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2264 lines
95 KiB
.. SPDX-License-Identifier: GPL-2.0 |
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==================== |
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The /proc Filesystem |
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==================== |
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|
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===================== ======================================= ================ |
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/proc/sys Terrehon Bowden <[email protected]>, October 7 1999 |
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Bodo Bauer <[email protected]> |
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2.4.x update Jorge Nerin <[email protected]> November 14 2000 |
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move /proc/sys Shen Feng <[email protected]> April 1 2009 |
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fixes/update part 1.1 Stefani Seibold <[email protected]> June 9 2009 |
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===================== ======================================= ================ |
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.. Table of Contents |
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0 Preface |
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0.1 Introduction/Credits |
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0.2 Legal Stuff |
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1 Collecting System Information |
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1.1 Process-Specific Subdirectories |
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1.2 Kernel data |
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1.3 IDE devices in /proc/ide |
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1.4 Networking info in /proc/net |
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1.5 SCSI info |
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1.6 Parallel port info in /proc/parport |
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1.7 TTY info in /proc/tty |
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1.8 Miscellaneous kernel statistics in /proc/stat |
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1.9 Ext4 file system parameters |
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2 Modifying System Parameters |
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3 Per-Process Parameters |
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3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer |
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score |
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3.2 /proc/<pid>/oom_score - Display current oom-killer score |
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3.3 /proc/<pid>/io - Display the IO accounting fields |
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3.4 /proc/<pid>/coredump_filter - Core dump filtering settings |
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3.5 /proc/<pid>/mountinfo - Information about mounts |
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3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm |
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3.7 /proc/<pid>/task/<tid>/children - Information about task children |
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3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file |
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3.9 /proc/<pid>/map_files - Information about memory mapped files |
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3.10 /proc/<pid>/timerslack_ns - Task timerslack value |
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3.11 /proc/<pid>/patch_state - Livepatch patch operation state |
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3.12 /proc/<pid>/arch_status - Task architecture specific information |
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4 Configuring procfs |
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4.1 Mount options |
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5 Filesystem behavior |
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Preface |
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======= |
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0.1 Introduction/Credits |
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------------------------ |
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|
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This documentation is part of a soon (or so we hope) to be released book on |
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the SuSE Linux distribution. As there is no complete documentation for the |
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/proc file system and we've used many freely available sources to write these |
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chapters, it seems only fair to give the work back to the Linux community. |
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This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm |
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afraid it's still far from complete, but we hope it will be useful. As far as |
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we know, it is the first 'all-in-one' document about the /proc file system. It |
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is focused on the Intel x86 hardware, so if you are looking for PPC, ARM, |
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SPARC, AXP, etc., features, you probably won't find what you are looking for. |
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It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But |
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additions and patches are welcome and will be added to this document if you |
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mail them to Bodo. |
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We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of |
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other people for help compiling this documentation. We'd also like to extend a |
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special thank you to Andi Kleen for documentation, which we relied on heavily |
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to create this document, as well as the additional information he provided. |
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Thanks to everybody else who contributed source or docs to the Linux kernel |
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and helped create a great piece of software... :) |
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If you have any comments, corrections or additions, please don't hesitate to |
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contact Bodo Bauer at [email protected]. We'll be happy to add them to this |
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document. |
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The latest version of this document is available online at |
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http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html |
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If the above direction does not works for you, you could try the kernel |
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mailing list at [email protected] and/or try to reach me at |
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[email protected]. |
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0.2 Legal Stuff |
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--------------- |
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We don't guarantee the correctness of this document, and if you come to us |
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complaining about how you screwed up your system because of incorrect |
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documentation, we won't feel responsible... |
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Chapter 1: Collecting System Information |
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======================================== |
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In This Chapter |
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--------------- |
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* Investigating the properties of the pseudo file system /proc and its |
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ability to provide information on the running Linux system |
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* Examining /proc's structure |
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* Uncovering various information about the kernel and the processes running |
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on the system |
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------------------------------------------------------------------------------ |
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The proc file system acts as an interface to internal data structures in the |
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kernel. It can be used to obtain information about the system and to change |
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certain kernel parameters at runtime (sysctl). |
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First, we'll take a look at the read-only parts of /proc. In Chapter 2, we |
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show you how you can use /proc/sys to change settings. |
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1.1 Process-Specific Subdirectories |
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----------------------------------- |
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The directory /proc contains (among other things) one subdirectory for each |
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process running on the system, which is named after the process ID (PID). |
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The link 'self' points to the process reading the file system. Each process |
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subdirectory has the entries listed in Table 1-1. |
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Note that an open file descriptor to /proc/<pid> or to any of its |
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contained files or subdirectories does not prevent <pid> being reused |
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for some other process in the event that <pid> exits. Operations on |
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open /proc/<pid> file descriptors corresponding to dead processes |
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never act on any new process that the kernel may, through chance, have |
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also assigned the process ID <pid>. Instead, operations on these FDs |
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usually fail with ESRCH. |
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.. table:: Table 1-1: Process specific entries in /proc |
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============= =============================================================== |
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File Content |
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============= =============================================================== |
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clear_refs Clears page referenced bits shown in smaps output |
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cmdline Command line arguments |
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cpu Current and last cpu in which it was executed (2.4)(smp) |
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cwd Link to the current working directory |
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environ Values of environment variables |
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exe Link to the executable of this process |
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fd Directory, which contains all file descriptors |
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maps Memory maps to executables and library files (2.4) |
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mem Memory held by this process |
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root Link to the root directory of this process |
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stat Process status |
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statm Process memory status information |
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status Process status in human readable form |
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wchan Present with CONFIG_KALLSYMS=y: it shows the kernel function |
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symbol the task is blocked in - or "0" if not blocked. |
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pagemap Page table |
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stack Report full stack trace, enable via CONFIG_STACKTRACE |
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smaps An extension based on maps, showing the memory consumption of |
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each mapping and flags associated with it |
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smaps_rollup Accumulated smaps stats for all mappings of the process. This |
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can be derived from smaps, but is faster and more convenient |
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numa_maps An extension based on maps, showing the memory locality and |
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binding policy as well as mem usage (in pages) of each mapping. |
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============= =============================================================== |
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For example, to get the status information of a process, all you have to do is |
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read the file /proc/PID/status:: |
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>cat /proc/self/status |
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Name: cat |
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State: R (running) |
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Tgid: 5452 |
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Pid: 5452 |
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PPid: 743 |
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TracerPid: 0 (2.4) |
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Uid: 501 501 501 501 |
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Gid: 100 100 100 100 |
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FDSize: 256 |
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Groups: 100 14 16 |
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VmPeak: 5004 kB |
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VmSize: 5004 kB |
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VmLck: 0 kB |
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VmHWM: 476 kB |
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VmRSS: 476 kB |
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RssAnon: 352 kB |
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RssFile: 120 kB |
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RssShmem: 4 kB |
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VmData: 156 kB |
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VmStk: 88 kB |
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VmExe: 68 kB |
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VmLib: 1412 kB |
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VmPTE: 20 kb |
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VmSwap: 0 kB |
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HugetlbPages: 0 kB |
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CoreDumping: 0 |
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THP_enabled: 1 |
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Threads: 1 |
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SigQ: 0/28578 |
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SigPnd: 0000000000000000 |
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ShdPnd: 0000000000000000 |
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SigBlk: 0000000000000000 |
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SigIgn: 0000000000000000 |
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SigCgt: 0000000000000000 |
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CapInh: 00000000fffffeff |
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CapPrm: 0000000000000000 |
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CapEff: 0000000000000000 |
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CapBnd: ffffffffffffffff |
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CapAmb: 0000000000000000 |
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NoNewPrivs: 0 |
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Seccomp: 0 |
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Speculation_Store_Bypass: thread vulnerable |
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SpeculationIndirectBranch: conditional enabled |
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voluntary_ctxt_switches: 0 |
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nonvoluntary_ctxt_switches: 1 |
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This shows you nearly the same information you would get if you viewed it with |
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the ps command. In fact, ps uses the proc file system to obtain its |
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information. But you get a more detailed view of the process by reading the |
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file /proc/PID/status. It fields are described in table 1-2. |
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The statm file contains more detailed information about the process |
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memory usage. Its seven fields are explained in Table 1-3. The stat file |
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contains detailed information about the process itself. Its fields are |
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explained in Table 1-4. |
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(for SMP CONFIG users) |
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For making accounting scalable, RSS related information are handled in an |
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asynchronous manner and the value may not be very precise. To see a precise |
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snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table. |
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It's slow but very precise. |
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.. table:: Table 1-2: Contents of the status files (as of 4.19) |
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========================== =================================================== |
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Field Content |
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========================== =================================================== |
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Name filename of the executable |
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Umask file mode creation mask |
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State state (R is running, S is sleeping, D is sleeping |
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in an uninterruptible wait, Z is zombie, |
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T is traced or stopped) |
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Tgid thread group ID |
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Ngid NUMA group ID (0 if none) |
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Pid process id |
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PPid process id of the parent process |
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TracerPid PID of process tracing this process (0 if not) |
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Uid Real, effective, saved set, and file system UIDs |
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Gid Real, effective, saved set, and file system GIDs |
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FDSize number of file descriptor slots currently allocated |
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Groups supplementary group list |
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NStgid descendant namespace thread group ID hierarchy |
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NSpid descendant namespace process ID hierarchy |
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NSpgid descendant namespace process group ID hierarchy |
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NSsid descendant namespace session ID hierarchy |
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VmPeak peak virtual memory size |
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VmSize total program size |
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VmLck locked memory size |
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VmPin pinned memory size |
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VmHWM peak resident set size ("high water mark") |
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VmRSS size of memory portions. It contains the three |
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following parts |
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(VmRSS = RssAnon + RssFile + RssShmem) |
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RssAnon size of resident anonymous memory |
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RssFile size of resident file mappings |
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RssShmem size of resident shmem memory (includes SysV shm, |
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mapping of tmpfs and shared anonymous mappings) |
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VmData size of private data segments |
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VmStk size of stack segments |
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VmExe size of text segment |
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VmLib size of shared library code |
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VmPTE size of page table entries |
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VmSwap amount of swap used by anonymous private data |
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(shmem swap usage is not included) |
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HugetlbPages size of hugetlb memory portions |
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CoreDumping process's memory is currently being dumped |
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(killing the process may lead to a corrupted core) |
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THP_enabled process is allowed to use THP (returns 0 when |
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PR_SET_THP_DISABLE is set on the process |
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Threads number of threads |
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SigQ number of signals queued/max. number for queue |
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SigPnd bitmap of pending signals for the thread |
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ShdPnd bitmap of shared pending signals for the process |
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SigBlk bitmap of blocked signals |
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SigIgn bitmap of ignored signals |
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SigCgt bitmap of caught signals |
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CapInh bitmap of inheritable capabilities |
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CapPrm bitmap of permitted capabilities |
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CapEff bitmap of effective capabilities |
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CapBnd bitmap of capabilities bounding set |
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CapAmb bitmap of ambient capabilities |
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NoNewPrivs no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...) |
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Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...) |
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Speculation_Store_Bypass speculative store bypass mitigation status |
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SpeculationIndirectBranch indirect branch speculation mode |
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Cpus_allowed mask of CPUs on which this process may run |
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Cpus_allowed_list Same as previous, but in "list format" |
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Mems_allowed mask of memory nodes allowed to this process |
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Mems_allowed_list Same as previous, but in "list format" |
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voluntary_ctxt_switches number of voluntary context switches |
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nonvoluntary_ctxt_switches number of non voluntary context switches |
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========================== =================================================== |
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.. table:: Table 1-3: Contents of the statm files (as of 2.6.8-rc3) |
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======== =============================== ============================== |
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Field Content |
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======== =============================== ============================== |
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size total program size (pages) (same as VmSize in status) |
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resident size of memory portions (pages) (same as VmRSS in status) |
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shared number of pages that are shared (i.e. backed by a file, same |
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as RssFile+RssShmem in status) |
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trs number of pages that are 'code' (not including libs; broken, |
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includes data segment) |
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lrs number of pages of library (always 0 on 2.6) |
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drs number of pages of data/stack (including libs; broken, |
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includes library text) |
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dt number of dirty pages (always 0 on 2.6) |
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======== =============================== ============================== |
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.. table:: Table 1-4: Contents of the stat files (as of 2.6.30-rc7) |
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============= =============================================================== |
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Field Content |
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============= =============================================================== |
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pid process id |
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tcomm filename of the executable |
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state state (R is running, S is sleeping, D is sleeping in an |
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uninterruptible wait, Z is zombie, T is traced or stopped) |
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ppid process id of the parent process |
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pgrp pgrp of the process |
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sid session id |
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tty_nr tty the process uses |
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tty_pgrp pgrp of the tty |
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flags task flags |
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min_flt number of minor faults |
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cmin_flt number of minor faults with child's |
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maj_flt number of major faults |
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cmaj_flt number of major faults with child's |
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utime user mode jiffies |
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stime kernel mode jiffies |
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cutime user mode jiffies with child's |
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cstime kernel mode jiffies with child's |
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priority priority level |
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nice nice level |
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num_threads number of threads |
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it_real_value (obsolete, always 0) |
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start_time time the process started after system boot |
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vsize virtual memory size |
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rss resident set memory size |
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rsslim current limit in bytes on the rss |
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start_code address above which program text can run |
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end_code address below which program text can run |
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start_stack address of the start of the main process stack |
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esp current value of ESP |
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eip current value of EIP |
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pending bitmap of pending signals |
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blocked bitmap of blocked signals |
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sigign bitmap of ignored signals |
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sigcatch bitmap of caught signals |
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0 (place holder, used to be the wchan address, |
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use /proc/PID/wchan instead) |
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0 (place holder) |
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0 (place holder) |
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exit_signal signal to send to parent thread on exit |
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task_cpu which CPU the task is scheduled on |
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rt_priority realtime priority |
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policy scheduling policy (man sched_setscheduler) |
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blkio_ticks time spent waiting for block IO |
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gtime guest time of the task in jiffies |
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cgtime guest time of the task children in jiffies |
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start_data address above which program data+bss is placed |
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end_data address below which program data+bss is placed |
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start_brk address above which program heap can be expanded with brk() |
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arg_start address above which program command line is placed |
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arg_end address below which program command line is placed |
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env_start address above which program environment is placed |
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env_end address below which program environment is placed |
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exit_code the thread's exit_code in the form reported by the waitpid |
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system call |
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============= =============================================================== |
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The /proc/PID/maps file contains the currently mapped memory regions and |
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their access permissions. |
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The format is:: |
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address perms offset dev inode pathname |
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08048000-08049000 r-xp 00000000 03:00 8312 /opt/test |
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08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test |
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0804a000-0806b000 rw-p 00000000 00:00 0 [heap] |
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a7cb1000-a7cb2000 ---p 00000000 00:00 0 |
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a7cb2000-a7eb2000 rw-p 00000000 00:00 0 |
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a7eb2000-a7eb3000 ---p 00000000 00:00 0 |
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a7eb3000-a7ed5000 rw-p 00000000 00:00 0 |
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a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6 |
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a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6 |
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a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6 |
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a800b000-a800e000 rw-p 00000000 00:00 0 |
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a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0 |
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a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0 |
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a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0 |
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a8024000-a8027000 rw-p 00000000 00:00 0 |
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a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2 |
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a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2 |
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a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2 |
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aff35000-aff4a000 rw-p 00000000 00:00 0 [stack] |
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ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso] |
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|
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where "address" is the address space in the process that it occupies, "perms" |
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is a set of permissions:: |
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|
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r = read |
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w = write |
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x = execute |
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s = shared |
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p = private (copy on write) |
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"offset" is the offset into the mapping, "dev" is the device (major:minor), and |
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"inode" is the inode on that device. 0 indicates that no inode is associated |
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with the memory region, as the case would be with BSS (uninitialized data). |
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The "pathname" shows the name associated file for this mapping. If the mapping |
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is not associated with a file: |
|
|
|
============= ==================================== |
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[heap] the heap of the program |
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[stack] the stack of the main process |
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[vdso] the "virtual dynamic shared object", |
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the kernel system call handler |
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[anon:<name>] an anonymous mapping that has been |
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named by userspace |
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============= ==================================== |
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|
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or if empty, the mapping is anonymous. |
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|
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The /proc/PID/smaps is an extension based on maps, showing the memory |
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consumption for each of the process's mappings. For each mapping (aka Virtual |
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Memory Area, or VMA) there is a series of lines such as the following:: |
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08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash |
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Size: 1084 kB |
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KernelPageSize: 4 kB |
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MMUPageSize: 4 kB |
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Rss: 892 kB |
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Pss: 374 kB |
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Shared_Clean: 892 kB |
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Shared_Dirty: 0 kB |
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Private_Clean: 0 kB |
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Private_Dirty: 0 kB |
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Referenced: 892 kB |
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Anonymous: 0 kB |
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LazyFree: 0 kB |
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AnonHugePages: 0 kB |
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ShmemPmdMapped: 0 kB |
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Shared_Hugetlb: 0 kB |
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Private_Hugetlb: 0 kB |
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Swap: 0 kB |
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SwapPss: 0 kB |
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KernelPageSize: 4 kB |
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MMUPageSize: 4 kB |
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Locked: 0 kB |
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THPeligible: 0 |
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VmFlags: rd ex mr mw me dw |
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|
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The first of these lines shows the same information as is displayed for the |
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mapping in /proc/PID/maps. Following lines show the size of the mapping |
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(size); the size of each page allocated when backing a VMA (KernelPageSize), |
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which is usually the same as the size in the page table entries; the page size |
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used by the MMU when backing a VMA (in most cases, the same as KernelPageSize); |
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the amount of the mapping that is currently resident in RAM (RSS); the |
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process' proportional share of this mapping (PSS); and the number of clean and |
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dirty shared and private pages in the mapping. |
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|
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The "proportional set size" (PSS) of a process is the count of pages it has |
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in memory, where each page is divided by the number of processes sharing it. |
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So if a process has 1000 pages all to itself, and 1000 shared with one other |
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process, its PSS will be 1500. |
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|
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Note that even a page which is part of a MAP_SHARED mapping, but has only |
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a single pte mapped, i.e. is currently used by only one process, is accounted |
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as private and not as shared. |
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|
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"Referenced" indicates the amount of memory currently marked as referenced or |
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accessed. |
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|
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"Anonymous" shows the amount of memory that does not belong to any file. Even |
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a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE |
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and a page is modified, the file page is replaced by a private anonymous copy. |
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|
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"LazyFree" shows the amount of memory which is marked by madvise(MADV_FREE). |
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The memory isn't freed immediately with madvise(). It's freed in memory |
|
pressure if the memory is clean. Please note that the printed value might |
|
be lower than the real value due to optimizations used in the current |
|
implementation. If this is not desirable please file a bug report. |
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|
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"AnonHugePages" shows the ammount of memory backed by transparent hugepage. |
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|
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"ShmemPmdMapped" shows the ammount of shared (shmem/tmpfs) memory backed by |
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huge pages. |
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|
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"Shared_Hugetlb" and "Private_Hugetlb" show the ammounts of memory backed by |
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hugetlbfs page which is *not* counted in "RSS" or "PSS" field for historical |
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reasons. And these are not included in {Shared,Private}_{Clean,Dirty} field. |
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|
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"Swap" shows how much would-be-anonymous memory is also used, but out on swap. |
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|
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For shmem mappings, "Swap" includes also the size of the mapped (and not |
|
replaced by copy-on-write) part of the underlying shmem object out on swap. |
|
"SwapPss" shows proportional swap share of this mapping. Unlike "Swap", this |
|
does not take into account swapped out page of underlying shmem objects. |
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"Locked" indicates whether the mapping is locked in memory or not. |
|
"THPeligible" indicates whether the mapping is eligible for allocating THP |
|
pages - 1 if true, 0 otherwise. It just shows the current status. |
|
|
|
"VmFlags" field deserves a separate description. This member represents the |
|
kernel flags associated with the particular virtual memory area in two letter |
|
encoded manner. The codes are the following: |
|
|
|
== ======================================= |
|
rd readable |
|
wr writeable |
|
ex executable |
|
sh shared |
|
mr may read |
|
mw may write |
|
me may execute |
|
ms may share |
|
gd stack segment growns down |
|
pf pure PFN range |
|
dw disabled write to the mapped file |
|
lo pages are locked in memory |
|
io memory mapped I/O area |
|
sr sequential read advise provided |
|
rr random read advise provided |
|
dc do not copy area on fork |
|
de do not expand area on remapping |
|
ac area is accountable |
|
nr swap space is not reserved for the area |
|
ht area uses huge tlb pages |
|
sf synchronous page fault |
|
ar architecture specific flag |
|
wf wipe on fork |
|
dd do not include area into core dump |
|
sd soft dirty flag |
|
mm mixed map area |
|
hg huge page advise flag |
|
nh no huge page advise flag |
|
mg mergable advise flag |
|
bt arm64 BTI guarded page |
|
mt arm64 MTE allocation tags are enabled |
|
um userfaultfd missing tracking |
|
uw userfaultfd wr-protect tracking |
|
== ======================================= |
|
|
|
Note that there is no guarantee that every flag and associated mnemonic will |
|
be present in all further kernel releases. Things get changed, the flags may |
|
be vanished or the reverse -- new added. Interpretation of their meaning |
|
might change in future as well. So each consumer of these flags has to |
|
follow each specific kernel version for the exact semantic. |
|
|
|
This file is only present if the CONFIG_MMU kernel configuration option is |
|
enabled. |
|
|
|
Note: reading /proc/PID/maps or /proc/PID/smaps is inherently racy (consistent |
|
output can be achieved only in the single read call). |
|
|
|
This typically manifests when doing partial reads of these files while the |
|
memory map is being modified. Despite the races, we do provide the following |
|
guarantees: |
|
|
|
1) The mapped addresses never go backwards, which implies no two |
|
regions will ever overlap. |
|
2) If there is something at a given vaddr during the entirety of the |
|
life of the smaps/maps walk, there will be some output for it. |
|
|
|
The /proc/PID/smaps_rollup file includes the same fields as /proc/PID/smaps, |
|
but their values are the sums of the corresponding values for all mappings of |
|
the process. Additionally, it contains these fields: |
|
|
|
- Pss_Anon |
|
- Pss_File |
|
- Pss_Shmem |
|
|
|
They represent the proportional shares of anonymous, file, and shmem pages, as |
|
described for smaps above. These fields are omitted in smaps since each |
|
mapping identifies the type (anon, file, or shmem) of all pages it contains. |
|
Thus all information in smaps_rollup can be derived from smaps, but at a |
|
significantly higher cost. |
|
|
|
The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG |
|
bits on both physical and virtual pages associated with a process, and the |
|
soft-dirty bit on pte (see Documentation/admin-guide/mm/soft-dirty.rst |
|
for details). |
|
To clear the bits for all the pages associated with the process:: |
|
|
|
> echo 1 > /proc/PID/clear_refs |
|
|
|
To clear the bits for the anonymous pages associated with the process:: |
|
|
|
> echo 2 > /proc/PID/clear_refs |
|
|
|
To clear the bits for the file mapped pages associated with the process:: |
|
|
|
> echo 3 > /proc/PID/clear_refs |
|
|
|
To clear the soft-dirty bit:: |
|
|
|
> echo 4 > /proc/PID/clear_refs |
|
|
|
To reset the peak resident set size ("high water mark") to the process's |
|
current value:: |
|
|
|
> echo 5 > /proc/PID/clear_refs |
|
|
|
Any other value written to /proc/PID/clear_refs will have no effect. |
|
|
|
The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags |
|
using /proc/kpageflags and number of times a page is mapped using |
|
/proc/kpagecount. For detailed explanation, see |
|
Documentation/admin-guide/mm/pagemap.rst. |
|
|
|
The /proc/pid/numa_maps is an extension based on maps, showing the memory |
|
locality and binding policy, as well as the memory usage (in pages) of |
|
each mapping. The output follows a general format where mapping details get |
|
summarized separated by blank spaces, one mapping per each file line:: |
|
|
|
address policy mapping details |
|
|
|
00400000 default file=/usr/local/bin/app mapped=1 active=0 N3=1 kernelpagesize_kB=4 |
|
00600000 default file=/usr/local/bin/app anon=1 dirty=1 N3=1 kernelpagesize_kB=4 |
|
3206000000 default file=/lib64/ld-2.12.so mapped=26 mapmax=6 N0=24 N3=2 kernelpagesize_kB=4 |
|
320621f000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4 |
|
3206220000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4 |
|
3206221000 default anon=1 dirty=1 N3=1 kernelpagesize_kB=4 |
|
3206800000 default file=/lib64/libc-2.12.so mapped=59 mapmax=21 active=55 N0=41 N3=18 kernelpagesize_kB=4 |
|
320698b000 default file=/lib64/libc-2.12.so |
|
3206b8a000 default file=/lib64/libc-2.12.so anon=2 dirty=2 N3=2 kernelpagesize_kB=4 |
|
3206b8e000 default file=/lib64/libc-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4 |
|
3206b8f000 default anon=3 dirty=3 active=1 N3=3 kernelpagesize_kB=4 |
|
7f4dc10a2000 default anon=3 dirty=3 N3=3 kernelpagesize_kB=4 |
|
7f4dc10b4000 default anon=2 dirty=2 active=1 N3=2 kernelpagesize_kB=4 |
|
7f4dc1200000 default file=/anon_hugepage\040(deleted) huge anon=1 dirty=1 N3=1 kernelpagesize_kB=2048 |
|
7fff335f0000 default stack anon=3 dirty=3 N3=3 kernelpagesize_kB=4 |
|
7fff3369d000 default mapped=1 mapmax=35 active=0 N3=1 kernelpagesize_kB=4 |
|
|
|
Where: |
|
|
|
"address" is the starting address for the mapping; |
|
|
|
"policy" reports the NUMA memory policy set for the mapping (see Documentation/admin-guide/mm/numa_memory_policy.rst); |
|
|
|
"mapping details" summarizes mapping data such as mapping type, page usage counters, |
|
node locality page counters (N0 == node0, N1 == node1, ...) and the kernel page |
|
size, in KB, that is backing the mapping up. |
|
|
|
1.2 Kernel data |
|
--------------- |
|
|
|
Similar to the process entries, the kernel data files give information about |
|
the running kernel. The files used to obtain this information are contained in |
|
/proc and are listed in Table 1-5. Not all of these will be present in your |
|
system. It depends on the kernel configuration and the loaded modules, which |
|
files are there, and which are missing. |
|
|
|
.. table:: Table 1-5: Kernel info in /proc |
|
|
|
============ =============================================================== |
|
File Content |
|
============ =============================================================== |
|
apm Advanced power management info |
|
buddyinfo Kernel memory allocator information (see text) (2.5) |
|
bus Directory containing bus specific information |
|
cmdline Kernel command line |
|
cpuinfo Info about the CPU |
|
devices Available devices (block and character) |
|
dma Used DMS channels |
|
filesystems Supported filesystems |
|
driver Various drivers grouped here, currently rtc (2.4) |
|
execdomains Execdomains, related to security (2.4) |
|
fb Frame Buffer devices (2.4) |
|
fs File system parameters, currently nfs/exports (2.4) |
|
ide Directory containing info about the IDE subsystem |
|
interrupts Interrupt usage |
|
iomem Memory map (2.4) |
|
ioports I/O port usage |
|
irq Masks for irq to cpu affinity (2.4)(smp?) |
|
isapnp ISA PnP (Plug&Play) Info (2.4) |
|
kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4)) |
|
kmsg Kernel messages |
|
ksyms Kernel symbol table |
|
loadavg Load average of last 1, 5 & 15 minutes; |
|
number of processes currently runnable (running or on ready queue); |
|
total number of processes in system; |
|
last pid created. |
|
All fields are separated by one space except "number of |
|
processes currently runnable" and "total number of processes |
|
in system", which are separated by a slash ('/'). Example: |
|
0.61 0.61 0.55 3/828 22084 |
|
locks Kernel locks |
|
meminfo Memory info |
|
misc Miscellaneous |
|
modules List of loaded modules |
|
mounts Mounted filesystems |
|
net Networking info (see text) |
|
pagetypeinfo Additional page allocator information (see text) (2.5) |
|
partitions Table of partitions known to the system |
|
pci Deprecated info of PCI bus (new way -> /proc/bus/pci/, |
|
decoupled by lspci (2.4) |
|
rtc Real time clock |
|
scsi SCSI info (see text) |
|
slabinfo Slab pool info |
|
softirqs softirq usage |
|
stat Overall statistics |
|
swaps Swap space utilization |
|
sys See chapter 2 |
|
sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4) |
|
tty Info of tty drivers |
|
uptime Wall clock since boot, combined idle time of all cpus |
|
version Kernel version |
|
video bttv info of video resources (2.4) |
|
vmallocinfo Show vmalloced areas |
|
============ =============================================================== |
|
|
|
You can, for example, check which interrupts are currently in use and what |
|
they are used for by looking in the file /proc/interrupts:: |
|
|
|
> cat /proc/interrupts |
|
CPU0 |
|
0: 8728810 XT-PIC timer |
|
1: 895 XT-PIC keyboard |
|
2: 0 XT-PIC cascade |
|
3: 531695 XT-PIC aha152x |
|
4: 2014133 XT-PIC serial |
|
5: 44401 XT-PIC pcnet_cs |
|
8: 2 XT-PIC rtc |
|
11: 8 XT-PIC i82365 |
|
12: 182918 XT-PIC PS/2 Mouse |
|
13: 1 XT-PIC fpu |
|
14: 1232265 XT-PIC ide0 |
|
15: 7 XT-PIC ide1 |
|
NMI: 0 |
|
|
|
In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the |
|
output of a SMP machine):: |
|
|
|
> cat /proc/interrupts |
|
|
|
CPU0 CPU1 |
|
0: 1243498 1214548 IO-APIC-edge timer |
|
1: 8949 8958 IO-APIC-edge keyboard |
|
2: 0 0 XT-PIC cascade |
|
5: 11286 10161 IO-APIC-edge soundblaster |
|
8: 1 0 IO-APIC-edge rtc |
|
9: 27422 27407 IO-APIC-edge 3c503 |
|
12: 113645 113873 IO-APIC-edge PS/2 Mouse |
|
13: 0 0 XT-PIC fpu |
|
14: 22491 24012 IO-APIC-edge ide0 |
|
15: 2183 2415 IO-APIC-edge ide1 |
|
17: 30564 30414 IO-APIC-level eth0 |
|
18: 177 164 IO-APIC-level bttv |
|
NMI: 2457961 2457959 |
|
LOC: 2457882 2457881 |
|
ERR: 2155 |
|
|
|
NMI is incremented in this case because every timer interrupt generates a NMI |
|
(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups. |
|
|
|
LOC is the local interrupt counter of the internal APIC of every CPU. |
|
|
|
ERR is incremented in the case of errors in the IO-APIC bus (the bus that |
|
connects the CPUs in a SMP system. This means that an error has been detected, |
|
the IO-APIC automatically retry the transmission, so it should not be a big |
|
problem, but you should read the SMP-FAQ. |
|
|
|
In 2.6.2* /proc/interrupts was expanded again. This time the goal was for |
|
/proc/interrupts to display every IRQ vector in use by the system, not |
|
just those considered 'most important'. The new vectors are: |
|
|
|
THR |
|
interrupt raised when a machine check threshold counter |
|
(typically counting ECC corrected errors of memory or cache) exceeds |
|
a configurable threshold. Only available on some systems. |
|
|
|
TRM |
|
a thermal event interrupt occurs when a temperature threshold |
|
has been exceeded for the CPU. This interrupt may also be generated |
|
when the temperature drops back to normal. |
|
|
|
SPU |
|
a spurious interrupt is some interrupt that was raised then lowered |
|
by some IO device before it could be fully processed by the APIC. Hence |
|
the APIC sees the interrupt but does not know what device it came from. |
|
For this case the APIC will generate the interrupt with a IRQ vector |
|
of 0xff. This might also be generated by chipset bugs. |
|
|
|
RES, CAL, TLB |
|
rescheduling, call and TLB flush interrupts are |
|
sent from one CPU to another per the needs of the OS. Typically, |
|
their statistics are used by kernel developers and interested users to |
|
determine the occurrence of interrupts of the given type. |
|
|
|
The above IRQ vectors are displayed only when relevant. For example, |
|
the threshold vector does not exist on x86_64 platforms. Others are |
|
suppressed when the system is a uniprocessor. As of this writing, only |
|
i386 and x86_64 platforms support the new IRQ vector displays. |
|
|
|
Of some interest is the introduction of the /proc/irq directory to 2.4. |
|
It could be used to set IRQ to CPU affinity. This means that you can "hook" an |
|
IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the |
|
irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and |
|
prof_cpu_mask. |
|
|
|
For example:: |
|
|
|
> ls /proc/irq/ |
|
0 10 12 14 16 18 2 4 6 8 prof_cpu_mask |
|
1 11 13 15 17 19 3 5 7 9 default_smp_affinity |
|
> ls /proc/irq/0/ |
|
smp_affinity |
|
|
|
smp_affinity is a bitmask, in which you can specify which CPUs can handle the |
|
IRQ. You can set it by doing:: |
|
|
|
> echo 1 > /proc/irq/10/smp_affinity |
|
|
|
This means that only the first CPU will handle the IRQ, but you can also echo |
|
5 which means that only the first and third CPU can handle the IRQ. |
|
|
|
The contents of each smp_affinity file is the same by default:: |
|
|
|
> cat /proc/irq/0/smp_affinity |
|
ffffffff |
|
|
|
There is an alternate interface, smp_affinity_list which allows specifying |
|
a CPU range instead of a bitmask:: |
|
|
|
> cat /proc/irq/0/smp_affinity_list |
|
1024-1031 |
|
|
|
The default_smp_affinity mask applies to all non-active IRQs, which are the |
|
IRQs which have not yet been allocated/activated, and hence which lack a |
|
/proc/irq/[0-9]* directory. |
|
|
|
The node file on an SMP system shows the node to which the device using the IRQ |
|
reports itself as being attached. This hardware locality information does not |
|
include information about any possible driver locality preference. |
|
|
|
prof_cpu_mask specifies which CPUs are to be profiled by the system wide |
|
profiler. Default value is ffffffff (all CPUs if there are only 32 of them). |
|
|
|
The way IRQs are routed is handled by the IO-APIC, and it's Round Robin |
|
between all the CPUs which are allowed to handle it. As usual the kernel has |
|
more info than you and does a better job than you, so the defaults are the |
|
best choice for almost everyone. [Note this applies only to those IO-APIC's |
|
that support "Round Robin" interrupt distribution.] |
|
|
|
There are three more important subdirectories in /proc: net, scsi, and sys. |
|
The general rule is that the contents, or even the existence of these |
|
directories, depend on your kernel configuration. If SCSI is not enabled, the |
|
directory scsi may not exist. The same is true with the net, which is there |
|
only when networking support is present in the running kernel. |
|
|
|
The slabinfo file gives information about memory usage at the slab level. |
|
Linux uses slab pools for memory management above page level in version 2.2. |
|
Commonly used objects have their own slab pool (such as network buffers, |
|
directory cache, and so on). |
|
|
|
:: |
|
|
|
> cat /proc/buddyinfo |
|
|
|
Node 0, zone DMA 0 4 5 4 4 3 ... |
|
Node 0, zone Normal 1 0 0 1 101 8 ... |
|
Node 0, zone HighMem 2 0 0 1 1 0 ... |
|
|
|
External fragmentation is a problem under some workloads, and buddyinfo is a |
|
useful tool for helping diagnose these problems. Buddyinfo will give you a |
|
clue as to how big an area you can safely allocate, or why a previous |
|
allocation failed. |
|
|
|
Each column represents the number of pages of a certain order which are |
|
available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in |
|
ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE |
|
available in ZONE_NORMAL, etc... |
|
|
|
More information relevant to external fragmentation can be found in |
|
pagetypeinfo:: |
|
|
|
> cat /proc/pagetypeinfo |
|
Page block order: 9 |
|
Pages per block: 512 |
|
|
|
Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10 |
|
Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0 |
|
Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0 |
|
Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2 |
|
Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0 |
|
Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0 |
|
Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9 |
|
Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0 |
|
Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452 |
|
Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0 |
|
Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0 |
|
|
|
Number of blocks type Unmovable Reclaimable Movable Reserve Isolate |
|
Node 0, zone DMA 2 0 5 1 0 |
|
Node 0, zone DMA32 41 6 967 2 0 |
|
|
|
Fragmentation avoidance in the kernel works by grouping pages of different |
|
migrate types into the same contiguous regions of memory called page blocks. |
|
A page block is typically the size of the default hugepage size, e.g. 2MB on |
|
X86-64. By keeping pages grouped based on their ability to move, the kernel |
|
can reclaim pages within a page block to satisfy a high-order allocation. |
|
|
|
The pagetypinfo begins with information on the size of a page block. It |
|
then gives the same type of information as buddyinfo except broken down |
|
by migrate-type and finishes with details on how many page blocks of each |
|
type exist. |
|
|
|
If min_free_kbytes has been tuned correctly (recommendations made by hugeadm |
|
from libhugetlbfs https://github.com/libhugetlbfs/libhugetlbfs/), one can |
|
make an estimate of the likely number of huge pages that can be allocated |
|
at a given point in time. All the "Movable" blocks should be allocatable |
|
unless memory has been mlock()'d. Some of the Reclaimable blocks should |
|
also be allocatable although a lot of filesystem metadata may have to be |
|
reclaimed to achieve this. |
|
|
|
|
|
meminfo |
|
~~~~~~~ |
|
|
|
Provides information about distribution and utilization of memory. This |
|
varies by architecture and compile options. Some of the counters reported |
|
here overlap. The memory reported by the non overlapping counters may not |
|
add up to the overall memory usage and the difference for some workloads |
|
can be substantial. In many cases there are other means to find out |
|
additional memory using subsystem specific interfaces, for instance |
|
/proc/net/sockstat for TCP memory allocations. |
|
|
|
The following is from a 16GB PIII, which has highmem enabled. |
|
You may not have all of these fields. |
|
|
|
:: |
|
|
|
> cat /proc/meminfo |
|
|
|
MemTotal: 16344972 kB |
|
MemFree: 13634064 kB |
|
MemAvailable: 14836172 kB |
|
Buffers: 3656 kB |
|
Cached: 1195708 kB |
|
SwapCached: 0 kB |
|
Active: 891636 kB |
|
Inactive: 1077224 kB |
|
HighTotal: 15597528 kB |
|
HighFree: 13629632 kB |
|
LowTotal: 747444 kB |
|
LowFree: 4432 kB |
|
SwapTotal: 0 kB |
|
SwapFree: 0 kB |
|
Dirty: 968 kB |
|
Writeback: 0 kB |
|
AnonPages: 861800 kB |
|
Mapped: 280372 kB |
|
Shmem: 644 kB |
|
KReclaimable: 168048 kB |
|
Slab: 284364 kB |
|
SReclaimable: 159856 kB |
|
SUnreclaim: 124508 kB |
|
PageTables: 24448 kB |
|
NFS_Unstable: 0 kB |
|
Bounce: 0 kB |
|
WritebackTmp: 0 kB |
|
CommitLimit: 7669796 kB |
|
Committed_AS: 100056 kB |
|
VmallocTotal: 112216 kB |
|
VmallocUsed: 428 kB |
|
VmallocChunk: 111088 kB |
|
Percpu: 62080 kB |
|
HardwareCorrupted: 0 kB |
|
AnonHugePages: 49152 kB |
|
ShmemHugePages: 0 kB |
|
ShmemPmdMapped: 0 kB |
|
|
|
MemTotal |
|
Total usable RAM (i.e. physical RAM minus a few reserved |
|
bits and the kernel binary code) |
|
MemFree |
|
The sum of LowFree+HighFree |
|
MemAvailable |
|
An estimate of how much memory is available for starting new |
|
applications, without swapping. Calculated from MemFree, |
|
SReclaimable, the size of the file LRU lists, and the low |
|
watermarks in each zone. |
|
The estimate takes into account that the system needs some |
|
page cache to function well, and that not all reclaimable |
|
slab will be reclaimable, due to items being in use. The |
|
impact of those factors will vary from system to system. |
|
Buffers |
|
Relatively temporary storage for raw disk blocks |
|
shouldn't get tremendously large (20MB or so) |
|
Cached |
|
in-memory cache for files read from the disk (the |
|
pagecache). Doesn't include SwapCached |
|
SwapCached |
|
Memory that once was swapped out, is swapped back in but |
|
still also is in the swapfile (if memory is needed it |
|
doesn't need to be swapped out AGAIN because it is already |
|
in the swapfile. This saves I/O) |
|
Active |
|
Memory that has been used more recently and usually not |
|
reclaimed unless absolutely necessary. |
|
Inactive |
|
Memory which has been less recently used. It is more |
|
eligible to be reclaimed for other purposes |
|
HighTotal, HighFree |
|
Highmem is all memory above ~860MB of physical memory. |
|
Highmem areas are for use by userspace programs, or |
|
for the pagecache. The kernel must use tricks to access |
|
this memory, making it slower to access than lowmem. |
|
LowTotal, LowFree |
|
Lowmem is memory which can be used for everything that |
|
highmem can be used for, but it is also available for the |
|
kernel's use for its own data structures. Among many |
|
other things, it is where everything from the Slab is |
|
allocated. Bad things happen when you're out of lowmem. |
|
SwapTotal |
|
total amount of swap space available |
|
SwapFree |
|
Memory which has been evicted from RAM, and is temporarily |
|
on the disk |
|
Dirty |
|
Memory which is waiting to get written back to the disk |
|
Writeback |
|
Memory which is actively being written back to the disk |
|
AnonPages |
|
Non-file backed pages mapped into userspace page tables |
|
HardwareCorrupted |
|
The amount of RAM/memory in KB, the kernel identifies as |
|
corrupted. |
|
AnonHugePages |
|
Non-file backed huge pages mapped into userspace page tables |
|
Mapped |
|
files which have been mmaped, such as libraries |
|
Shmem |
|
Total memory used by shared memory (shmem) and tmpfs |
|
ShmemHugePages |
|
Memory used by shared memory (shmem) and tmpfs allocated |
|
with huge pages |
|
ShmemPmdMapped |
|
Shared memory mapped into userspace with huge pages |
|
KReclaimable |
|
Kernel allocations that the kernel will attempt to reclaim |
|
under memory pressure. Includes SReclaimable (below), and other |
|
direct allocations with a shrinker. |
|
Slab |
|
in-kernel data structures cache |
|
SReclaimable |
|
Part of Slab, that might be reclaimed, such as caches |
|
SUnreclaim |
|
Part of Slab, that cannot be reclaimed on memory pressure |
|
PageTables |
|
amount of memory dedicated to the lowest level of page |
|
tables. |
|
NFS_Unstable |
|
Always zero. Previous counted pages which had been written to |
|
the server, but has not been committed to stable storage. |
|
Bounce |
|
Memory used for block device "bounce buffers" |
|
WritebackTmp |
|
Memory used by FUSE for temporary writeback buffers |
|
CommitLimit |
|
Based on the overcommit ratio ('vm.overcommit_ratio'), |
|
this is the total amount of memory currently available to |
|
be allocated on the system. This limit is only adhered to |
|
if strict overcommit accounting is enabled (mode 2 in |
|
'vm.overcommit_memory'). |
|
|
|
The CommitLimit is calculated with the following formula:: |
|
|
|
CommitLimit = ([total RAM pages] - [total huge TLB pages]) * |
|
overcommit_ratio / 100 + [total swap pages] |
|
|
|
For example, on a system with 1G of physical RAM and 7G |
|
of swap with a `vm.overcommit_ratio` of 30 it would |
|
yield a CommitLimit of 7.3G. |
|
|
|
For more details, see the memory overcommit documentation |
|
in vm/overcommit-accounting. |
|
Committed_AS |
|
The amount of memory presently allocated on the system. |
|
The committed memory is a sum of all of the memory which |
|
has been allocated by processes, even if it has not been |
|
"used" by them as of yet. A process which malloc()'s 1G |
|
of memory, but only touches 300M of it will show up as |
|
using 1G. This 1G is memory which has been "committed" to |
|
by the VM and can be used at any time by the allocating |
|
application. With strict overcommit enabled on the system |
|
(mode 2 in 'vm.overcommit_memory'), allocations which would |
|
exceed the CommitLimit (detailed above) will not be permitted. |
|
This is useful if one needs to guarantee that processes will |
|
not fail due to lack of memory once that memory has been |
|
successfully allocated. |
|
VmallocTotal |
|
total size of vmalloc memory area |
|
VmallocUsed |
|
amount of vmalloc area which is used |
|
VmallocChunk |
|
largest contiguous block of vmalloc area which is free |
|
Percpu |
|
Memory allocated to the percpu allocator used to back percpu |
|
allocations. This stat excludes the cost of metadata. |
|
|
|
vmallocinfo |
|
~~~~~~~~~~~ |
|
|
|
Provides information about vmalloced/vmaped areas. One line per area, |
|
containing the virtual address range of the area, size in bytes, |
|
caller information of the creator, and optional information depending |
|
on the kind of area: |
|
|
|
========== =================================================== |
|
pages=nr number of pages |
|
phys=addr if a physical address was specified |
|
ioremap I/O mapping (ioremap() and friends) |
|
vmalloc vmalloc() area |
|
vmap vmap()ed pages |
|
user VM_USERMAP area |
|
vpages buffer for pages pointers was vmalloced (huge area) |
|
N<node>=nr (Only on NUMA kernels) |
|
Number of pages allocated on memory node <node> |
|
========== =================================================== |
|
|
|
:: |
|
|
|
> cat /proc/vmallocinfo |
|
0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ... |
|
/0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128 |
|
0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ... |
|
/0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64 |
|
0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f... |
|
phys=7fee8000 ioremap |
|
0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f... |
|
phys=7fee7000 ioremap |
|
0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210 |
|
0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ... |
|
/0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3 |
|
0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ... |
|
pages=2 vmalloc N1=2 |
|
0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ... |
|
/0x130 [x_tables] pages=4 vmalloc N0=4 |
|
0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ... |
|
pages=14 vmalloc N2=14 |
|
0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ... |
|
pages=4 vmalloc N1=4 |
|
0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ... |
|
pages=2 vmalloc N1=2 |
|
0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ... |
|
pages=10 vmalloc N0=10 |
|
|
|
|
|
softirqs |
|
~~~~~~~~ |
|
|
|
Provides counts of softirq handlers serviced since boot time, for each CPU. |
|
|
|
:: |
|
|
|
> cat /proc/softirqs |
|
CPU0 CPU1 CPU2 CPU3 |
|
HI: 0 0 0 0 |
|
TIMER: 27166 27120 27097 27034 |
|
NET_TX: 0 0 0 17 |
|
NET_RX: 42 0 0 39 |
|
BLOCK: 0 0 107 1121 |
|
TASKLET: 0 0 0 290 |
|
SCHED: 27035 26983 26971 26746 |
|
HRTIMER: 0 0 0 0 |
|
RCU: 1678 1769 2178 2250 |
|
|
|
|
|
1.3 IDE devices in /proc/ide |
|
---------------------------- |
|
|
|
The subdirectory /proc/ide contains information about all IDE devices of which |
|
the kernel is aware. There is one subdirectory for each IDE controller, the |
|
file drivers and a link for each IDE device, pointing to the device directory |
|
in the controller specific subtree. |
|
|
|
The file 'drivers' contains general information about the drivers used for the |
|
IDE devices:: |
|
|
|
> cat /proc/ide/drivers |
|
ide-cdrom version 4.53 |
|
ide-disk version 1.08 |
|
|
|
More detailed information can be found in the controller specific |
|
subdirectories. These are named ide0, ide1 and so on. Each of these |
|
directories contains the files shown in table 1-6. |
|
|
|
|
|
.. table:: Table 1-6: IDE controller info in /proc/ide/ide? |
|
|
|
======= ======================================= |
|
File Content |
|
======= ======================================= |
|
channel IDE channel (0 or 1) |
|
config Configuration (only for PCI/IDE bridge) |
|
mate Mate name |
|
model Type/Chipset of IDE controller |
|
======= ======================================= |
|
|
|
Each device connected to a controller has a separate subdirectory in the |
|
controllers directory. The files listed in table 1-7 are contained in these |
|
directories. |
|
|
|
|
|
.. table:: Table 1-7: IDE device information |
|
|
|
================ ========================================== |
|
File Content |
|
================ ========================================== |
|
cache The cache |
|
capacity Capacity of the medium (in 512Byte blocks) |
|
driver driver and version |
|
geometry physical and logical geometry |
|
identify device identify block |
|
media media type |
|
model device identifier |
|
settings device setup |
|
smart_thresholds IDE disk management thresholds |
|
smart_values IDE disk management values |
|
================ ========================================== |
|
|
|
The most interesting file is ``settings``. This file contains a nice |
|
overview of the drive parameters:: |
|
|
|
# cat /proc/ide/ide0/hda/settings |
|
name value min max mode |
|
---- ----- --- --- ---- |
|
bios_cyl 526 0 65535 rw |
|
bios_head 255 0 255 rw |
|
bios_sect 63 0 63 rw |
|
breada_readahead 4 0 127 rw |
|
bswap 0 0 1 r |
|
file_readahead 72 0 2097151 rw |
|
io_32bit 0 0 3 rw |
|
keepsettings 0 0 1 rw |
|
max_kb_per_request 122 1 127 rw |
|
multcount 0 0 8 rw |
|
nice1 1 0 1 rw |
|
nowerr 0 0 1 rw |
|
pio_mode write-only 0 255 w |
|
slow 0 0 1 rw |
|
unmaskirq 0 0 1 rw |
|
using_dma 0 0 1 rw |
|
|
|
|
|
1.4 Networking info in /proc/net |
|
-------------------------------- |
|
|
|
The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the |
|
additional values you get for IP version 6 if you configure the kernel to |
|
support this. Table 1-9 lists the files and their meaning. |
|
|
|
|
|
.. table:: Table 1-8: IPv6 info in /proc/net |
|
|
|
========== ===================================================== |
|
File Content |
|
========== ===================================================== |
|
udp6 UDP sockets (IPv6) |
|
tcp6 TCP sockets (IPv6) |
|
raw6 Raw device statistics (IPv6) |
|
igmp6 IP multicast addresses, which this host joined (IPv6) |
|
if_inet6 List of IPv6 interface addresses |
|
ipv6_route Kernel routing table for IPv6 |
|
rt6_stats Global IPv6 routing tables statistics |
|
sockstat6 Socket statistics (IPv6) |
|
snmp6 Snmp data (IPv6) |
|
========== ===================================================== |
|
|
|
.. table:: Table 1-9: Network info in /proc/net |
|
|
|
============= ================================================================ |
|
File Content |
|
============= ================================================================ |
|
arp Kernel ARP table |
|
dev network devices with statistics |
|
dev_mcast the Layer2 multicast groups a device is listening too |
|
(interface index, label, number of references, number of bound |
|
addresses). |
|
dev_stat network device status |
|
ip_fwchains Firewall chain linkage |
|
ip_fwnames Firewall chain names |
|
ip_masq Directory containing the masquerading tables |
|
ip_masquerade Major masquerading table |
|
netstat Network statistics |
|
raw raw device statistics |
|
route Kernel routing table |
|
rpc Directory containing rpc info |
|
rt_cache Routing cache |
|
snmp SNMP data |
|
sockstat Socket statistics |
|
tcp TCP sockets |
|
udp UDP sockets |
|
unix UNIX domain sockets |
|
wireless Wireless interface data (Wavelan etc) |
|
igmp IP multicast addresses, which this host joined |
|
psched Global packet scheduler parameters. |
|
netlink List of PF_NETLINK sockets |
|
ip_mr_vifs List of multicast virtual interfaces |
|
ip_mr_cache List of multicast routing cache |
|
============= ================================================================ |
|
|
|
You can use this information to see which network devices are available in |
|
your system and how much traffic was routed over those devices:: |
|
|
|
> cat /proc/net/dev |
|
Inter-|Receive |[... |
|
face |bytes packets errs drop fifo frame compressed multicast|[... |
|
lo: 908188 5596 0 0 0 0 0 0 [... |
|
ppp0:15475140 20721 410 0 0 410 0 0 [... |
|
eth0: 614530 7085 0 0 0 0 0 1 [... |
|
|
|
...] Transmit |
|
...] bytes packets errs drop fifo colls carrier compressed |
|
...] 908188 5596 0 0 0 0 0 0 |
|
...] 1375103 17405 0 0 0 0 0 0 |
|
...] 1703981 5535 0 0 0 3 0 0 |
|
|
|
In addition, each Channel Bond interface has its own directory. For |
|
example, the bond0 device will have a directory called /proc/net/bond0/. |
|
It will contain information that is specific to that bond, such as the |
|
current slaves of the bond, the link status of the slaves, and how |
|
many times the slaves link has failed. |
|
|
|
1.5 SCSI info |
|
------------- |
|
|
|
If you have a SCSI host adapter in your system, you'll find a subdirectory |
|
named after the driver for this adapter in /proc/scsi. You'll also see a list |
|
of all recognized SCSI devices in /proc/scsi:: |
|
|
|
>cat /proc/scsi/scsi |
|
Attached devices: |
|
Host: scsi0 Channel: 00 Id: 00 Lun: 00 |
|
Vendor: IBM Model: DGHS09U Rev: 03E0 |
|
Type: Direct-Access ANSI SCSI revision: 03 |
|
Host: scsi0 Channel: 00 Id: 06 Lun: 00 |
|
Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04 |
|
Type: CD-ROM ANSI SCSI revision: 02 |
|
|
|
|
|
The directory named after the driver has one file for each adapter found in |
|
the system. These files contain information about the controller, including |
|
the used IRQ and the IO address range. The amount of information shown is |
|
dependent on the adapter you use. The example shows the output for an Adaptec |
|
AHA-2940 SCSI adapter:: |
|
|
|
> cat /proc/scsi/aic7xxx/0 |
|
|
|
Adaptec AIC7xxx driver version: 5.1.19/3.2.4 |
|
Compile Options: |
|
TCQ Enabled By Default : Disabled |
|
AIC7XXX_PROC_STATS : Disabled |
|
AIC7XXX_RESET_DELAY : 5 |
|
Adapter Configuration: |
|
SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter |
|
Ultra Wide Controller |
|
PCI MMAPed I/O Base: 0xeb001000 |
|
Adapter SEEPROM Config: SEEPROM found and used. |
|
Adaptec SCSI BIOS: Enabled |
|
IRQ: 10 |
|
SCBs: Active 0, Max Active 2, |
|
Allocated 15, HW 16, Page 255 |
|
Interrupts: 160328 |
|
BIOS Control Word: 0x18b6 |
|
Adapter Control Word: 0x005b |
|
Extended Translation: Enabled |
|
Disconnect Enable Flags: 0xffff |
|
Ultra Enable Flags: 0x0001 |
|
Tag Queue Enable Flags: 0x0000 |
|
Ordered Queue Tag Flags: 0x0000 |
|
Default Tag Queue Depth: 8 |
|
Tagged Queue By Device array for aic7xxx host instance 0: |
|
{255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255} |
|
Actual queue depth per device for aic7xxx host instance 0: |
|
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1} |
|
Statistics: |
|
(scsi0:0:0:0) |
|
Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8 |
|
Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0) |
|
Total transfers 160151 (74577 reads and 85574 writes) |
|
(scsi0:0:6:0) |
|
Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15 |
|
Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0) |
|
Total transfers 0 (0 reads and 0 writes) |
|
|
|
|
|
1.6 Parallel port info in /proc/parport |
|
--------------------------------------- |
|
|
|
The directory /proc/parport contains information about the parallel ports of |
|
your system. It has one subdirectory for each port, named after the port |
|
number (0,1,2,...). |
|
|
|
These directories contain the four files shown in Table 1-10. |
|
|
|
|
|
.. table:: Table 1-10: Files in /proc/parport |
|
|
|
========= ==================================================================== |
|
File Content |
|
========= ==================================================================== |
|
autoprobe Any IEEE-1284 device ID information that has been acquired. |
|
devices list of the device drivers using that port. A + will appear by the |
|
name of the device currently using the port (it might not appear |
|
against any). |
|
hardware Parallel port's base address, IRQ line and DMA channel. |
|
irq IRQ that parport is using for that port. This is in a separate |
|
file to allow you to alter it by writing a new value in (IRQ |
|
number or none). |
|
========= ==================================================================== |
|
|
|
1.7 TTY info in /proc/tty |
|
------------------------- |
|
|
|
Information about the available and actually used tty's can be found in the |
|
directory /proc/tty. You'll find entries for drivers and line disciplines in |
|
this directory, as shown in Table 1-11. |
|
|
|
|
|
.. table:: Table 1-11: Files in /proc/tty |
|
|
|
============= ============================================== |
|
File Content |
|
============= ============================================== |
|
drivers list of drivers and their usage |
|
ldiscs registered line disciplines |
|
driver/serial usage statistic and status of single tty lines |
|
============= ============================================== |
|
|
|
To see which tty's are currently in use, you can simply look into the file |
|
/proc/tty/drivers:: |
|
|
|
> cat /proc/tty/drivers |
|
pty_slave /dev/pts 136 0-255 pty:slave |
|
pty_master /dev/ptm 128 0-255 pty:master |
|
pty_slave /dev/ttyp 3 0-255 pty:slave |
|
pty_master /dev/pty 2 0-255 pty:master |
|
serial /dev/cua 5 64-67 serial:callout |
|
serial /dev/ttyS 4 64-67 serial |
|
/dev/tty0 /dev/tty0 4 0 system:vtmaster |
|
/dev/ptmx /dev/ptmx 5 2 system |
|
/dev/console /dev/console 5 1 system:console |
|
/dev/tty /dev/tty 5 0 system:/dev/tty |
|
unknown /dev/tty 4 1-63 console |
|
|
|
|
|
1.8 Miscellaneous kernel statistics in /proc/stat |
|
------------------------------------------------- |
|
|
|
Various pieces of information about kernel activity are available in the |
|
/proc/stat file. All of the numbers reported in this file are aggregates |
|
since the system first booted. For a quick look, simply cat the file:: |
|
|
|
> cat /proc/stat |
|
cpu 2255 34 2290 22625563 6290 127 456 0 0 0 |
|
cpu0 1132 34 1441 11311718 3675 127 438 0 0 0 |
|
cpu1 1123 0 849 11313845 2614 0 18 0 0 0 |
|
intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...] |
|
ctxt 1990473 |
|
btime 1062191376 |
|
processes 2915 |
|
procs_running 1 |
|
procs_blocked 0 |
|
softirq 183433 0 21755 12 39 1137 231 21459 2263 |
|
|
|
The very first "cpu" line aggregates the numbers in all of the other "cpuN" |
|
lines. These numbers identify the amount of time the CPU has spent performing |
|
different kinds of work. Time units are in USER_HZ (typically hundredths of a |
|
second). The meanings of the columns are as follows, from left to right: |
|
|
|
- user: normal processes executing in user mode |
|
- nice: niced processes executing in user mode |
|
- system: processes executing in kernel mode |
|
- idle: twiddling thumbs |
|
- iowait: In a word, iowait stands for waiting for I/O to complete. But there |
|
are several problems: |
|
|
|
1. CPU will not wait for I/O to complete, iowait is the time that a task is |
|
waiting for I/O to complete. When CPU goes into idle state for |
|
outstanding task I/O, another task will be scheduled on this CPU. |
|
2. In a multi-core CPU, the task waiting for I/O to complete is not running |
|
on any CPU, so the iowait of each CPU is difficult to calculate. |
|
3. The value of iowait field in /proc/stat will decrease in certain |
|
conditions. |
|
|
|
So, the iowait is not reliable by reading from /proc/stat. |
|
- irq: servicing interrupts |
|
- softirq: servicing softirqs |
|
- steal: involuntary wait |
|
- guest: running a normal guest |
|
- guest_nice: running a niced guest |
|
|
|
The "intr" line gives counts of interrupts serviced since boot time, for each |
|
of the possible system interrupts. The first column is the total of all |
|
interrupts serviced including unnumbered architecture specific interrupts; |
|
each subsequent column is the total for that particular numbered interrupt. |
|
Unnumbered interrupts are not shown, only summed into the total. |
|
|
|
The "ctxt" line gives the total number of context switches across all CPUs. |
|
|
|
The "btime" line gives the time at which the system booted, in seconds since |
|
the Unix epoch. |
|
|
|
The "processes" line gives the number of processes and threads created, which |
|
includes (but is not limited to) those created by calls to the fork() and |
|
clone() system calls. |
|
|
|
The "procs_running" line gives the total number of threads that are |
|
running or ready to run (i.e., the total number of runnable threads). |
|
|
|
The "procs_blocked" line gives the number of processes currently blocked, |
|
waiting for I/O to complete. |
|
|
|
The "softirq" line gives counts of softirqs serviced since boot time, for each |
|
of the possible system softirqs. The first column is the total of all |
|
softirqs serviced; each subsequent column is the total for that particular |
|
softirq. |
|
|
|
|
|
1.9 Ext4 file system parameters |
|
------------------------------- |
|
|
|
Information about mounted ext4 file systems can be found in |
|
/proc/fs/ext4. Each mounted filesystem will have a directory in |
|
/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or |
|
/proc/fs/ext4/dm-0). The files in each per-device directory are shown |
|
in Table 1-12, below. |
|
|
|
.. table:: Table 1-12: Files in /proc/fs/ext4/<devname> |
|
|
|
============== ========================================================== |
|
File Content |
|
mb_groups details of multiblock allocator buddy cache of free blocks |
|
============== ========================================================== |
|
|
|
1.10 /proc/consoles |
|
------------------- |
|
Shows registered system console lines. |
|
|
|
To see which character device lines are currently used for the system console |
|
/dev/console, you may simply look into the file /proc/consoles:: |
|
|
|
> cat /proc/consoles |
|
tty0 -WU (ECp) 4:7 |
|
ttyS0 -W- (Ep) 4:64 |
|
|
|
The columns are: |
|
|
|
+--------------------+-------------------------------------------------------+ |
|
| device | name of the device | |
|
+====================+=======================================================+ |
|
| operations | * R = can do read operations | |
|
| | * W = can do write operations | |
|
| | * U = can do unblank | |
|
+--------------------+-------------------------------------------------------+ |
|
| flags | * E = it is enabled | |
|
| | * C = it is preferred console | |
|
| | * B = it is primary boot console | |
|
| | * p = it is used for printk buffer | |
|
| | * b = it is not a TTY but a Braille device | |
|
| | * a = it is safe to use when cpu is offline | |
|
+--------------------+-------------------------------------------------------+ |
|
| major:minor | major and minor number of the device separated by a | |
|
| | colon | |
|
+--------------------+-------------------------------------------------------+ |
|
|
|
Summary |
|
------- |
|
|
|
The /proc file system serves information about the running system. It not only |
|
allows access to process data but also allows you to request the kernel status |
|
by reading files in the hierarchy. |
|
|
|
The directory structure of /proc reflects the types of information and makes |
|
it easy, if not obvious, where to look for specific data. |
|
|
|
Chapter 2: Modifying System Parameters |
|
====================================== |
|
|
|
In This Chapter |
|
--------------- |
|
|
|
* Modifying kernel parameters by writing into files found in /proc/sys |
|
* Exploring the files which modify certain parameters |
|
* Review of the /proc/sys file tree |
|
|
|
------------------------------------------------------------------------------ |
|
|
|
A very interesting part of /proc is the directory /proc/sys. This is not only |
|
a source of information, it also allows you to change parameters within the |
|
kernel. Be very careful when attempting this. You can optimize your system, |
|
but you can also cause it to crash. Never alter kernel parameters on a |
|
production system. Set up a development machine and test to make sure that |
|
everything works the way you want it to. You may have no alternative but to |
|
reboot the machine once an error has been made. |
|
|
|
To change a value, simply echo the new value into the file. |
|
You need to be root to do this. You can create your own boot script |
|
to perform this every time your system boots. |
|
|
|
The files in /proc/sys can be used to fine tune and monitor miscellaneous and |
|
general things in the operation of the Linux kernel. Since some of the files |
|
can inadvertently disrupt your system, it is advisable to read both |
|
documentation and source before actually making adjustments. In any case, be |
|
very careful when writing to any of these files. The entries in /proc may |
|
change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt |
|
review the kernel documentation in the directory /usr/src/linux/Documentation. |
|
This chapter is heavily based on the documentation included in the pre 2.2 |
|
kernels, and became part of it in version 2.2.1 of the Linux kernel. |
|
|
|
Please see: Documentation/admin-guide/sysctl/ directory for descriptions of these |
|
entries. |
|
|
|
Summary |
|
------- |
|
|
|
Certain aspects of kernel behavior can be modified at runtime, without the |
|
need to recompile the kernel, or even to reboot the system. The files in the |
|
/proc/sys tree can not only be read, but also modified. You can use the echo |
|
command to write value into these files, thereby changing the default settings |
|
of the kernel. |
|
|
|
|
|
Chapter 3: Per-process Parameters |
|
================================= |
|
|
|
3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score |
|
-------------------------------------------------------------------------------- |
|
|
|
These files can be used to adjust the badness heuristic used to select which |
|
process gets killed in out of memory (oom) conditions. |
|
|
|
The badness heuristic assigns a value to each candidate task ranging from 0 |
|
(never kill) to 1000 (always kill) to determine which process is targeted. The |
|
units are roughly a proportion along that range of allowed memory the process |
|
may allocate from based on an estimation of its current memory and swap use. |
|
For example, if a task is using all allowed memory, its badness score will be |
|
1000. If it is using half of its allowed memory, its score will be 500. |
|
|
|
The amount of "allowed" memory depends on the context in which the oom killer |
|
was called. If it is due to the memory assigned to the allocating task's cpuset |
|
being exhausted, the allowed memory represents the set of mems assigned to that |
|
cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed |
|
memory represents the set of mempolicy nodes. If it is due to a memory |
|
limit (or swap limit) being reached, the allowed memory is that configured |
|
limit. Finally, if it is due to the entire system being out of memory, the |
|
allowed memory represents all allocatable resources. |
|
|
|
The value of /proc/<pid>/oom_score_adj is added to the badness score before it |
|
is used to determine which task to kill. Acceptable values range from -1000 |
|
(OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to |
|
polarize the preference for oom killing either by always preferring a certain |
|
task or completely disabling it. The lowest possible value, -1000, is |
|
equivalent to disabling oom killing entirely for that task since it will always |
|
report a badness score of 0. |
|
|
|
Consequently, it is very simple for userspace to define the amount of memory to |
|
consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for |
|
example, is roughly equivalent to allowing the remainder of tasks sharing the |
|
same system, cpuset, mempolicy, or memory controller resources to use at least |
|
50% more memory. A value of -500, on the other hand, would be roughly |
|
equivalent to discounting 50% of the task's allowed memory from being considered |
|
as scoring against the task. |
|
|
|
For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also |
|
be used to tune the badness score. Its acceptable values range from -16 |
|
(OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17 |
|
(OOM_DISABLE) to disable oom killing entirely for that task. Its value is |
|
scaled linearly with /proc/<pid>/oom_score_adj. |
|
|
|
The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last |
|
value set by a CAP_SYS_RESOURCE process. To reduce the value any lower |
|
requires CAP_SYS_RESOURCE. |
|
|
|
|
|
3.2 /proc/<pid>/oom_score - Display current oom-killer score |
|
------------------------------------------------------------- |
|
|
|
This file can be used to check the current score used by the oom-killer for |
|
any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which |
|
process should be killed in an out-of-memory situation. |
|
|
|
Please note that the exported value includes oom_score_adj so it is |
|
effectively in range [0,2000]. |
|
|
|
|
|
3.3 /proc/<pid>/io - Display the IO accounting fields |
|
------------------------------------------------------- |
|
|
|
This file contains IO statistics for each running process. |
|
|
|
Example |
|
~~~~~~~ |
|
|
|
:: |
|
|
|
test:/tmp # dd if=/dev/zero of=/tmp/test.dat & |
|
[1] 3828 |
|
|
|
test:/tmp # cat /proc/3828/io |
|
rchar: 323934931 |
|
wchar: 323929600 |
|
syscr: 632687 |
|
syscw: 632675 |
|
read_bytes: 0 |
|
write_bytes: 323932160 |
|
cancelled_write_bytes: 0 |
|
|
|
|
|
Description |
|
~~~~~~~~~~~ |
|
|
|
rchar |
|
^^^^^ |
|
|
|
I/O counter: chars read |
|
The number of bytes which this task has caused to be read from storage. This |
|
is simply the sum of bytes which this process passed to read() and pread(). |
|
It includes things like tty IO and it is unaffected by whether or not actual |
|
physical disk IO was required (the read might have been satisfied from |
|
pagecache). |
|
|
|
|
|
wchar |
|
^^^^^ |
|
|
|
I/O counter: chars written |
|
The number of bytes which this task has caused, or shall cause to be written |
|
to disk. Similar caveats apply here as with rchar. |
|
|
|
|
|
syscr |
|
^^^^^ |
|
|
|
I/O counter: read syscalls |
|
Attempt to count the number of read I/O operations, i.e. syscalls like read() |
|
and pread(). |
|
|
|
|
|
syscw |
|
^^^^^ |
|
|
|
I/O counter: write syscalls |
|
Attempt to count the number of write I/O operations, i.e. syscalls like |
|
write() and pwrite(). |
|
|
|
|
|
read_bytes |
|
^^^^^^^^^^ |
|
|
|
I/O counter: bytes read |
|
Attempt to count the number of bytes which this process really did cause to |
|
be fetched from the storage layer. Done at the submit_bio() level, so it is |
|
accurate for block-backed filesystems. <please add status regarding NFS and |
|
CIFS at a later time> |
|
|
|
|
|
write_bytes |
|
^^^^^^^^^^^ |
|
|
|
I/O counter: bytes written |
|
Attempt to count the number of bytes which this process caused to be sent to |
|
the storage layer. This is done at page-dirtying time. |
|
|
|
|
|
cancelled_write_bytes |
|
^^^^^^^^^^^^^^^^^^^^^ |
|
|
|
The big inaccuracy here is truncate. If a process writes 1MB to a file and |
|
then deletes the file, it will in fact perform no writeout. But it will have |
|
been accounted as having caused 1MB of write. |
|
In other words: The number of bytes which this process caused to not happen, |
|
by truncating pagecache. A task can cause "negative" IO too. If this task |
|
truncates some dirty pagecache, some IO which another task has been accounted |
|
for (in its write_bytes) will not be happening. We _could_ just subtract that |
|
from the truncating task's write_bytes, but there is information loss in doing |
|
that. |
|
|
|
|
|
.. Note:: |
|
|
|
At its current implementation state, this is a bit racy on 32-bit machines: |
|
if process A reads process B's /proc/pid/io while process B is updating one |
|
of those 64-bit counters, process A could see an intermediate result. |
|
|
|
|
|
More information about this can be found within the taskstats documentation in |
|
Documentation/accounting. |
|
|
|
3.4 /proc/<pid>/coredump_filter - Core dump filtering settings |
|
--------------------------------------------------------------- |
|
When a process is dumped, all anonymous memory is written to a core file as |
|
long as the size of the core file isn't limited. But sometimes we don't want |
|
to dump some memory segments, for example, huge shared memory or DAX. |
|
Conversely, sometimes we want to save file-backed memory segments into a core |
|
file, not only the individual files. |
|
|
|
/proc/<pid>/coredump_filter allows you to customize which memory segments |
|
will be dumped when the <pid> process is dumped. coredump_filter is a bitmask |
|
of memory types. If a bit of the bitmask is set, memory segments of the |
|
corresponding memory type are dumped, otherwise they are not dumped. |
|
|
|
The following 9 memory types are supported: |
|
|
|
- (bit 0) anonymous private memory |
|
- (bit 1) anonymous shared memory |
|
- (bit 2) file-backed private memory |
|
- (bit 3) file-backed shared memory |
|
- (bit 4) ELF header pages in file-backed private memory areas (it is |
|
effective only if the bit 2 is cleared) |
|
- (bit 5) hugetlb private memory |
|
- (bit 6) hugetlb shared memory |
|
- (bit 7) DAX private memory |
|
- (bit 8) DAX shared memory |
|
|
|
Note that MMIO pages such as frame buffer are never dumped and vDSO pages |
|
are always dumped regardless of the bitmask status. |
|
|
|
Note that bits 0-4 don't affect hugetlb or DAX memory. hugetlb memory is |
|
only affected by bit 5-6, and DAX is only affected by bits 7-8. |
|
|
|
The default value of coredump_filter is 0x33; this means all anonymous memory |
|
segments, ELF header pages and hugetlb private memory are dumped. |
|
|
|
If you don't want to dump all shared memory segments attached to pid 1234, |
|
write 0x31 to the process's proc file:: |
|
|
|
$ echo 0x31 > /proc/1234/coredump_filter |
|
|
|
When a new process is created, the process inherits the bitmask status from its |
|
parent. It is useful to set up coredump_filter before the program runs. |
|
For example:: |
|
|
|
$ echo 0x7 > /proc/self/coredump_filter |
|
$ ./some_program |
|
|
|
3.5 /proc/<pid>/mountinfo - Information about mounts |
|
-------------------------------------------------------- |
|
|
|
This file contains lines of the form:: |
|
|
|
36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue |
|
(1)(2)(3) (4) (5) (6) (n…m) (m+1)(m+2) (m+3) (m+4) |
|
|
|
(1) mount ID: unique identifier of the mount (may be reused after umount) |
|
(2) parent ID: ID of parent (or of self for the top of the mount tree) |
|
(3) major:minor: value of st_dev for files on filesystem |
|
(4) root: root of the mount within the filesystem |
|
(5) mount point: mount point relative to the process's root |
|
(6) mount options: per mount options |
|
(n…m) optional fields: zero or more fields of the form "tag[:value]" |
|
(m+1) separator: marks the end of the optional fields |
|
(m+2) filesystem type: name of filesystem of the form "type[.subtype]" |
|
(m+3) mount source: filesystem specific information or "none" |
|
(m+4) super options: per super block options |
|
|
|
Parsers should ignore all unrecognised optional fields. Currently the |
|
possible optional fields are: |
|
|
|
================ ============================================================== |
|
shared:X mount is shared in peer group X |
|
master:X mount is slave to peer group X |
|
propagate_from:X mount is slave and receives propagation from peer group X [#]_ |
|
unbindable mount is unbindable |
|
================ ============================================================== |
|
|
|
.. [#] X is the closest dominant peer group under the process's root. If |
|
X is the immediate master of the mount, or if there's no dominant peer |
|
group under the same root, then only the "master:X" field is present |
|
and not the "propagate_from:X" field. |
|
|
|
For more information on mount propagation see: |
|
|
|
Documentation/filesystems/sharedsubtree.rst |
|
|
|
|
|
3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm |
|
-------------------------------------------------------- |
|
These files provide a method to access a task's comm value. It also allows for |
|
a task to set its own or one of its thread siblings comm value. The comm value |
|
is limited in size compared to the cmdline value, so writing anything longer |
|
then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated |
|
comm value. |
|
|
|
|
|
3.7 /proc/<pid>/task/<tid>/children - Information about task children |
|
------------------------------------------------------------------------- |
|
This file provides a fast way to retrieve first level children pids |
|
of a task pointed by <pid>/<tid> pair. The format is a space separated |
|
stream of pids. |
|
|
|
Note the "first level" here -- if a child has its own children they will |
|
not be listed here; one needs to read /proc/<children-pid>/task/<tid>/children |
|
to obtain the descendants. |
|
|
|
Since this interface is intended to be fast and cheap it doesn't |
|
guarantee to provide precise results and some children might be |
|
skipped, especially if they've exited right after we printed their |
|
pids, so one needs to either stop or freeze processes being inspected |
|
if precise results are needed. |
|
|
|
|
|
3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file |
|
--------------------------------------------------------------- |
|
This file provides information associated with an opened file. The regular |
|
files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'. |
|
The 'pos' represents the current offset of the opened file in decimal |
|
form [see lseek(2) for details], 'flags' denotes the octal O_xxx mask the |
|
file has been created with [see open(2) for details] and 'mnt_id' represents |
|
mount ID of the file system containing the opened file [see 3.5 |
|
/proc/<pid>/mountinfo for details]. 'ino' represents the inode number of |
|
the file. |
|
|
|
A typical output is:: |
|
|
|
pos: 0 |
|
flags: 0100002 |
|
mnt_id: 19 |
|
ino: 63107 |
|
|
|
All locks associated with a file descriptor are shown in its fdinfo too:: |
|
|
|
lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF |
|
|
|
The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags |
|
pair provide additional information particular to the objects they represent. |
|
|
|
Eventfd files |
|
~~~~~~~~~~~~~ |
|
|
|
:: |
|
|
|
pos: 0 |
|
flags: 04002 |
|
mnt_id: 9 |
|
ino: 63107 |
|
eventfd-count: 5a |
|
|
|
where 'eventfd-count' is hex value of a counter. |
|
|
|
Signalfd files |
|
~~~~~~~~~~~~~~ |
|
|
|
:: |
|
|
|
pos: 0 |
|
flags: 04002 |
|
mnt_id: 9 |
|
ino: 63107 |
|
sigmask: 0000000000000200 |
|
|
|
where 'sigmask' is hex value of the signal mask associated |
|
with a file. |
|
|
|
Epoll files |
|
~~~~~~~~~~~ |
|
|
|
:: |
|
|
|
pos: 0 |
|
flags: 02 |
|
mnt_id: 9 |
|
ino: 63107 |
|
tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7 |
|
|
|
where 'tfd' is a target file descriptor number in decimal form, |
|
'events' is events mask being watched and the 'data' is data |
|
associated with a target [see epoll(7) for more details]. |
|
|
|
The 'pos' is current offset of the target file in decimal form |
|
[see lseek(2)], 'ino' and 'sdev' are inode and device numbers |
|
where target file resides, all in hex format. |
|
|
|
Fsnotify files |
|
~~~~~~~~~~~~~~ |
|
For inotify files the format is the following:: |
|
|
|
pos: 0 |
|
flags: 02000000 |
|
mnt_id: 9 |
|
ino: 63107 |
|
inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d |
|
|
|
where 'wd' is a watch descriptor in decimal form, i.e. a target file |
|
descriptor number, 'ino' and 'sdev' are inode and device where the |
|
target file resides and the 'mask' is the mask of events, all in hex |
|
form [see inotify(7) for more details]. |
|
|
|
If the kernel was built with exportfs support, the path to the target |
|
file is encoded as a file handle. The file handle is provided by three |
|
fields 'fhandle-bytes', 'fhandle-type' and 'f_handle', all in hex |
|
format. |
|
|
|
If the kernel is built without exportfs support the file handle won't be |
|
printed out. |
|
|
|
If there is no inotify mark attached yet the 'inotify' line will be omitted. |
|
|
|
For fanotify files the format is:: |
|
|
|
pos: 0 |
|
flags: 02 |
|
mnt_id: 9 |
|
ino: 63107 |
|
fanotify flags:10 event-flags:0 |
|
fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003 |
|
fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4 |
|
|
|
where fanotify 'flags' and 'event-flags' are values used in fanotify_init |
|
call, 'mnt_id' is the mount point identifier, 'mflags' is the value of |
|
flags associated with mark which are tracked separately from events |
|
mask. 'ino' and 'sdev' are target inode and device, 'mask' is the events |
|
mask and 'ignored_mask' is the mask of events which are to be ignored. |
|
All are in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask' |
|
provide information about flags and mask used in fanotify_mark |
|
call [see fsnotify manpage for details]. |
|
|
|
While the first three lines are mandatory and always printed, the rest is |
|
optional and may be omitted if no marks created yet. |
|
|
|
Timerfd files |
|
~~~~~~~~~~~~~ |
|
|
|
:: |
|
|
|
pos: 0 |
|
flags: 02 |
|
mnt_id: 9 |
|
ino: 63107 |
|
clockid: 0 |
|
ticks: 0 |
|
settime flags: 01 |
|
it_value: (0, 49406829) |
|
it_interval: (1, 0) |
|
|
|
where 'clockid' is the clock type and 'ticks' is the number of the timer expirations |
|
that have occurred [see timerfd_create(2) for details]. 'settime flags' are |
|
flags in octal form been used to setup the timer [see timerfd_settime(2) for |
|
details]. 'it_value' is remaining time until the timer expiration. |
|
'it_interval' is the interval for the timer. Note the timer might be set up |
|
with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value' |
|
still exhibits timer's remaining time. |
|
|
|
DMA Buffer files |
|
~~~~~~~~~~~~~~~~ |
|
|
|
:: |
|
|
|
pos: 0 |
|
flags: 04002 |
|
mnt_id: 9 |
|
ino: 63107 |
|
size: 32768 |
|
count: 2 |
|
exp_name: system-heap |
|
|
|
where 'size' is the size of the DMA buffer in bytes. 'count' is the file count of |
|
the DMA buffer file. 'exp_name' is the name of the DMA buffer exporter. |
|
|
|
3.9 /proc/<pid>/map_files - Information about memory mapped files |
|
--------------------------------------------------------------------- |
|
This directory contains symbolic links which represent memory mapped files |
|
the process is maintaining. Example output:: |
|
|
|
| lr-------- 1 root root 64 Jan 27 11:24 333c600000-333c620000 -> /usr/lib64/ld-2.18.so |
|
| lr-------- 1 root root 64 Jan 27 11:24 333c81f000-333c820000 -> /usr/lib64/ld-2.18.so |
|
| lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so |
|
| ... |
|
| lr-------- 1 root root 64 Jan 27 11:24 35d0421000-35d0422000 -> /usr/lib64/libselinux.so.1 |
|
| lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls |
|
|
|
The name of a link represents the virtual memory bounds of a mapping, i.e. |
|
vm_area_struct::vm_start-vm_area_struct::vm_end. |
|
|
|
The main purpose of the map_files is to retrieve a set of memory mapped |
|
files in a fast way instead of parsing /proc/<pid>/maps or |
|
/proc/<pid>/smaps, both of which contain many more records. At the same |
|
time one can open(2) mappings from the listings of two processes and |
|
comparing their inode numbers to figure out which anonymous memory areas |
|
are actually shared. |
|
|
|
3.10 /proc/<pid>/timerslack_ns - Task timerslack value |
|
--------------------------------------------------------- |
|
This file provides the value of the task's timerslack value in nanoseconds. |
|
This value specifies an amount of time that normal timers may be deferred |
|
in order to coalesce timers and avoid unnecessary wakeups. |
|
|
|
This allows a task's interactivity vs power consumption tradeoff to be |
|
adjusted. |
|
|
|
Writing 0 to the file will set the task's timerslack to the default value. |
|
|
|
Valid values are from 0 - ULLONG_MAX |
|
|
|
An application setting the value must have PTRACE_MODE_ATTACH_FSCREDS level |
|
permissions on the task specified to change its timerslack_ns value. |
|
|
|
3.11 /proc/<pid>/patch_state - Livepatch patch operation state |
|
----------------------------------------------------------------- |
|
When CONFIG_LIVEPATCH is enabled, this file displays the value of the |
|
patch state for the task. |
|
|
|
A value of '-1' indicates that no patch is in transition. |
|
|
|
A value of '0' indicates that a patch is in transition and the task is |
|
unpatched. If the patch is being enabled, then the task hasn't been |
|
patched yet. If the patch is being disabled, then the task has already |
|
been unpatched. |
|
|
|
A value of '1' indicates that a patch is in transition and the task is |
|
patched. If the patch is being enabled, then the task has already been |
|
patched. If the patch is being disabled, then the task hasn't been |
|
unpatched yet. |
|
|
|
3.12 /proc/<pid>/arch_status - task architecture specific status |
|
------------------------------------------------------------------- |
|
When CONFIG_PROC_PID_ARCH_STATUS is enabled, this file displays the |
|
architecture specific status of the task. |
|
|
|
Example |
|
~~~~~~~ |
|
|
|
:: |
|
|
|
$ cat /proc/6753/arch_status |
|
AVX512_elapsed_ms: 8 |
|
|
|
Description |
|
~~~~~~~~~~~ |
|
|
|
x86 specific entries |
|
~~~~~~~~~~~~~~~~~~~~~ |
|
|
|
AVX512_elapsed_ms |
|
^^^^^^^^^^^^^^^^^^ |
|
|
|
If AVX512 is supported on the machine, this entry shows the milliseconds |
|
elapsed since the last time AVX512 usage was recorded. The recording |
|
happens on a best effort basis when a task is scheduled out. This means |
|
that the value depends on two factors: |
|
|
|
1) The time which the task spent on the CPU without being scheduled |
|
out. With CPU isolation and a single runnable task this can take |
|
several seconds. |
|
|
|
2) The time since the task was scheduled out last. Depending on the |
|
reason for being scheduled out (time slice exhausted, syscall ...) |
|
this can be arbitrary long time. |
|
|
|
As a consequence the value cannot be considered precise and authoritative |
|
information. The application which uses this information has to be aware |
|
of the overall scenario on the system in order to determine whether a |
|
task is a real AVX512 user or not. Precise information can be obtained |
|
with performance counters. |
|
|
|
A special value of '-1' indicates that no AVX512 usage was recorded, thus |
|
the task is unlikely an AVX512 user, but depends on the workload and the |
|
scheduling scenario, it also could be a false negative mentioned above. |
|
|
|
Chapter 4: Configuring procfs |
|
============================= |
|
|
|
4.1 Mount options |
|
--------------------- |
|
|
|
The following mount options are supported: |
|
|
|
========= ======================================================== |
|
hidepid= Set /proc/<pid>/ access mode. |
|
gid= Set the group authorized to learn processes information. |
|
subset= Show only the specified subset of procfs. |
|
========= ======================================================== |
|
|
|
hidepid=off or hidepid=0 means classic mode - everybody may access all |
|
/proc/<pid>/ directories (default). |
|
|
|
hidepid=noaccess or hidepid=1 means users may not access any /proc/<pid>/ |
|
directories but their own. Sensitive files like cmdline, sched*, status are now |
|
protected against other users. This makes it impossible to learn whether any |
|
user runs specific program (given the program doesn't reveal itself by its |
|
behaviour). As an additional bonus, as /proc/<pid>/cmdline is unaccessible for |
|
other users, poorly written programs passing sensitive information via program |
|
arguments are now protected against local eavesdroppers. |
|
|
|
hidepid=invisible or hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be |
|
fully invisible to other users. It doesn't mean that it hides a fact whether a |
|
process with a specific pid value exists (it can be learned by other means, e.g. |
|
by "kill -0 $PID"), but it hides process' uid and gid, which may be learned by |
|
stat()'ing /proc/<pid>/ otherwise. It greatly complicates an intruder's task of |
|
gathering information about running processes, whether some daemon runs with |
|
elevated privileges, whether other user runs some sensitive program, whether |
|
other users run any program at all, etc. |
|
|
|
hidepid=ptraceable or hidepid=4 means that procfs should only contain |
|
/proc/<pid>/ directories that the caller can ptrace. |
|
|
|
gid= defines a group authorized to learn processes information otherwise |
|
prohibited by hidepid=. If you use some daemon like identd which needs to learn |
|
information about processes information, just add identd to this group. |
|
|
|
subset=pid hides all top level files and directories in the procfs that |
|
are not related to tasks. |
|
|
|
Chapter 5: Filesystem behavior |
|
============================== |
|
|
|
Originally, before the advent of pid namepsace, procfs was a global file |
|
system. It means that there was only one procfs instance in the system. |
|
|
|
When pid namespace was added, a separate procfs instance was mounted in |
|
each pid namespace. So, procfs mount options are global among all |
|
mountpoints within the same namespace:: |
|
|
|
# grep ^proc /proc/mounts |
|
proc /proc proc rw,relatime,hidepid=2 0 0 |
|
|
|
# strace -e mount mount -o hidepid=1 -t proc proc /tmp/proc |
|
mount("proc", "/tmp/proc", "proc", 0, "hidepid=1") = 0 |
|
+++ exited with 0 +++ |
|
|
|
# grep ^proc /proc/mounts |
|
proc /proc proc rw,relatime,hidepid=2 0 0 |
|
proc /tmp/proc proc rw,relatime,hidepid=2 0 0 |
|
|
|
and only after remounting procfs mount options will change at all |
|
mountpoints:: |
|
|
|
# mount -o remount,hidepid=1 -t proc proc /tmp/proc |
|
|
|
# grep ^proc /proc/mounts |
|
proc /proc proc rw,relatime,hidepid=1 0 0 |
|
proc /tmp/proc proc rw,relatime,hidepid=1 0 0 |
|
|
|
This behavior is different from the behavior of other filesystems. |
|
|
|
The new procfs behavior is more like other filesystems. Each procfs mount |
|
creates a new procfs instance. Mount options affect own procfs instance. |
|
It means that it became possible to have several procfs instances |
|
displaying tasks with different filtering options in one pid namespace:: |
|
|
|
# mount -o hidepid=invisible -t proc proc /proc |
|
# mount -o hidepid=noaccess -t proc proc /tmp/proc |
|
# grep ^proc /proc/mounts |
|
proc /proc proc rw,relatime,hidepid=invisible 0 0 |
|
proc /tmp/proc proc rw,relatime,hidepid=noaccess 0 0
|
|
|