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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 | |
| 760df93e | 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 | ------------------------------------------------------------------------------ | |
| 13 | ||
| 14 | Table of Contents | |
| 15 | ----------------- | |
| 16 | ||
| 17 | 0 Preface | |
| 18 | 0.1 Introduction/Credits | |
| 19 | 0.2 Legal Stuff | |
| 20 | ||
| 21 | 1 Collecting System Information | |
| 22 | 1.1 Process-Specific Subdirectories | |
| 23 | 1.2 Kernel data | |
| 24 | 1.3 IDE devices in /proc/ide | |
| 25 | 1.4 Networking info in /proc/net | |
| 26 | 1.5 SCSI info | |
| 27 | 1.6 Parallel port info in /proc/parport | |
| 28 | 1.7 TTY info in /proc/tty | |
| 29 | 1.8 Miscellaneous kernel statistics in /proc/stat | |
| 760df93e | 30 | 1.9 Ext4 file system parameters |
| 1da177e4 LT |
31 | |
| 32 | 2 Modifying System Parameters | |
| 760df93e SF |
33 | |
| 34 | 3 Per-Process Parameters | |
| 35 | 3.1 /proc/<pid>/oom_adj - Adjust the oom-killer score | |
| 36 | 3.2 /proc/<pid>/oom_score - Display current oom-killer score | |
| 37 | 3.3 /proc/<pid>/io - Display the IO accounting fields | |
| 38 | 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings | |
| 39 | 3.5 /proc/<pid>/mountinfo - Information about mounts | |
| 40 | ||
| 1da177e4 LT |
41 | |
| 42 | ------------------------------------------------------------------------------ | |
| 43 | Preface | |
| 44 | ------------------------------------------------------------------------------ | |
| 45 | ||
| 46 | 0.1 Introduction/Credits | |
| 47 | ------------------------ | |
| 48 | ||
| 49 | This documentation is part of a soon (or so we hope) to be released book on | |
| 50 | the SuSE Linux distribution. As there is no complete documentation for the | |
| 51 | /proc file system and we've used many freely available sources to write these | |
| 52 | chapters, it seems only fair to give the work back to the Linux community. | |
| 53 | This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm | |
| 54 | afraid it's still far from complete, but we hope it will be useful. As far as | |
| 55 | we know, it is the first 'all-in-one' document about the /proc file system. It | |
| 56 | is focused on the Intel x86 hardware, so if you are looking for PPC, ARM, | |
| 57 | SPARC, AXP, etc., features, you probably won't find what you are looking for. | |
| 58 | It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But | |
| 59 | additions and patches are welcome and will be added to this document if you | |
| 60 | mail them to Bodo. | |
| 61 | ||
| 62 | We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of | |
| 63 | other people for help compiling this documentation. We'd also like to extend a | |
| 64 | special thank you to Andi Kleen for documentation, which we relied on heavily | |
| 65 | to create this document, as well as the additional information he provided. | |
| 66 | Thanks to everybody else who contributed source or docs to the Linux kernel | |
| 67 | and helped create a great piece of software... :) | |
| 68 | ||
| 69 | If you have any comments, corrections or additions, please don't hesitate to | |
| 70 | contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this | |
| 71 | document. | |
| 72 | ||
| 73 | The latest version of this document is available online at | |
| 74 | http://skaro.nightcrawler.com/~bb/Docs/Proc as HTML version. | |
| 75 | ||
| 76 | If the above direction does not works for you, ypu could try the kernel | |
| 77 | mailing list at linux-kernel@vger.kernel.org and/or try to reach me at | |
| 78 | comandante@zaralinux.com. | |
| 79 | ||
| 80 | 0.2 Legal Stuff | |
| 81 | --------------- | |
| 82 | ||
| 83 | We don't guarantee the correctness of this document, and if you come to us | |
| 84 | complaining about how you screwed up your system because of incorrect | |
| 85 | documentation, we won't feel responsible... | |
| 86 | ||
| 87 | ------------------------------------------------------------------------------ | |
| 88 | CHAPTER 1: COLLECTING SYSTEM INFORMATION | |
| 89 | ------------------------------------------------------------------------------ | |
| 90 | ||
| 91 | ------------------------------------------------------------------------------ | |
| 92 | In This Chapter | |
| 93 | ------------------------------------------------------------------------------ | |
| 94 | * Investigating the properties of the pseudo file system /proc and its | |
| 95 | ability to provide information on the running Linux system | |
| 96 | * Examining /proc's structure | |
| 97 | * Uncovering various information about the kernel and the processes running | |
| 98 | on the system | |
| 99 | ------------------------------------------------------------------------------ | |
| 100 | ||
| 101 | ||
| 102 | The proc file system acts as an interface to internal data structures in the | |
| 103 | kernel. It can be used to obtain information about the system and to change | |
| 104 | certain kernel parameters at runtime (sysctl). | |
| 105 | ||
| 106 | First, we'll take a look at the read-only parts of /proc. In Chapter 2, we | |
| 107 | show you how you can use /proc/sys to change settings. | |
| 108 | ||
| 109 | 1.1 Process-Specific Subdirectories | |
| 110 | ----------------------------------- | |
| 111 | ||
| 112 | The directory /proc contains (among other things) one subdirectory for each | |
| 113 | process running on the system, which is named after the process ID (PID). | |
| 114 | ||
| 115 | The link self points to the process reading the file system. Each process | |
| 116 | subdirectory has the entries listed in Table 1-1. | |
| 117 | ||
| 118 | ||
| 119 | Table 1-1: Process specific entries in /proc | |
| 120 | .............................................................................. | |
| b813e931 DR |
121 | File Content |
| 122 | clear_refs Clears page referenced bits shown in smaps output | |
| 123 | cmdline Command line arguments | |
| 124 | cpu Current and last cpu in which it was executed (2.4)(smp) | |
| 125 | cwd Link to the current working directory | |
| 126 | environ Values of environment variables | |
| 127 | exe Link to the executable of this process | |
| 128 | fd Directory, which contains all file descriptors | |
| 129 | maps Memory maps to executables and library files (2.4) | |
| 130 | mem Memory held by this process | |
| 131 | root Link to the root directory of this process | |
| 132 | stat Process status | |
| 133 | statm Process memory status information | |
| 134 | status Process status in human readable form | |
| 135 | wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan | |
| 2ec220e2 | 136 | stack Report full stack trace, enable via CONFIG_STACKTRACE |
| b813e931 | 137 | smaps Extension based on maps, the rss size for each mapped file |
| 1da177e4 LT |
138 | .............................................................................. |
| 139 | ||
| 140 | For example, to get the status information of a process, all you have to do is | |
| 141 | read the file /proc/PID/status: | |
| 142 | ||
| 143 | >cat /proc/self/status | |
| 144 | Name: cat | |
| 145 | State: R (running) | |
| 146 | Pid: 5452 | |
| 147 | PPid: 743 | |
| 148 | TracerPid: 0 (2.4) | |
| 149 | Uid: 501 501 501 501 | |
| 150 | Gid: 100 100 100 100 | |
| 151 | Groups: 100 14 16 | |
| 152 | VmSize: 1112 kB | |
| 153 | VmLck: 0 kB | |
| 154 | VmRSS: 348 kB | |
| 155 | VmData: 24 kB | |
| 156 | VmStk: 12 kB | |
| 157 | VmExe: 8 kB | |
| 158 | VmLib: 1044 kB | |
| 159 | SigPnd: 0000000000000000 | |
| 160 | SigBlk: 0000000000000000 | |
| 161 | SigIgn: 0000000000000000 | |
| 162 | SigCgt: 0000000000000000 | |
| 163 | CapInh: 00000000fffffeff | |
| 164 | CapPrm: 0000000000000000 | |
| 165 | CapEff: 0000000000000000 | |
| 166 | ||
| 167 | ||
| 168 | This shows you nearly the same information you would get if you viewed it with | |
| 169 | the ps command. In fact, ps uses the proc file system to obtain its | |
| 170 | information. The statm file contains more detailed information about the | |
| 18d96779 KC |
171 | process memory usage. Its seven fields are explained in Table 1-2. The stat |
| 172 | file contains details information about the process itself. Its fields are | |
| 173 | explained in Table 1-3. | |
| 1da177e4 LT |
174 | |
| 175 | ||
| 176 | Table 1-2: Contents of the statm files (as of 2.6.8-rc3) | |
| 177 | .............................................................................. | |
| 178 | Field Content | |
| 179 | size total program size (pages) (same as VmSize in status) | |
| 180 | resident size of memory portions (pages) (same as VmRSS in status) | |
| 181 | shared number of pages that are shared (i.e. backed by a file) | |
| 182 | trs number of pages that are 'code' (not including libs; broken, | |
| 183 | includes data segment) | |
| 184 | lrs number of pages of library (always 0 on 2.6) | |
| 185 | drs number of pages of data/stack (including libs; broken, | |
| 186 | includes library text) | |
| 187 | dt number of dirty pages (always 0 on 2.6) | |
| 188 | .............................................................................. | |
| 189 | ||
| 18d96779 KC |
190 | |
| 191 | Table 1-3: Contents of the stat files (as of 2.6.22-rc3) | |
| 192 | .............................................................................. | |
| 193 | Field Content | |
| 194 | pid process id | |
| 195 | tcomm filename of the executable | |
| 196 | state state (R is running, S is sleeping, D is sleeping in an | |
| 197 | uninterruptible wait, Z is zombie, T is traced or stopped) | |
| 198 | ppid process id of the parent process | |
| 199 | pgrp pgrp of the process | |
| 200 | sid session id | |
| 201 | tty_nr tty the process uses | |
| 202 | tty_pgrp pgrp of the tty | |
| 203 | flags task flags | |
| 204 | min_flt number of minor faults | |
| 205 | cmin_flt number of minor faults with child's | |
| 206 | maj_flt number of major faults | |
| 207 | cmaj_flt number of major faults with child's | |
| 208 | utime user mode jiffies | |
| 209 | stime kernel mode jiffies | |
| 210 | cutime user mode jiffies with child's | |
| 211 | cstime kernel mode jiffies with child's | |
| 212 | priority priority level | |
| 213 | nice nice level | |
| 214 | num_threads number of threads | |
| 2e01e00e | 215 | it_real_value (obsolete, always 0) |
| 18d96779 KC |
216 | start_time time the process started after system boot |
| 217 | vsize virtual memory size | |
| 218 | rss resident set memory size | |
| 219 | rsslim current limit in bytes on the rss | |
| 220 | start_code address above which program text can run | |
| 221 | end_code address below which program text can run | |
| 222 | start_stack address of the start of the stack | |
| 223 | esp current value of ESP | |
| 224 | eip current value of EIP | |
| 225 | pending bitmap of pending signals (obsolete) | |
| 226 | blocked bitmap of blocked signals (obsolete) | |
| 227 | sigign bitmap of ignored signals (obsolete) | |
| 228 | sigcatch bitmap of catched signals (obsolete) | |
| 229 | wchan address where process went to sleep | |
| 230 | 0 (place holder) | |
| 231 | 0 (place holder) | |
| 232 | exit_signal signal to send to parent thread on exit | |
| 233 | task_cpu which CPU the task is scheduled on | |
| 234 | rt_priority realtime priority | |
| 235 | policy scheduling policy (man sched_setscheduler) | |
| 236 | blkio_ticks time spent waiting for block IO | |
| 237 | .............................................................................. | |
| 238 | ||
| 239 | ||
| 1da177e4 LT |
240 | 1.2 Kernel data |
| 241 | --------------- | |
| 242 | ||
| 243 | Similar to the process entries, the kernel data files give information about | |
| 244 | the running kernel. The files used to obtain this information are contained in | |
| 18d96779 | 245 | /proc and are listed in Table 1-4. Not all of these will be present in your |
| 1da177e4 LT |
246 | system. It depends on the kernel configuration and the loaded modules, which |
| 247 | files are there, and which are missing. | |
| 248 | ||
| 18d96779 | 249 | Table 1-4: Kernel info in /proc |
| 1da177e4 LT |
250 | .............................................................................. |
| 251 | File Content | |
| 252 | apm Advanced power management info | |
| 253 | buddyinfo Kernel memory allocator information (see text) (2.5) | |
| 254 | bus Directory containing bus specific information | |
| 255 | cmdline Kernel command line | |
| 256 | cpuinfo Info about the CPU | |
| 257 | devices Available devices (block and character) | |
| 258 | dma Used DMS channels | |
| 259 | filesystems Supported filesystems | |
| 260 | driver Various drivers grouped here, currently rtc (2.4) | |
| 261 | execdomains Execdomains, related to security (2.4) | |
| 262 | fb Frame Buffer devices (2.4) | |
| 263 | fs File system parameters, currently nfs/exports (2.4) | |
| 264 | ide Directory containing info about the IDE subsystem | |
| 265 | interrupts Interrupt usage | |
| 266 | iomem Memory map (2.4) | |
| 267 | ioports I/O port usage | |
| 268 | irq Masks for irq to cpu affinity (2.4)(smp?) | |
| 269 | isapnp ISA PnP (Plug&Play) Info (2.4) | |
| 270 | kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4)) | |
| 271 | kmsg Kernel messages | |
| 272 | ksyms Kernel symbol table | |
| 273 | loadavg Load average of last 1, 5 & 15 minutes | |
| 274 | locks Kernel locks | |
| 275 | meminfo Memory info | |
| 276 | misc Miscellaneous | |
| 277 | modules List of loaded modules | |
| 278 | mounts Mounted filesystems | |
| 279 | net Networking info (see text) | |
| 280 | partitions Table of partitions known to the system | |
| 8b60756a | 281 | pci Deprecated info of PCI bus (new way -> /proc/bus/pci/, |
| 1da177e4 LT |
282 | decoupled by lspci (2.4) |
| 283 | rtc Real time clock | |
| 284 | scsi SCSI info (see text) | |
| 285 | slabinfo Slab pool info | |
| 286 | stat Overall statistics | |
| 287 | swaps Swap space utilization | |
| 288 | sys See chapter 2 | |
| 289 | sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4) | |
| 290 | tty Info of tty drivers | |
| 291 | uptime System uptime | |
| 292 | version Kernel version | |
| 293 | video bttv info of video resources (2.4) | |
| a47a126a | 294 | vmallocinfo Show vmalloced areas |
| 1da177e4 LT |
295 | .............................................................................. |
| 296 | ||
| 297 | You can, for example, check which interrupts are currently in use and what | |
| 298 | they are used for by looking in the file /proc/interrupts: | |
| 299 | ||
| 300 | > cat /proc/interrupts | |
| 301 | CPU0 | |
| 302 | 0: 8728810 XT-PIC timer | |
| 303 | 1: 895 XT-PIC keyboard | |
| 304 | 2: 0 XT-PIC cascade | |
| 305 | 3: 531695 XT-PIC aha152x | |
| 306 | 4: 2014133 XT-PIC serial | |
| 307 | 5: 44401 XT-PIC pcnet_cs | |
| 308 | 8: 2 XT-PIC rtc | |
| 309 | 11: 8 XT-PIC i82365 | |
| 310 | 12: 182918 XT-PIC PS/2 Mouse | |
| 311 | 13: 1 XT-PIC fpu | |
| 312 | 14: 1232265 XT-PIC ide0 | |
| 313 | 15: 7 XT-PIC ide1 | |
| 314 | NMI: 0 | |
| 315 | ||
| 316 | In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the | |
| 317 | output of a SMP machine): | |
| 318 | ||
| 319 | > cat /proc/interrupts | |
| 320 | ||
| 321 | CPU0 CPU1 | |
| 322 | 0: 1243498 1214548 IO-APIC-edge timer | |
| 323 | 1: 8949 8958 IO-APIC-edge keyboard | |
| 324 | 2: 0 0 XT-PIC cascade | |
| 325 | 5: 11286 10161 IO-APIC-edge soundblaster | |
| 326 | 8: 1 0 IO-APIC-edge rtc | |
| 327 | 9: 27422 27407 IO-APIC-edge 3c503 | |
| 328 | 12: 113645 113873 IO-APIC-edge PS/2 Mouse | |
| 329 | 13: 0 0 XT-PIC fpu | |
| 330 | 14: 22491 24012 IO-APIC-edge ide0 | |
| 331 | 15: 2183 2415 IO-APIC-edge ide1 | |
| 332 | 17: 30564 30414 IO-APIC-level eth0 | |
| 333 | 18: 177 164 IO-APIC-level bttv | |
| 334 | NMI: 2457961 2457959 | |
| 335 | LOC: 2457882 2457881 | |
| 336 | ERR: 2155 | |
| 337 | ||
| 338 | NMI is incremented in this case because every timer interrupt generates a NMI | |
| 339 | (Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups. | |
| 340 | ||
| 341 | LOC is the local interrupt counter of the internal APIC of every CPU. | |
| 342 | ||
| 343 | ERR is incremented in the case of errors in the IO-APIC bus (the bus that | |
| 344 | connects the CPUs in a SMP system. This means that an error has been detected, | |
| 345 | the IO-APIC automatically retry the transmission, so it should not be a big | |
| 346 | problem, but you should read the SMP-FAQ. | |
| 347 | ||
| 38e760a1 JK |
348 | In 2.6.2* /proc/interrupts was expanded again. This time the goal was for |
| 349 | /proc/interrupts to display every IRQ vector in use by the system, not | |
| 350 | just those considered 'most important'. The new vectors are: | |
| 351 | ||
| 352 | THR -- interrupt raised when a machine check threshold counter | |
| 353 | (typically counting ECC corrected errors of memory or cache) exceeds | |
| 354 | a configurable threshold. Only available on some systems. | |
| 355 | ||
| 356 | TRM -- a thermal event interrupt occurs when a temperature threshold | |
| 357 | has been exceeded for the CPU. This interrupt may also be generated | |
| 358 | when the temperature drops back to normal. | |
| 359 | ||
| 360 | SPU -- a spurious interrupt is some interrupt that was raised then lowered | |
| 361 | by some IO device before it could be fully processed by the APIC. Hence | |
| 362 | the APIC sees the interrupt but does not know what device it came from. | |
| 363 | For this case the APIC will generate the interrupt with a IRQ vector | |
| 364 | of 0xff. This might also be generated by chipset bugs. | |
| 365 | ||
| 366 | RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are | |
| 367 | sent from one CPU to another per the needs of the OS. Typically, | |
| 368 | their statistics are used by kernel developers and interested users to | |
| 369 | determine the occurance of interrupt of the given type. | |
| 370 | ||
| 371 | The above IRQ vectors are displayed only when relevent. For example, | |
| 372 | the threshold vector does not exist on x86_64 platforms. Others are | |
| 373 | suppressed when the system is a uniprocessor. As of this writing, only | |
| 374 | i386 and x86_64 platforms support the new IRQ vector displays. | |
| 375 | ||
| 376 | Of some interest is the introduction of the /proc/irq directory to 2.4. | |
| 1da177e4 LT |
377 | It could be used to set IRQ to CPU affinity, this means that you can "hook" an |
| 378 | IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the | |
| 18404756 MK |
379 | irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and |
| 380 | prof_cpu_mask. | |
| 1da177e4 LT |
381 | |
| 382 | For example | |
| 383 | > ls /proc/irq/ | |
| 384 | 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask | |
| 18404756 | 385 | 1 11 13 15 17 19 3 5 7 9 default_smp_affinity |
| 1da177e4 LT |
386 | > ls /proc/irq/0/ |
| 387 | smp_affinity | |
| 388 | ||
| 18404756 MK |
389 | smp_affinity is a bitmask, in which you can specify which CPUs can handle the |
| 390 | IRQ, you can set it by doing: | |
| 1da177e4 | 391 | |
| 18404756 MK |
392 | > echo 1 > /proc/irq/10/smp_affinity |
| 393 | ||
| 394 | This means that only the first CPU will handle the IRQ, but you can also echo | |
| 395 | 5 which means that only the first and fourth CPU can handle the IRQ. | |
| 1da177e4 | 396 | |
| 18404756 MK |
397 | The contents of each smp_affinity file is the same by default: |
| 398 | ||
| 399 | > cat /proc/irq/0/smp_affinity | |
| 400 | ffffffff | |
| 1da177e4 | 401 | |
| 18404756 MK |
402 | The default_smp_affinity mask applies to all non-active IRQs, which are the |
| 403 | IRQs which have not yet been allocated/activated, and hence which lack a | |
| 404 | /proc/irq/[0-9]* directory. | |
| 1da177e4 | 405 | |
| 18404756 MK |
406 | prof_cpu_mask specifies which CPUs are to be profiled by the system wide |
| 407 | profiler. Default value is ffffffff (all cpus). | |
| 1da177e4 LT |
408 | |
| 409 | The way IRQs are routed is handled by the IO-APIC, and it's Round Robin | |
| 410 | between all the CPUs which are allowed to handle it. As usual the kernel has | |
| 411 | more info than you and does a better job than you, so the defaults are the | |
| 412 | best choice for almost everyone. | |
| 413 | ||
| 414 | There are three more important subdirectories in /proc: net, scsi, and sys. | |
| 415 | The general rule is that the contents, or even the existence of these | |
| 416 | directories, depend on your kernel configuration. If SCSI is not enabled, the | |
| 417 | directory scsi may not exist. The same is true with the net, which is there | |
| 418 | only when networking support is present in the running kernel. | |
| 419 | ||
| 420 | The slabinfo file gives information about memory usage at the slab level. | |
| 421 | Linux uses slab pools for memory management above page level in version 2.2. | |
| 422 | Commonly used objects have their own slab pool (such as network buffers, | |
| 423 | directory cache, and so on). | |
| 424 | ||
| 425 | .............................................................................. | |
| 426 | ||
| 427 | > cat /proc/buddyinfo | |
| 428 | ||
| 429 | Node 0, zone DMA 0 4 5 4 4 3 ... | |
| 430 | Node 0, zone Normal 1 0 0 1 101 8 ... | |
| 431 | Node 0, zone HighMem 2 0 0 1 1 0 ... | |
| 432 | ||
| 433 | Memory fragmentation is a problem under some workloads, and buddyinfo is a | |
| 434 | useful tool for helping diagnose these problems. Buddyinfo will give you a | |
| 435 | clue as to how big an area you can safely allocate, or why a previous | |
| 436 | allocation failed. | |
| 437 | ||
| 438 | Each column represents the number of pages of a certain order which are | |
| 439 | available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in | |
| 440 | ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE | |
| 441 | available in ZONE_NORMAL, etc... | |
| 442 | ||
| 443 | .............................................................................. | |
| 444 | ||
| 445 | meminfo: | |
| 446 | ||
| 447 | Provides information about distribution and utilization of memory. This | |
| 448 | varies by architecture and compile options. The following is from a | |
| 449 | 16GB PIII, which has highmem enabled. You may not have all of these fields. | |
| 450 | ||
| 451 | > cat /proc/meminfo | |
| 452 | ||
| 453 | ||
| 454 | MemTotal: 16344972 kB | |
| 455 | MemFree: 13634064 kB | |
| 456 | Buffers: 3656 kB | |
| 457 | Cached: 1195708 kB | |
| 458 | SwapCached: 0 kB | |
| 459 | Active: 891636 kB | |
| 460 | Inactive: 1077224 kB | |
| 461 | HighTotal: 15597528 kB | |
| 462 | HighFree: 13629632 kB | |
| 463 | LowTotal: 747444 kB | |
| 464 | LowFree: 4432 kB | |
| 465 | SwapTotal: 0 kB | |
| 466 | SwapFree: 0 kB | |
| 467 | Dirty: 968 kB | |
| 468 | Writeback: 0 kB | |
| b88473f7 | 469 | AnonPages: 861800 kB |
| 1da177e4 | 470 | Mapped: 280372 kB |
| b88473f7 MS |
471 | Slab: 284364 kB |
| 472 | SReclaimable: 159856 kB | |
| 473 | SUnreclaim: 124508 kB | |
| 474 | PageTables: 24448 kB | |
| 475 | NFS_Unstable: 0 kB | |
| 476 | Bounce: 0 kB | |
| 477 | WritebackTmp: 0 kB | |
| 1da177e4 LT |
478 | CommitLimit: 7669796 kB |
| 479 | Committed_AS: 100056 kB | |
| 1da177e4 LT |
480 | VmallocTotal: 112216 kB |
| 481 | VmallocUsed: 428 kB | |
| 482 | VmallocChunk: 111088 kB | |
| 483 | ||
| 484 | MemTotal: Total usable ram (i.e. physical ram minus a few reserved | |
| 485 | bits and the kernel binary code) | |
| 486 | MemFree: The sum of LowFree+HighFree | |
| 487 | Buffers: Relatively temporary storage for raw disk blocks | |
| 488 | shouldn't get tremendously large (20MB or so) | |
| 489 | Cached: in-memory cache for files read from the disk (the | |
| 490 | pagecache). Doesn't include SwapCached | |
| 491 | SwapCached: Memory that once was swapped out, is swapped back in but | |
| 492 | still also is in the swapfile (if memory is needed it | |
| 493 | doesn't need to be swapped out AGAIN because it is already | |
| 494 | in the swapfile. This saves I/O) | |
| 495 | Active: Memory that has been used more recently and usually not | |
| 496 | reclaimed unless absolutely necessary. | |
| 497 | Inactive: Memory which has been less recently used. It is more | |
| 498 | eligible to be reclaimed for other purposes | |
| 499 | HighTotal: | |
| 500 | HighFree: Highmem is all memory above ~860MB of physical memory | |
| 501 | Highmem areas are for use by userspace programs, or | |
| 502 | for the pagecache. The kernel must use tricks to access | |
| 503 | this memory, making it slower to access than lowmem. | |
| 504 | LowTotal: | |
| 505 | LowFree: Lowmem is memory which can be used for everything that | |
| 3f6dee9b | 506 | highmem can be used for, but it is also available for the |
| 1da177e4 LT |
507 | kernel's use for its own data structures. Among many |
| 508 | other things, it is where everything from the Slab is | |
| 509 | allocated. Bad things happen when you're out of lowmem. | |
| 510 | SwapTotal: total amount of swap space available | |
| 511 | SwapFree: Memory which has been evicted from RAM, and is temporarily | |
| 512 | on the disk | |
| 513 | Dirty: Memory which is waiting to get written back to the disk | |
| 514 | Writeback: Memory which is actively being written back to the disk | |
| b88473f7 | 515 | AnonPages: Non-file backed pages mapped into userspace page tables |
| 1da177e4 | 516 | Mapped: files which have been mmaped, such as libraries |
| e82443c0 | 517 | Slab: in-kernel data structures cache |
| b88473f7 MS |
518 | SReclaimable: Part of Slab, that might be reclaimed, such as caches |
| 519 | SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure | |
| 520 | PageTables: amount of memory dedicated to the lowest level of page | |
| 521 | tables. | |
| 522 | NFS_Unstable: NFS pages sent to the server, but not yet committed to stable | |
| 523 | storage | |
| 524 | Bounce: Memory used for block device "bounce buffers" | |
| 525 | WritebackTmp: Memory used by FUSE for temporary writeback buffers | |
| 1da177e4 LT |
526 | CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'), |
| 527 | this is the total amount of memory currently available to | |
| 528 | be allocated on the system. This limit is only adhered to | |
| 529 | if strict overcommit accounting is enabled (mode 2 in | |
| 530 | 'vm.overcommit_memory'). | |
| 531 | The CommitLimit is calculated with the following formula: | |
| 532 | CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap | |
| 533 | For example, on a system with 1G of physical RAM and 7G | |
| 534 | of swap with a `vm.overcommit_ratio` of 30 it would | |
| 535 | yield a CommitLimit of 7.3G. | |
| 536 | For more details, see the memory overcommit documentation | |
| 537 | in vm/overcommit-accounting. | |
| 538 | Committed_AS: The amount of memory presently allocated on the system. | |
| 539 | The committed memory is a sum of all of the memory which | |
| 540 | has been allocated by processes, even if it has not been | |
| 541 | "used" by them as of yet. A process which malloc()'s 1G | |
| 542 | of memory, but only touches 300M of it will only show up | |
| 543 | as using 300M of memory even if it has the address space | |
| 544 | allocated for the entire 1G. This 1G is memory which has | |
| 545 | been "committed" to by the VM and can be used at any time | |
| 546 | by the allocating application. With strict overcommit | |
| 547 | enabled on the system (mode 2 in 'vm.overcommit_memory'), | |
| 548 | allocations which would exceed the CommitLimit (detailed | |
| 549 | above) will not be permitted. This is useful if one needs | |
| 550 | to guarantee that processes will not fail due to lack of | |
| 551 | memory once that memory has been successfully allocated. | |
| 1da177e4 LT |
552 | VmallocTotal: total size of vmalloc memory area |
| 553 | VmallocUsed: amount of vmalloc area which is used | |
| 554 | VmallocChunk: largest contigious block of vmalloc area which is free | |
| 555 | ||
| a47a126a ED |
556 | .............................................................................. |
| 557 | ||
| 558 | vmallocinfo: | |
| 559 | ||
| 560 | Provides information about vmalloced/vmaped areas. One line per area, | |
| 561 | containing the virtual address range of the area, size in bytes, | |
| 562 | caller information of the creator, and optional information depending | |
| 563 | on the kind of area : | |
| 564 | ||
| 565 | pages=nr number of pages | |
| 566 | phys=addr if a physical address was specified | |
| 567 | ioremap I/O mapping (ioremap() and friends) | |
| 568 | vmalloc vmalloc() area | |
| 569 | vmap vmap()ed pages | |
| 570 | user VM_USERMAP area | |
| 571 | vpages buffer for pages pointers was vmalloced (huge area) | |
| 572 | N<node>=nr (Only on NUMA kernels) | |
| 573 | Number of pages allocated on memory node <node> | |
| 574 | ||
| 575 | > cat /proc/vmallocinfo | |
| 576 | 0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ... | |
| 577 | /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128 | |
| 578 | 0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ... | |
| 579 | /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64 | |
| 580 | 0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f... | |
| 581 | phys=7fee8000 ioremap | |
| 582 | 0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f... | |
| 583 | phys=7fee7000 ioremap | |
| 584 | 0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210 | |
| 585 | 0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ... | |
| 586 | /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3 | |
| 587 | 0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ... | |
| 588 | pages=2 vmalloc N1=2 | |
| 589 | 0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ... | |
| 590 | /0x130 [x_tables] pages=4 vmalloc N0=4 | |
| 591 | 0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ... | |
| 592 | pages=14 vmalloc N2=14 | |
| 593 | 0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ... | |
| 594 | pages=4 vmalloc N1=4 | |
| 595 | 0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ... | |
| 596 | pages=2 vmalloc N1=2 | |
| 597 | 0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ... | |
| 598 | pages=10 vmalloc N0=10 | |
| 1da177e4 LT |
599 | |
| 600 | 1.3 IDE devices in /proc/ide | |
| 601 | ---------------------------- | |
| 602 | ||
| 603 | The subdirectory /proc/ide contains information about all IDE devices of which | |
| 604 | the kernel is aware. There is one subdirectory for each IDE controller, the | |
| 605 | file drivers and a link for each IDE device, pointing to the device directory | |
| 606 | in the controller specific subtree. | |
| 607 | ||
| 608 | The file drivers contains general information about the drivers used for the | |
| 609 | IDE devices: | |
| 610 | ||
| 611 | > cat /proc/ide/drivers | |
| 612 | ide-cdrom version 4.53 | |
| 613 | ide-disk version 1.08 | |
| 614 | ||
| 615 | More detailed information can be found in the controller specific | |
| 616 | subdirectories. These are named ide0, ide1 and so on. Each of these | |
| 18d96779 | 617 | directories contains the files shown in table 1-5. |
| 1da177e4 LT |
618 | |
| 619 | ||
| 18d96779 | 620 | Table 1-5: IDE controller info in /proc/ide/ide? |
| 1da177e4 LT |
621 | .............................................................................. |
| 622 | File Content | |
| 623 | channel IDE channel (0 or 1) | |
| 624 | config Configuration (only for PCI/IDE bridge) | |
| 625 | mate Mate name | |
| 626 | model Type/Chipset of IDE controller | |
| 627 | .............................................................................. | |
| 628 | ||
| 629 | Each device connected to a controller has a separate subdirectory in the | |
| 18d96779 | 630 | controllers directory. The files listed in table 1-6 are contained in these |
| 1da177e4 LT |
631 | directories. |
| 632 | ||
| 633 | ||
| 18d96779 | 634 | Table 1-6: IDE device information |
| 1da177e4 LT |
635 | .............................................................................. |
| 636 | File Content | |
| 637 | cache The cache | |
| 638 | capacity Capacity of the medium (in 512Byte blocks) | |
| 639 | driver driver and version | |
| 640 | geometry physical and logical geometry | |
| 641 | identify device identify block | |
| 642 | media media type | |
| 643 | model device identifier | |
| 644 | settings device setup | |
| 645 | smart_thresholds IDE disk management thresholds | |
| 646 | smart_values IDE disk management values | |
| 647 | .............................................................................. | |
| 648 | ||
| 649 | The most interesting file is settings. This file contains a nice overview of | |
| 650 | the drive parameters: | |
| 651 | ||
| 652 | # cat /proc/ide/ide0/hda/settings | |
| 653 | name value min max mode | |
| 654 | ---- ----- --- --- ---- | |
| 655 | bios_cyl 526 0 65535 rw | |
| 656 | bios_head 255 0 255 rw | |
| 657 | bios_sect 63 0 63 rw | |
| 658 | breada_readahead 4 0 127 rw | |
| 659 | bswap 0 0 1 r | |
| 660 | file_readahead 72 0 2097151 rw | |
| 661 | io_32bit 0 0 3 rw | |
| 662 | keepsettings 0 0 1 rw | |
| 663 | max_kb_per_request 122 1 127 rw | |
| 664 | multcount 0 0 8 rw | |
| 665 | nice1 1 0 1 rw | |
| 666 | nowerr 0 0 1 rw | |
| 667 | pio_mode write-only 0 255 w | |
| 668 | slow 0 0 1 rw | |
| 669 | unmaskirq 0 0 1 rw | |
| 670 | using_dma 0 0 1 rw | |
| 671 | ||
| 672 | ||
| 673 | 1.4 Networking info in /proc/net | |
| 674 | -------------------------------- | |
| 675 | ||
| 676 | The subdirectory /proc/net follows the usual pattern. Table 1-6 shows the | |
| 677 | additional values you get for IP version 6 if you configure the kernel to | |
| 678 | support this. Table 1-7 lists the files and their meaning. | |
| 679 | ||
| 680 | ||
| 681 | Table 1-6: IPv6 info in /proc/net | |
| 682 | .............................................................................. | |
| 683 | File Content | |
| 684 | udp6 UDP sockets (IPv6) | |
| 685 | tcp6 TCP sockets (IPv6) | |
| 686 | raw6 Raw device statistics (IPv6) | |
| 687 | igmp6 IP multicast addresses, which this host joined (IPv6) | |
| 688 | if_inet6 List of IPv6 interface addresses | |
| 689 | ipv6_route Kernel routing table for IPv6 | |
| 690 | rt6_stats Global IPv6 routing tables statistics | |
| 691 | sockstat6 Socket statistics (IPv6) | |
| 692 | snmp6 Snmp data (IPv6) | |
| 693 | .............................................................................. | |
| 694 | ||
| 695 | ||
| 696 | Table 1-7: Network info in /proc/net | |
| 697 | .............................................................................. | |
| 698 | File Content | |
| 699 | arp Kernel ARP table | |
| 700 | dev network devices with statistics | |
| 701 | dev_mcast the Layer2 multicast groups a device is listening too | |
| 702 | (interface index, label, number of references, number of bound | |
| 703 | addresses). | |
| 704 | dev_stat network device status | |
| 705 | ip_fwchains Firewall chain linkage | |
| 706 | ip_fwnames Firewall chain names | |
| 707 | ip_masq Directory containing the masquerading tables | |
| 708 | ip_masquerade Major masquerading table | |
| 709 | netstat Network statistics | |
| 710 | raw raw device statistics | |
| 711 | route Kernel routing table | |
| 712 | rpc Directory containing rpc info | |
| 713 | rt_cache Routing cache | |
| 714 | snmp SNMP data | |
| 715 | sockstat Socket statistics | |
| 716 | tcp TCP sockets | |
| 717 | tr_rif Token ring RIF routing table | |
| 718 | udp UDP sockets | |
| 719 | unix UNIX domain sockets | |
| 720 | wireless Wireless interface data (Wavelan etc) | |
| 721 | igmp IP multicast addresses, which this host joined | |
| 722 | psched Global packet scheduler parameters. | |
| 723 | netlink List of PF_NETLINK sockets | |
| 724 | ip_mr_vifs List of multicast virtual interfaces | |
| 725 | ip_mr_cache List of multicast routing cache | |
| 726 | .............................................................................. | |
| 727 | ||
| 728 | You can use this information to see which network devices are available in | |
| 729 | your system and how much traffic was routed over those devices: | |
| 730 | ||
| 731 | > cat /proc/net/dev | |
| 732 | Inter-|Receive |[... | |
| 733 | face |bytes packets errs drop fifo frame compressed multicast|[... | |
| 734 | lo: 908188 5596 0 0 0 0 0 0 [... | |
| 735 | ppp0:15475140 20721 410 0 0 410 0 0 [... | |
| 736 | eth0: 614530 7085 0 0 0 0 0 1 [... | |
| 737 | ||
| 738 | ...] Transmit | |
| 739 | ...] bytes packets errs drop fifo colls carrier compressed | |
| 740 | ...] 908188 5596 0 0 0 0 0 0 | |
| 741 | ...] 1375103 17405 0 0 0 0 0 0 | |
| 742 | ...] 1703981 5535 0 0 0 3 0 0 | |
| 743 | ||
| 744 | In addition, each Channel Bond interface has it's own directory. For | |
| 745 | example, the bond0 device will have a directory called /proc/net/bond0/. | |
| 746 | It will contain information that is specific to that bond, such as the | |
| 747 | current slaves of the bond, the link status of the slaves, and how | |
| 748 | many times the slaves link has failed. | |
| 749 | ||
| 750 | 1.5 SCSI info | |
| 751 | ------------- | |
| 752 | ||
| 753 | If you have a SCSI host adapter in your system, you'll find a subdirectory | |
| 754 | named after the driver for this adapter in /proc/scsi. You'll also see a list | |
| 755 | of all recognized SCSI devices in /proc/scsi: | |
| 756 | ||
| 757 | >cat /proc/scsi/scsi | |
| 758 | Attached devices: | |
| 759 | Host: scsi0 Channel: 00 Id: 00 Lun: 00 | |
| 760 | Vendor: IBM Model: DGHS09U Rev: 03E0 | |
| 761 | Type: Direct-Access ANSI SCSI revision: 03 | |
| 762 | Host: scsi0 Channel: 00 Id: 06 Lun: 00 | |
| 763 | Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04 | |
| 764 | Type: CD-ROM ANSI SCSI revision: 02 | |
| 765 | ||
| 766 | ||
| 767 | The directory named after the driver has one file for each adapter found in | |
| 768 | the system. These files contain information about the controller, including | |
| 769 | the used IRQ and the IO address range. The amount of information shown is | |
| 770 | dependent on the adapter you use. The example shows the output for an Adaptec | |
| 771 | AHA-2940 SCSI adapter: | |
| 772 | ||
| 773 | > cat /proc/scsi/aic7xxx/0 | |
| 774 | ||
| 775 | Adaptec AIC7xxx driver version: 5.1.19/3.2.4 | |
| 776 | Compile Options: | |
| 777 | TCQ Enabled By Default : Disabled | |
| 778 | AIC7XXX_PROC_STATS : Disabled | |
| 779 | AIC7XXX_RESET_DELAY : 5 | |
| 780 | Adapter Configuration: | |
| 781 | SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter | |
| 782 | Ultra Wide Controller | |
| 783 | PCI MMAPed I/O Base: 0xeb001000 | |
| 784 | Adapter SEEPROM Config: SEEPROM found and used. | |
| 785 | Adaptec SCSI BIOS: Enabled | |
| 786 | IRQ: 10 | |
| 787 | SCBs: Active 0, Max Active 2, | |
| 788 | Allocated 15, HW 16, Page 255 | |
| 789 | Interrupts: 160328 | |
| 790 | BIOS Control Word: 0x18b6 | |
| 791 | Adapter Control Word: 0x005b | |
| 792 | Extended Translation: Enabled | |
| 793 | Disconnect Enable Flags: 0xffff | |
| 794 | Ultra Enable Flags: 0x0001 | |
| 795 | Tag Queue Enable Flags: 0x0000 | |
| 796 | Ordered Queue Tag Flags: 0x0000 | |
| 797 | Default Tag Queue Depth: 8 | |
| 798 | Tagged Queue By Device array for aic7xxx host instance 0: | |
| 799 | {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255} | |
| 800 | Actual queue depth per device for aic7xxx host instance 0: | |
| 801 | {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1} | |
| 802 | Statistics: | |
| 803 | (scsi0:0:0:0) | |
| 804 | Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8 | |
| 805 | Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0) | |
| 806 | Total transfers 160151 (74577 reads and 85574 writes) | |
| 807 | (scsi0:0:6:0) | |
| 808 | Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15 | |
| 809 | Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0) | |
| 810 | Total transfers 0 (0 reads and 0 writes) | |
| 811 | ||
| 812 | ||
| 813 | 1.6 Parallel port info in /proc/parport | |
| 814 | --------------------------------------- | |
| 815 | ||
| 816 | The directory /proc/parport contains information about the parallel ports of | |
| 817 | your system. It has one subdirectory for each port, named after the port | |
| 818 | number (0,1,2,...). | |
| 819 | ||
| 820 | These directories contain the four files shown in Table 1-8. | |
| 821 | ||
| 822 | ||
| 823 | Table 1-8: Files in /proc/parport | |
| 824 | .............................................................................. | |
| 825 | File Content | |
| 826 | autoprobe Any IEEE-1284 device ID information that has been acquired. | |
| 827 | devices list of the device drivers using that port. A + will appear by the | |
| 828 | name of the device currently using the port (it might not appear | |
| 829 | against any). | |
| 830 | hardware Parallel port's base address, IRQ line and DMA channel. | |
| 831 | irq IRQ that parport is using for that port. This is in a separate | |
| 832 | file to allow you to alter it by writing a new value in (IRQ | |
| 833 | number or none). | |
| 834 | .............................................................................. | |
| 835 | ||
| 836 | 1.7 TTY info in /proc/tty | |
| 837 | ------------------------- | |
| 838 | ||
| 839 | Information about the available and actually used tty's can be found in the | |
| 840 | directory /proc/tty.You'll find entries for drivers and line disciplines in | |
| 841 | this directory, as shown in Table 1-9. | |
| 842 | ||
| 843 | ||
| 844 | Table 1-9: Files in /proc/tty | |
| 845 | .............................................................................. | |
| 846 | File Content | |
| 847 | drivers list of drivers and their usage | |
| 848 | ldiscs registered line disciplines | |
| 849 | driver/serial usage statistic and status of single tty lines | |
| 850 | .............................................................................. | |
| 851 | ||
| 852 | To see which tty's are currently in use, you can simply look into the file | |
| 853 | /proc/tty/drivers: | |
| 854 | ||
| 855 | > cat /proc/tty/drivers | |
| 856 | pty_slave /dev/pts 136 0-255 pty:slave | |
| 857 | pty_master /dev/ptm 128 0-255 pty:master | |
| 858 | pty_slave /dev/ttyp 3 0-255 pty:slave | |
| 859 | pty_master /dev/pty 2 0-255 pty:master | |
| 860 | serial /dev/cua 5 64-67 serial:callout | |
| 861 | serial /dev/ttyS 4 64-67 serial | |
| 862 | /dev/tty0 /dev/tty0 4 0 system:vtmaster | |
| 863 | /dev/ptmx /dev/ptmx 5 2 system | |
| 864 | /dev/console /dev/console 5 1 system:console | |
| 865 | /dev/tty /dev/tty 5 0 system:/dev/tty | |
| 866 | unknown /dev/tty 4 1-63 console | |
| 867 | ||
| 868 | ||
| 869 | 1.8 Miscellaneous kernel statistics in /proc/stat | |
| 870 | ------------------------------------------------- | |
| 871 | ||
| 872 | Various pieces of information about kernel activity are available in the | |
| 873 | /proc/stat file. All of the numbers reported in this file are aggregates | |
| 874 | since the system first booted. For a quick look, simply cat the file: | |
| 875 | ||
| 876 | > cat /proc/stat | |
| b68f2c3a LC |
877 | cpu 2255 34 2290 22625563 6290 127 456 0 |
| 878 | cpu0 1132 34 1441 11311718 3675 127 438 0 | |
| 879 | cpu1 1123 0 849 11313845 2614 0 18 0 | |
| 1da177e4 LT |
880 | intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...] |
| 881 | ctxt 1990473 | |
| 882 | btime 1062191376 | |
| 883 | processes 2915 | |
| 884 | procs_running 1 | |
| 885 | procs_blocked 0 | |
| 886 | ||
| 887 | The very first "cpu" line aggregates the numbers in all of the other "cpuN" | |
| 888 | lines. These numbers identify the amount of time the CPU has spent performing | |
| 889 | different kinds of work. Time units are in USER_HZ (typically hundredths of a | |
| 890 | second). The meanings of the columns are as follows, from left to right: | |
| 891 | ||
| 892 | - user: normal processes executing in user mode | |
| 893 | - nice: niced processes executing in user mode | |
| 894 | - system: processes executing in kernel mode | |
| 895 | - idle: twiddling thumbs | |
| 896 | - iowait: waiting for I/O to complete | |
| 897 | - irq: servicing interrupts | |
| 898 | - softirq: servicing softirqs | |
| b68f2c3a | 899 | - steal: involuntary wait |
| 1da177e4 LT |
900 | |
| 901 | The "intr" line gives counts of interrupts serviced since boot time, for each | |
| 902 | of the possible system interrupts. The first column is the total of all | |
| 903 | interrupts serviced; each subsequent column is the total for that particular | |
| 904 | interrupt. | |
| 905 | ||
| 906 | The "ctxt" line gives the total number of context switches across all CPUs. | |
| 907 | ||
| 908 | The "btime" line gives the time at which the system booted, in seconds since | |
| 909 | the Unix epoch. | |
| 910 | ||
| 911 | The "processes" line gives the number of processes and threads created, which | |
| 912 | includes (but is not limited to) those created by calls to the fork() and | |
| 913 | clone() system calls. | |
| 914 | ||
| 915 | The "procs_running" line gives the number of processes currently running on | |
| 916 | CPUs. | |
| 917 | ||
| 918 | The "procs_blocked" line gives the number of processes currently blocked, | |
| 919 | waiting for I/O to complete. | |
| 920 | ||
| 37515fac | 921 | |
| c9de560d AT |
922 | 1.9 Ext4 file system parameters |
| 923 | ------------------------------ | |
| 37515fac TT |
924 | |
| 925 | Information about mounted ext4 file systems can be found in | |
| 926 | /proc/fs/ext4. Each mounted filesystem will have a directory in | |
| 927 | /proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or | |
| 928 | /proc/fs/ext4/dm-0). The files in each per-device directory are shown | |
| 929 | in Table 1-10, below. | |
| 930 | ||
| 931 | Table 1-10: Files in /proc/fs/ext4/<devname> | |
| 932 | .............................................................................. | |
| 933 | File Content | |
| 934 | mb_groups details of multiblock allocator buddy cache of free blocks | |
| 935 | mb_history multiblock allocation history | |
| 37515fac TT |
936 | .............................................................................. |
| 937 | ||
| 1da177e4 LT |
938 | |
| 939 | ------------------------------------------------------------------------------ | |
| 940 | Summary | |
| 941 | ------------------------------------------------------------------------------ | |
| 942 | The /proc file system serves information about the running system. It not only | |
| 943 | allows access to process data but also allows you to request the kernel status | |
| 944 | by reading files in the hierarchy. | |
| 945 | ||
| 946 | The directory structure of /proc reflects the types of information and makes | |
| 947 | it easy, if not obvious, where to look for specific data. | |
| 948 | ------------------------------------------------------------------------------ | |
| 949 | ||
| 950 | ------------------------------------------------------------------------------ | |
| 951 | CHAPTER 2: MODIFYING SYSTEM PARAMETERS | |
| 952 | ------------------------------------------------------------------------------ | |
| 953 | ||
| 954 | ------------------------------------------------------------------------------ | |
| 955 | In This Chapter | |
| 956 | ------------------------------------------------------------------------------ | |
| 957 | * Modifying kernel parameters by writing into files found in /proc/sys | |
| 958 | * Exploring the files which modify certain parameters | |
| 959 | * Review of the /proc/sys file tree | |
| 960 | ------------------------------------------------------------------------------ | |
| 961 | ||
| 962 | ||
| 963 | A very interesting part of /proc is the directory /proc/sys. This is not only | |
| 964 | a source of information, it also allows you to change parameters within the | |
| 965 | kernel. Be very careful when attempting this. You can optimize your system, | |
| 966 | but you can also cause it to crash. Never alter kernel parameters on a | |
| 967 | production system. Set up a development machine and test to make sure that | |
| 968 | everything works the way you want it to. You may have no alternative but to | |
| 969 | reboot the machine once an error has been made. | |
| 970 | ||
| 971 | To change a value, simply echo the new value into the file. An example is | |
| 972 | given below in the section on the file system data. You need to be root to do | |
| 973 | this. You can create your own boot script to perform this every time your | |
| 974 | system boots. | |
| 975 | ||
| 976 | The files in /proc/sys can be used to fine tune and monitor miscellaneous and | |
| 977 | general things in the operation of the Linux kernel. Since some of the files | |
| 978 | can inadvertently disrupt your system, it is advisable to read both | |
| 979 | documentation and source before actually making adjustments. In any case, be | |
| 980 | very careful when writing to any of these files. The entries in /proc may | |
| 981 | change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt | |
| 982 | review the kernel documentation in the directory /usr/src/linux/Documentation. | |
| 983 | This chapter is heavily based on the documentation included in the pre 2.2 | |
| 984 | kernels, and became part of it in version 2.2.1 of the Linux kernel. | |
| 985 | ||
| 760df93e | 986 | Please see: Documentation/sysctls/ directory for descriptions of these |
| db0fb184 | 987 | entries. |
| 9d0243bc | 988 | |
| 760df93e SF |
989 | ------------------------------------------------------------------------------ |
| 990 | Summary | |
| 991 | ------------------------------------------------------------------------------ | |
| 992 | Certain aspects of kernel behavior can be modified at runtime, without the | |
| 993 | need to recompile the kernel, or even to reboot the system. The files in the | |
| 994 | /proc/sys tree can not only be read, but also modified. You can use the echo | |
| 995 | command to write value into these files, thereby changing the default settings | |
| 996 | of the kernel. | |
| 997 | ------------------------------------------------------------------------------ | |
| 9d0243bc | 998 | |
| 760df93e SF |
999 | ------------------------------------------------------------------------------ |
| 1000 | CHAPTER 3: PER-PROCESS PARAMETERS | |
| 1001 | ------------------------------------------------------------------------------ | |
| 1da177e4 | 1002 | |
| 760df93e | 1003 | 3.1 /proc/<pid>/oom_adj - Adjust the oom-killer score |
| d7ff0dbf JFM |
1004 | ------------------------------------------------------ |
| 1005 | ||
| 1006 | This file can be used to adjust the score used to select which processes | |
| 1007 | should be killed in an out-of-memory situation. Giving it a high score will | |
| 1008 | increase the likelihood of this process being killed by the oom-killer. Valid | |
| 1009 | values are in the range -16 to +15, plus the special value -17, which disables | |
| 1010 | oom-killing altogether for this process. | |
| 1011 | ||
| 9e9e3cbc EP |
1012 | The process to be killed in an out-of-memory situation is selected among all others |
| 1013 | based on its badness score. This value equals the original memory size of the process | |
| 1014 | and is then updated according to its CPU time (utime + stime) and the | |
| 1015 | run time (uptime - start time). The longer it runs the smaller is the score. | |
| 1016 | Badness score is divided by the square root of the CPU time and then by | |
| 1017 | the double square root of the run time. | |
| 1018 | ||
| 1019 | Swapped out tasks are killed first. Half of each child's memory size is added to | |
| 1020 | the parent's score if they do not share the same memory. Thus forking servers | |
| 1021 | are the prime candidates to be killed. Having only one 'hungry' child will make | |
| 1022 | parent less preferable than the child. | |
| 1023 | ||
| 1024 | /proc/<pid>/oom_score shows process' current badness score. | |
| 1025 | ||
| 1026 | The following heuristics are then applied: | |
| 1027 | * if the task was reniced, its score doubles | |
| 1028 | * superuser or direct hardware access tasks (CAP_SYS_ADMIN, CAP_SYS_RESOURCE | |
| 1029 | or CAP_SYS_RAWIO) have their score divided by 4 | |
| 1030 | * if oom condition happened in one cpuset and checked task does not belong | |
| 1031 | to it, its score is divided by 8 | |
| 1032 | * the resulting score is multiplied by two to the power of oom_adj, i.e. | |
| 1033 | points <<= oom_adj when it is positive and | |
| 1034 | points >>= -(oom_adj) otherwise | |
| 1035 | ||
| 1036 | The task with the highest badness score is then selected and its children | |
| 1037 | are killed, process itself will be killed in an OOM situation when it does | |
| 1038 | not have children or some of them disabled oom like described above. | |
| 1039 | ||
| 760df93e | 1040 | 3.2 /proc/<pid>/oom_score - Display current oom-killer score |
| d7ff0dbf JFM |
1041 | ------------------------------------------------------------- |
| 1042 | ||
| d7ff0dbf JFM |
1043 | This file can be used to check the current score used by the oom-killer is for |
| 1044 | any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which | |
| 1045 | process should be killed in an out-of-memory situation. | |
| 1da177e4 | 1046 | |
| f9c99463 | 1047 | |
| 760df93e | 1048 | 3.3 /proc/<pid>/io - Display the IO accounting fields |
| f9c99463 RK |
1049 | ------------------------------------------------------- |
| 1050 | ||
| 1051 | This file contains IO statistics for each running process | |
| 1052 | ||
| 1053 | Example | |
| 1054 | ------- | |
| 1055 | ||
| 1056 | test:/tmp # dd if=/dev/zero of=/tmp/test.dat & | |
| 1057 | [1] 3828 | |
| 1058 | ||
| 1059 | test:/tmp # cat /proc/3828/io | |
| 1060 | rchar: 323934931 | |
| 1061 | wchar: 323929600 | |
| 1062 | syscr: 632687 | |
| 1063 | syscw: 632675 | |
| 1064 | read_bytes: 0 | |
| 1065 | write_bytes: 323932160 | |
| 1066 | cancelled_write_bytes: 0 | |
| 1067 | ||
| 1068 | ||
| 1069 | Description | |
| 1070 | ----------- | |
| 1071 | ||
| 1072 | rchar | |
| 1073 | ----- | |
| 1074 | ||
| 1075 | I/O counter: chars read | |
| 1076 | The number of bytes which this task has caused to be read from storage. This | |
| 1077 | is simply the sum of bytes which this process passed to read() and pread(). | |
| 1078 | It includes things like tty IO and it is unaffected by whether or not actual | |
| 1079 | physical disk IO was required (the read might have been satisfied from | |
| 1080 | pagecache) | |
| 1081 | ||
| 1082 | ||
| 1083 | wchar | |
| 1084 | ----- | |
| 1085 | ||
| 1086 | I/O counter: chars written | |
| 1087 | The number of bytes which this task has caused, or shall cause to be written | |
| 1088 | to disk. Similar caveats apply here as with rchar. | |
| 1089 | ||
| 1090 | ||
| 1091 | syscr | |
| 1092 | ----- | |
| 1093 | ||
| 1094 | I/O counter: read syscalls | |
| 1095 | Attempt to count the number of read I/O operations, i.e. syscalls like read() | |
| 1096 | and pread(). | |
| 1097 | ||
| 1098 | ||
| 1099 | syscw | |
| 1100 | ----- | |
| 1101 | ||
| 1102 | I/O counter: write syscalls | |
| 1103 | Attempt to count the number of write I/O operations, i.e. syscalls like | |
| 1104 | write() and pwrite(). | |
| 1105 | ||
| 1106 | ||
| 1107 | read_bytes | |
| 1108 | ---------- | |
| 1109 | ||
| 1110 | I/O counter: bytes read | |
| 1111 | Attempt to count the number of bytes which this process really did cause to | |
| 1112 | be fetched from the storage layer. Done at the submit_bio() level, so it is | |
| 1113 | accurate for block-backed filesystems. <please add status regarding NFS and | |
| 1114 | CIFS at a later time> | |
| 1115 | ||
| 1116 | ||
| 1117 | write_bytes | |
| 1118 | ----------- | |
| 1119 | ||
| 1120 | I/O counter: bytes written | |
| 1121 | Attempt to count the number of bytes which this process caused to be sent to | |
| 1122 | the storage layer. This is done at page-dirtying time. | |
| 1123 | ||
| 1124 | ||
| 1125 | cancelled_write_bytes | |
| 1126 | --------------------- | |
| 1127 | ||
| 1128 | The big inaccuracy here is truncate. If a process writes 1MB to a file and | |
| 1129 | then deletes the file, it will in fact perform no writeout. But it will have | |
| 1130 | been accounted as having caused 1MB of write. | |
| 1131 | In other words: The number of bytes which this process caused to not happen, | |
| 1132 | by truncating pagecache. A task can cause "negative" IO too. If this task | |
| 1133 | truncates some dirty pagecache, some IO which another task has been accounted | |
| 1134 | for (in it's write_bytes) will not be happening. We _could_ just subtract that | |
| 1135 | from the truncating task's write_bytes, but there is information loss in doing | |
| 1136 | that. | |
| 1137 | ||
| 1138 | ||
| 1139 | Note | |
| 1140 | ---- | |
| 1141 | ||
| 1142 | At its current implementation state, this is a bit racy on 32-bit machines: if | |
| 1143 | process A reads process B's /proc/pid/io while process B is updating one of | |
| 1144 | those 64-bit counters, process A could see an intermediate result. | |
| 1145 | ||
| 1146 | ||
| 1147 | More information about this can be found within the taskstats documentation in | |
| 1148 | Documentation/accounting. | |
| 1149 | ||
| 760df93e | 1150 | 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings |
| bb90110d KH |
1151 | --------------------------------------------------------------- |
| 1152 | When a process is dumped, all anonymous memory is written to a core file as | |
| 1153 | long as the size of the core file isn't limited. But sometimes we don't want | |
| 1154 | to dump some memory segments, for example, huge shared memory. Conversely, | |
| 1155 | sometimes we want to save file-backed memory segments into a core file, not | |
| 1156 | only the individual files. | |
| 1157 | ||
| 1158 | /proc/<pid>/coredump_filter allows you to customize which memory segments | |
| 1159 | will be dumped when the <pid> process is dumped. coredump_filter is a bitmask | |
| 1160 | of memory types. If a bit of the bitmask is set, memory segments of the | |
| 1161 | corresponding memory type are dumped, otherwise they are not dumped. | |
| 1162 | ||
| e575f111 | 1163 | The following 7 memory types are supported: |
| bb90110d KH |
1164 | - (bit 0) anonymous private memory |
| 1165 | - (bit 1) anonymous shared memory | |
| 1166 | - (bit 2) file-backed private memory | |
| 1167 | - (bit 3) file-backed shared memory | |
| b261dfea HK |
1168 | - (bit 4) ELF header pages in file-backed private memory areas (it is |
| 1169 | effective only if the bit 2 is cleared) | |
| e575f111 KM |
1170 | - (bit 5) hugetlb private memory |
| 1171 | - (bit 6) hugetlb shared memory | |
| bb90110d KH |
1172 | |
| 1173 | Note that MMIO pages such as frame buffer are never dumped and vDSO pages | |
| 1174 | are always dumped regardless of the bitmask status. | |
| 1175 | ||
| e575f111 KM |
1176 | Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only |
| 1177 | effected by bit 5-6. | |
| 1178 | ||
| 1179 | Default value of coredump_filter is 0x23; this means all anonymous memory | |
| 1180 | segments and hugetlb private memory are dumped. | |
| bb90110d KH |
1181 | |
| 1182 | If you don't want to dump all shared memory segments attached to pid 1234, | |
| e575f111 | 1183 | write 0x21 to the process's proc file. |
| bb90110d | 1184 | |
| e575f111 | 1185 | $ echo 0x21 > /proc/1234/coredump_filter |
| bb90110d KH |
1186 | |
| 1187 | When a new process is created, the process inherits the bitmask status from its | |
| 1188 | parent. It is useful to set up coredump_filter before the program runs. | |
| 1189 | For example: | |
| 1190 | ||
| 1191 | $ echo 0x7 > /proc/self/coredump_filter | |
| 1192 | $ ./some_program | |
| 1193 | ||
| 760df93e | 1194 | 3.5 /proc/<pid>/mountinfo - Information about mounts |
| 2d4d4864 RP |
1195 | -------------------------------------------------------- |
| 1196 | ||
| 1197 | This file contains lines of the form: | |
| 1198 | ||
| 1199 | 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue | |
| 1200 | (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) | |
| 1201 | ||
| 1202 | (1) mount ID: unique identifier of the mount (may be reused after umount) | |
| 1203 | (2) parent ID: ID of parent (or of self for the top of the mount tree) | |
| 1204 | (3) major:minor: value of st_dev for files on filesystem | |
| 1205 | (4) root: root of the mount within the filesystem | |
| 1206 | (5) mount point: mount point relative to the process's root | |
| 1207 | (6) mount options: per mount options | |
| 1208 | (7) optional fields: zero or more fields of the form "tag[:value]" | |
| 1209 | (8) separator: marks the end of the optional fields | |
| 1210 | (9) filesystem type: name of filesystem of the form "type[.subtype]" | |
| 1211 | (10) mount source: filesystem specific information or "none" | |
| 1212 | (11) super options: per super block options | |
| 1213 | ||
| 1214 | Parsers should ignore all unrecognised optional fields. Currently the | |
| 1215 | possible optional fields are: | |
| 1216 | ||
| 1217 | shared:X mount is shared in peer group X | |
| 1218 | master:X mount is slave to peer group X | |
| 97e7e0f7 | 1219 | propagate_from:X mount is slave and receives propagation from peer group X (*) |
| 2d4d4864 RP |
1220 | unbindable mount is unbindable |
| 1221 | ||
| 97e7e0f7 MS |
1222 | (*) X is the closest dominant peer group under the process's root. If |
| 1223 | X is the immediate master of the mount, or if there's no dominant peer | |
| 1224 | group under the same root, then only the "master:X" field is present | |
| 1225 | and not the "propagate_from:X" field. | |
| 1226 | ||
| 2d4d4864 RP |
1227 | For more information on mount propagation see: |
| 1228 | ||
| 1229 | Documentation/filesystems/sharedsubtree.txt | |
| 1230 |