projects / GitHub / mt8127 / android_kernel_alcatel_ttab.git / blame
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|---|---|---|
| 1da177e4 LT |
1 | ------------------------------------------------------------------------------ |
| 2 | T H E /proc F I L E S Y S T E M | |
| 3 | ------------------------------------------------------------------------------ | |
| 4 | /proc/sys Terrehon Bowden <terrehon@pacbell.net> October 7 1999 | |
| 5 | Bodo Bauer <bb@ricochet.net> | |
| 6 | ||
| 7 | 2.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000 | |
| 349888ee | 8 | move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009 |
| 1da177e4 LT |
9 | ------------------------------------------------------------------------------ |
| 10 | Version 1.3 Kernel version 2.2.12 | |
| 11 | Kernel version 2.4.0-test11-pre4 | |
| 12 | ------------------------------------------------------------------------------ | |
| 349888ee | 13 | fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009 |
| 1da177e4 LT |
14 | |
| 15 | Table of Contents | |
| 16 | ----------------- | |
| 17 | ||
| 18 | 0 Preface | |
| 19 | 0.1 Introduction/Credits | |
| 20 | 0.2 Legal Stuff | |
| 21 | ||
| 22 | 1 Collecting System Information | |
| 23 | 1.1 Process-Specific Subdirectories | |
| 24 | 1.2 Kernel data | |
| 25 | 1.3 IDE devices in /proc/ide | |
| 26 | 1.4 Networking info in /proc/net | |
| 27 | 1.5 SCSI info | |
| 28 | 1.6 Parallel port info in /proc/parport | |
| 29 | 1.7 TTY info in /proc/tty | |
| 30 | 1.8 Miscellaneous kernel statistics in /proc/stat | |
| 760df93e | 31 | 1.9 Ext4 file system parameters |
| 1da177e4 LT |
32 | |
| 33 | 2 Modifying System Parameters | |
| 760df93e SF |
34 | |
| 35 | 3 Per-Process Parameters | |
| a63d83f4 DR |
36 | 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer |
| 37 | score | |
| 760df93e SF |
38 | 3.2 /proc/<pid>/oom_score - Display current oom-killer score |
| 39 | 3.3 /proc/<pid>/io - Display the IO accounting fields | |
| 40 | 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings | |
| 41 | 3.5 /proc/<pid>/mountinfo - Information about mounts | |
| 4614a696 | 42 | 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm |
| 760df93e | 43 | |
| 0499680a VK |
44 | 4 Configuring procfs |
| 45 | 4.1 Mount options | |
| 1da177e4 LT |
46 | |
| 47 | ------------------------------------------------------------------------------ | |
| 48 | Preface | |
| 49 | ------------------------------------------------------------------------------ | |
| 50 | ||
| 51 | 0.1 Introduction/Credits | |
| 52 | ------------------------ | |
| 53 | ||
| 54 | This documentation is part of a soon (or so we hope) to be released book on | |
| 55 | the SuSE Linux distribution. As there is no complete documentation for the | |
| 56 | /proc file system and we've used many freely available sources to write these | |
| 57 | chapters, it seems only fair to give the work back to the Linux community. | |
| 58 | This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm | |
| 59 | afraid it's still far from complete, but we hope it will be useful. As far as | |
| 60 | we know, it is the first 'all-in-one' document about the /proc file system. It | |
| 61 | is focused on the Intel x86 hardware, so if you are looking for PPC, ARM, | |
| 62 | SPARC, AXP, etc., features, you probably won't find what you are looking for. | |
| 63 | It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But | |
| 64 | additions and patches are welcome and will be added to this document if you | |
| 65 | mail them to Bodo. | |
| 66 | ||
| 67 | We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of | |
| 68 | other people for help compiling this documentation. We'd also like to extend a | |
| 69 | special thank you to Andi Kleen for documentation, which we relied on heavily | |
| 70 | to create this document, as well as the additional information he provided. | |
| 71 | Thanks to everybody else who contributed source or docs to the Linux kernel | |
| 72 | and helped create a great piece of software... :) | |
| 73 | ||
| 74 | If you have any comments, corrections or additions, please don't hesitate to | |
| 75 | contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this | |
| 76 | document. | |
| 77 | ||
| 78 | The latest version of this document is available online at | |
| 0ea6e611 | 79 | http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html |
| 1da177e4 | 80 | |
| 0ea6e611 | 81 | If the above direction does not works for you, you could try the kernel |
| 1da177e4 LT |
82 | mailing list at linux-kernel@vger.kernel.org and/or try to reach me at |
| 83 | comandante@zaralinux.com. | |
| 84 | ||
| 85 | 0.2 Legal Stuff | |
| 86 | --------------- | |
| 87 | ||
| 88 | We don't guarantee the correctness of this document, and if you come to us | |
| 89 | complaining about how you screwed up your system because of incorrect | |
| 90 | documentation, we won't feel responsible... | |
| 91 | ||
| 92 | ------------------------------------------------------------------------------ | |
| 93 | CHAPTER 1: COLLECTING SYSTEM INFORMATION | |
| 94 | ------------------------------------------------------------------------------ | |
| 95 | ||
| 96 | ------------------------------------------------------------------------------ | |
| 97 | In This Chapter | |
| 98 | ------------------------------------------------------------------------------ | |
| 99 | * Investigating the properties of the pseudo file system /proc and its | |
| 100 | ability to provide information on the running Linux system | |
| 101 | * Examining /proc's structure | |
| 102 | * Uncovering various information about the kernel and the processes running | |
| 103 | on the system | |
| 104 | ------------------------------------------------------------------------------ | |
| 105 | ||
| 106 | ||
| 107 | The proc file system acts as an interface to internal data structures in the | |
| 108 | kernel. It can be used to obtain information about the system and to change | |
| 109 | certain kernel parameters at runtime (sysctl). | |
| 110 | ||
| 111 | First, we'll take a look at the read-only parts of /proc. In Chapter 2, we | |
| 112 | show you how you can use /proc/sys to change settings. | |
| 113 | ||
| 114 | 1.1 Process-Specific Subdirectories | |
| 115 | ----------------------------------- | |
| 116 | ||
| 117 | The directory /proc contains (among other things) one subdirectory for each | |
| 118 | process running on the system, which is named after the process ID (PID). | |
| 119 | ||
| 120 | The link self points to the process reading the file system. Each process | |
| 121 | subdirectory has the entries listed in Table 1-1. | |
| 122 | ||
| 123 | ||
| 349888ee | 124 | Table 1-1: Process specific entries in /proc |
| 1da177e4 | 125 | .............................................................................. |
| b813e931 DR |
126 | File Content |
| 127 | clear_refs Clears page referenced bits shown in smaps output | |
| 128 | cmdline Command line arguments | |
| 129 | cpu Current and last cpu in which it was executed (2.4)(smp) | |
| 130 | cwd Link to the current working directory | |
| 131 | environ Values of environment variables | |
| 132 | exe Link to the executable of this process | |
| 133 | fd Directory, which contains all file descriptors | |
| 134 | maps Memory maps to executables and library files (2.4) | |
| 135 | mem Memory held by this process | |
| 136 | root Link to the root directory of this process | |
| 137 | stat Process status | |
| 138 | statm Process memory status information | |
| 139 | status Process status in human readable form | |
| 140 | wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan | |
| 03f890f8 | 141 | pagemap Page table |
| 2ec220e2 | 142 | stack Report full stack trace, enable via CONFIG_STACKTRACE |
| 349888ee SS |
143 | smaps a extension based on maps, showing the memory consumption of |
| 144 | each mapping | |
| 1da177e4 LT |
145 | .............................................................................. |
| 146 | ||
| 147 | For example, to get the status information of a process, all you have to do is | |
| 148 | read the file /proc/PID/status: | |
| 149 | ||
| 349888ee SS |
150 | >cat /proc/self/status |
| 151 | Name: cat | |
| 152 | State: R (running) | |
| 153 | Tgid: 5452 | |
| 154 | Pid: 5452 | |
| 155 | PPid: 743 | |
| 1da177e4 | 156 | TracerPid: 0 (2.4) |
| 349888ee SS |
157 | Uid: 501 501 501 501 |
| 158 | Gid: 100 100 100 100 | |
| 159 | FDSize: 256 | |
| 160 | Groups: 100 14 16 | |
| 161 | VmPeak: 5004 kB | |
| 162 | VmSize: 5004 kB | |
| 163 | VmLck: 0 kB | |
| 164 | VmHWM: 476 kB | |
| 165 | VmRSS: 476 kB | |
| 166 | VmData: 156 kB | |
| 167 | VmStk: 88 kB | |
| 168 | VmExe: 68 kB | |
| 169 | VmLib: 1412 kB | |
| 170 | VmPTE: 20 kb | |
| b084d435 | 171 | VmSwap: 0 kB |
| 349888ee SS |
172 | Threads: 1 |
| 173 | SigQ: 0/28578 | |
| 174 | SigPnd: 0000000000000000 | |
| 175 | ShdPnd: 0000000000000000 | |
| 176 | SigBlk: 0000000000000000 | |
| 177 | SigIgn: 0000000000000000 | |
| 178 | SigCgt: 0000000000000000 | |
| 179 | CapInh: 00000000fffffeff | |
| 180 | CapPrm: 0000000000000000 | |
| 181 | CapEff: 0000000000000000 | |
| 182 | CapBnd: ffffffffffffffff | |
| 183 | voluntary_ctxt_switches: 0 | |
| 184 | nonvoluntary_ctxt_switches: 1 | |
| 1da177e4 LT |
185 | |
| 186 | This shows you nearly the same information you would get if you viewed it with | |
| 187 | the ps command. In fact, ps uses the proc file system to obtain its | |
| 349888ee SS |
188 | information. But you get a more detailed view of the process by reading the |
| 189 | file /proc/PID/status. It fields are described in table 1-2. | |
| 190 | ||
| 191 | The statm file contains more detailed information about the process | |
| 192 | memory usage. Its seven fields are explained in Table 1-3. The stat file | |
| 193 | contains details information about the process itself. Its fields are | |
| 194 | explained in Table 1-4. | |
| 1da177e4 | 195 | |
| 34e55232 KH |
196 | (for SMP CONFIG users) |
| 197 | For making accounting scalable, RSS related information are handled in | |
| 198 | asynchronous manner and the vaule may not be very precise. To see a precise | |
| 199 | snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table. | |
| 200 | It's slow but very precise. | |
| 201 | ||
| cb2992a6 | 202 | Table 1-2: Contents of the status files (as of 2.6.30-rc7) |
| 349888ee SS |
203 | .............................................................................. |
| 204 | Field Content | |
| 205 | Name filename of the executable | |
| 206 | State state (R is running, S is sleeping, D is sleeping | |
| 207 | in an uninterruptible wait, Z is zombie, | |
| 208 | T is traced or stopped) | |
| 209 | Tgid thread group ID | |
| 210 | Pid process id | |
| 211 | PPid process id of the parent process | |
| 212 | TracerPid PID of process tracing this process (0 if not) | |
| 213 | Uid Real, effective, saved set, and file system UIDs | |
| 214 | Gid Real, effective, saved set, and file system GIDs | |
| 215 | FDSize number of file descriptor slots currently allocated | |
| 216 | Groups supplementary group list | |
| 217 | VmPeak peak virtual memory size | |
| 218 | VmSize total program size | |
| 219 | VmLck locked memory size | |
| 220 | VmHWM peak resident set size ("high water mark") | |
| 221 | VmRSS size of memory portions | |
| 222 | VmData size of data, stack, and text segments | |
| 223 | VmStk size of data, stack, and text segments | |
| 224 | VmExe size of text segment | |
| 225 | VmLib size of shared library code | |
| 226 | VmPTE size of page table entries | |
| b084d435 | 227 | VmSwap size of swap usage (the number of referred swapents) |
| 349888ee SS |
228 | Threads number of threads |
| 229 | SigQ number of signals queued/max. number for queue | |
| 230 | SigPnd bitmap of pending signals for the thread | |
| 231 | ShdPnd bitmap of shared pending signals for the process | |
| 232 | SigBlk bitmap of blocked signals | |
| 233 | SigIgn bitmap of ignored signals | |
| 234 | SigCgt bitmap of catched signals | |
| 235 | CapInh bitmap of inheritable capabilities | |
| 236 | CapPrm bitmap of permitted capabilities | |
| 237 | CapEff bitmap of effective capabilities | |
| 238 | CapBnd bitmap of capabilities bounding set | |
| 239 | Cpus_allowed mask of CPUs on which this process may run | |
| 240 | Cpus_allowed_list Same as previous, but in "list format" | |
| 241 | Mems_allowed mask of memory nodes allowed to this process | |
| 242 | Mems_allowed_list Same as previous, but in "list format" | |
| 243 | voluntary_ctxt_switches number of voluntary context switches | |
| 244 | nonvoluntary_ctxt_switches number of non voluntary context switches | |
| 245 | .............................................................................. | |
| 1da177e4 | 246 | |
| 349888ee | 247 | Table 1-3: Contents of the statm files (as of 2.6.8-rc3) |
| 1da177e4 LT |
248 | .............................................................................. |
| 249 | Field Content | |
| 250 | size total program size (pages) (same as VmSize in status) | |
| 251 | resident size of memory portions (pages) (same as VmRSS in status) | |
| 252 | shared number of pages that are shared (i.e. backed by a file) | |
| 253 | trs number of pages that are 'code' (not including libs; broken, | |
| 254 | includes data segment) | |
| 255 | lrs number of pages of library (always 0 on 2.6) | |
| 256 | drs number of pages of data/stack (including libs; broken, | |
| 257 | includes library text) | |
| 258 | dt number of dirty pages (always 0 on 2.6) | |
| 259 | .............................................................................. | |
| 260 | ||
| 18d96779 | 261 | |
| 349888ee | 262 | Table 1-4: Contents of the stat files (as of 2.6.30-rc7) |
| 18d96779 KC |
263 | .............................................................................. |
| 264 | Field Content | |
| 265 | pid process id | |
| 266 | tcomm filename of the executable | |
| 267 | state state (R is running, S is sleeping, D is sleeping in an | |
| 268 | uninterruptible wait, Z is zombie, T is traced or stopped) | |
| 269 | ppid process id of the parent process | |
| 270 | pgrp pgrp of the process | |
| 271 | sid session id | |
| 272 | tty_nr tty the process uses | |
| 273 | tty_pgrp pgrp of the tty | |
| 274 | flags task flags | |
| 275 | min_flt number of minor faults | |
| 276 | cmin_flt number of minor faults with child's | |
| 277 | maj_flt number of major faults | |
| 278 | cmaj_flt number of major faults with child's | |
| 279 | utime user mode jiffies | |
| 280 | stime kernel mode jiffies | |
| 281 | cutime user mode jiffies with child's | |
| 282 | cstime kernel mode jiffies with child's | |
| 283 | priority priority level | |
| 284 | nice nice level | |
| 285 | num_threads number of threads | |
| 2e01e00e | 286 | it_real_value (obsolete, always 0) |
| 18d96779 KC |
287 | start_time time the process started after system boot |
| 288 | vsize virtual memory size | |
| 289 | rss resident set memory size | |
| 290 | rsslim current limit in bytes on the rss | |
| 291 | start_code address above which program text can run | |
| 292 | end_code address below which program text can run | |
| b7643757 | 293 | start_stack address of the start of the main process stack |
| 18d96779 KC |
294 | esp current value of ESP |
| 295 | eip current value of EIP | |
| 349888ee SS |
296 | pending bitmap of pending signals |
| 297 | blocked bitmap of blocked signals | |
| 298 | sigign bitmap of ignored signals | |
| 299 | sigcatch bitmap of catched signals | |
| 18d96779 KC |
300 | wchan address where process went to sleep |
| 301 | 0 (place holder) | |
| 302 | 0 (place holder) | |
| 303 | exit_signal signal to send to parent thread on exit | |
| 304 | task_cpu which CPU the task is scheduled on | |
| 305 | rt_priority realtime priority | |
| 306 | policy scheduling policy (man sched_setscheduler) | |
| 307 | blkio_ticks time spent waiting for block IO | |
| 349888ee SS |
308 | gtime guest time of the task in jiffies |
| 309 | cgtime guest time of the task children in jiffies | |
| b3f7f573 CG |
310 | start_data address above which program data+bss is placed |
| 311 | end_data address below which program data+bss is placed | |
| 312 | start_brk address above which program heap can be expanded with brk() | |
| 18d96779 KC |
313 | .............................................................................. |
| 314 | ||
| 32e688b8 | 315 | The /proc/PID/maps file containing the currently mapped memory regions and |
| 349888ee SS |
316 | their access permissions. |
| 317 | ||
| 318 | The format is: | |
| 319 | ||
| 320 | address perms offset dev inode pathname | |
| 321 | ||
| 322 | 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test | |
| 323 | 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test | |
| 324 | 0804a000-0806b000 rw-p 00000000 00:00 0 [heap] | |
| 325 | a7cb1000-a7cb2000 ---p 00000000 00:00 0 | |
| 34441427 | 326 | a7cb2000-a7eb2000 rw-p 00000000 00:00 0 |
| 349888ee | 327 | a7eb2000-a7eb3000 ---p 00000000 00:00 0 |
| b7643757 | 328 | a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack:1001] |
| 349888ee SS |
329 | a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6 |
| 330 | a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6 | |
| 331 | a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6 | |
| 332 | a800b000-a800e000 rw-p 00000000 00:00 0 | |
| 333 | a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0 | |
| 334 | a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0 | |
| 335 | a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0 | |
| 336 | a8024000-a8027000 rw-p 00000000 00:00 0 | |
| 337 | a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2 | |
| 338 | a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2 | |
| 339 | a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2 | |
| 340 | aff35000-aff4a000 rw-p 00000000 00:00 0 [stack] | |
| 341 | ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso] | |
| 342 | ||
| 343 | where "address" is the address space in the process that it occupies, "perms" | |
| 344 | is a set of permissions: | |
| 345 | ||
| 346 | r = read | |
| 347 | w = write | |
| 348 | x = execute | |
| 349 | s = shared | |
| 350 | p = private (copy on write) | |
| 351 | ||
| 352 | "offset" is the offset into the mapping, "dev" is the device (major:minor), and | |
| 353 | "inode" is the inode on that device. 0 indicates that no inode is associated | |
| 354 | with the memory region, as the case would be with BSS (uninitialized data). | |
| 355 | The "pathname" shows the name associated file for this mapping. If the mapping | |
| 356 | is not associated with a file: | |
| 357 | ||
| 358 | [heap] = the heap of the program | |
| 359 | [stack] = the stack of the main process | |
| b7643757 | 360 | [stack:1001] = the stack of the thread with tid 1001 |
| 349888ee SS |
361 | [vdso] = the "virtual dynamic shared object", |
| 362 | the kernel system call handler | |
| 363 | ||
| 364 | or if empty, the mapping is anonymous. | |
| 365 | ||
| b7643757 SP |
366 | The /proc/PID/task/TID/maps is a view of the virtual memory from the viewpoint |
| 367 | of the individual tasks of a process. In this file you will see a mapping marked | |
| 368 | as [stack] if that task sees it as a stack. This is a key difference from the | |
| 369 | content of /proc/PID/maps, where you will see all mappings that are being used | |
| 370 | as stack by all of those tasks. Hence, for the example above, the task-level | |
| 371 | map, i.e. /proc/PID/task/TID/maps for thread 1001 will look like this: | |
| 372 | ||
| 373 | 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test | |
| 374 | 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test | |
| 375 | 0804a000-0806b000 rw-p 00000000 00:00 0 [heap] | |
| 376 | a7cb1000-a7cb2000 ---p 00000000 00:00 0 | |
| 377 | a7cb2000-a7eb2000 rw-p 00000000 00:00 0 | |
| 378 | a7eb2000-a7eb3000 ---p 00000000 00:00 0 | |
| 379 | a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack] | |
| 380 | a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6 | |
| 381 | a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6 | |
| 382 | a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6 | |
| 383 | a800b000-a800e000 rw-p 00000000 00:00 0 | |
| 384 | a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0 | |
| 385 | a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0 | |
| 386 | a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0 | |
| 387 | a8024000-a8027000 rw-p 00000000 00:00 0 | |
| 388 | a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2 | |
| 389 | a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2 | |
| 390 | a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2 | |
| 391 | aff35000-aff4a000 rw-p 00000000 00:00 0 | |
| 392 | ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso] | |
| 349888ee SS |
393 | |
| 394 | The /proc/PID/smaps is an extension based on maps, showing the memory | |
| 395 | consumption for each of the process's mappings. For each of mappings there | |
| 396 | is a series of lines such as the following: | |
| 397 | ||
| 398 | 08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash | |
| 399 | Size: 1084 kB | |
| 400 | Rss: 892 kB | |
| 401 | Pss: 374 kB | |
| 402 | Shared_Clean: 892 kB | |
| 403 | Shared_Dirty: 0 kB | |
| 404 | Private_Clean: 0 kB | |
| 405 | Private_Dirty: 0 kB | |
| 406 | Referenced: 892 kB | |
| b40d4f84 | 407 | Anonymous: 0 kB |
| 349888ee SS |
408 | Swap: 0 kB |
| 409 | KernelPageSize: 4 kB | |
| 410 | MMUPageSize: 4 kB | |
| 2d90508f | 411 | Locked: 374 kB |
| 349888ee | 412 | |
| 0f4d208f MM |
413 | The first of these lines shows the same information as is displayed for the |
| 414 | mapping in /proc/PID/maps. The remaining lines show the size of the mapping | |
| 415 | (size), the amount of the mapping that is currently resident in RAM (RSS), the | |
| 416 | process' proportional share of this mapping (PSS), the number of clean and | |
| b40d4f84 NK |
417 | dirty private pages in the mapping. Note that even a page which is part of a |
| 418 | MAP_SHARED mapping, but has only a single pte mapped, i.e. is currently used | |
| 419 | by only one process, is accounted as private and not as shared. "Referenced" | |
| 420 | indicates the amount of memory currently marked as referenced or accessed. | |
| 421 | "Anonymous" shows the amount of memory that does not belong to any file. Even | |
| 422 | a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE | |
| 423 | and a page is modified, the file page is replaced by a private anonymous copy. | |
| 424 | "Swap" shows how much would-be-anonymous memory is also used, but out on | |
| 425 | swap. | |
| 349888ee SS |
426 | |
| 427 | This file is only present if the CONFIG_MMU kernel configuration option is | |
| 428 | enabled. | |
| 18d96779 | 429 | |
| 398499d5 MB |
430 | The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG |
| 431 | bits on both physical and virtual pages associated with a process. | |
| 432 | To clear the bits for all the pages associated with the process | |
| 433 | > echo 1 > /proc/PID/clear_refs | |
| 434 | ||
| 435 | To clear the bits for the anonymous pages associated with the process | |
| 436 | > echo 2 > /proc/PID/clear_refs | |
| 437 | ||
| 438 | To clear the bits for the file mapped pages associated with the process | |
| 439 | > echo 3 > /proc/PID/clear_refs | |
| 440 | Any other value written to /proc/PID/clear_refs will have no effect. | |
| 441 | ||
| 03f890f8 NK |
442 | The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags |
| 443 | using /proc/kpageflags and number of times a page is mapped using | |
| 444 | /proc/kpagecount. For detailed explanation, see Documentation/vm/pagemap.txt. | |
| 398499d5 | 445 | |
| 1da177e4 LT |
446 | 1.2 Kernel data |
| 447 | --------------- | |
| 448 | ||
| 449 | Similar to the process entries, the kernel data files give information about | |
| 450 | the running kernel. The files used to obtain this information are contained in | |
| 349888ee | 451 | /proc and are listed in Table 1-5. Not all of these will be present in your |
| 1da177e4 LT |
452 | system. It depends on the kernel configuration and the loaded modules, which |
| 453 | files are there, and which are missing. | |
| 454 | ||
| 349888ee | 455 | Table 1-5: Kernel info in /proc |
| 1da177e4 LT |
456 | .............................................................................. |
| 457 | File Content | |
| 458 | apm Advanced power management info | |
| 459 | buddyinfo Kernel memory allocator information (see text) (2.5) | |
| 460 | bus Directory containing bus specific information | |
| 461 | cmdline Kernel command line | |
| 462 | cpuinfo Info about the CPU | |
| 463 | devices Available devices (block and character) | |
| 464 | dma Used DMS channels | |
| 465 | filesystems Supported filesystems | |
| 466 | driver Various drivers grouped here, currently rtc (2.4) | |
| 467 | execdomains Execdomains, related to security (2.4) | |
| 468 | fb Frame Buffer devices (2.4) | |
| 469 | fs File system parameters, currently nfs/exports (2.4) | |
| 470 | ide Directory containing info about the IDE subsystem | |
| 471 | interrupts Interrupt usage | |
| 472 | iomem Memory map (2.4) | |
| 473 | ioports I/O port usage | |
| 474 | irq Masks for irq to cpu affinity (2.4)(smp?) | |
| 475 | isapnp ISA PnP (Plug&Play) Info (2.4) | |
| 476 | kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4)) | |
| 477 | kmsg Kernel messages | |
| 478 | ksyms Kernel symbol table | |
| 479 | loadavg Load average of last 1, 5 & 15 minutes | |
| 480 | locks Kernel locks | |
| 481 | meminfo Memory info | |
| 482 | misc Miscellaneous | |
| 483 | modules List of loaded modules | |
| 484 | mounts Mounted filesystems | |
| 485 | net Networking info (see text) | |
| a1b57ac0 | 486 | pagetypeinfo Additional page allocator information (see text) (2.5) |
| 1da177e4 | 487 | partitions Table of partitions known to the system |
| 8b60756a | 488 | pci Deprecated info of PCI bus (new way -> /proc/bus/pci/, |
| 1da177e4 LT |
489 | decoupled by lspci (2.4) |
| 490 | rtc Real time clock | |
| 491 | scsi SCSI info (see text) | |
| 492 | slabinfo Slab pool info | |
| d3d64df2 | 493 | softirqs softirq usage |
| 1da177e4 LT |
494 | stat Overall statistics |
| 495 | swaps Swap space utilization | |
| 496 | sys See chapter 2 | |
| 497 | sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4) | |
| 498 | tty Info of tty drivers | |
| 499 | uptime System uptime | |
| 500 | version Kernel version | |
| 501 | video bttv info of video resources (2.4) | |
| a47a126a | 502 | vmallocinfo Show vmalloced areas |
| 1da177e4 LT |
503 | .............................................................................. |
| 504 | ||
| 505 | You can, for example, check which interrupts are currently in use and what | |
| 506 | they are used for by looking in the file /proc/interrupts: | |
| 507 | ||
| 508 | > cat /proc/interrupts | |
| 509 | CPU0 | |
| 510 | 0: 8728810 XT-PIC timer | |
| 511 | 1: 895 XT-PIC keyboard | |
| 512 | 2: 0 XT-PIC cascade | |
| 513 | 3: 531695 XT-PIC aha152x | |
| 514 | 4: 2014133 XT-PIC serial | |
| 515 | 5: 44401 XT-PIC pcnet_cs | |
| 516 | 8: 2 XT-PIC rtc | |
| 517 | 11: 8 XT-PIC i82365 | |
| 518 | 12: 182918 XT-PIC PS/2 Mouse | |
| 519 | 13: 1 XT-PIC fpu | |
| 520 | 14: 1232265 XT-PIC ide0 | |
| 521 | 15: 7 XT-PIC ide1 | |
| 522 | NMI: 0 | |
| 523 | ||
| 524 | In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the | |
| 525 | output of a SMP machine): | |
| 526 | ||
| 527 | > cat /proc/interrupts | |
| 528 | ||
| 529 | CPU0 CPU1 | |
| 530 | 0: 1243498 1214548 IO-APIC-edge timer | |
| 531 | 1: 8949 8958 IO-APIC-edge keyboard | |
| 532 | 2: 0 0 XT-PIC cascade | |
| 533 | 5: 11286 10161 IO-APIC-edge soundblaster | |
| 534 | 8: 1 0 IO-APIC-edge rtc | |
| 535 | 9: 27422 27407 IO-APIC-edge 3c503 | |
| 536 | 12: 113645 113873 IO-APIC-edge PS/2 Mouse | |
| 537 | 13: 0 0 XT-PIC fpu | |
| 538 | 14: 22491 24012 IO-APIC-edge ide0 | |
| 539 | 15: 2183 2415 IO-APIC-edge ide1 | |
| 540 | 17: 30564 30414 IO-APIC-level eth0 | |
| 541 | 18: 177 164 IO-APIC-level bttv | |
| 542 | NMI: 2457961 2457959 | |
| 543 | LOC: 2457882 2457881 | |
| 544 | ERR: 2155 | |
| 545 | ||
| 546 | NMI is incremented in this case because every timer interrupt generates a NMI | |
| 547 | (Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups. | |
| 548 | ||
| 549 | LOC is the local interrupt counter of the internal APIC of every CPU. | |
| 550 | ||
| 551 | ERR is incremented in the case of errors in the IO-APIC bus (the bus that | |
| 552 | connects the CPUs in a SMP system. This means that an error has been detected, | |
| 553 | the IO-APIC automatically retry the transmission, so it should not be a big | |
| 554 | problem, but you should read the SMP-FAQ. | |
| 555 | ||
| 38e760a1 JK |
556 | In 2.6.2* /proc/interrupts was expanded again. This time the goal was for |
| 557 | /proc/interrupts to display every IRQ vector in use by the system, not | |
| 558 | just those considered 'most important'. The new vectors are: | |
| 559 | ||
| 560 | THR -- interrupt raised when a machine check threshold counter | |
| 561 | (typically counting ECC corrected errors of memory or cache) exceeds | |
| 562 | a configurable threshold. Only available on some systems. | |
| 563 | ||
| 564 | TRM -- a thermal event interrupt occurs when a temperature threshold | |
| 565 | has been exceeded for the CPU. This interrupt may also be generated | |
| 566 | when the temperature drops back to normal. | |
| 567 | ||
| 568 | SPU -- a spurious interrupt is some interrupt that was raised then lowered | |
| 569 | by some IO device before it could be fully processed by the APIC. Hence | |
| 570 | the APIC sees the interrupt but does not know what device it came from. | |
| 571 | For this case the APIC will generate the interrupt with a IRQ vector | |
| 572 | of 0xff. This might also be generated by chipset bugs. | |
| 573 | ||
| 574 | RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are | |
| 575 | sent from one CPU to another per the needs of the OS. Typically, | |
| 576 | their statistics are used by kernel developers and interested users to | |
| 19f59460 | 577 | determine the occurrence of interrupts of the given type. |
| 38e760a1 | 578 | |
| 25985edc | 579 | The above IRQ vectors are displayed only when relevant. For example, |
| 38e760a1 JK |
580 | the threshold vector does not exist on x86_64 platforms. Others are |
| 581 | suppressed when the system is a uniprocessor. As of this writing, only | |
| 582 | i386 and x86_64 platforms support the new IRQ vector displays. | |
| 583 | ||
| 584 | Of some interest is the introduction of the /proc/irq directory to 2.4. | |
| 1da177e4 LT |
585 | It could be used to set IRQ to CPU affinity, this means that you can "hook" an |
| 586 | IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the | |
| 18404756 MK |
587 | irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and |
| 588 | prof_cpu_mask. | |
| 1da177e4 LT |
589 | |
| 590 | For example | |
| 591 | > ls /proc/irq/ | |
| 592 | 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask | |
| 18404756 | 593 | 1 11 13 15 17 19 3 5 7 9 default_smp_affinity |
| 1da177e4 LT |
594 | > ls /proc/irq/0/ |
| 595 | smp_affinity | |
| 596 | ||
| 18404756 MK |
597 | smp_affinity is a bitmask, in which you can specify which CPUs can handle the |
| 598 | IRQ, you can set it by doing: | |
| 1da177e4 | 599 | |
| 18404756 MK |
600 | > echo 1 > /proc/irq/10/smp_affinity |
| 601 | ||
| 602 | This means that only the first CPU will handle the IRQ, but you can also echo | |
| 603 | 5 which means that only the first and fourth CPU can handle the IRQ. | |
| 1da177e4 | 604 | |
| 18404756 MK |
605 | The contents of each smp_affinity file is the same by default: |
| 606 | ||
| 607 | > cat /proc/irq/0/smp_affinity | |
| 608 | ffffffff | |
| 1da177e4 | 609 | |
| 4b060420 MT |
610 | There is an alternate interface, smp_affinity_list which allows specifying |
| 611 | a cpu range instead of a bitmask: | |
| 612 | ||
| 613 | > cat /proc/irq/0/smp_affinity_list | |
| 614 | 1024-1031 | |
| 615 | ||
| 18404756 MK |
616 | The default_smp_affinity mask applies to all non-active IRQs, which are the |
| 617 | IRQs which have not yet been allocated/activated, and hence which lack a | |
| 618 | /proc/irq/[0-9]* directory. | |
| 1da177e4 | 619 | |
| 92d6b71a DS |
620 | The node file on an SMP system shows the node to which the device using the IRQ |
| 621 | reports itself as being attached. This hardware locality information does not | |
| 622 | include information about any possible driver locality preference. | |
| 623 | ||
| 18404756 | 624 | prof_cpu_mask specifies which CPUs are to be profiled by the system wide |
| 4b060420 | 625 | profiler. Default value is ffffffff (all cpus if there are only 32 of them). |
| 1da177e4 LT |
626 | |
| 627 | The way IRQs are routed is handled by the IO-APIC, and it's Round Robin | |
| 628 | between all the CPUs which are allowed to handle it. As usual the kernel has | |
| 629 | more info than you and does a better job than you, so the defaults are the | |
| 4b060420 MT |
630 | best choice for almost everyone. [Note this applies only to those IO-APIC's |
| 631 | that support "Round Robin" interrupt distribution.] | |
| 1da177e4 LT |
632 | |
| 633 | There are three more important subdirectories in /proc: net, scsi, and sys. | |
| 634 | The general rule is that the contents, or even the existence of these | |
| 635 | directories, depend on your kernel configuration. If SCSI is not enabled, the | |
| 636 | directory scsi may not exist. The same is true with the net, which is there | |
| 637 | only when networking support is present in the running kernel. | |
| 638 | ||
| 639 | The slabinfo file gives information about memory usage at the slab level. | |
| 640 | Linux uses slab pools for memory management above page level in version 2.2. | |
| 641 | Commonly used objects have their own slab pool (such as network buffers, | |
| 642 | directory cache, and so on). | |
| 643 | ||
| 644 | .............................................................................. | |
| 645 | ||
| 646 | > cat /proc/buddyinfo | |
| 647 | ||
| 648 | Node 0, zone DMA 0 4 5 4 4 3 ... | |
| 649 | Node 0, zone Normal 1 0 0 1 101 8 ... | |
| 650 | Node 0, zone HighMem 2 0 0 1 1 0 ... | |
| 651 | ||
| a1b57ac0 | 652 | External fragmentation is a problem under some workloads, and buddyinfo is a |
| 1da177e4 LT |
653 | useful tool for helping diagnose these problems. Buddyinfo will give you a |
| 654 | clue as to how big an area you can safely allocate, or why a previous | |
| 655 | allocation failed. | |
| 656 | ||
| 657 | Each column represents the number of pages of a certain order which are | |
| 658 | available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in | |
| 659 | ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE | |
| 660 | available in ZONE_NORMAL, etc... | |
| 661 | ||
| a1b57ac0 MG |
662 | More information relevant to external fragmentation can be found in |
| 663 | pagetypeinfo. | |
| 664 | ||
| 665 | > cat /proc/pagetypeinfo | |
| 666 | Page block order: 9 | |
| 667 | Pages per block: 512 | |
| 668 | ||
| 669 | Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10 | |
| 670 | Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0 | |
| 671 | Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0 | |
| 672 | Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2 | |
| 673 | Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0 | |
| 674 | Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0 | |
| 675 | Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9 | |
| 676 | Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0 | |
| 677 | Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452 | |
| 678 | Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0 | |
| 679 | Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0 | |
| 680 | ||
| 681 | Number of blocks type Unmovable Reclaimable Movable Reserve Isolate | |
| 682 | Node 0, zone DMA 2 0 5 1 0 | |
| 683 | Node 0, zone DMA32 41 6 967 2 0 | |
| 684 | ||
| 685 | Fragmentation avoidance in the kernel works by grouping pages of different | |
| 686 | migrate types into the same contiguous regions of memory called page blocks. | |
| 687 | A page block is typically the size of the default hugepage size e.g. 2MB on | |
| 688 | X86-64. By keeping pages grouped based on their ability to move, the kernel | |
| 689 | can reclaim pages within a page block to satisfy a high-order allocation. | |
| 690 | ||
| 691 | The pagetypinfo begins with information on the size of a page block. It | |
| 692 | then gives the same type of information as buddyinfo except broken down | |
| 693 | by migrate-type and finishes with details on how many page blocks of each | |
| 694 | type exist. | |
| 695 | ||
| 696 | If min_free_kbytes has been tuned correctly (recommendations made by hugeadm | |
| 697 | from libhugetlbfs http://sourceforge.net/projects/libhugetlbfs/), one can | |
| 698 | make an estimate of the likely number of huge pages that can be allocated | |
| 699 | at a given point in time. All the "Movable" blocks should be allocatable | |
| 700 | unless memory has been mlock()'d. Some of the Reclaimable blocks should | |
| 701 | also be allocatable although a lot of filesystem metadata may have to be | |
| 702 | reclaimed to achieve this. | |
| 703 | ||
| 1da177e4 LT |
704 | .............................................................................. |
| 705 | ||
| 706 | meminfo: | |
| 707 | ||
| 708 | Provides information about distribution and utilization of memory. This | |
| 709 | varies by architecture and compile options. The following is from a | |
| 710 | 16GB PIII, which has highmem enabled. You may not have all of these fields. | |
| 711 | ||
| 712 | > cat /proc/meminfo | |
| 713 | ||
| 2d90508f NK |
714 | The "Locked" indicates whether the mapping is locked in memory or not. |
| 715 | ||
| 1da177e4 LT |
716 | |
| 717 | MemTotal: 16344972 kB | |
| 718 | MemFree: 13634064 kB | |
| 719 | Buffers: 3656 kB | |
| 720 | Cached: 1195708 kB | |
| 721 | SwapCached: 0 kB | |
| 722 | Active: 891636 kB | |
| 723 | Inactive: 1077224 kB | |
| 724 | HighTotal: 15597528 kB | |
| 725 | HighFree: 13629632 kB | |
| 726 | LowTotal: 747444 kB | |
| 727 | LowFree: 4432 kB | |
| 728 | SwapTotal: 0 kB | |
| 729 | SwapFree: 0 kB | |
| 730 | Dirty: 968 kB | |
| 731 | Writeback: 0 kB | |
| b88473f7 | 732 | AnonPages: 861800 kB |
| 1da177e4 | 733 | Mapped: 280372 kB |
| b88473f7 MS |
734 | Slab: 284364 kB |
| 735 | SReclaimable: 159856 kB | |
| 736 | SUnreclaim: 124508 kB | |
| 737 | PageTables: 24448 kB | |
| 738 | NFS_Unstable: 0 kB | |
| 739 | Bounce: 0 kB | |
| 740 | WritebackTmp: 0 kB | |
| 1da177e4 LT |
741 | CommitLimit: 7669796 kB |
| 742 | Committed_AS: 100056 kB | |
| 1da177e4 LT |
743 | VmallocTotal: 112216 kB |
| 744 | VmallocUsed: 428 kB | |
| 745 | VmallocChunk: 111088 kB | |
| 746 | ||
| 747 | MemTotal: Total usable ram (i.e. physical ram minus a few reserved | |
| 748 | bits and the kernel binary code) | |
| 749 | MemFree: The sum of LowFree+HighFree | |
| 750 | Buffers: Relatively temporary storage for raw disk blocks | |
| 751 | shouldn't get tremendously large (20MB or so) | |
| 752 | Cached: in-memory cache for files read from the disk (the | |
| 753 | pagecache). Doesn't include SwapCached | |
| 754 | SwapCached: Memory that once was swapped out, is swapped back in but | |
| 755 | still also is in the swapfile (if memory is needed it | |
| 756 | doesn't need to be swapped out AGAIN because it is already | |
| 757 | in the swapfile. This saves I/O) | |
| 758 | Active: Memory that has been used more recently and usually not | |
| 759 | reclaimed unless absolutely necessary. | |
| 760 | Inactive: Memory which has been less recently used. It is more | |
| 761 | eligible to be reclaimed for other purposes | |
| 762 | HighTotal: | |
| 763 | HighFree: Highmem is all memory above ~860MB of physical memory | |
| 764 | Highmem areas are for use by userspace programs, or | |
| 765 | for the pagecache. The kernel must use tricks to access | |
| 766 | this memory, making it slower to access than lowmem. | |
| 767 | LowTotal: | |
| 768 | LowFree: Lowmem is memory which can be used for everything that | |
| 3f6dee9b | 769 | highmem can be used for, but it is also available for the |
| 1da177e4 LT |
770 | kernel's use for its own data structures. Among many |
| 771 | other things, it is where everything from the Slab is | |
| 772 | allocated. Bad things happen when you're out of lowmem. | |
| 773 | SwapTotal: total amount of swap space available | |
| 774 | SwapFree: Memory which has been evicted from RAM, and is temporarily | |
| 775 | on the disk | |
| 776 | Dirty: Memory which is waiting to get written back to the disk | |
| 777 | Writeback: Memory which is actively being written back to the disk | |
| b88473f7 | 778 | AnonPages: Non-file backed pages mapped into userspace page tables |
| 1da177e4 | 779 | Mapped: files which have been mmaped, such as libraries |
| e82443c0 | 780 | Slab: in-kernel data structures cache |
| b88473f7 MS |
781 | SReclaimable: Part of Slab, that might be reclaimed, such as caches |
| 782 | SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure | |
| 783 | PageTables: amount of memory dedicated to the lowest level of page | |
| 784 | tables. | |
| 785 | NFS_Unstable: NFS pages sent to the server, but not yet committed to stable | |
| 786 | storage | |
| 787 | Bounce: Memory used for block device "bounce buffers" | |
| 788 | WritebackTmp: Memory used by FUSE for temporary writeback buffers | |
| 1da177e4 LT |
789 | CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'), |
| 790 | this is the total amount of memory currently available to | |
| 791 | be allocated on the system. This limit is only adhered to | |
| 792 | if strict overcommit accounting is enabled (mode 2 in | |
| 793 | 'vm.overcommit_memory'). | |
| 794 | The CommitLimit is calculated with the following formula: | |
| 795 | CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap | |
| 796 | For example, on a system with 1G of physical RAM and 7G | |
| 797 | of swap with a `vm.overcommit_ratio` of 30 it would | |
| 798 | yield a CommitLimit of 7.3G. | |
| 799 | For more details, see the memory overcommit documentation | |
| 800 | in vm/overcommit-accounting. | |
| 801 | Committed_AS: The amount of memory presently allocated on the system. | |
| 802 | The committed memory is a sum of all of the memory which | |
| 803 | has been allocated by processes, even if it has not been | |
| 804 | "used" by them as of yet. A process which malloc()'s 1G | |
| 805 | of memory, but only touches 300M of it will only show up | |
| 806 | as using 300M of memory even if it has the address space | |
| 807 | allocated for the entire 1G. This 1G is memory which has | |
| 808 | been "committed" to by the VM and can be used at any time | |
| 809 | by the allocating application. With strict overcommit | |
| 810 | enabled on the system (mode 2 in 'vm.overcommit_memory'), | |
| 811 | allocations which would exceed the CommitLimit (detailed | |
| 812 | above) will not be permitted. This is useful if one needs | |
| 813 | to guarantee that processes will not fail due to lack of | |
| 814 | memory once that memory has been successfully allocated. | |
| 1da177e4 LT |
815 | VmallocTotal: total size of vmalloc memory area |
| 816 | VmallocUsed: amount of vmalloc area which is used | |
| 19f59460 | 817 | VmallocChunk: largest contiguous block of vmalloc area which is free |
| 1da177e4 | 818 | |
| a47a126a ED |
819 | .............................................................................. |
| 820 | ||
| 821 | vmallocinfo: | |
| 822 | ||
| 823 | Provides information about vmalloced/vmaped areas. One line per area, | |
| 824 | containing the virtual address range of the area, size in bytes, | |
| 825 | caller information of the creator, and optional information depending | |
| 826 | on the kind of area : | |
| 827 | ||
| 828 | pages=nr number of pages | |
| 829 | phys=addr if a physical address was specified | |
| 830 | ioremap I/O mapping (ioremap() and friends) | |
| 831 | vmalloc vmalloc() area | |
| 832 | vmap vmap()ed pages | |
| 833 | user VM_USERMAP area | |
| 834 | vpages buffer for pages pointers was vmalloced (huge area) | |
| 835 | N<node>=nr (Only on NUMA kernels) | |
| 836 | Number of pages allocated on memory node <node> | |
| 837 | ||
| 838 | > cat /proc/vmallocinfo | |
| 839 | 0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ... | |
| 840 | /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128 | |
| 841 | 0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ... | |
| 842 | /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64 | |
| 843 | 0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f... | |
| 844 | phys=7fee8000 ioremap | |
| 845 | 0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f... | |
| 846 | phys=7fee7000 ioremap | |
| 847 | 0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210 | |
| 848 | 0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ... | |
| 849 | /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3 | |
| 850 | 0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ... | |
| 851 | pages=2 vmalloc N1=2 | |
| 852 | 0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ... | |
| 853 | /0x130 [x_tables] pages=4 vmalloc N0=4 | |
| 854 | 0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ... | |
| 855 | pages=14 vmalloc N2=14 | |
| 856 | 0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ... | |
| 857 | pages=4 vmalloc N1=4 | |
| 858 | 0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ... | |
| 859 | pages=2 vmalloc N1=2 | |
| 860 | 0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ... | |
| 861 | pages=10 vmalloc N0=10 | |
| 1da177e4 | 862 | |
| d3d64df2 KK |
863 | .............................................................................. |
| 864 | ||
| 865 | softirqs: | |
| 866 | ||
| 867 | Provides counts of softirq handlers serviced since boot time, for each cpu. | |
| 868 | ||
| 869 | > cat /proc/softirqs | |
| 870 | CPU0 CPU1 CPU2 CPU3 | |
| 871 | HI: 0 0 0 0 | |
| 872 | TIMER: 27166 27120 27097 27034 | |
| 873 | NET_TX: 0 0 0 17 | |
| 874 | NET_RX: 42 0 0 39 | |
| 875 | BLOCK: 0 0 107 1121 | |
| 876 | TASKLET: 0 0 0 290 | |
| 877 | SCHED: 27035 26983 26971 26746 | |
| 878 | HRTIMER: 0 0 0 0 | |
| 09223371 | 879 | RCU: 1678 1769 2178 2250 |
| d3d64df2 KK |
880 | |
| 881 | ||
| 1da177e4 LT |
882 | 1.3 IDE devices in /proc/ide |
| 883 | ---------------------------- | |
| 884 | ||
| 885 | The subdirectory /proc/ide contains information about all IDE devices of which | |
| 886 | the kernel is aware. There is one subdirectory for each IDE controller, the | |
| 887 | file drivers and a link for each IDE device, pointing to the device directory | |
| 888 | in the controller specific subtree. | |
| 889 | ||
| 890 | The file drivers contains general information about the drivers used for the | |
| 891 | IDE devices: | |
| 892 | ||
| 893 | > cat /proc/ide/drivers | |
| 894 | ide-cdrom version 4.53 | |
| 895 | ide-disk version 1.08 | |
| 896 | ||
| 897 | More detailed information can be found in the controller specific | |
| 898 | subdirectories. These are named ide0, ide1 and so on. Each of these | |
| 349888ee | 899 | directories contains the files shown in table 1-6. |
| 1da177e4 LT |
900 | |
| 901 | ||
| 349888ee | 902 | Table 1-6: IDE controller info in /proc/ide/ide? |
| 1da177e4 LT |
903 | .............................................................................. |
| 904 | File Content | |
| 905 | channel IDE channel (0 or 1) | |
| 906 | config Configuration (only for PCI/IDE bridge) | |
| 907 | mate Mate name | |
| 908 | model Type/Chipset of IDE controller | |
| 909 | .............................................................................. | |
| 910 | ||
| 911 | Each device connected to a controller has a separate subdirectory in the | |
| 349888ee | 912 | controllers directory. The files listed in table 1-7 are contained in these |
| 1da177e4 LT |
913 | directories. |
| 914 | ||
| 915 | ||
| 349888ee | 916 | Table 1-7: IDE device information |
| 1da177e4 LT |
917 | .............................................................................. |
| 918 | File Content | |
| 919 | cache The cache | |
| 920 | capacity Capacity of the medium (in 512Byte blocks) | |
| 921 | driver driver and version | |
| 922 | geometry physical and logical geometry | |
| 923 | identify device identify block | |
| 924 | media media type | |
| 925 | model device identifier | |
| 926 | settings device setup | |
| 927 | smart_thresholds IDE disk management thresholds | |
| 928 | smart_values IDE disk management values | |
| 929 | .............................................................................. | |
| 930 | ||
| 931 | The most interesting file is settings. This file contains a nice overview of | |
| 932 | the drive parameters: | |
| 933 | ||
| 934 | # cat /proc/ide/ide0/hda/settings | |
| 935 | name value min max mode | |
| 936 | ---- ----- --- --- ---- | |
| 937 | bios_cyl 526 0 65535 rw | |
| 938 | bios_head 255 0 255 rw | |
| 939 | bios_sect 63 0 63 rw | |
| 940 | breada_readahead 4 0 127 rw | |
| 941 | bswap 0 0 1 r | |
| 942 | file_readahead 72 0 2097151 rw | |
| 943 | io_32bit 0 0 3 rw | |
| 944 | keepsettings 0 0 1 rw | |
| 945 | max_kb_per_request 122 1 127 rw | |
| 946 | multcount 0 0 8 rw | |
| 947 | nice1 1 0 1 rw | |
| 948 | nowerr 0 0 1 rw | |
| 949 | pio_mode write-only 0 255 w | |
| 950 | slow 0 0 1 rw | |
| 951 | unmaskirq 0 0 1 rw | |
| 952 | using_dma 0 0 1 rw | |
| 953 | ||
| 954 | ||
| 955 | 1.4 Networking info in /proc/net | |
| 956 | -------------------------------- | |
| 957 | ||
| 349888ee | 958 | The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the |
| 1da177e4 | 959 | additional values you get for IP version 6 if you configure the kernel to |
| 349888ee | 960 | support this. Table 1-9 lists the files and their meaning. |
| 1da177e4 LT |
961 | |
| 962 | ||
| 349888ee | 963 | Table 1-8: IPv6 info in /proc/net |
| 1da177e4 LT |
964 | .............................................................................. |
| 965 | File Content | |
| 966 | udp6 UDP sockets (IPv6) | |
| 967 | tcp6 TCP sockets (IPv6) | |
| 968 | raw6 Raw device statistics (IPv6) | |
| 969 | igmp6 IP multicast addresses, which this host joined (IPv6) | |
| 970 | if_inet6 List of IPv6 interface addresses | |
| 971 | ipv6_route Kernel routing table for IPv6 | |
| 972 | rt6_stats Global IPv6 routing tables statistics | |
| 973 | sockstat6 Socket statistics (IPv6) | |
| 974 | snmp6 Snmp data (IPv6) | |
| 975 | .............................................................................. | |
| 976 | ||
| 977 | ||
| 349888ee | 978 | Table 1-9: Network info in /proc/net |
| 1da177e4 LT |
979 | .............................................................................. |
| 980 | File Content | |
| 981 | arp Kernel ARP table | |
| 982 | dev network devices with statistics | |
| 983 | dev_mcast the Layer2 multicast groups a device is listening too | |
| 984 | (interface index, label, number of references, number of bound | |
| 985 | addresses). | |
| 986 | dev_stat network device status | |
| 987 | ip_fwchains Firewall chain linkage | |
| 988 | ip_fwnames Firewall chain names | |
| 989 | ip_masq Directory containing the masquerading tables | |
| 990 | ip_masquerade Major masquerading table | |
| 991 | netstat Network statistics | |
| 992 | raw raw device statistics | |
| 993 | route Kernel routing table | |
| 994 | rpc Directory containing rpc info | |
| 995 | rt_cache Routing cache | |
| 996 | snmp SNMP data | |
| 997 | sockstat Socket statistics | |
| 998 | tcp TCP sockets | |
| 1da177e4 LT |
999 | udp UDP sockets |
| 1000 | unix UNIX domain sockets | |
| 1001 | wireless Wireless interface data (Wavelan etc) | |
| 1002 | igmp IP multicast addresses, which this host joined | |
| 1003 | psched Global packet scheduler parameters. | |
| 1004 | netlink List of PF_NETLINK sockets | |
| 1005 | ip_mr_vifs List of multicast virtual interfaces | |
| 1006 | ip_mr_cache List of multicast routing cache | |
| 1007 | .............................................................................. | |
| 1008 | ||
| 1009 | You can use this information to see which network devices are available in | |
| 1010 | your system and how much traffic was routed over those devices: | |
| 1011 | ||
| 1012 | > cat /proc/net/dev | |
| 1013 | Inter-|Receive |[... | |
| 1014 | face |bytes packets errs drop fifo frame compressed multicast|[... | |
| 1015 | lo: 908188 5596 0 0 0 0 0 0 [... | |
| 1016 | ppp0:15475140 20721 410 0 0 410 0 0 [... | |
| 1017 | eth0: 614530 7085 0 0 0 0 0 1 [... | |
| 1018 | ||
| 1019 | ...] Transmit | |
| 1020 | ...] bytes packets errs drop fifo colls carrier compressed | |
| 1021 | ...] 908188 5596 0 0 0 0 0 0 | |
| 1022 | ...] 1375103 17405 0 0 0 0 0 0 | |
| 1023 | ...] 1703981 5535 0 0 0 3 0 0 | |
| 1024 | ||
| a33f3224 | 1025 | In addition, each Channel Bond interface has its own directory. For |
| 1da177e4 LT |
1026 | example, the bond0 device will have a directory called /proc/net/bond0/. |
| 1027 | It will contain information that is specific to that bond, such as the | |
| 1028 | current slaves of the bond, the link status of the slaves, and how | |
| 1029 | many times the slaves link has failed. | |
| 1030 | ||
| 1031 | 1.5 SCSI info | |
| 1032 | ------------- | |
| 1033 | ||
| 1034 | If you have a SCSI host adapter in your system, you'll find a subdirectory | |
| 1035 | named after the driver for this adapter in /proc/scsi. You'll also see a list | |
| 1036 | of all recognized SCSI devices in /proc/scsi: | |
| 1037 | ||
| 1038 | >cat /proc/scsi/scsi | |
| 1039 | Attached devices: | |
| 1040 | Host: scsi0 Channel: 00 Id: 00 Lun: 00 | |
| 1041 | Vendor: IBM Model: DGHS09U Rev: 03E0 | |
| 1042 | Type: Direct-Access ANSI SCSI revision: 03 | |
| 1043 | Host: scsi0 Channel: 00 Id: 06 Lun: 00 | |
| 1044 | Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04 | |
| 1045 | Type: CD-ROM ANSI SCSI revision: 02 | |
| 1046 | ||
| 1047 | ||
| 1048 | The directory named after the driver has one file for each adapter found in | |
| 1049 | the system. These files contain information about the controller, including | |
| 1050 | the used IRQ and the IO address range. The amount of information shown is | |
| 1051 | dependent on the adapter you use. The example shows the output for an Adaptec | |
| 1052 | AHA-2940 SCSI adapter: | |
| 1053 | ||
| 1054 | > cat /proc/scsi/aic7xxx/0 | |
| 1055 | ||
| 1056 | Adaptec AIC7xxx driver version: 5.1.19/3.2.4 | |
| 1057 | Compile Options: | |
| 1058 | TCQ Enabled By Default : Disabled | |
| 1059 | AIC7XXX_PROC_STATS : Disabled | |
| 1060 | AIC7XXX_RESET_DELAY : 5 | |
| 1061 | Adapter Configuration: | |
| 1062 | SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter | |
| 1063 | Ultra Wide Controller | |
| 1064 | PCI MMAPed I/O Base: 0xeb001000 | |
| 1065 | Adapter SEEPROM Config: SEEPROM found and used. | |
| 1066 | Adaptec SCSI BIOS: Enabled | |
| 1067 | IRQ: 10 | |
| 1068 | SCBs: Active 0, Max Active 2, | |
| 1069 | Allocated 15, HW 16, Page 255 | |
| 1070 | Interrupts: 160328 | |
| 1071 | BIOS Control Word: 0x18b6 | |
| 1072 | Adapter Control Word: 0x005b | |
| 1073 | Extended Translation: Enabled | |
| 1074 | Disconnect Enable Flags: 0xffff | |
| 1075 | Ultra Enable Flags: 0x0001 | |
| 1076 | Tag Queue Enable Flags: 0x0000 | |
| 1077 | Ordered Queue Tag Flags: 0x0000 | |
| 1078 | Default Tag Queue Depth: 8 | |
| 1079 | Tagged Queue By Device array for aic7xxx host instance 0: | |
| 1080 | {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255} | |
| 1081 | Actual queue depth per device for aic7xxx host instance 0: | |
| 1082 | {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1} | |
| 1083 | Statistics: | |
| 1084 | (scsi0:0:0:0) | |
| 1085 | Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8 | |
| 1086 | Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0) | |
| 1087 | Total transfers 160151 (74577 reads and 85574 writes) | |
| 1088 | (scsi0:0:6:0) | |
| 1089 | Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15 | |
| 1090 | Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0) | |
| 1091 | Total transfers 0 (0 reads and 0 writes) | |
| 1092 | ||
| 1093 | ||
| 1094 | 1.6 Parallel port info in /proc/parport | |
| 1095 | --------------------------------------- | |
| 1096 | ||
| 1097 | The directory /proc/parport contains information about the parallel ports of | |
| 1098 | your system. It has one subdirectory for each port, named after the port | |
| 1099 | number (0,1,2,...). | |
| 1100 | ||
| 349888ee | 1101 | These directories contain the four files shown in Table 1-10. |
| 1da177e4 LT |
1102 | |
| 1103 | ||
| 349888ee | 1104 | Table 1-10: Files in /proc/parport |
| 1da177e4 LT |
1105 | .............................................................................. |
| 1106 | File Content | |
| 1107 | autoprobe Any IEEE-1284 device ID information that has been acquired. | |
| 1108 | devices list of the device drivers using that port. A + will appear by the | |
| 1109 | name of the device currently using the port (it might not appear | |
| 1110 | against any). | |
| 1111 | hardware Parallel port's base address, IRQ line and DMA channel. | |
| 1112 | irq IRQ that parport is using for that port. This is in a separate | |
| 1113 | file to allow you to alter it by writing a new value in (IRQ | |
| 1114 | number or none). | |
| 1115 | .............................................................................. | |
| 1116 | ||
| 1117 | 1.7 TTY info in /proc/tty | |
| 1118 | ------------------------- | |
| 1119 | ||
| 1120 | Information about the available and actually used tty's can be found in the | |
| 1121 | directory /proc/tty.You'll find entries for drivers and line disciplines in | |
| 349888ee | 1122 | this directory, as shown in Table 1-11. |
| 1da177e4 LT |
1123 | |
| 1124 | ||
| 349888ee | 1125 | Table 1-11: Files in /proc/tty |
| 1da177e4 LT |
1126 | .............................................................................. |
| 1127 | File Content | |
| 1128 | drivers list of drivers and their usage | |
| 1129 | ldiscs registered line disciplines | |
| 1130 | driver/serial usage statistic and status of single tty lines | |
| 1131 | .............................................................................. | |
| 1132 | ||
| 1133 | To see which tty's are currently in use, you can simply look into the file | |
| 1134 | /proc/tty/drivers: | |
| 1135 | ||
| 1136 | > cat /proc/tty/drivers | |
| 1137 | pty_slave /dev/pts 136 0-255 pty:slave | |
| 1138 | pty_master /dev/ptm 128 0-255 pty:master | |
| 1139 | pty_slave /dev/ttyp 3 0-255 pty:slave | |
| 1140 | pty_master /dev/pty 2 0-255 pty:master | |
| 1141 | serial /dev/cua 5 64-67 serial:callout | |
| 1142 | serial /dev/ttyS 4 64-67 serial | |
| 1143 | /dev/tty0 /dev/tty0 4 0 system:vtmaster | |
| 1144 | /dev/ptmx /dev/ptmx 5 2 system | |
| 1145 | /dev/console /dev/console 5 1 system:console | |
| 1146 | /dev/tty /dev/tty 5 0 system:/dev/tty | |
| 1147 | unknown /dev/tty 4 1-63 console | |
| 1148 | ||
| 1149 | ||
| 1150 | 1.8 Miscellaneous kernel statistics in /proc/stat | |
| 1151 | ------------------------------------------------- | |
| 1152 | ||
| 1153 | Various pieces of information about kernel activity are available in the | |
| 1154 | /proc/stat file. All of the numbers reported in this file are aggregates | |
| 1155 | since the system first booted. For a quick look, simply cat the file: | |
| 1156 | ||
| 1157 | > cat /proc/stat | |
| c574358e ED |
1158 | cpu 2255 34 2290 22625563 6290 127 456 0 0 |
| 1159 | cpu0 1132 34 1441 11311718 3675 127 438 0 0 | |
| 1160 | cpu1 1123 0 849 11313845 2614 0 18 0 0 | |
| 1da177e4 LT |
1161 | intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...] |
| 1162 | ctxt 1990473 | |
| 1163 | btime 1062191376 | |
| 1164 | processes 2915 | |
| 1165 | procs_running 1 | |
| 1166 | procs_blocked 0 | |
| d3d64df2 | 1167 | softirq 183433 0 21755 12 39 1137 231 21459 2263 |
| 1da177e4 LT |
1168 | |
| 1169 | The very first "cpu" line aggregates the numbers in all of the other "cpuN" | |
| 1170 | lines. These numbers identify the amount of time the CPU has spent performing | |
| 1171 | different kinds of work. Time units are in USER_HZ (typically hundredths of a | |
| 1172 | second). The meanings of the columns are as follows, from left to right: | |
| 1173 | ||
| 1174 | - user: normal processes executing in user mode | |
| 1175 | - nice: niced processes executing in user mode | |
| 1176 | - system: processes executing in kernel mode | |
| 1177 | - idle: twiddling thumbs | |
| 1178 | - iowait: waiting for I/O to complete | |
| 1179 | - irq: servicing interrupts | |
| 1180 | - softirq: servicing softirqs | |
| b68f2c3a | 1181 | - steal: involuntary wait |
| ce0e7b28 RO |
1182 | - guest: running a normal guest |
| 1183 | - guest_nice: running a niced guest | |
| 1da177e4 LT |
1184 | |
| 1185 | The "intr" line gives counts of interrupts serviced since boot time, for each | |
| 1186 | of the possible system interrupts. The first column is the total of all | |
| 1187 | interrupts serviced; each subsequent column is the total for that particular | |
| 1188 | interrupt. | |
| 1189 | ||
| 1190 | The "ctxt" line gives the total number of context switches across all CPUs. | |
| 1191 | ||
| 1192 | The "btime" line gives the time at which the system booted, in seconds since | |
| 1193 | the Unix epoch. | |
| 1194 | ||
| 1195 | The "processes" line gives the number of processes and threads created, which | |
| 1196 | includes (but is not limited to) those created by calls to the fork() and | |
| 1197 | clone() system calls. | |
| 1198 | ||
| e3cc2226 LGE |
1199 | The "procs_running" line gives the total number of threads that are |
| 1200 | running or ready to run (i.e., the total number of runnable threads). | |
| 1da177e4 LT |
1201 | |
| 1202 | The "procs_blocked" line gives the number of processes currently blocked, | |
| 1203 | waiting for I/O to complete. | |
| 1204 | ||
| d3d64df2 KK |
1205 | The "softirq" line gives counts of softirqs serviced since boot time, for each |
| 1206 | of the possible system softirqs. The first column is the total of all | |
| 1207 | softirqs serviced; each subsequent column is the total for that particular | |
| 1208 | softirq. | |
| 1209 | ||
| 37515fac | 1210 | |
| c9de560d AT |
1211 | 1.9 Ext4 file system parameters |
| 1212 | ------------------------------ | |
| 37515fac TT |
1213 | |
| 1214 | Information about mounted ext4 file systems can be found in | |
| 1215 | /proc/fs/ext4. Each mounted filesystem will have a directory in | |
| 1216 | /proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or | |
| 1217 | /proc/fs/ext4/dm-0). The files in each per-device directory are shown | |
| 349888ee | 1218 | in Table 1-12, below. |
| 37515fac | 1219 | |
| 349888ee | 1220 | Table 1-12: Files in /proc/fs/ext4/<devname> |
| 37515fac TT |
1221 | .............................................................................. |
| 1222 | File Content | |
| 1223 | mb_groups details of multiblock allocator buddy cache of free blocks | |
| 37515fac TT |
1224 | .............................................................................. |
| 1225 | ||
| 23308ba5 JS |
1226 | 2.0 /proc/consoles |
| 1227 | ------------------ | |
| 1228 | Shows registered system console lines. | |
| 1229 | ||
| 1230 | To see which character device lines are currently used for the system console | |
| 1231 | /dev/console, you may simply look into the file /proc/consoles: | |
| 1232 | ||
| 1233 | > cat /proc/consoles | |
| 1234 | tty0 -WU (ECp) 4:7 | |
| 1235 | ttyS0 -W- (Ep) 4:64 | |
| 1236 | ||
| 1237 | The columns are: | |
| 1238 | ||
| 1239 | device name of the device | |
| 1240 | operations R = can do read operations | |
| 1241 | W = can do write operations | |
| 1242 | U = can do unblank | |
| 1243 | flags E = it is enabled | |
| 25985edc | 1244 | C = it is preferred console |
| 23308ba5 JS |
1245 | B = it is primary boot console |
| 1246 | p = it is used for printk buffer | |
| 1247 | b = it is not a TTY but a Braille device | |
| 1248 | a = it is safe to use when cpu is offline | |
| 1249 | major:minor major and minor number of the device separated by a colon | |
| 1da177e4 LT |
1250 | |
| 1251 | ------------------------------------------------------------------------------ | |
| 1252 | Summary | |
| 1253 | ------------------------------------------------------------------------------ | |
| 1254 | The /proc file system serves information about the running system. It not only | |
| 1255 | allows access to process data but also allows you to request the kernel status | |
| 1256 | by reading files in the hierarchy. | |
| 1257 | ||
| 1258 | The directory structure of /proc reflects the types of information and makes | |
| 1259 | it easy, if not obvious, where to look for specific data. | |
| 1260 | ------------------------------------------------------------------------------ | |
| 1261 | ||
| 1262 | ------------------------------------------------------------------------------ | |
| 1263 | CHAPTER 2: MODIFYING SYSTEM PARAMETERS | |
| 1264 | ------------------------------------------------------------------------------ | |
| 1265 | ||
| 1266 | ------------------------------------------------------------------------------ | |
| 1267 | In This Chapter | |
| 1268 | ------------------------------------------------------------------------------ | |
| 1269 | * Modifying kernel parameters by writing into files found in /proc/sys | |
| 1270 | * Exploring the files which modify certain parameters | |
| 1271 | * Review of the /proc/sys file tree | |
| 1272 | ------------------------------------------------------------------------------ | |
| 1273 | ||
| 1274 | ||
| 1275 | A very interesting part of /proc is the directory /proc/sys. This is not only | |
| 1276 | a source of information, it also allows you to change parameters within the | |
| 1277 | kernel. Be very careful when attempting this. You can optimize your system, | |
| 1278 | but you can also cause it to crash. Never alter kernel parameters on a | |
| 1279 | production system. Set up a development machine and test to make sure that | |
| 1280 | everything works the way you want it to. You may have no alternative but to | |
| 1281 | reboot the machine once an error has been made. | |
| 1282 | ||
| 1283 | To change a value, simply echo the new value into the file. An example is | |
| 1284 | given below in the section on the file system data. You need to be root to do | |
| 1285 | this. You can create your own boot script to perform this every time your | |
| 1286 | system boots. | |
| 1287 | ||
| 1288 | The files in /proc/sys can be used to fine tune and monitor miscellaneous and | |
| 1289 | general things in the operation of the Linux kernel. Since some of the files | |
| 1290 | can inadvertently disrupt your system, it is advisable to read both | |
| 1291 | documentation and source before actually making adjustments. In any case, be | |
| 1292 | very careful when writing to any of these files. The entries in /proc may | |
| 1293 | change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt | |
| 1294 | review the kernel documentation in the directory /usr/src/linux/Documentation. | |
| 1295 | This chapter is heavily based on the documentation included in the pre 2.2 | |
| 1296 | kernels, and became part of it in version 2.2.1 of the Linux kernel. | |
| 1297 | ||
| 395cf969 | 1298 | Please see: Documentation/sysctl/ directory for descriptions of these |
| db0fb184 | 1299 | entries. |
| 9d0243bc | 1300 | |
| 760df93e SF |
1301 | ------------------------------------------------------------------------------ |
| 1302 | Summary | |
| 1303 | ------------------------------------------------------------------------------ | |
| 1304 | Certain aspects of kernel behavior can be modified at runtime, without the | |
| 1305 | need to recompile the kernel, or even to reboot the system. The files in the | |
| 1306 | /proc/sys tree can not only be read, but also modified. You can use the echo | |
| 1307 | command to write value into these files, thereby changing the default settings | |
| 1308 | of the kernel. | |
| 1309 | ------------------------------------------------------------------------------ | |
| 9d0243bc | 1310 | |
| 760df93e SF |
1311 | ------------------------------------------------------------------------------ |
| 1312 | CHAPTER 3: PER-PROCESS PARAMETERS | |
| 1313 | ------------------------------------------------------------------------------ | |
| 1da177e4 | 1314 | |
| a63d83f4 DR |
1315 | 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score |
| 1316 | -------------------------------------------------------------------------------- | |
| 1317 | ||
| 1318 | These file can be used to adjust the badness heuristic used to select which | |
| 1319 | process gets killed in out of memory conditions. | |
| 1320 | ||
| 1321 | The badness heuristic assigns a value to each candidate task ranging from 0 | |
| 1322 | (never kill) to 1000 (always kill) to determine which process is targeted. The | |
| 1323 | units are roughly a proportion along that range of allowed memory the process | |
| 1324 | may allocate from based on an estimation of its current memory and swap use. | |
| 1325 | For example, if a task is using all allowed memory, its badness score will be | |
| 1326 | 1000. If it is using half of its allowed memory, its score will be 500. | |
| 1327 | ||
| 1328 | There is an additional factor included in the badness score: root | |
| 1329 | processes are given 3% extra memory over other tasks. | |
| 1330 | ||
| 1331 | The amount of "allowed" memory depends on the context in which the oom killer | |
| 1332 | was called. If it is due to the memory assigned to the allocating task's cpuset | |
| 1333 | being exhausted, the allowed memory represents the set of mems assigned to that | |
| 1334 | cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed | |
| 1335 | memory represents the set of mempolicy nodes. If it is due to a memory | |
| 1336 | limit (or swap limit) being reached, the allowed memory is that configured | |
| 1337 | limit. Finally, if it is due to the entire system being out of memory, the | |
| 1338 | allowed memory represents all allocatable resources. | |
| 1339 | ||
| 1340 | The value of /proc/<pid>/oom_score_adj is added to the badness score before it | |
| 1341 | is used to determine which task to kill. Acceptable values range from -1000 | |
| 1342 | (OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to | |
| 1343 | polarize the preference for oom killing either by always preferring a certain | |
| 1344 | task or completely disabling it. The lowest possible value, -1000, is | |
| 1345 | equivalent to disabling oom killing entirely for that task since it will always | |
| 1346 | report a badness score of 0. | |
| 1347 | ||
| 1348 | Consequently, it is very simple for userspace to define the amount of memory to | |
| 1349 | consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for | |
| 1350 | example, is roughly equivalent to allowing the remainder of tasks sharing the | |
| 1351 | same system, cpuset, mempolicy, or memory controller resources to use at least | |
| 1352 | 50% more memory. A value of -500, on the other hand, would be roughly | |
| 1353 | equivalent to discounting 50% of the task's allowed memory from being considered | |
| 1354 | as scoring against the task. | |
| 1355 | ||
| 1356 | For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also | |
| 1357 | be used to tune the badness score. Its acceptable values range from -16 | |
| 1358 | (OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17 | |
| 1359 | (OOM_DISABLE) to disable oom killing entirely for that task. Its value is | |
| 1360 | scaled linearly with /proc/<pid>/oom_score_adj. | |
| 1361 | ||
| 1362 | Writing to /proc/<pid>/oom_score_adj or /proc/<pid>/oom_adj will change the | |
| 1363 | other with its scaled value. | |
| 1364 | ||
| dabb16f6 MSB |
1365 | The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last |
| 1366 | value set by a CAP_SYS_RESOURCE process. To reduce the value any lower | |
| 1367 | requires CAP_SYS_RESOURCE. | |
| 1368 | ||
| 51b1bd2a DR |
1369 | NOTICE: /proc/<pid>/oom_adj is deprecated and will be removed, please see |
| 1370 | Documentation/feature-removal-schedule.txt. | |
| 1371 | ||
| a63d83f4 | 1372 | Caveat: when a parent task is selected, the oom killer will sacrifice any first |
| 25985edc | 1373 | generation children with separate address spaces instead, if possible. This |
| a63d83f4 DR |
1374 | avoids servers and important system daemons from being killed and loses the |
| 1375 | minimal amount of work. | |
| 1376 | ||
| 9e9e3cbc | 1377 | |
| 760df93e | 1378 | 3.2 /proc/<pid>/oom_score - Display current oom-killer score |
| d7ff0dbf JFM |
1379 | ------------------------------------------------------------- |
| 1380 | ||
| d7ff0dbf JFM |
1381 | This file can be used to check the current score used by the oom-killer is for |
| 1382 | any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which | |
| 1383 | process should be killed in an out-of-memory situation. | |
| 1da177e4 | 1384 | |
| f9c99463 | 1385 | |
| 760df93e | 1386 | 3.3 /proc/<pid>/io - Display the IO accounting fields |
| f9c99463 RK |
1387 | ------------------------------------------------------- |
| 1388 | ||
| 1389 | This file contains IO statistics for each running process | |
| 1390 | ||
| 1391 | Example | |
| 1392 | ------- | |
| 1393 | ||
| 1394 | test:/tmp # dd if=/dev/zero of=/tmp/test.dat & | |
| 1395 | [1] 3828 | |
| 1396 | ||
| 1397 | test:/tmp # cat /proc/3828/io | |
| 1398 | rchar: 323934931 | |
| 1399 | wchar: 323929600 | |
| 1400 | syscr: 632687 | |
| 1401 | syscw: 632675 | |
| 1402 | read_bytes: 0 | |
| 1403 | write_bytes: 323932160 | |
| 1404 | cancelled_write_bytes: 0 | |
| 1405 | ||
| 1406 | ||
| 1407 | Description | |
| 1408 | ----------- | |
| 1409 | ||
| 1410 | rchar | |
| 1411 | ----- | |
| 1412 | ||
| 1413 | I/O counter: chars read | |
| 1414 | The number of bytes which this task has caused to be read from storage. This | |
| 1415 | is simply the sum of bytes which this process passed to read() and pread(). | |
| 1416 | It includes things like tty IO and it is unaffected by whether or not actual | |
| 1417 | physical disk IO was required (the read might have been satisfied from | |
| 1418 | pagecache) | |
| 1419 | ||
| 1420 | ||
| 1421 | wchar | |
| 1422 | ----- | |
| 1423 | ||
| 1424 | I/O counter: chars written | |
| 1425 | The number of bytes which this task has caused, or shall cause to be written | |
| 1426 | to disk. Similar caveats apply here as with rchar. | |
| 1427 | ||
| 1428 | ||
| 1429 | syscr | |
| 1430 | ----- | |
| 1431 | ||
| 1432 | I/O counter: read syscalls | |
| 1433 | Attempt to count the number of read I/O operations, i.e. syscalls like read() | |
| 1434 | and pread(). | |
| 1435 | ||
| 1436 | ||
| 1437 | syscw | |
| 1438 | ----- | |
| 1439 | ||
| 1440 | I/O counter: write syscalls | |
| 1441 | Attempt to count the number of write I/O operations, i.e. syscalls like | |
| 1442 | write() and pwrite(). | |
| 1443 | ||
| 1444 | ||
| 1445 | read_bytes | |
| 1446 | ---------- | |
| 1447 | ||
| 1448 | I/O counter: bytes read | |
| 1449 | Attempt to count the number of bytes which this process really did cause to | |
| 1450 | be fetched from the storage layer. Done at the submit_bio() level, so it is | |
| 1451 | accurate for block-backed filesystems. <please add status regarding NFS and | |
| 1452 | CIFS at a later time> | |
| 1453 | ||
| 1454 | ||
| 1455 | write_bytes | |
| 1456 | ----------- | |
| 1457 | ||
| 1458 | I/O counter: bytes written | |
| 1459 | Attempt to count the number of bytes which this process caused to be sent to | |
| 1460 | the storage layer. This is done at page-dirtying time. | |
| 1461 | ||
| 1462 | ||
| 1463 | cancelled_write_bytes | |
| 1464 | --------------------- | |
| 1465 | ||
| 1466 | The big inaccuracy here is truncate. If a process writes 1MB to a file and | |
| 1467 | then deletes the file, it will in fact perform no writeout. But it will have | |
| 1468 | been accounted as having caused 1MB of write. | |
| 1469 | In other words: The number of bytes which this process caused to not happen, | |
| 1470 | by truncating pagecache. A task can cause "negative" IO too. If this task | |
| 1471 | truncates some dirty pagecache, some IO which another task has been accounted | |
| a33f3224 | 1472 | for (in its write_bytes) will not be happening. We _could_ just subtract that |
| f9c99463 RK |
1473 | from the truncating task's write_bytes, but there is information loss in doing |
| 1474 | that. | |
| 1475 | ||
| 1476 | ||
| 1477 | Note | |
| 1478 | ---- | |
| 1479 | ||
| 1480 | At its current implementation state, this is a bit racy on 32-bit machines: if | |
| 1481 | process A reads process B's /proc/pid/io while process B is updating one of | |
| 1482 | those 64-bit counters, process A could see an intermediate result. | |
| 1483 | ||
| 1484 | ||
| 1485 | More information about this can be found within the taskstats documentation in | |
| 1486 | Documentation/accounting. | |
| 1487 | ||
| 760df93e | 1488 | 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings |
| bb90110d KH |
1489 | --------------------------------------------------------------- |
| 1490 | When a process is dumped, all anonymous memory is written to a core file as | |
| 1491 | long as the size of the core file isn't limited. But sometimes we don't want | |
| 1492 | to dump some memory segments, for example, huge shared memory. Conversely, | |
| 1493 | sometimes we want to save file-backed memory segments into a core file, not | |
| 1494 | only the individual files. | |
| 1495 | ||
| 1496 | /proc/<pid>/coredump_filter allows you to customize which memory segments | |
| 1497 | will be dumped when the <pid> process is dumped. coredump_filter is a bitmask | |
| 1498 | of memory types. If a bit of the bitmask is set, memory segments of the | |
| 1499 | corresponding memory type are dumped, otherwise they are not dumped. | |
| 1500 | ||
| e575f111 | 1501 | The following 7 memory types are supported: |
| bb90110d KH |
1502 | - (bit 0) anonymous private memory |
| 1503 | - (bit 1) anonymous shared memory | |
| 1504 | - (bit 2) file-backed private memory | |
| 1505 | - (bit 3) file-backed shared memory | |
| b261dfea HK |
1506 | - (bit 4) ELF header pages in file-backed private memory areas (it is |
| 1507 | effective only if the bit 2 is cleared) | |
| e575f111 KM |
1508 | - (bit 5) hugetlb private memory |
| 1509 | - (bit 6) hugetlb shared memory | |
| bb90110d KH |
1510 | |
| 1511 | Note that MMIO pages such as frame buffer are never dumped and vDSO pages | |
| 1512 | are always dumped regardless of the bitmask status. | |
| 1513 | ||
| e575f111 KM |
1514 | Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only |
| 1515 | effected by bit 5-6. | |
| 1516 | ||
| 1517 | Default value of coredump_filter is 0x23; this means all anonymous memory | |
| 1518 | segments and hugetlb private memory are dumped. | |
| bb90110d KH |
1519 | |
| 1520 | If you don't want to dump all shared memory segments attached to pid 1234, | |
| e575f111 | 1521 | write 0x21 to the process's proc file. |
| bb90110d | 1522 | |
| e575f111 | 1523 | $ echo 0x21 > /proc/1234/coredump_filter |
| bb90110d KH |
1524 | |
| 1525 | When a new process is created, the process inherits the bitmask status from its | |
| 1526 | parent. It is useful to set up coredump_filter before the program runs. | |
| 1527 | For example: | |
| 1528 | ||
| 1529 | $ echo 0x7 > /proc/self/coredump_filter | |
| 1530 | $ ./some_program | |
| 1531 | ||
| 760df93e | 1532 | 3.5 /proc/<pid>/mountinfo - Information about mounts |
| 2d4d4864 RP |
1533 | -------------------------------------------------------- |
| 1534 | ||
| 1535 | This file contains lines of the form: | |
| 1536 | ||
| 1537 | 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue | |
| 1538 | (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) | |
| 1539 | ||
| 1540 | (1) mount ID: unique identifier of the mount (may be reused after umount) | |
| 1541 | (2) parent ID: ID of parent (or of self for the top of the mount tree) | |
| 1542 | (3) major:minor: value of st_dev for files on filesystem | |
| 1543 | (4) root: root of the mount within the filesystem | |
| 1544 | (5) mount point: mount point relative to the process's root | |
| 1545 | (6) mount options: per mount options | |
| 1546 | (7) optional fields: zero or more fields of the form "tag[:value]" | |
| 1547 | (8) separator: marks the end of the optional fields | |
| 1548 | (9) filesystem type: name of filesystem of the form "type[.subtype]" | |
| 1549 | (10) mount source: filesystem specific information or "none" | |
| 1550 | (11) super options: per super block options | |
| 1551 | ||
| 1552 | Parsers should ignore all unrecognised optional fields. Currently the | |
| 1553 | possible optional fields are: | |
| 1554 | ||
| 1555 | shared:X mount is shared in peer group X | |
| 1556 | master:X mount is slave to peer group X | |
| 97e7e0f7 | 1557 | propagate_from:X mount is slave and receives propagation from peer group X (*) |
| 2d4d4864 RP |
1558 | unbindable mount is unbindable |
| 1559 | ||
| 97e7e0f7 MS |
1560 | (*) X is the closest dominant peer group under the process's root. If |
| 1561 | X is the immediate master of the mount, or if there's no dominant peer | |
| 1562 | group under the same root, then only the "master:X" field is present | |
| 1563 | and not the "propagate_from:X" field. | |
| 1564 | ||
| 2d4d4864 RP |
1565 | For more information on mount propagation see: |
| 1566 | ||
| 1567 | Documentation/filesystems/sharedsubtree.txt | |
| 1568 | ||
| 4614a696 JS |
1569 | |
| 1570 | 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm | |
| 1571 | -------------------------------------------------------- | |
| 1572 | These files provide a method to access a tasks comm value. It also allows for | |
| 1573 | a task to set its own or one of its thread siblings comm value. The comm value | |
| 1574 | is limited in size compared to the cmdline value, so writing anything longer | |
| 1575 | then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated | |
| 1576 | comm value. | |
| 0499680a VK |
1577 | |
| 1578 | ||
| 1579 | ------------------------------------------------------------------------------ | |
| 1580 | Configuring procfs | |
| 1581 | ------------------------------------------------------------------------------ | |
| 1582 | ||
| 1583 | 4.1 Mount options | |
| 1584 | --------------------- | |
| 1585 | ||
| 1586 | The following mount options are supported: | |
| 1587 | ||
| 1588 | hidepid= Set /proc/<pid>/ access mode. | |
| 1589 | gid= Set the group authorized to learn processes information. | |
| 1590 | ||
| 1591 | hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories | |
| 1592 | (default). | |
| 1593 | ||
| 1594 | hidepid=1 means users may not access any /proc/<pid>/ directories but their | |
| 1595 | own. Sensitive files like cmdline, sched*, status are now protected against | |
| 1596 | other users. This makes it impossible to learn whether any user runs | |
| 1597 | specific program (given the program doesn't reveal itself by its behaviour). | |
| 1598 | As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users, | |
| 1599 | poorly written programs passing sensitive information via program arguments are | |
| 1600 | now protected against local eavesdroppers. | |
| 1601 | ||
| 1602 | hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other | |
| 1603 | users. It doesn't mean that it hides a fact whether a process with a specific | |
| 1604 | pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"), | |
| 1605 | but it hides process' uid and gid, which may be learned by stat()'ing | |
| 1606 | /proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering | |
| 1607 | information about running processes, whether some daemon runs with elevated | |
| 1608 | privileges, whether other user runs some sensitive program, whether other users | |
| 1609 | run any program at all, etc. | |
| 1610 | ||
| 1611 | gid= defines a group authorized to learn processes information otherwise | |
| 1612 | prohibited by hidepid=. If you use some daemon like identd which needs to learn | |
| 1613 | information about processes information, just add identd to this group. |