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==================== The /proc Filesystem ==================== ===================== ======================================= ================ /proc/sys Terrehon Bowden <terrehon@pacbell.net>, October 7 1999 Bodo Bauer <bb@ricochet.net> 2.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000 move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009 fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009 ===================== ======================================= ================ .. Table of Contents 0 Preface 0.1 Introduction/Credits 0.2 Legal Stuff 1 Collecting System Information 1.1 Process-Specific Subdirectories 1.2 Kernel data 1.3 IDE devices in /proc/ide 1.4 Networking info in /proc/net 1.5 SCSI info 1.6 Parallel port info in /proc/parport 1.7 TTY info in /proc/tty 1.8 Miscellaneous kernel statistics in /proc/stat 1.9 Ext4 file system parameters 2 Modifying System Parameters 3 Per-Process Parameters 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer score 3.2 /proc/<pid>/oom_score - Display current oom-killer score 3.3 /proc/<pid>/io - Display the IO accounting fields 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings 3.5 /proc/<pid>/mountinfo - Information about mounts 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm 3.7 /proc/<pid>/task/<tid>/children - Information about task children 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file 3.9 /proc/<pid>/map_files - Information about memory mapped files 3.10 /proc/<pid>/timerslack_ns - Task timerslack value 3.11 /proc/<pid>/patch_state - Livepatch patch operation state 3.12 /proc/<pid>/arch_status - Task architecture specific information 3.13 /proc/<pid>/fd - List of symlinks to open files 3.14 /proc/<pid/ksm_stat - Information about the process's ksm status. 4 Configuring procfs 4.1 Mount options 5 Filesystem behavior Preface ======= 0.1 Introduction/Credits ------------------------ This documentation is part of a soon (or so we hope) to be released book on the SuSE Linux distribution. As there is no complete documentation for the /proc file system and we've used many freely available sources to write these chapters, it seems only fair to give the work back to the Linux community. This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm afraid it's still far from complete, but we hope it will be useful. As far as we know, it is the first 'all-in-one' document about the /proc file system. It is focused on the Intel x86 hardware, so if you are looking for PPC, ARM, SPARC, AXP, etc., features, you probably won't find what you are looking for. It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But additions and patches are welcome and will be added to this document if you mail them to Bodo. We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of other people for help compiling this documentation. We'd also like to extend a special thank you to Andi Kleen for documentation, which we relied on heavily to create this document, as well as the additional information he provided. Thanks to everybody else who contributed source or docs to the Linux kernel and helped create a great piece of software... :) If you have any comments, corrections or additions, please don't hesitate to contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this document. The latest version of this document is available online at https://www.kernel.org/doc/html/latest/filesystems/proc.html If the above direction does not works for you, you could try the kernel mailing list at linux-kernel@vger.kernel.org and/or try to reach me at comandante@zaralinux.com. 0.2 Legal Stuff --------------- We don't guarantee the correctness of this document, and if you come to us complaining about how you screwed up your system because of incorrect documentation, we won't feel responsible... Chapter 1: Collecting System Information ======================================== In This Chapter --------------- * Investigating the properties of the pseudo file system /proc and its ability to provide information on the running Linux system * Examining /proc's structure * Uncovering various information about the kernel and the processes running on the system ------------------------------------------------------------------------------ The proc file system acts as an interface to internal data structures in the kernel. It can be used to obtain information about the system and to change certain kernel parameters at runtime (sysctl). First, we'll take a look at the read-only parts of /proc. In Chapter 2, we show you how you can use /proc/sys to change settings. 1.1 Process-Specific Subdirectories ----------------------------------- The directory /proc contains (among other things) one subdirectory for each process running on the system, which is named after the process ID (PID). The link 'self' points to the process reading the file system. Each process subdirectory has the entries listed in Table 1-1. A process can read its own information from /proc/PID/* with no extra permissions. When reading /proc/PID/* information for other processes, reading process is required to have either CAP_SYS_PTRACE capability with PTRACE_MODE_READ access permissions, or, alternatively, CAP_PERFMON capability. This applies to all read-only information like `maps`, `environ`, `pagemap`, etc. The only exception is `mem` file due to its read-write nature, which requires CAP_SYS_PTRACE capabilities with more elevated PTRACE_MODE_ATTACH permissions; CAP_PERFMON capability does not grant access to /proc/PID/mem for other processes. Note that an open file descriptor to /proc/<pid> or to any of its contained files or subdirectories does not prevent <pid> being reused for some other process in the event that <pid> exits. Operations on open /proc/<pid> file descriptors corresponding to dead processes never act on any new process that the kernel may, through chance, have also assigned the process ID <pid>. Instead, operations on these FDs usually fail with ESRCH. .. table:: Table 1-1: Process specific entries in /proc ============= =============================================================== File Content ============= =============================================================== clear_refs Clears page referenced bits shown in smaps output cmdline Command line arguments cpu Current and last cpu in which it was executed (2.4)(smp) cwd Link to the current working directory environ Values of environment variables exe Link to the executable of this process fd Directory, which contains all file descriptors maps Memory maps to executables and library files (2.4) mem Memory held by this process root Link to the root directory of this process stat Process status statm Process memory status information status Process status in human readable form wchan Present with CONFIG_KALLSYMS=y: it shows the kernel function symbol the task is blocked in - or "0" if not blocked. pagemap Page table stack Report full stack trace, enable via CONFIG_STACKTRACE smaps An extension based on maps, showing the memory consumption of each mapping and flags associated with it smaps_rollup Accumulated smaps stats for all mappings of the process. This can be derived from smaps, but is faster and more convenient numa_maps An extension based on maps, showing the memory locality and binding policy as well as mem usage (in pages) of each mapping. ============= =============================================================== For example, to get the status information of a process, all you have to do is read the file /proc/PID/status:: >cat /proc/self/status Name: cat State: R (running) Tgid: 5452 Pid: 5452 PPid: 743 TracerPid: 0 (2.4) Uid: 501 501 501 501 Gid: 100 100 100 100 FDSize: 256 Groups: 100 14 16 Kthread: 0 VmPeak: 5004 kB VmSize: 5004 kB VmLck: 0 kB VmHWM: 476 kB VmRSS: 476 kB RssAnon: 352 kB RssFile: 120 kB RssShmem: 4 kB VmData: 156 kB VmStk: 88 kB VmExe: 68 kB VmLib: 1412 kB VmPTE: 20 kb VmSwap: 0 kB HugetlbPages: 0 kB CoreDumping: 0 THP_enabled: 1 Threads: 1 SigQ: 0/28578 SigPnd: 0000000000000000 ShdPnd: 0000000000000000 SigBlk: 0000000000000000 SigIgn: 0000000000000000 SigCgt: 0000000000000000 CapInh: 00000000fffffeff CapPrm: 0000000000000000 CapEff: 0000000000000000 CapBnd: ffffffffffffffff CapAmb: 0000000000000000 NoNewPrivs: 0 Seccomp: 0 Speculation_Store_Bypass: thread vulnerable SpeculationIndirectBranch: conditional enabled voluntary_ctxt_switches: 0 nonvoluntary_ctxt_switches: 1 This shows you nearly the same information you would get if you viewed it with the ps command. In fact, ps uses the proc file system to obtain its information. But you get a more detailed view of the process by reading the file /proc/PID/status. It fields are described in table 1-2. The statm file contains more detailed information about the process memory usage. Its seven fields are explained in Table 1-3. The stat file contains detailed information about the process itself. Its fields are explained in Table 1-4. (for SMP CONFIG users) For making accounting scalable, RSS related information are handled in an asynchronous manner and the value may not be very precise. To see a precise snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table. It's slow but very precise. .. table:: Table 1-2: Contents of the status fields (as of 4.19) ========================== =================================================== Field Content ========================== =================================================== Name filename of the executable Umask file mode creation mask State state (R is running, S is sleeping, D is sleeping in an uninterruptible wait, Z is zombie, T is traced or stopped) Tgid thread group ID Ngid NUMA group ID (0 if none) Pid process id PPid process id of the parent process TracerPid PID of process tracing this process (0 if not, or the tracer is outside of the current pid namespace) Uid Real, effective, saved set, and file system UIDs Gid Real, effective, saved set, and file system GIDs FDSize number of file descriptor slots currently allocated Groups supplementary group list NStgid descendant namespace thread group ID hierarchy NSpid descendant namespace process ID hierarchy NSpgid descendant namespace process group ID hierarchy NSsid descendant namespace session ID hierarchy Kthread kernel thread flag, 1 is yes, 0 is no VmPeak peak virtual memory size VmSize total program size VmLck locked memory size VmPin pinned memory size VmHWM peak resident set size ("high water mark") VmRSS size of memory portions. It contains the three following parts (VmRSS = RssAnon + RssFile + RssShmem) RssAnon size of resident anonymous memory RssFile size of resident file mappings RssShmem size of resident shmem memory (includes SysV shm, mapping of tmpfs and shared anonymous mappings) VmData size of private data segments VmStk size of stack segments VmExe size of text segment VmLib size of shared library code VmPTE size of page table entries VmSwap amount of swap used by anonymous private data (shmem swap usage is not included) HugetlbPages size of hugetlb memory portions CoreDumping process's memory is currently being dumped (killing the process may lead to a corrupted core) THP_enabled process is allowed to use THP (returns 0 when PR_SET_THP_DISABLE is set on the process Threads number of threads SigQ number of signals queued/max. number for queue SigPnd bitmap of pending signals for the thread ShdPnd bitmap of shared pending signals for the process SigBlk bitmap of blocked signals SigIgn bitmap of ignored signals SigCgt bitmap of caught signals CapInh bitmap of inheritable capabilities CapPrm bitmap of permitted capabilities CapEff bitmap of effective capabilities CapBnd bitmap of capabilities bounding set CapAmb bitmap of ambient capabilities NoNewPrivs no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...) Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...) Speculation_Store_Bypass speculative store bypass mitigation status SpeculationIndirectBranch indirect branch speculation mode Cpus_allowed mask of CPUs on which this process may run Cpus_allowed_list Same as previous, but in "list format" Mems_allowed mask of memory nodes allowed to this process Mems_allowed_list Same as previous, but in "list format" voluntary_ctxt_switches number of voluntary context switches nonvoluntary_ctxt_switches number of non voluntary context switches ========================== =================================================== .. table:: Table 1-3: Contents of the statm fields (as of 2.6.8-rc3) ======== =============================== ============================== Field Content ======== =============================== ============================== size total program size (pages) (same as VmSize in status) resident size of memory portions (pages) (same as VmRSS in status) shared number of pages that are shared (i.e. backed by a file, same as RssFile+RssShmem in status) trs number of pages that are 'code' (not including libs; broken, includes data segment) lrs number of pages of library (always 0 on 2.6) drs number of pages of data/stack (including libs; broken, includes library text) dt number of dirty pages (always 0 on 2.6) ======== =============================== ============================== .. table:: Table 1-4: Contents of the stat fields (as of 2.6.30-rc7) ============= =============================================================== Field Content ============= =============================================================== pid process id tcomm filename of the executable state state (R is running, S is sleeping, D is sleeping in an uninterruptible wait, Z is zombie, T is traced or stopped) ppid process id of the parent process pgrp pgrp of the process sid session id tty_nr tty the process uses tty_pgrp pgrp of the tty flags task flags min_flt number of minor faults cmin_flt number of minor faults with child's maj_flt number of major faults cmaj_flt number of major faults with child's utime user mode jiffies stime kernel mode jiffies cutime user mode jiffies with child's cstime kernel mode jiffies with child's priority priority level nice nice level num_threads number of threads it_real_value (obsolete, always 0) start_time time the process started after system boot vsize virtual memory size rss resident set memory size rsslim current limit in bytes on the rss start_code address above which program text can run end_code address below which program text can run start_stack address of the start of the main process stack esp current value of ESP eip current value of EIP pending bitmap of pending signals blocked bitmap of blocked signals sigign bitmap of ignored signals sigcatch bitmap of caught signals 0 (place holder, used to be the wchan address, use /proc/PID/wchan instead) 0 (place holder) 0 (place holder) exit_signal signal to send to parent thread on exit task_cpu which CPU the task is scheduled on rt_priority realtime priority policy scheduling policy (man sched_setscheduler) blkio_ticks time spent waiting for block IO gtime guest time of the task in jiffies cgtime guest time of the task children in jiffies start_data address above which program data+bss is placed end_data address below which program data+bss is placed start_brk address above which program heap can be expanded with brk() arg_start address above which program command line is placed arg_end address below which program command line is placed env_start address above which program environment is placed env_end address below which program environment is placed exit_code the thread's exit_code in the form reported by the waitpid system call ============= =============================================================== The /proc/PID/maps file contains the currently mapped memory regions and their access permissions. The format is:: address perms offset dev inode pathname 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test 0804a000-0806b000 rw-p 00000000 00:00 0 [heap] a7cb1000-a7cb2000 ---p 00000000 00:00 0 a7cb2000-a7eb2000 rw-p 00000000 00:00 0 a7eb2000-a7eb3000 ---p 00000000 00:00 0 a7eb3000-a7ed5000 rw-p 00000000 00:00 0 a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6 a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6 a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6 a800b000-a800e000 rw-p 00000000 00:00 0 a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0 a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0 a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0 a8024000-a8027000 rw-p 00000000 00:00 0 a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2 a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2 a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2 aff35000-aff4a000 rw-p 00000000 00:00 0 [stack] ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso] where "address" is the address space in the process that it occupies, "perms" is a set of permissions:: r = read w = write x = execute s = shared p = private (copy on write) "offset" is the offset into the mapping, "dev" is the device (major:minor), and "inode" is the inode on that device. 0 indicates that no inode is associated with the memory region, as the case would be with BSS (uninitialized data). The "pathname" shows the name associated file for this mapping. If the mapping is not associated with a file: =================== =========================================== [heap] the heap of the program [stack] the stack of the main process [vdso] the "virtual dynamic shared object", the kernel system call handler [anon:<name>] a private anonymous mapping that has been named by userspace [anon_shmem:<name>] an anonymous shared memory mapping that has been named by userspace =================== =========================================== or if empty, the mapping is anonymous. Starting with 6.11 kernel, /proc/PID/maps provides an alternative ioctl()-based API that gives ability to flexibly and efficiently query and filter individual VMAs. This interface is binary and is meant for more efficient and easy programmatic use. `struct procmap_query`, defined in linux/fs.h UAPI header, serves as an input/output argument to the `PROCMAP_QUERY` ioctl() command. See comments in linus/fs.h UAPI header for details on query semantics, supported flags, data returned, and general API usage information. The /proc/PID/smaps is an extension based on maps, showing the memory consumption for each of the process's mappings. For each mapping (aka Virtual Memory Area, or VMA) there is a series of lines such as the following:: 08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash Size: 1084 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Rss: 892 kB Pss: 374 kB Pss_Dirty: 0 kB Shared_Clean: 892 kB Shared_Dirty: 0 kB Private_Clean: 0 kB Private_Dirty: 0 kB Referenced: 892 kB Anonymous: 0 kB KSM: 0 kB LazyFree: 0 kB AnonHugePages: 0 kB ShmemPmdMapped: 0 kB Shared_Hugetlb: 0 kB Private_Hugetlb: 0 kB Swap: 0 kB SwapPss: 0 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Locked: 0 kB THPeligible: 0 VmFlags: rd ex mr mw me dw The first of these lines shows the same information as is displayed for the mapping in /proc/PID/maps. Following lines show the size of the mapping (size); the size of each page allocated when backing a VMA (KernelPageSize), which is usually the same as the size in the page table entries; the page size used by the MMU when backing a VMA (in most cases, the same as KernelPageSize); the amount of the mapping that is currently resident in RAM (RSS); the process's proportional share of this mapping (PSS); and the number of clean and dirty shared and private pages in the mapping. The "proportional set size" (PSS) of a process is the count of pages it has in memory, where each page is divided by the number of processes sharing it. So if a process has 1000 pages all to itself, and 1000 shared with one other process, its PSS will be 1500. "Pss_Dirty" is the portion of PSS which consists of dirty pages. ("Pss_Clean" is not included, but it can be calculated by subtracting "Pss_Dirty" from "Pss".) Traditionally, a page is accounted as "private" if it is mapped exactly once, and a page is accounted as "shared" when mapped multiple times, even when mapped in the same process multiple times. Note that this accounting is independent of MAP_SHARED. In some kernel configurations, the semantics of pages part of a larger allocation (e.g., THP) can differ: a page is accounted as "private" if all pages part of the corresponding large allocation are *certainly* mapped in the same process, even if the page is mapped multiple times in that process. A page is accounted as "shared" if any page page of the larger allocation is *maybe* mapped in a different process. In some cases, a large allocation might be treated as "maybe mapped by multiple processes" even though this is no longer the case. Some kernel configurations do not track the precise number of times a page part of a larger allocation is mapped. In this case, when calculating the PSS, the average number of mappings per page in this larger allocation might be used as an approximation for the number of mappings of a page. The PSS calculation will be imprecise in this case. "Referenced" indicates the amount of memory currently marked as referenced or accessed. "Anonymous" shows the amount of memory that does not belong to any file. Even a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE and a page is modified, the file page is replaced by a private anonymous copy. "KSM" reports how many of the pages are KSM pages. Note that KSM-placed zeropages are not included, only actual KSM pages. "LazyFree" shows the amount of memory which is marked by madvise(MADV_FREE). 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. "AnonHugePages" shows the amount of memory backed by transparent hugepage. "ShmemPmdMapped" shows the amount of shared (shmem/tmpfs) memory backed by huge pages. "Shared_Hugetlb" and "Private_Hugetlb" show the amounts of memory backed by hugetlbfs page which is *not* counted in "RSS" or "PSS" field for historical reasons. And these are not included in {Shared,Private}_{Clean,Dirty} field. "Swap" shows how much would-be-anonymous memory is also used, but out on swap. 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. "Locked" indicates whether the mapping is locked in memory or not. "THPeligible" indicates whether the mapping is eligible for allocating naturally aligned THP pages of any currently enabled size. 1 if true, 0 otherwise. "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 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 mergeable advise flag bt arm64 BTI guarded page mt arm64 MTE allocation tags are enabled um userfaultfd missing tracking uw userfaultfd wr-protect tracking ui userfaultfd minor fault ss shadow/guarded control stack page sl sealed lf lock on fault pages dp always lazily freeable mapping == ======================================= 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_ 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 ke 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 kernelpa 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/ "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. Note that some kernel configurations do not track the precise number of times a page part of a larger allocation (e.g., THP) is mapped. In these configurations, "mapmax" might corresponds to the average number of mappings per page in such a larger allocation instead. 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 ============ =============================================================== allocinfo Memory allocations profiling information apm Advanced power management info bootconfig Kernel command line obtained from boot config, and, if there were kernel parameters from the boot loader, a "# Parameters from bootloader:" line followed by a line containing those parameters prefixed by "# ". (5.5) buddyinfo Kernel memory allocator information (see text) (2.5) bus Directory containing bus specific information cmdline Kernel command line, both from bootloader and embedded in the kernel image 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. allocinfo ~~~~~~~~~ Provides information about memory allocations at all locations in the code base. Each allocation in the code is identified by its source file, line number, module (if originates from a loadable module) and the function calling the allocation. The number of bytes allocated and number of calls at each location are reported. The first line indicates the version of the file, the second line is the header listing fields in the file. Example output. :: > tail -n +3 /proc/allocinfo | sort -rn 127664128 31168 mm/page_ext.c:270 func:alloc_page_ext 56373248 4737 mm/slub.c:2259 func:alloc_slab_page 14880768 3633 mm/readahead.c:247 func:page_cache_ra_unbounded 14417920 3520 mm/mm_init.c:2530 func:alloc_large_system_hash 13377536 234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs 11718656 2861 mm/filemap.c:1919 func:__filemap_get_folio 9192960 2800 kernel/fork.c:307 func:alloc_thread_stack_node 4206592 4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable 4136960 1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start 3940352 962 mm/memory.c:4214 func:alloc_anon_folio 2894464 22613 fs/kernfs/dir.c:615 func:__kernfs_new_node ... 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. Example output. You may not have all of these fields. :: > cat /proc/meminfo MemTotal: 32858820 kB MemFree: 21001236 kB MemAvailable: 27214312 kB Buffers: 581092 kB Cached: 5587612 kB SwapCached: 0 kB Active: 3237152 kB Inactive: 7586256 kB Active(anon): 94064 kB Inactive(anon): 4570616 kB Active(file): 3143088 kB Inactive(file): 3015640 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB Zswap: 1904 kB Zswapped: 7792 kB Dirty: 12 kB Writeback: 0 kB AnonPages: 4654780 kB Mapped: 266244 kB Shmem: 9976 kB KReclaimable: 517708 kB Slab: 660044 kB SReclaimable: 517708 kB SUnreclaim: 142336 kB KernelStack: 11168 kB PageTables: 20540 kB SecPageTables: 0 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 16429408 kB Committed_AS: 7715148 kB VmallocTotal: 34359738367 kB VmallocUsed: 40444 kB VmallocChunk: 0 kB Percpu: 29312 kB EarlyMemtestBad: 0 kB HardwareCorrupted: 0 kB AnonHugePages: 4149248 kB ShmemHugePages: 0 kB ShmemPmdMapped: 0 kB FileHugePages: 0 kB FilePmdMapped: 0 kB CmaTotal: 0 kB CmaFree: 0 kB Unaccepted: 0 kB Balloon: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB Hugetlb: 0 kB DirectMap4k: 401152 kB DirectMap2M: 10008576 kB DirectMap1G: 24117248 kB MemTotal Total usable RAM (i.e. physical RAM minus a few reserved bits and the kernel binary code) MemFree Total free RAM. On highmem systems, 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) as well as tmpfs & shmem. 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 Unevictable Memory allocated for userspace which cannot be reclaimed, such as mlocked pages, ramfs backing pages, secret memfd pages etc. Mlocked Memory locked with mlock(). 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 Zswap Memory consumed by the zswap backend (compressed size) Zswapped Amount of anonymous memory stored in zswap (original size) 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. Note that some kernel configurations might consider all pages part of a larger allocation (e.g., THP) as "mapped", as soon as a single page is mapped. Mapped files which have been mmapped, such as libraries. Note that some kernel configurations might consider all pages part of a larger allocation (e.g., THP) as "mapped", as soon as a single page is mapped. Shmem Total memory used by shared memory (shmem) and tmpfs 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 KernelStack Memory consumed by the kernel stacks of all tasks PageTables Memory consumed by userspace page tables SecPageTables Memory consumed by secondary page tables, this currently includes KVM mmu and IOMMU allocations on x86 and arm64. NFS_Unstable Always zero. Previously counted pages which had been written to the server, but has not been committed to stable storage. Bounce Always zero. Previously memory used for block device "bounce buffers". WritebackTmp Always zero. Previously 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 mm/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 virtual address space 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. EarlyMemtestBad The amount of RAM/memory in kB, that was identified as corrupted by early memtest. If memtest was not run, this field will not be displayed at all. Size is never rounded down to 0 kB. That means if 0 kB is reported, you can safely assume there was at least one pass of memtest and none of the passes found a single faulty byte of RAM. HardwareCorrupted The amount of RAM/memory in KB, the kernel identifies as corrupted. AnonHugePages Non-file backed huge pages mapped into userspace page tables ShmemHugePages Memory used by shared memory (shmem) and tmpfs allocated with huge pages ShmemPmdMapped Shared memory mapped into userspace with huge pages FileHugePages Memory used for filesystem data (page cache) allocated with huge pages FilePmdMapped Page cache mapped into userspace with huge pages CmaTotal Memory reserved for the Contiguous Memory Allocator (CMA) CmaFree Free remaining memory in the CMA reserves Unaccepted Memory that has not been accepted by the guest Balloon Memory returned to Host by VM Balloon Drivers HugePages_Total, HugePages_Free, HugePages_Rsvd, HugePages_Surp, Hugepagesize, Hugetl See Documentation/admin-guide/mm/hugetlbpage.rst. DirectMap4k, DirectMap2M, DirectMap1G Breakdown of page table sizes used in the kernel's identity mapping of RAM 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 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 softnet_stat Per-CPU incoming packets queues statistics of online CPUs 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. 1.4 SCSI info ------------- If you have a SCSI or ATA 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 --> -------------------- --> maximum size reached --> -------------------- [ Dauer der Verarbeitung: 0.20 Sekunden (vorverarbeitet) ] |
2026-04-04