x2c0 pages=512 vmalloc N0=128 N1=128 N2 1198 /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
1260 0xffffc20000201000-0xffffc20000302000 105 1199 0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
1261 /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=6 1200 /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
1262 0xffffc20000302000-0xffffc20000304000 1201 0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
1263 phys=7fee8000 ioremap 1202 phys=7fee8000 ioremap
1264 0xffffc20000304000-0xffffc20000307000 1 1203 0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
1265 phys=7fee7000 ioremap 1204 phys=7fee7000 ioremap
1266 0xffffc2000031d000-0xffffc2000031f000 1205 0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
1267 0xffffc2000031f000-0xffffc2000032b000 4 1206 0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
1268 /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3= 1207 /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
1269 0xffffc2000033a000-0xffffc2000033d000 1 1208 0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
1270 pages=2 vmalloc N1=2 1209 pages=2 vmalloc N1=2
1271 0xffffc20000347000-0xffffc2000034c000 2 1210 0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
1272 /0x130 [x_tables] pages=4 vmalloc N0=4 1211 /0x130 [x_tables] pages=4 vmalloc N0=4
1273 0xffffffffa0000000-0xffffffffa000f000 6 1212 0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
1274 pages=14 vmalloc N2=14 1213 pages=14 vmalloc N2=14
1275 0xffffffffa000f000-0xffffffffa0014000 2 1214 0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
1276 pages=4 vmalloc N1=4 1215 pages=4 vmalloc N1=4
1277 0xffffffffa0014000-0xffffffffa0017000 1 1216 0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
1278 pages=2 vmalloc N1=2 1217 pages=2 vmalloc N1=2
1279 0xffffffffa0017000-0xffffffffa0022000 4 1218 0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
1280 pages=10 vmalloc N0=10 1219 pages=10 vmalloc N0=10
1281 1220
1282 1221
1283 softirqs 1222 softirqs
1284 ~~~~~~~~ 1223 ~~~~~~~~
1285 1224
1286 Provides counts of softirq handlers serviced 1225 Provides counts of softirq handlers serviced since boot time, for each CPU.
1287 1226
1288 :: 1227 ::
1289 1228
1290 > cat /proc/softirqs 1229 > cat /proc/softirqs
1291 CPU0 CPU1 CPU2 1230 CPU0 CPU1 CPU2 CPU3
1292 HI: 0 0 0 1231 HI: 0 0 0 0
1293 TIMER: 27166 27120 27097 1232 TIMER: 27166 27120 27097 27034
1294 NET_TX: 0 0 0 1233 NET_TX: 0 0 0 17
1295 NET_RX: 42 0 0 1234 NET_RX: 42 0 0 39
1296 BLOCK: 0 0 107 1235 BLOCK: 0 0 107 1121
1297 TASKLET: 0 0 0 1236 TASKLET: 0 0 0 290
1298 SCHED: 27035 26983 26971 1237 SCHED: 27035 26983 26971 26746
1299 HRTIMER: 0 0 0 1238 HRTIMER: 0 0 0 0
1300 RCU: 1678 1769 2178 1239 RCU: 1678 1769 2178 2250
1301 1240
1302 1.3 Networking info in /proc/net 1241 1.3 Networking info in /proc/net
1303 -------------------------------- 1242 --------------------------------
1304 1243
1305 The subdirectory /proc/net follows the us 1244 The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
1306 additional values you get for IP version 1245 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 1246 support this. Table 1-9 lists the files and their meaning.
1308 1247
1309 1248
1310 .. table:: Table 1-8: IPv6 info in /proc/net 1249 .. table:: Table 1-8: IPv6 info in /proc/net
1311 1250
1312 ========== ================================= 1251 ========== =====================================================
1313 File Content 1252 File Content
1314 ========== ================================= 1253 ========== =====================================================
1315 udp6 UDP sockets (IPv6) 1254 udp6 UDP sockets (IPv6)
1316 tcp6 TCP sockets (IPv6) 1255 tcp6 TCP sockets (IPv6)
1317 raw6 Raw device statistics (IPv6) 1256 raw6 Raw device statistics (IPv6)
1318 igmp6 IP multicast addresses, which thi 1257 igmp6 IP multicast addresses, which this host joined (IPv6)
1319 if_inet6 List of IPv6 interface addresses 1258 if_inet6 List of IPv6 interface addresses
1320 ipv6_route Kernel routing table for IPv6 1259 ipv6_route Kernel routing table for IPv6
1321 rt6_stats Global IPv6 routing tables statis 1260 rt6_stats Global IPv6 routing tables statistics
1322 sockstat6 Socket statistics (IPv6) 1261 sockstat6 Socket statistics (IPv6)
1323 snmp6 Snmp data (IPv6) 1262 snmp6 Snmp data (IPv6)
1324 ========== ================================= 1263 ========== =====================================================
1325 1264
1326 .. table:: Table 1-9: Network info in /proc/n 1265 .. table:: Table 1-9: Network info in /proc/net
1327 1266
1328 ============= ============================== 1267 ============= ================================================================
1329 File Content 1268 File Content
1330 ============= ============================== 1269 ============= ================================================================
1331 arp Kernel ARP table 1270 arp Kernel ARP table
1332 dev network devices with statistic 1271 dev network devices with statistics
1333 dev_mcast the Layer2 multicast groups a 1272 dev_mcast the Layer2 multicast groups a device is listening too
1334 (interface index, label, numbe 1273 (interface index, label, number of references, number of bound
1335 addresses). 1274 addresses).
1336 dev_stat network device status 1275 dev_stat network device status
1337 ip_fwchains Firewall chain linkage 1276 ip_fwchains Firewall chain linkage
1338 ip_fwnames Firewall chain names 1277 ip_fwnames Firewall chain names
1339 ip_masq Directory containing the masqu 1278 ip_masq Directory containing the masquerading tables
1340 ip_masquerade Major masquerading table 1279 ip_masquerade Major masquerading table
1341 netstat Network statistics 1280 netstat Network statistics
1342 raw raw device statistics 1281 raw raw device statistics
1343 route Kernel routing table 1282 route Kernel routing table
1344 rpc Directory containing rpc info 1283 rpc Directory containing rpc info
1345 rt_cache Routing cache 1284 rt_cache Routing cache
1346 snmp SNMP data 1285 snmp SNMP data
1347 sockstat Socket statistics 1286 sockstat Socket statistics
1348 softnet_stat Per-CPU incoming packets queue <<
1349 tcp TCP sockets 1287 tcp TCP sockets
1350 udp UDP sockets 1288 udp UDP sockets
1351 unix UNIX domain sockets 1289 unix UNIX domain sockets
1352 wireless Wireless interface data (Wavel 1290 wireless Wireless interface data (Wavelan etc)
1353 igmp IP multicast addresses, which 1291 igmp IP multicast addresses, which this host joined
1354 psched Global packet scheduler parame 1292 psched Global packet scheduler parameters.
1355 netlink List of PF_NETLINK sockets 1293 netlink List of PF_NETLINK sockets
1356 ip_mr_vifs List of multicast virtual inte 1294 ip_mr_vifs List of multicast virtual interfaces
1357 ip_mr_cache List of multicast routing cach 1295 ip_mr_cache List of multicast routing cache
1358 ============= ============================== 1296 ============= ================================================================
1359 1297
1360 You can use this information to see which 1298 You can use this information to see which network devices are available in
1361 your system and how much traffic was routed o 1299 your system and how much traffic was routed over those devices::
1362 1300
1363 > cat /proc/net/dev 1301 > cat /proc/net/dev
1364 Inter-|Receive 1302 Inter-|Receive |[...
1365 face |bytes packets errs drop fifo fram 1303 face |bytes packets errs drop fifo frame compressed multicast|[...
1366 lo: 908188 5596 0 0 0 1304 lo: 908188 5596 0 0 0 0 0 0 [...
1367 ppp0:15475140 20721 410 0 0 41 1305 ppp0:15475140 20721 410 0 0 410 0 0 [...
1368 eth0: 614530 7085 0 0 0 1306 eth0: 614530 7085 0 0 0 0 0 1 [...
1369 1307
1370 ...] Transmit 1308 ...] Transmit
1371 ...] bytes packets errs drop fifo colls 1309 ...] bytes packets errs drop fifo colls carrier compressed
1372 ...] 908188 5596 0 0 0 0 1310 ...] 908188 5596 0 0 0 0 0 0
1373 ...] 1375103 17405 0 0 0 0 1311 ...] 1375103 17405 0 0 0 0 0 0
1374 ...] 1703981 5535 0 0 0 3 1312 ...] 1703981 5535 0 0 0 3 0 0
1375 1313
1376 In addition, each Channel Bond interface has 1314 In addition, each Channel Bond interface has its own directory. For
1377 example, the bond0 device will have a directo 1315 example, the bond0 device will have a directory called /proc/net/bond0/.
1378 It will contain information that is specific 1316 It will contain information that is specific to that bond, such as the
1379 current slaves of the bond, the link status o 1317 current slaves of the bond, the link status of the slaves, and how
1380 many times the slaves link has failed. 1318 many times the slaves link has failed.
1381 1319
1382 1.4 SCSI info 1320 1.4 SCSI info
1383 ------------- 1321 -------------
1384 1322
1385 If you have a SCSI or ATA host adapter in you !! 1323 If you have a SCSI host adapter in your system, you'll find a subdirectory
1386 subdirectory named after the driver for this !! 1324 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 !! 1325 of all recognized SCSI devices in /proc/scsi::
1388 1326
1389 >cat /proc/scsi/scsi 1327 >cat /proc/scsi/scsi
1390 Attached devices: 1328 Attached devices:
1391 Host: scsi0 Channel: 00 Id: 00 Lun: 00 1329 Host: scsi0 Channel: 00 Id: 00 Lun: 00
1392 Vendor: IBM Model: DGHS09U 1330 Vendor: IBM Model: DGHS09U Rev: 03E0
1393 Type: Direct-Access 1331 Type: Direct-Access ANSI SCSI revision: 03
1394 Host: scsi0 Channel: 00 Id: 06 Lun: 00 1332 Host: scsi0 Channel: 00 Id: 06 Lun: 00
1395 Vendor: PIONEER Model: CD-ROM DR-U06S 1333 Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
1396 Type: CD-ROM 1334 Type: CD-ROM ANSI SCSI revision: 02
1397 1335
1398 1336
1399 The directory named after the driver has o 1337 The directory named after the driver has one file for each adapter found in
1400 the system. These files contain informatio 1338 the system. These files contain information about the controller, including
1401 the used IRQ and the IO address range. T 1339 the used IRQ and the IO address range. The amount of information shown is
1402 dependent on the adapter you use. The exampl 1340 dependent on the adapter you use. The example shows the output for an Adaptec
1403 AHA-2940 SCSI adapter:: 1341 AHA-2940 SCSI adapter::
1404 1342
1405 > cat /proc/scsi/aic7xxx/0 1343 > cat /proc/scsi/aic7xxx/0
1406 1344
1407 Adaptec AIC7xxx driver version: 5.1.19/3.2. 1345 Adaptec AIC7xxx driver version: 5.1.19/3.2.4
1408 Compile Options: 1346 Compile Options:
1409 TCQ Enabled By Default : Disabled 1347 TCQ Enabled By Default : Disabled
1410 AIC7XXX_PROC_STATS : Disabled 1348 AIC7XXX_PROC_STATS : Disabled
1411 AIC7XXX_RESET_DELAY : 5 1349 AIC7XXX_RESET_DELAY : 5
1412 Adapter Configuration: 1350 Adapter Configuration:
1413 SCSI Adapter: Adaptec AHA-294X U 1351 SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
1414 Ultra Wide Contr 1352 Ultra Wide Controller
1415 PCI MMAPed I/O Base: 0xeb001000 1353 PCI MMAPed I/O Base: 0xeb001000
1416 Adapter SEEPROM Config: SEEPROM found and 1354 Adapter SEEPROM Config: SEEPROM found and used.
1417 Adaptec SCSI BIOS: Enabled 1355 Adaptec SCSI BIOS: Enabled
1418 IRQ: 10 1356 IRQ: 10
1419 SCBs: Active 0, Max Acti 1357 SCBs: Active 0, Max Active 2,
1420 Allocated 15, HW 1 1358 Allocated 15, HW 16, Page 255
1421 Interrupts: 160328 1359 Interrupts: 160328
1422 BIOS Control Word: 0x18b6 1360 BIOS Control Word: 0x18b6
1423 Adapter Control Word: 0x005b 1361 Adapter Control Word: 0x005b
1424 Extended Translation: Enabled 1362 Extended Translation: Enabled
1425 Disconnect Enable Flags: 0xffff 1363 Disconnect Enable Flags: 0xffff
1426 Ultra Enable Flags: 0x0001 1364 Ultra Enable Flags: 0x0001
1427 Tag Queue Enable Flags: 0x0000 1365 Tag Queue Enable Flags: 0x0000
1428 Ordered Queue Tag Flags: 0x0000 1366 Ordered Queue Tag Flags: 0x0000
1429 Default Tag Queue Depth: 8 1367 Default Tag Queue Depth: 8
1430 Tagged Queue By Device array for aic7xx 1368 Tagged Queue By Device array for aic7xxx host instance 0:
1431 {255,255,255,255,255,255,255,255,255, 1369 {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
1432 Actual queue depth per device for aic7x 1370 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} 1371 {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
1434 Statistics: 1372 Statistics:
1435 (scsi0:0:0:0) 1373 (scsi0:0:0:0)
1436 Device using Wide/Sync transfers at 40.0 1374 Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
1437 Transinfo settings: current(12/8/1/0), go 1375 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 1376 Total transfers 160151 (74577 reads and 85574 writes)
1439 (scsi0:0:6:0) 1377 (scsi0:0:6:0)
1440 Device using Narrow/Sync transfers at 5.0 1378 Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
1441 Transinfo settings: current(50/15/0/0), g 1379 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) 1380 Total transfers 0 (0 reads and 0 writes)
1443 1381
1444 1382
1445 1.5 Parallel port info in /proc/parport 1383 1.5 Parallel port info in /proc/parport
1446 --------------------------------------- 1384 ---------------------------------------
1447 1385
1448 The directory /proc/parport contains inform 1386 The directory /proc/parport contains information about the parallel ports of
1449 your system. It has one subdirectory for 1387 your system. It has one subdirectory for each port, named after the port
1450 number (0,1,2,...). 1388 number (0,1,2,...).
1451 1389
1452 These directories contain the four files show 1390 These directories contain the four files shown in Table 1-10.
1453 1391
1454 1392
1455 .. table:: Table 1-10: Files in /proc/parport 1393 .. table:: Table 1-10: Files in /proc/parport
1456 1394
1457 ========= ================================== 1395 ========= ====================================================================
1458 File Content 1396 File Content
1459 ========= ================================== 1397 ========= ====================================================================
1460 autoprobe Any IEEE-1284 device ID informatio 1398 autoprobe Any IEEE-1284 device ID information that has been acquired.
1461 devices list of the device drivers using t 1399 devices list of the device drivers using that port. A + will appear by the
1462 name of the device currently using 1400 name of the device currently using the port (it might not appear
1463 against any). 1401 against any).
1464 hardware Parallel port's base address, IRQ 1402 hardware Parallel port's base address, IRQ line and DMA channel.
1465 irq IRQ that parport is using for that 1403 irq IRQ that parport is using for that port. This is in a separate
1466 file to allow you to alter it by w 1404 file to allow you to alter it by writing a new value in (IRQ
1467 number or none). 1405 number or none).
1468 ========= ================================== 1406 ========= ====================================================================
1469 1407
1470 1.6 TTY info in /proc/tty 1408 1.6 TTY info in /proc/tty
1471 ------------------------- 1409 -------------------------
1472 1410
1473 Information about the available and actual 1411 Information about the available and actually used tty's can be found in the
1474 directory /proc/tty. You'll find entries fo 1412 directory /proc/tty. You'll find entries for drivers and line disciplines in
1475 this directory, as shown in Table 1-11. 1413 this directory, as shown in Table 1-11.
1476 1414
1477 1415
1478 .. table:: Table 1-11: Files in /proc/tty 1416 .. table:: Table 1-11: Files in /proc/tty
1479 1417
1480 ============= ============================== 1418 ============= ==============================================
1481 File Content 1419 File Content
1482 ============= ============================== 1420 ============= ==============================================
1483 drivers list of drivers and their usag 1421 drivers list of drivers and their usage
1484 ldiscs registered line disciplines 1422 ldiscs registered line disciplines
1485 driver/serial usage statistic and status of 1423 driver/serial usage statistic and status of single tty lines
1486 ============= ============================== 1424 ============= ==============================================
1487 1425
1488 To see which tty's are currently in use, 1426 To see which tty's are currently in use, you can simply look into the file
1489 /proc/tty/drivers:: 1427 /proc/tty/drivers::
1490 1428
1491 > cat /proc/tty/drivers 1429 > cat /proc/tty/drivers
1492 pty_slave /dev/pts 136 0- 1430 pty_slave /dev/pts 136 0-255 pty:slave
1493 pty_master /dev/ptm 128 0- 1431 pty_master /dev/ptm 128 0-255 pty:master
1494 pty_slave /dev/ttyp 3 0- 1432 pty_slave /dev/ttyp 3 0-255 pty:slave
1495 pty_master /dev/pty 2 0- 1433 pty_master /dev/pty 2 0-255 pty:master
1496 serial /dev/cua 5 64 1434 serial /dev/cua 5 64-67 serial:callout
1497 serial /dev/ttyS 4 64 1435 serial /dev/ttyS 4 64-67 serial
1498 /dev/tty0 /dev/tty0 4 1436 /dev/tty0 /dev/tty0 4 0 system:vtmaster
1499 /dev/ptmx /dev/ptmx 5 1437 /dev/ptmx /dev/ptmx 5 2 system
1500 /dev/console /dev/console 5 1438 /dev/console /dev/console 5 1 system:console
1501 /dev/tty /dev/tty 5 1439 /dev/tty /dev/tty 5 0 system:/dev/tty
1502 unknown /dev/tty 4 1 1440 unknown /dev/tty 4 1-63 console
1503 1441
1504 1442
1505 1.7 Miscellaneous kernel statistics in /proc/ 1443 1.7 Miscellaneous kernel statistics in /proc/stat
1506 --------------------------------------------- 1444 -------------------------------------------------
1507 1445
1508 Various pieces of information about kerne 1446 Various pieces of information about kernel activity are available in the
1509 /proc/stat file. All of the numbers report 1447 /proc/stat file. All of the numbers reported in this file are aggregates
1510 since the system first booted. For a quick l 1448 since the system first booted. For a quick look, simply cat the file::
1511 1449
1512 > cat /proc/stat 1450 > cat /proc/stat
1513 cpu 237902850 368826709 106375398 18735175 !! 1451 cpu 2255 34 2290 22625563 6290 127 456 0 0 0
1514 cpu0 60045249 91891769 26331539 468411416 4 !! 1452 cpu0 1132 34 1441 11311718 3675 127 438 0 0 0
1515 cpu1 59746288 91759249 26609887 468860630 3 !! 1453 cpu1 1123 0 849 11313845 2614 0 18 0 0 0
1516 cpu2 59489247 92985423 26904446 467808813 1 !! 1454 intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
1517 cpu3 58622065 92190267 26529524 468436680 1 !! 1455 ctxt 1990473
1518 intr 8688370575 8 3373 0 0 0 0 0 0 1 40791 !! 1456 btime 1062191376
1519 ctxt 22848221062 !! 1457 processes 2915
1520 btime 1605316999 !! 1458 procs_running 1
1521 processes 746787147 <<
1522 procs_running 2 <<
1523 procs_blocked 0 1459 procs_blocked 0
1524 softirq 12121874454 100099120 3938138295 12 !! 1460 softirq 183433 0 21755 12 39 1137 231 21459 2263
1525 1461
1526 The very first "cpu" line aggregates the nu 1462 The very first "cpu" line aggregates the numbers in all of the other "cpuN"
1527 lines. These numbers identify the amount of 1463 lines. These numbers identify the amount of time the CPU has spent performing
1528 different kinds of work. Time units are in U 1464 different kinds of work. Time units are in USER_HZ (typically hundredths of a
1529 second). The meanings of the columns are as 1465 second). The meanings of the columns are as follows, from left to right:
1530 1466
1531 - user: normal processes executing in user mo 1467 - user: normal processes executing in user mode
1532 - nice: niced processes executing in user mod 1468 - nice: niced processes executing in user mode
1533 - system: processes executing in kernel mode 1469 - system: processes executing in kernel mode
1534 - idle: twiddling thumbs 1470 - idle: twiddling thumbs
1535 - iowait: In a word, iowait stands for waitin 1471 - iowait: In a word, iowait stands for waiting for I/O to complete. But there
1536 are several problems: 1472 are several problems:
1537 1473
1538 1. CPU will not wait for I/O to complete, i 1474 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 1475 waiting for I/O to complete. When CPU goes into idle state for
1540 outstanding task I/O, another task will 1476 outstanding task I/O, another task will be scheduled on this CPU.
1541 2. In a multi-core CPU, the task waiting fo 1477 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 1478 on any CPU, so the iowait of each CPU is difficult to calculate.
1543 3. The value of iowait field in /proc/stat 1479 3. The value of iowait field in /proc/stat will decrease in certain
1544 conditions. 1480 conditions.
1545 1481
1546 So, the iowait is not reliable by reading f 1482 So, the iowait is not reliable by reading from /proc/stat.
1547 - irq: servicing interrupts 1483 - irq: servicing interrupts
1548 - softirq: servicing softirqs 1484 - softirq: servicing softirqs
1549 - steal: involuntary wait 1485 - steal: involuntary wait
1550 - guest: running a normal guest 1486 - guest: running a normal guest
1551 - guest_nice: running a niced guest 1487 - guest_nice: running a niced guest
1552 1488
1553 The "intr" line gives counts of interrupts s 1489 The "intr" line gives counts of interrupts serviced since boot time, for each
1554 of the possible system interrupts. The fir 1490 of the possible system interrupts. The first column is the total of all
1555 interrupts serviced including unnumbered a 1491 interrupts serviced including unnumbered architecture specific interrupts;
1556 each subsequent column is the total for tha 1492 each subsequent column is the total for that particular numbered interrupt.
1557 Unnumbered interrupts are not shown, only sum 1493 Unnumbered interrupts are not shown, only summed into the total.
1558 1494
1559 The "ctxt" line gives the total number of con 1495 The "ctxt" line gives the total number of context switches across all CPUs.
1560 1496
1561 The "btime" line gives the time at which the 1497 The "btime" line gives the time at which the system booted, in seconds since
1562 the Unix epoch. 1498 the Unix epoch.
1563 1499
1564 The "processes" line gives the number of pro 1500 The "processes" line gives the number of processes and threads created, which
1565 includes (but is not limited to) those cre 1501 includes (but is not limited to) those created by calls to the fork() and
1566 clone() system calls. 1502 clone() system calls.
1567 1503
1568 The "procs_running" line gives the total numb 1504 The "procs_running" line gives the total number of threads that are
1569 running or ready to run (i.e., the total numb 1505 running or ready to run (i.e., the total number of runnable threads).
1570 1506
1571 The "procs_blocked" line gives the number 1507 The "procs_blocked" line gives the number of processes currently blocked,
1572 waiting for I/O to complete. 1508 waiting for I/O to complete.
1573 1509
1574 The "softirq" line gives counts of softirqs s 1510 The "softirq" line gives counts of softirqs serviced since boot time, for each
1575 of the possible system softirqs. The first co 1511 of the possible system softirqs. The first column is the total of all
1576 softirqs serviced; each subsequent column is 1512 softirqs serviced; each subsequent column is the total for that particular
1577 softirq. 1513 softirq.
1578 1514
1579 1515
1580 1.8 Ext4 file system parameters 1516 1.8 Ext4 file system parameters
1581 ------------------------------- 1517 -------------------------------
1582 1518
1583 Information about mounted ext4 file systems c 1519 Information about mounted ext4 file systems can be found in
1584 /proc/fs/ext4. Each mounted filesystem will 1520 /proc/fs/ext4. Each mounted filesystem will have a directory in
1585 /proc/fs/ext4 based on its device name (i.e., 1521 /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). !! 1522 /proc/fs/ext4/dm-0). The files in each per-device directory are shown
1587 directory are shown in Table 1-12, below. !! 1523 in Table 1-12, below.
1588 1524
1589 .. table:: Table 1-12: Files in /proc/fs/ext4 1525 .. table:: Table 1-12: Files in /proc/fs/ext4/<devname>
1590 1526
1591 ============== ============================ 1527 ============== ==========================================================
1592 File Content 1528 File Content
1593 mb_groups details of multiblock alloca 1529 mb_groups details of multiblock allocator buddy cache of free blocks
1594 ============== ============================ 1530 ============== ==========================================================
1595 1531
1596 1.9 /proc/consoles 1532 1.9 /proc/consoles
1597 ------------------- 1533 -------------------
1598 Shows registered system console lines. 1534 Shows registered system console lines.
1599 1535
1600 To see which character device lines are curre 1536 To see which character device lines are currently used for the system console
1601 /dev/console, you may simply look into the fi 1537 /dev/console, you may simply look into the file /proc/consoles::
1602 1538
1603 > cat /proc/consoles 1539 > cat /proc/consoles
1604 tty0 -WU (ECp) 4:7 1540 tty0 -WU (ECp) 4:7
1605 ttyS0 -W- (Ep) 4:64 1541 ttyS0 -W- (Ep) 4:64
1606 1542
1607 The columns are: 1543 The columns are:
1608 1544
1609 +--------------------+----------------------- 1545 +--------------------+-------------------------------------------------------+
1610 | device | name of the device 1546 | device | name of the device |
1611 +====================+======================= 1547 +====================+=======================================================+
1612 | operations | * R = can do read oper 1548 | operations | * R = can do read operations |
1613 | | * W = can do write ope 1549 | | * W = can do write operations |
1614 | | * U = can do unblank 1550 | | * U = can do unblank |
1615 +--------------------+----------------------- 1551 +--------------------+-------------------------------------------------------+
1616 | flags | * E = it is enabled 1552 | flags | * E = it is enabled |
1617 | | * C = it is preferred 1553 | | * C = it is preferred console |
1618 | | * B = it is primary bo 1554 | | * B = it is primary boot console |
1619 | | * p = it is used for p 1555 | | * p = it is used for printk buffer |
1620 | | * b = it is not a TTY 1556 | | * b = it is not a TTY but a Braille device |
1621 | | * a = it is safe to us 1557 | | * a = it is safe to use when cpu is offline |
1622 +--------------------+----------------------- 1558 +--------------------+-------------------------------------------------------+
1623 | major:minor | major and minor number 1559 | major:minor | major and minor number of the device separated by a |
1624 | | colon 1560 | | colon |
1625 +--------------------+----------------------- 1561 +--------------------+-------------------------------------------------------+
1626 1562
1627 Summary 1563 Summary
1628 ------- 1564 -------
1629 1565
1630 The /proc file system serves information abou 1566 The /proc file system serves information about the running system. It not only
1631 allows access to process data but also allows 1567 allows access to process data but also allows you to request the kernel status
1632 by reading files in the hierarchy. 1568 by reading files in the hierarchy.
1633 1569
1634 The directory structure of /proc reflects t 1570 The directory structure of /proc reflects the types of information and makes
1635 it easy, if not obvious, where to look for sp 1571 it easy, if not obvious, where to look for specific data.
1636 1572
1637 Chapter 2: Modifying System Parameters 1573 Chapter 2: Modifying System Parameters
1638 ====================================== 1574 ======================================
1639 1575
1640 In This Chapter 1576 In This Chapter
1641 --------------- 1577 ---------------
1642 1578
1643 * Modifying kernel parameters by writing into 1579 * Modifying kernel parameters by writing into files found in /proc/sys
1644 * Exploring the files which modify certain pa 1580 * Exploring the files which modify certain parameters
1645 * Review of the /proc/sys file tree 1581 * Review of the /proc/sys file tree
1646 1582
1647 --------------------------------------------- 1583 ------------------------------------------------------------------------------
1648 1584
1649 A very interesting part of /proc is the dire 1585 A very interesting part of /proc is the directory /proc/sys. This is not only
1650 a source of information, it also allows yo 1586 a source of information, it also allows you to change parameters within the
1651 kernel. Be very careful when attempting th 1587 kernel. Be very careful when attempting this. You can optimize your system,
1652 but you can also cause it to crash. Ne 1588 but you can also cause it to crash. Never alter kernel parameters on a
1653 production system. Set up a development m 1589 production system. Set up a development machine and test to make sure that
1654 everything works the way you want it to. Y 1590 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 1591 reboot the machine once an error has been made.
1656 1592
1657 To change a value, simply echo the new v 1593 To change a value, simply echo the new value into the file.
1658 You need to be root to do this. You can cre 1594 You need to be root to do this. You can create your own boot script
1659 to perform this every time your system boots. 1595 to perform this every time your system boots.
1660 1596
1661 The files in /proc/sys can be used to fine t 1597 The files in /proc/sys can be used to fine tune and monitor miscellaneous and
1662 general things in the operation of the Linu 1598 general things in the operation of the Linux kernel. Since some of the files
1663 can inadvertently disrupt your system, it 1599 can inadvertently disrupt your system, it is advisable to read both
1664 documentation and source before actually ma 1600 documentation and source before actually making adjustments. In any case, be
1665 very careful when writing to any of thes 1601 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 1602 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 !! 1603 review the kernel documentation in the directory /usr/src/linux/Documentation.
1668 This chapter is heavily based on the docu 1604 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 1605 kernels, and became part of it in version 2.2.1 of the Linux kernel.
1670 1606
1671 Please see: Documentation/admin-guide/sysctl/ !! 1607 Please see: Documentation/admin-guide/sysctl/ directory for descriptions of these
1672 these entries. !! 1608 entries.
1673 1609
1674 Summary 1610 Summary
1675 ------- 1611 -------
1676 1612
1677 Certain aspects of kernel behavior can be 1613 Certain aspects of kernel behavior can be modified at runtime, without the
1678 need to recompile the kernel, or even to re 1614 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 1615 /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 1616 command to write value into these files, thereby changing the default settings
1681 of the kernel. 1617 of the kernel.
1682 1618
1683 1619
1684 Chapter 3: Per-process Parameters 1620 Chapter 3: Per-process Parameters
1685 ================================= 1621 =================================
1686 1622
1687 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_sco 1623 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
1688 --------------------------------------------- 1624 --------------------------------------------------------------------------------
1689 1625
1690 These files can be used to adjust the badness 1626 These files can be used to adjust the badness heuristic used to select which
1691 process gets killed in out of memory (oom) co 1627 process gets killed in out of memory (oom) conditions.
1692 1628
1693 The badness heuristic assigns a value to each 1629 The badness heuristic assigns a value to each candidate task ranging from 0
1694 (never kill) to 1000 (always kill) to determi 1630 (never kill) to 1000 (always kill) to determine which process is targeted. The
1695 units are roughly a proportion along that ran 1631 units are roughly a proportion along that range of allowed memory the process
1696 may allocate from based on an estimation of i 1632 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 1633 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 1634 1000. If it is using half of its allowed memory, its score will be 500.
1699 1635
1700 The amount of "allowed" memory depends on the 1636 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 1637 was called. If it is due to the memory assigned to the allocating task's cpuset
1702 being exhausted, the allowed memory represent 1638 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 1639 cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed
1704 memory represents the set of mempolicy nodes. 1640 memory represents the set of mempolicy nodes. If it is due to a memory
1705 limit (or swap limit) being reached, the allo 1641 limit (or swap limit) being reached, the allowed memory is that configured
1706 limit. Finally, if it is due to the entire s 1642 limit. Finally, if it is due to the entire system being out of memory, the
1707 allowed memory represents all allocatable res 1643 allowed memory represents all allocatable resources.
1708 1644
1709 The value of /proc/<pid>/oom_score_adj is add 1645 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 1646 is used to determine which task to kill. Acceptable values range from -1000
1711 (OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_M 1647 (OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to
1712 polarize the preference for oom killing eithe 1648 polarize the preference for oom killing either by always preferring a certain
1713 task or completely disabling it. The lowest 1649 task or completely disabling it. The lowest possible value, -1000, is
1714 equivalent to disabling oom killing entirely 1650 equivalent to disabling oom killing entirely for that task since it will always
1715 report a badness score of 0. 1651 report a badness score of 0.
1716 1652
1717 Consequently, it is very simple for userspace 1653 Consequently, it is very simple for userspace to define the amount of memory to
1718 consider for each task. Setting a /proc/<pid 1654 consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for
1719 example, is roughly equivalent to allowing th 1655 example, is roughly equivalent to allowing the remainder of tasks sharing the
1720 same system, cpuset, mempolicy, or memory con 1656 same system, cpuset, mempolicy, or memory controller resources to use at least
1721 50% more memory. A value of -500, on the oth 1657 50% more memory. A value of -500, on the other hand, would be roughly
1722 equivalent to discounting 50% of the task's a 1658 equivalent to discounting 50% of the task's allowed memory from being considered
1723 as scoring against the task. 1659 as scoring against the task.
1724 1660
1725 For backwards compatibility with previous ker 1661 For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
1726 be used to tune the badness score. Its accep 1662 be used to tune the badness score. Its acceptable values range from -16
1727 (OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and 1663 (OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
1728 (OOM_DISABLE) to disable oom killing entirely 1664 (OOM_DISABLE) to disable oom killing entirely for that task. Its value is
1729 scaled linearly with /proc/<pid>/oom_score_ad 1665 scaled linearly with /proc/<pid>/oom_score_adj.
1730 1666
1731 The value of /proc/<pid>/oom_score_adj may be 1667 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 1668 value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
1733 requires CAP_SYS_RESOURCE. 1669 requires CAP_SYS_RESOURCE.
1734 1670
1735 1671
1736 3.2 /proc/<pid>/oom_score - Display current o 1672 3.2 /proc/<pid>/oom_score - Display current oom-killer score
1737 --------------------------------------------- 1673 -------------------------------------------------------------
1738 1674
1739 This file can be used to check the current sc 1675 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/< 1676 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 1677 process should be killed in an out-of-memory situation.
1742 1678
1743 Please note that the exported value includes 1679 Please note that the exported value includes oom_score_adj so it is
1744 effectively in range [0,2000]. 1680 effectively in range [0,2000].
1745 1681
1746 1682
1747 3.3 /proc/<pid>/io - Display the IO accounti 1683 3.3 /proc/<pid>/io - Display the IO accounting fields
1748 --------------------------------------------- 1684 -------------------------------------------------------
1749 1685
1750 This file contains IO statistics for each run 1686 This file contains IO statistics for each running process.
1751 1687
1752 Example 1688 Example
1753 ~~~~~~~ 1689 ~~~~~~~
1754 1690
1755 :: 1691 ::
1756 1692
1757 test:/tmp # dd if=/dev/zero of=/tmp/test. 1693 test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
1758 [1] 3828 1694 [1] 3828
1759 1695
1760 test:/tmp # cat /proc/3828/io 1696 test:/tmp # cat /proc/3828/io
1761 rchar: 323934931 1697 rchar: 323934931
1762 wchar: 323929600 1698 wchar: 323929600
1763 syscr: 632687 1699 syscr: 632687
1764 syscw: 632675 1700 syscw: 632675
1765 read_bytes: 0 1701 read_bytes: 0
1766 write_bytes: 323932160 1702 write_bytes: 323932160
1767 cancelled_write_bytes: 0 1703 cancelled_write_bytes: 0
1768 1704
1769 1705
1770 Description 1706 Description
1771 ~~~~~~~~~~~ 1707 ~~~~~~~~~~~
1772 1708
1773 rchar 1709 rchar
1774 ^^^^^ 1710 ^^^^^
1775 1711
1776 I/O counter: chars read 1712 I/O counter: chars read
1777 The number of bytes which this task has cause 1713 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 1714 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 1715 It includes things like tty IO and it is unaffected by whether or not actual
1780 physical disk IO was required (the read might 1716 physical disk IO was required (the read might have been satisfied from
1781 pagecache). 1717 pagecache).
1782 1718
1783 1719
1784 wchar 1720 wchar
1785 ^^^^^ 1721 ^^^^^
1786 1722
1787 I/O counter: chars written 1723 I/O counter: chars written
1788 The number of bytes which this task has cause 1724 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 1725 to disk. Similar caveats apply here as with rchar.
1790 1726
1791 1727
1792 syscr 1728 syscr
1793 ^^^^^ 1729 ^^^^^
1794 1730
1795 I/O counter: read syscalls 1731 I/O counter: read syscalls
1796 Attempt to count the number of read I/O opera 1732 Attempt to count the number of read I/O operations, i.e. syscalls like read()
1797 and pread(). 1733 and pread().
1798 1734
1799 1735
1800 syscw 1736 syscw
1801 ^^^^^ 1737 ^^^^^
1802 1738
1803 I/O counter: write syscalls 1739 I/O counter: write syscalls
1804 Attempt to count the number of write I/O oper 1740 Attempt to count the number of write I/O operations, i.e. syscalls like
1805 write() and pwrite(). 1741 write() and pwrite().
1806 1742
1807 1743
1808 read_bytes 1744 read_bytes
1809 ^^^^^^^^^^ 1745 ^^^^^^^^^^
1810 1746
1811 I/O counter: bytes read 1747 I/O counter: bytes read
1812 Attempt to count the number of bytes which th 1748 Attempt to count the number of bytes which this process really did cause to
1813 be fetched from the storage layer. Done at th 1749 be fetched from the storage layer. Done at the submit_bio() level, so it is
1814 accurate for block-backed filesystems. <pleas 1750 accurate for block-backed filesystems. <please add status regarding NFS and
1815 CIFS at a later time> 1751 CIFS at a later time>
1816 1752
1817 1753
1818 write_bytes 1754 write_bytes
1819 ^^^^^^^^^^^ 1755 ^^^^^^^^^^^
1820 1756
1821 I/O counter: bytes written 1757 I/O counter: bytes written
1822 Attempt to count the number of bytes which th 1758 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 1759 the storage layer. This is done at page-dirtying time.
1824 1760
1825 1761
1826 cancelled_write_bytes 1762 cancelled_write_bytes
1827 ^^^^^^^^^^^^^^^^^^^^^ 1763 ^^^^^^^^^^^^^^^^^^^^^
1828 1764
1829 The big inaccuracy here is truncate. If a pro 1765 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 1766 then deletes the file, it will in fact perform no writeout. But it will have
1831 been accounted as having caused 1MB of write. 1767 been accounted as having caused 1MB of write.
1832 In other words: The number of bytes which thi 1768 In other words: The number of bytes which this process caused to not happen,
1833 by truncating pagecache. A task can cause "ne 1769 by truncating pagecache. A task can cause "negative" IO too. If this task
1834 truncates some dirty pagecache, some IO which 1770 truncates some dirty pagecache, some IO which another task has been accounted
1835 for (in its write_bytes) will not be happenin 1771 for (in its write_bytes) will not be happening. We _could_ just subtract that
1836 from the truncating task's write_bytes, but t 1772 from the truncating task's write_bytes, but there is information loss in doing
1837 that. 1773 that.
1838 1774
1839 1775
1840 .. Note:: 1776 .. Note::
1841 1777
1842 At its current implementation state, this 1778 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 1779 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 1780 of those 64-bit counters, process A could see an intermediate result.
1845 1781
1846 1782
1847 More information about this can be found with 1783 More information about this can be found within the taskstats documentation in
1848 Documentation/accounting. 1784 Documentation/accounting.
1849 1785
1850 3.4 /proc/<pid>/coredump_filter - Core dump f 1786 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
1851 --------------------------------------------- 1787 ---------------------------------------------------------------
1852 When a process is dumped, all anonymous memor 1788 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 1789 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 1790 to dump some memory segments, for example, huge shared memory or DAX.
1855 Conversely, sometimes we want to save file-ba 1791 Conversely, sometimes we want to save file-backed memory segments into a core
1856 file, not only the individual files. 1792 file, not only the individual files.
1857 1793
1858 /proc/<pid>/coredump_filter allows you to cus 1794 /proc/<pid>/coredump_filter allows you to customize which memory segments
1859 will be dumped when the <pid> process is dump 1795 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 1796 of memory types. If a bit of the bitmask is set, memory segments of the
1861 corresponding memory type are dumped, otherwi 1797 corresponding memory type are dumped, otherwise they are not dumped.
1862 1798
1863 The following 9 memory types are supported: 1799 The following 9 memory types are supported:
1864 1800
1865 - (bit 0) anonymous private memory 1801 - (bit 0) anonymous private memory
1866 - (bit 1) anonymous shared memory 1802 - (bit 1) anonymous shared memory
1867 - (bit 2) file-backed private memory 1803 - (bit 2) file-backed private memory
1868 - (bit 3) file-backed shared memory 1804 - (bit 3) file-backed shared memory
1869 - (bit 4) ELF header pages in file-backed p 1805 - (bit 4) ELF header pages in file-backed private memory areas (it is
1870 effective only if the bit 2 is cleared) 1806 effective only if the bit 2 is cleared)
1871 - (bit 5) hugetlb private memory 1807 - (bit 5) hugetlb private memory
1872 - (bit 6) hugetlb shared memory 1808 - (bit 6) hugetlb shared memory
1873 - (bit 7) DAX private memory 1809 - (bit 7) DAX private memory
1874 - (bit 8) DAX shared memory 1810 - (bit 8) DAX shared memory
1875 1811
1876 Note that MMIO pages such as frame buffer a 1812 Note that MMIO pages such as frame buffer are never dumped and vDSO pages
1877 are always dumped regardless of the bitmask 1813 are always dumped regardless of the bitmask status.
1878 1814
1879 Note that bits 0-4 don't affect hugetlb or 1815 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 1816 only affected by bit 5-6, and DAX is only affected by bits 7-8.
1881 1817
1882 The default value of coredump_filter is 0x33; 1818 The default value of coredump_filter is 0x33; this means all anonymous memory
1883 segments, ELF header pages and hugetlb privat 1819 segments, ELF header pages and hugetlb private memory are dumped.
1884 1820
1885 If you don't want to dump all shared memory s 1821 If you don't want to dump all shared memory segments attached to pid 1234,
1886 write 0x31 to the process's proc file:: 1822 write 0x31 to the process's proc file::
1887 1823
1888 $ echo 0x31 > /proc/1234/coredump_filter 1824 $ echo 0x31 > /proc/1234/coredump_filter
1889 1825
1890 When a new process is created, the process in 1826 When a new process is created, the process inherits the bitmask status from its
1891 parent. It is useful to set up coredump_filte 1827 parent. It is useful to set up coredump_filter before the program runs.
1892 For example:: 1828 For example::
1893 1829
1894 $ echo 0x7 > /proc/self/coredump_filter 1830 $ echo 0x7 > /proc/self/coredump_filter
1895 $ ./some_program 1831 $ ./some_program
1896 1832
1897 3.5 /proc/<pid>/mountinfo - Information a 1833 3.5 /proc/<pid>/mountinfo - Information about mounts
1898 --------------------------------------------- 1834 --------------------------------------------------------
1899 1835
1900 This file contains lines of the form:: 1836 This file contains lines of the form::
1901 1837
1902 36 35 98:0 /mnt1 /mnt2 rw,noatime master: 1838 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 1839 (1)(2)(3) (4) (5) (6) (n…m) (m+1)(m+2) (m+3) (m+4)
1904 1840
1905 (1) mount ID: unique identifier 1841 (1) mount ID: unique identifier of the mount (may be reused after umount)
1906 (2) parent ID: ID of parent (or o 1842 (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 1843 (3) major:minor: value of st_dev for files on filesystem
1908 (4) root: root of the mount 1844 (4) root: root of the mount within the filesystem
1909 (5) mount point: mount point relati 1845 (5) mount point: mount point relative to the process's root
1910 (6) mount options: per mount options 1846 (6) mount options: per mount options
1911 (n…m) optional fields: zero or more fie 1847 (n…m) optional fields: zero or more fields of the form "tag[:value]"
1912 (m+1) separator: marks the end of t 1848 (m+1) separator: marks the end of the optional fields
1913 (m+2) filesystem type: name of filesystem 1849 (m+2) filesystem type: name of filesystem of the form "type[.subtype]"
1914 (m+3) mount source: filesystem specifi 1850 (m+3) mount source: filesystem specific information or "none"
1915 (m+4) super options: per super block op 1851 (m+4) super options: per super block options
1916 1852
1917 Parsers should ignore all unrecognised option 1853 Parsers should ignore all unrecognised optional fields. Currently the
1918 possible optional fields are: 1854 possible optional fields are:
1919 1855
1920 ================ =========================== 1856 ================ ==============================================================
1921 shared:X mount is shared in peer gro 1857 shared:X mount is shared in peer group X
1922 master:X mount is slave to peer grou 1858 master:X mount is slave to peer group X
1923 propagate_from:X mount is slave and receives 1859 propagate_from:X mount is slave and receives propagation from peer group X [#]_
1924 unbindable mount is unbindable 1860 unbindable mount is unbindable
1925 ================ =========================== 1861 ================ ==============================================================
1926 1862
1927 .. [#] X is the closest dominant peer group u 1863 .. [#] X is the closest dominant peer group under the process's root. If
1928 X is the immediate master of the mount 1864 X is the immediate master of the mount, or if there's no dominant peer
1929 group under the same root, then only t 1865 group under the same root, then only the "master:X" field is present
1930 and not the "propagate_from:X" field. 1866 and not the "propagate_from:X" field.
1931 1867
1932 For more information on mount propagation see 1868 For more information on mount propagation see:
1933 1869
1934 Documentation/filesystems/sharedsubtree.rst 1870 Documentation/filesystems/sharedsubtree.rst
1935 1871
1936 1872
1937 3.6 /proc/<pid>/comm & /proc/<pid>/task/ 1873 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
1938 --------------------------------------------- 1874 --------------------------------------------------------
1939 These files provide a method to access a task 1875 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 1876 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 1877 is limited in size compared to the cmdline value, so writing anything longer
1942 then the kernel's TASK_COMM_LEN (currently 16 !! 1878 then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
1943 terminator) will result in a truncated comm v !! 1879 comm value.
1944 1880
1945 1881
1946 3.7 /proc/<pid>/task/<tid>/children - Inf 1882 3.7 /proc/<pid>/task/<tid>/children - Information about task children
1947 --------------------------------------------- 1883 -------------------------------------------------------------------------
1948 This file provides a fast way to retrieve fir 1884 This file provides a fast way to retrieve first level children pids
1949 of a task pointed by <pid>/<tid> pair. The fo 1885 of a task pointed by <pid>/<tid> pair. The format is a space separated
1950 stream of pids. 1886 stream of pids.
1951 1887
1952 Note the "first level" here -- if a child has 1888 Note the "first level" here -- if a child has its own children they will
1953 not be listed here; one needs to read /proc/< 1889 not be listed here; one needs to read /proc/<children-pid>/task/<tid>/children
1954 to obtain the descendants. 1890 to obtain the descendants.
1955 1891
1956 Since this interface is intended to be fast a 1892 Since this interface is intended to be fast and cheap it doesn't
1957 guarantee to provide precise results and some 1893 guarantee to provide precise results and some children might be
1958 skipped, especially if they've exited right a 1894 skipped, especially if they've exited right after we printed their
1959 pids, so one needs to either stop or freeze p 1895 pids, so one needs to either stop or freeze processes being inspected
1960 if precise results are needed. 1896 if precise results are needed.
1961 1897
1962 1898
1963 3.8 /proc/<pid>/fdinfo/<fd> - Information 1899 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
1964 --------------------------------------------- 1900 ---------------------------------------------------------------
1965 This file provides information associated wit 1901 This file provides information associated with an opened file. The regular
1966 files have at least four fields -- 'pos', 'fl 1902 files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'.
1967 The 'pos' represents the current offset of th 1903 The 'pos' represents the current offset of the opened file in decimal
1968 form [see lseek(2) for details], 'flags' deno 1904 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 1905 file has been created with [see open(2) for details] and 'mnt_id' represents
1970 mount ID of the file system containing the op 1906 mount ID of the file system containing the opened file [see 3.5
1971 /proc/<pid>/mountinfo for details]. 'ino' rep 1907 /proc/<pid>/mountinfo for details]. 'ino' represents the inode number of
1972 the file. 1908 the file.
1973 1909
1974 A typical output is:: 1910 A typical output is::
1975 1911
1976 pos: 0 1912 pos: 0
1977 flags: 0100002 1913 flags: 0100002
1978 mnt_id: 19 1914 mnt_id: 19
1979 ino: 63107 1915 ino: 63107
1980 1916
1981 All locks associated with a file descriptor a 1917 All locks associated with a file descriptor are shown in its fdinfo too::
1982 1918
1983 lock: 1: FLOCK ADVISORY WRITE 359 1919 lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF
1984 1920
1985 The files such as eventfd, fsnotify, signalfd 1921 The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags
1986 pair provide additional information particula 1922 pair provide additional information particular to the objects they represent.
1987 1923
1988 Eventfd files 1924 Eventfd files
1989 ~~~~~~~~~~~~~ 1925 ~~~~~~~~~~~~~
1990 1926
1991 :: 1927 ::
1992 1928
1993 pos: 0 1929 pos: 0
1994 flags: 04002 1930 flags: 04002
1995 mnt_id: 9 1931 mnt_id: 9
1996 ino: 63107 1932 ino: 63107
1997 eventfd-count: 5a 1933 eventfd-count: 5a
1998 1934
1999 where 'eventfd-count' is hex value of a count 1935 where 'eventfd-count' is hex value of a counter.
2000 1936
2001 Signalfd files 1937 Signalfd files
2002 ~~~~~~~~~~~~~~ 1938 ~~~~~~~~~~~~~~
2003 1939
2004 :: 1940 ::
2005 1941
2006 pos: 0 1942 pos: 0
2007 flags: 04002 1943 flags: 04002
2008 mnt_id: 9 1944 mnt_id: 9
2009 ino: 63107 1945 ino: 63107
2010 sigmask: 0000000000000200 1946 sigmask: 0000000000000200
2011 1947
2012 where 'sigmask' is hex value of the signal ma 1948 where 'sigmask' is hex value of the signal mask associated
2013 with a file. 1949 with a file.
2014 1950
2015 Epoll files 1951 Epoll files
2016 ~~~~~~~~~~~ 1952 ~~~~~~~~~~~
2017 1953
2018 :: 1954 ::
2019 1955
2020 pos: 0 1956 pos: 0
2021 flags: 02 1957 flags: 02
2022 mnt_id: 9 1958 mnt_id: 9
2023 ino: 63107 1959 ino: 63107
2024 tfd: 5 events: 1d data: 1960 tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7
2025 1961
2026 where 'tfd' is a target file descriptor numbe 1962 where 'tfd' is a target file descriptor number in decimal form,
2027 'events' is events mask being watched and the 1963 'events' is events mask being watched and the 'data' is data
2028 associated with a target [see epoll(7) for mo 1964 associated with a target [see epoll(7) for more details].
2029 1965
2030 The 'pos' is current offset of the target fil 1966 The 'pos' is current offset of the target file in decimal form
2031 [see lseek(2)], 'ino' and 'sdev' are inode an 1967 [see lseek(2)], 'ino' and 'sdev' are inode and device numbers
2032 where target file resides, all in hex format. 1968 where target file resides, all in hex format.
2033 1969
2034 Fsnotify files 1970 Fsnotify files
2035 ~~~~~~~~~~~~~~ 1971 ~~~~~~~~~~~~~~
2036 For inotify files the format is the following 1972 For inotify files the format is the following::
2037 1973
2038 pos: 0 1974 pos: 0
2039 flags: 02000000 1975 flags: 02000000
2040 mnt_id: 9 1976 mnt_id: 9
2041 ino: 63107 1977 ino: 63107
2042 inotify wd:3 ino:9e7e sdev:800013 mas 1978 inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d
2043 1979
2044 where 'wd' is a watch descriptor in decimal f 1980 where 'wd' is a watch descriptor in decimal form, i.e. a target file
2045 descriptor number, 'ino' and 'sdev' are inode 1981 descriptor number, 'ino' and 'sdev' are inode and device where the
2046 target file resides and the 'mask' is the mas 1982 target file resides and the 'mask' is the mask of events, all in hex
2047 form [see inotify(7) for more details]. 1983 form [see inotify(7) for more details].
2048 1984
2049 If the kernel was built with exportfs support 1985 If the kernel was built with exportfs support, the path to the target
2050 file is encoded as a file handle. The file h 1986 file is encoded as a file handle. The file handle is provided by three
2051 fields 'fhandle-bytes', 'fhandle-type' and 'f 1987 fields 'fhandle-bytes', 'fhandle-type' and 'f_handle', all in hex
2052 format. 1988 format.
2053 1989
2054 If the kernel is built without exportfs suppo 1990 If the kernel is built without exportfs support the file handle won't be
2055 printed out. 1991 printed out.
2056 1992
2057 If there is no inotify mark attached yet the 1993 If there is no inotify mark attached yet the 'inotify' line will be omitted.
2058 1994
2059 For fanotify files the format is:: 1995 For fanotify files the format is::
2060 1996
2061 pos: 0 1997 pos: 0
2062 flags: 02 1998 flags: 02
2063 mnt_id: 9 1999 mnt_id: 9
2064 ino: 63107 2000 ino: 63107
2065 fanotify flags:10 event-flags:0 2001 fanotify flags:10 event-flags:0
2066 fanotify mnt_id:12 mflags:40 mask:38 2002 fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003
2067 fanotify ino:4f969 sdev:800013 mflags 2003 fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4
2068 2004
2069 where fanotify 'flags' and 'event-flags' are 2005 where fanotify 'flags' and 'event-flags' are values used in fanotify_init
2070 call, 'mnt_id' is the mount point identifier, 2006 call, 'mnt_id' is the mount point identifier, 'mflags' is the value of
2071 flags associated with mark which are tracked 2007 flags associated with mark which are tracked separately from events
2072 mask. 'ino' and 'sdev' are target inode and d 2008 mask. 'ino' and 'sdev' are target inode and device, 'mask' is the events
2073 mask and 'ignored_mask' is the mask of events 2009 mask and 'ignored_mask' is the mask of events which are to be ignored.
2074 All are in hex format. Incorporation of 'mfla 2010 All are in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask'
2075 provide information about flags and mask used 2011 provide information about flags and mask used in fanotify_mark
2076 call [see fsnotify manpage for details]. 2012 call [see fsnotify manpage for details].
2077 2013
2078 While the first three lines are mandatory and 2014 While the first three lines are mandatory and always printed, the rest is
2079 optional and may be omitted if no marks creat 2015 optional and may be omitted if no marks created yet.
2080 2016
2081 Timerfd files 2017 Timerfd files
2082 ~~~~~~~~~~~~~ 2018 ~~~~~~~~~~~~~
2083 2019
2084 :: 2020 ::
2085 2021
2086 pos: 0 2022 pos: 0
2087 flags: 02 2023 flags: 02
2088 mnt_id: 9 2024 mnt_id: 9
2089 ino: 63107 2025 ino: 63107
2090 clockid: 0 2026 clockid: 0
2091 ticks: 0 2027 ticks: 0
2092 settime flags: 01 2028 settime flags: 01
2093 it_value: (0, 49406829) 2029 it_value: (0, 49406829)
2094 it_interval: (1, 0) 2030 it_interval: (1, 0)
2095 2031
2096 where 'clockid' is the clock type and 'ticks' 2032 where 'clockid' is the clock type and 'ticks' is the number of the timer expirations
2097 that have occurred [see timerfd_create(2) for 2033 that have occurred [see timerfd_create(2) for details]. 'settime flags' are
2098 flags in octal form been used to setup the ti 2034 flags in octal form been used to setup the timer [see timerfd_settime(2) for
2099 details]. 'it_value' is remaining time until 2035 details]. 'it_value' is remaining time until the timer expiration.
2100 'it_interval' is the interval for the timer. 2036 'it_interval' is the interval for the timer. Note the timer might be set up
2101 with TIMER_ABSTIME option which will be shown 2037 with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value'
2102 still exhibits timer's remaining time. 2038 still exhibits timer's remaining time.
2103 2039
2104 DMA Buffer files 2040 DMA Buffer files
2105 ~~~~~~~~~~~~~~~~ 2041 ~~~~~~~~~~~~~~~~
2106 2042
2107 :: 2043 ::
2108 2044
2109 pos: 0 2045 pos: 0
2110 flags: 04002 2046 flags: 04002
2111 mnt_id: 9 2047 mnt_id: 9
2112 ino: 63107 2048 ino: 63107
2113 size: 32768 2049 size: 32768
2114 count: 2 2050 count: 2
2115 exp_name: system-heap 2051 exp_name: system-heap
2116 2052
2117 where 'size' is the size of the DMA buffer in 2053 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 2054 the DMA buffer file. 'exp_name' is the name of the DMA buffer exporter.
2119 2055
2120 3.9 /proc/<pid>/map_files - Information a 2056 3.9 /proc/<pid>/map_files - Information about memory mapped files
2121 --------------------------------------------- 2057 ---------------------------------------------------------------------
2122 This directory contains symbolic links which 2058 This directory contains symbolic links which represent memory mapped files
2123 the process is maintaining. Example output:: 2059 the process is maintaining. Example output::
2124 2060
2125 | lr-------- 1 root root 64 Jan 27 11:24 2061 | 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 2062 | 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 2063 | lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so
2128 | ... 2064 | ...
2129 | lr-------- 1 root root 64 Jan 27 11:24 2065 | 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 2066 | lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls
2131 2067
2132 The name of a link represents the virtual mem 2068 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 2069 vm_area_struct::vm_start-vm_area_struct::vm_end.
2134 2070
2135 The main purpose of the map_files is to retri 2071 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/ 2072 files in a fast way instead of parsing /proc/<pid>/maps or
2137 /proc/<pid>/smaps, both of which contain many 2073 /proc/<pid>/smaps, both of which contain many more records. At the same
2138 time one can open(2) mappings from the listin 2074 time one can open(2) mappings from the listings of two processes and
2139 comparing their inode numbers to figure out w 2075 comparing their inode numbers to figure out which anonymous memory areas
2140 are actually shared. 2076 are actually shared.
2141 2077
2142 3.10 /proc/<pid>/timerslack_ns - Task time 2078 3.10 /proc/<pid>/timerslack_ns - Task timerslack value
2143 --------------------------------------------- 2079 ---------------------------------------------------------
2144 This file provides the value of the task's ti 2080 This file provides the value of the task's timerslack value in nanoseconds.
2145 This value specifies an amount of time that n 2081 This value specifies an amount of time that normal timers may be deferred
2146 in order to coalesce timers and avoid unneces 2082 in order to coalesce timers and avoid unnecessary wakeups.
2147 2083
2148 This allows a task's interactivity vs power c 2084 This allows a task's interactivity vs power consumption tradeoff to be
2149 adjusted. 2085 adjusted.
2150 2086
2151 Writing 0 to the file will set the task's tim 2087 Writing 0 to the file will set the task's timerslack to the default value.
2152 2088
2153 Valid values are from 0 - ULLONG_MAX 2089 Valid values are from 0 - ULLONG_MAX
2154 2090
2155 An application setting the value must have PT 2091 An application setting the value must have PTRACE_MODE_ATTACH_FSCREDS level
2156 permissions on the task specified to change i 2092 permissions on the task specified to change its timerslack_ns value.
2157 2093
2158 3.11 /proc/<pid>/patch_state - Livepatch p 2094 3.11 /proc/<pid>/patch_state - Livepatch patch operation state
2159 --------------------------------------------- 2095 -----------------------------------------------------------------
2160 When CONFIG_LIVEPATCH is enabled, this file d 2096 When CONFIG_LIVEPATCH is enabled, this file displays the value of the
2161 patch state for the task. 2097 patch state for the task.
2162 2098
2163 A value of '-1' indicates that no patch is in 2099 A value of '-1' indicates that no patch is in transition.
2164 2100
2165 A value of '0' indicates that a patch is in t 2101 A value of '0' indicates that a patch is in transition and the task is
2166 unpatched. If the patch is being enabled, th 2102 unpatched. If the patch is being enabled, then the task hasn't been
2167 patched yet. If the patch is being disabled, 2103 patched yet. If the patch is being disabled, then the task has already
2168 been unpatched. 2104 been unpatched.
2169 2105
2170 A value of '1' indicates that a patch is in t 2106 A value of '1' indicates that a patch is in transition and the task is
2171 patched. If the patch is being enabled, then 2107 patched. If the patch is being enabled, then the task has already been
2172 patched. If the patch is being disabled, the 2108 patched. If the patch is being disabled, then the task hasn't been
2173 unpatched yet. 2109 unpatched yet.
2174 2110
2175 3.12 /proc/<pid>/arch_status - task architect 2111 3.12 /proc/<pid>/arch_status - task architecture specific status
2176 --------------------------------------------- 2112 -------------------------------------------------------------------
2177 When CONFIG_PROC_PID_ARCH_STATUS is enabled, 2113 When CONFIG_PROC_PID_ARCH_STATUS is enabled, this file displays the
2178 architecture specific status of the task. 2114 architecture specific status of the task.
2179 2115
2180 Example 2116 Example
2181 ~~~~~~~ 2117 ~~~~~~~
2182 2118
2183 :: 2119 ::
2184 2120
2185 $ cat /proc/6753/arch_status 2121 $ cat /proc/6753/arch_status
2186 AVX512_elapsed_ms: 8 2122 AVX512_elapsed_ms: 8
2187 2123
2188 Description 2124 Description
2189 ~~~~~~~~~~~ 2125 ~~~~~~~~~~~
2190 2126
2191 x86 specific entries 2127 x86 specific entries
2192 ~~~~~~~~~~~~~~~~~~~~~ 2128 ~~~~~~~~~~~~~~~~~~~~~
2193 2129
2194 AVX512_elapsed_ms 2130 AVX512_elapsed_ms
2195 ^^^^^^^^^^^^^^^^^^ 2131 ^^^^^^^^^^^^^^^^^^
2196 2132
2197 If AVX512 is supported on the machine, this 2133 If AVX512 is supported on the machine, this entry shows the milliseconds
2198 elapsed since the last time AVX512 usage wa 2134 elapsed since the last time AVX512 usage was recorded. The recording
2199 happens on a best effort basis when a task 2135 happens on a best effort basis when a task is scheduled out. This means
2200 that the value depends on two factors: 2136 that the value depends on two factors:
2201 2137
2202 1) The time which the task spent on the C 2138 1) The time which the task spent on the CPU without being scheduled
2203 out. With CPU isolation and a single r 2139 out. With CPU isolation and a single runnable task this can take
2204 several seconds. 2140 several seconds.
2205 2141
2206 2) The time since the task was scheduled 2142 2) The time since the task was scheduled out last. Depending on the
2207 reason for being scheduled out (time s 2143 reason for being scheduled out (time slice exhausted, syscall ...)
2208 this can be arbitrary long time. 2144 this can be arbitrary long time.
2209 2145
2210 As a consequence the value cannot be consid 2146 As a consequence the value cannot be considered precise and authoritative
2211 information. The application which uses thi 2147 information. The application which uses this information has to be aware
2212 of the overall scenario on the system in or 2148 of the overall scenario on the system in order to determine whether a
2213 task is a real AVX512 user or not. Precise 2149 task is a real AVX512 user or not. Precise information can be obtained
2214 with performance counters. 2150 with performance counters.
2215 2151
2216 A special value of '-1' indicates that no A 2152 A special value of '-1' indicates that no AVX512 usage was recorded, thus
2217 the task is unlikely an AVX512 user, but de 2153 the task is unlikely an AVX512 user, but depends on the workload and the
2218 scheduling scenario, it also could be a fal 2154 scheduling scenario, it also could be a false negative mentioned above.
2219 2155
2220 3.13 /proc/<pid>/fd - List of symlinks to ope 2156 3.13 /proc/<pid>/fd - List of symlinks to open files
2221 --------------------------------------------- 2157 -------------------------------------------------------
2222 This directory contains symbolic links which 2158 This directory contains symbolic links which represent open files
2223 the process is maintaining. Example output:: 2159 the process is maintaining. Example output::
2224 2160
2225 lr-x------ 1 root root 64 Sep 20 17:53 0 -> 2161 lr-x------ 1 root root 64 Sep 20 17:53 0 -> /dev/null
2226 l-wx------ 1 root root 64 Sep 20 17:53 1 -> 2162 l-wx------ 1 root root 64 Sep 20 17:53 1 -> /dev/null
2227 lrwx------ 1 root root 64 Sep 20 17:53 10 - 2163 lrwx------ 1 root root 64 Sep 20 17:53 10 -> 'socket:[12539]'
2228 lrwx------ 1 root root 64 Sep 20 17:53 11 - 2164 lrwx------ 1 root root 64 Sep 20 17:53 11 -> 'socket:[12540]'
2229 lrwx------ 1 root root 64 Sep 20 17:53 12 - 2165 lrwx------ 1 root root 64 Sep 20 17:53 12 -> 'socket:[12542]'
2230 2166
2231 The number of open files for the process is s 2167 The number of open files for the process is stored in 'size' member
2232 of stat() output for /proc/<pid>/fd for fast 2168 of stat() output for /proc/<pid>/fd for fast access.
2233 --------------------------------------------- 2169 -------------------------------------------------------
2234 2170
2235 2171
2236 Chapter 4: Configuring procfs 2172 Chapter 4: Configuring procfs
2237 ============================= 2173 =============================
2238 2174
2239 4.1 Mount options 2175 4.1 Mount options
2240 --------------------- 2176 ---------------------
2241 2177
2242 The following mount options are supported: 2178 The following mount options are supported:
2243 2179
2244 ========= ===================== 2180 ========= ========================================================
2245 hidepid= Set /proc/<pid>/ acce 2181 hidepid= Set /proc/<pid>/ access mode.
2246 gid= Set the group authori 2182 gid= Set the group authorized to learn processes information.
2247 subset= Show only the specifi 2183 subset= Show only the specified subset of procfs.
2248 ========= ===================== 2184 ========= ========================================================
2249 2185
2250 hidepid=off or hidepid=0 means classic mode - 2186 hidepid=off or hidepid=0 means classic mode - everybody may access all
2251 /proc/<pid>/ directories (default). 2187 /proc/<pid>/ directories (default).
2252 2188
2253 hidepid=noaccess or hidepid=1 means users may 2189 hidepid=noaccess or hidepid=1 means users may not access any /proc/<pid>/
2254 directories but their own. Sensitive files l 2190 directories but their own. Sensitive files like cmdline, sched*, status are now
2255 protected against other users. This makes it 2191 protected against other users. This makes it impossible to learn whether any
2256 user runs specific program (given the program 2192 user runs specific program (given the program doesn't reveal itself by its
2257 behaviour). As an additional bonus, as /proc 2193 behaviour). As an additional bonus, as /proc/<pid>/cmdline is unaccessible for
2258 other users, poorly written programs passing 2194 other users, poorly written programs passing sensitive information via program
2259 arguments are now protected against local eav 2195 arguments are now protected against local eavesdroppers.
2260 2196
2261 hidepid=invisible or hidepid=2 means hidepid= 2197 hidepid=invisible or hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be
2262 fully invisible to other users. It doesn't m 2198 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 2199 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 2200 by "kill -0 $PID"), but it hides process' uid and gid, which may be learned by
2265 stat()'ing /proc/<pid>/ otherwise. It greatl 2201 stat()'ing /proc/<pid>/ otherwise. It greatly complicates an intruder's task of
2266 gathering information about running processes 2202 gathering information about running processes, whether some daemon runs with
2267 elevated privileges, whether other user runs 2203 elevated privileges, whether other user runs some sensitive program, whether
2268 other users run any program at all, etc. 2204 other users run any program at all, etc.
2269 2205
2270 hidepid=ptraceable or hidepid=4 means that pr 2206 hidepid=ptraceable or hidepid=4 means that procfs should only contain
2271 /proc/<pid>/ directories that the caller can 2207 /proc/<pid>/ directories that the caller can ptrace.
2272 2208
2273 gid= defines a group authorized to learn proc 2209 gid= defines a group authorized to learn processes information otherwise
2274 prohibited by hidepid=. If you use some daem 2210 prohibited by hidepid=. If you use some daemon like identd which needs to learn
2275 information about processes information, just 2211 information about processes information, just add identd to this group.
2276 2212
2277 subset=pid hides all top level files and dire 2213 subset=pid hides all top level files and directories in the procfs that
2278 are not related to tasks. 2214 are not related to tasks.
2279 2215
2280 Chapter 5: Filesystem behavior 2216 Chapter 5: Filesystem behavior
2281 ============================== 2217 ==============================
2282 2218
2283 Originally, before the advent of pid namespac !! 2219 Originally, before the advent of pid namepsace, procfs was a global file
2284 system. It means that there was only one proc 2220 system. It means that there was only one procfs instance in the system.
2285 2221
2286 When pid namespace was added, a separate proc 2222 When pid namespace was added, a separate procfs instance was mounted in
2287 each pid namespace. So, procfs mount options 2223 each pid namespace. So, procfs mount options are global among all
2288 mountpoints within the same namespace:: 2224 mountpoints within the same namespace::
2289 2225
2290 # grep ^proc /proc/mounts 2226 # grep ^proc /proc/mounts
2291 proc /proc proc rw,relatime,hidepid=2 2227 proc /proc proc rw,relatime,hidepid=2 0 0
2292 2228
2293 # strace -e mount mount -o hidepid=1 2229 # strace -e mount mount -o hidepid=1 -t proc proc /tmp/proc
2294 mount("proc", "/tmp/proc", "proc", 0, 2230 mount("proc", "/tmp/proc", "proc", 0, "hidepid=1") = 0
2295 +++ exited with 0 +++ 2231 +++ exited with 0 +++
2296 2232
2297 # grep ^proc /proc/mounts 2233 # grep ^proc /proc/mounts
2298 proc /proc proc rw,relatime,hidepid=2 2234 proc /proc proc rw,relatime,hidepid=2 0 0
2299 proc /tmp/proc proc rw,relatime,hidep 2235 proc /tmp/proc proc rw,relatime,hidepid=2 0 0
2300 2236
2301 and only after remounting procfs mount option 2237 and only after remounting procfs mount options will change at all
2302 mountpoints:: 2238 mountpoints::
2303 2239
2304 # mount -o remount,hidepid=1 -t proc 2240 # mount -o remount,hidepid=1 -t proc proc /tmp/proc
2305 2241
2306 # grep ^proc /proc/mounts 2242 # grep ^proc /proc/mounts
2307 proc /proc proc rw,relatime,hidepid=1 2243 proc /proc proc rw,relatime,hidepid=1 0 0
2308 proc /tmp/proc proc rw,relatime,hidep 2244 proc /tmp/proc proc rw,relatime,hidepid=1 0 0
2309 2245
2310 This behavior is different from the behavior 2246 This behavior is different from the behavior of other filesystems.
2311 2247
2312 The new procfs behavior is more like other fi 2248 The new procfs behavior is more like other filesystems. Each procfs mount
2313 creates a new procfs instance. Mount options 2249 creates a new procfs instance. Mount options affect own procfs instance.
2314 It means that it became possible to have seve 2250 It means that it became possible to have several procfs instances
2315 displaying tasks with different filtering opt 2251 displaying tasks with different filtering options in one pid namespace::
2316 2252
2317 # mount -o hidepid=invisible -t proc 2253 # mount -o hidepid=invisible -t proc proc /proc
2318 # mount -o hidepid=noaccess -t proc p 2254 # mount -o hidepid=noaccess -t proc proc /tmp/proc
2319 # grep ^proc /proc/mounts 2255 # grep ^proc /proc/mounts
2320 proc /proc proc rw,relatime,hidepid=i 2256 proc /proc proc rw,relatime,hidepid=invisible 0 0
2321 proc /tmp/proc proc rw,relatime,hidep 2257 proc /tmp/proc proc rw,relatime,hidepid=noaccess 0 0
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