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