diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst
index fed53f83119284b490c1e85a45142835802c27b6..671906e2fee66123bd217b3b4d293bf79c354468 100644
--- a/Documentation/filesystems/index.rst
+++ b/Documentation/filesystems/index.rst
@@ -81,5 +81,6 @@ Documentation for filesystem implementations.
omfs
orangefs
overlayfs
+ proc
virtiofs
vfat
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.rst
similarity index 65%
rename from Documentation/filesystems/proc.txt
rename to Documentation/filesystems/proc.rst
index 99ca040e3f900e399b59e2b5233fa9169ac61ccb..38b606991065b3df4f075bb3120dc9e5db09bf71 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.rst
@@ -1,19 +1,20 @@
-------------------------------------------------------------------------------
- T H E /proc F I L E S Y S T E M
-------------------------------------------------------------------------------
-/proc/sys Terrehon Bowden <terrehon@pacbell.net> October 7 1999
- Bodo Bauer <bb@ricochet.net>
+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+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
+===================== ======================================= ================
+
-2.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000
-move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
-------------------------------------------------------------------------------
-Version 1.3 Kernel version 2.2.12
- Kernel version 2.4.0-test11-pre4
-------------------------------------------------------------------------------
-fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009
-Table of Contents
------------------
+.. Table of Contents
0 Preface
0.1 Introduction/Credits
@@ -50,9 +51,8 @@ Table of Contents
4 Configuring procfs
4.1 Mount options
-------------------------------------------------------------------------------
Preface
-------------------------------------------------------------------------------
+=======
0.1 Introduction/Credits
------------------------
@@ -95,20 +95,18 @@ 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
-------------------------------------------------------------------------------
+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
@@ -134,9 +132,11 @@ 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 1-1: Process specific entries in /proc
-..............................................................................
+.. 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)
@@ -160,10 +160,10 @@ Table 1-1: Process specific entries in /proc
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:
+read the file /proc/PID/status::
>cat /proc/self/status
Name: cat
@@ -222,14 +222,17 @@ contains details 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 1-2: Contents of the status files (as of 4.19)
-..............................................................................
+.. table:: Table 1-2: Contents of the status files (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
@@ -254,7 +257,8 @@ Table 1-2: Contents of the status files (as of 4.19)
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)
+ 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,
@@ -292,27 +296,32 @@ Table 1-2: Contents of the status files (as of 4.19)
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 1-3: Contents of the statm files (as of 2.6.8-rc3)
-..............................................................................
+
+.. table:: Table 1-3: Contents of the statm files (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)
+ 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)
+ includes library text)
dt number of dirty pages (always 0 on 2.6)
-..............................................................................
+ ======== =============================== ==============================
+
+.. table:: Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
-Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
-..............................................................................
- Field Content
+ ============= ===============================================================
+ Field Content
+ ============= ===============================================================
pid process id
tcomm filename of the executable
state state (R is running, S is sleeping, D is sleeping in an
@@ -348,7 +357,8 @@ Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
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, 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
@@ -365,39 +375,40 @@ Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
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
-..............................................................................
+ 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]
+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:
+is a set of permissions::
r = read
w = write
@@ -411,42 +422,44 @@ 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",
+ ======= ====================================
+ [heap] the heap of the program
+ [stack] the stack of the main process
+ [vdso] the "virtual dynamic shared object",
the kernel system call handler
+ ======= ====================================
or if empty, the mapping is anonymous.
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
-Shared_Clean: 892 kB
-Shared_Dirty: 0 kB
-Private_Clean: 0 kB
-Private_Dirty: 0 kB
-Referenced: 892 kB
-Anonymous: 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
+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
+ Shared_Clean: 892 kB
+ Shared_Dirty: 0 kB
+ Private_Clean: 0 kB
+ Private_Dirty: 0 kB
+ Referenced: 892 kB
+ Anonymous: 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
@@ -461,26 +474,35 @@ 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.
+
Note that even a page which is part of a MAP_SHARED mapping, but has only
a single pte mapped, i.e. is currently used by only one process, is accounted
as private and not as shared.
+
"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.
+
"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 ammount of memory backed by transparent hugepage.
+
"ShmemPmdMapped" shows the ammount of shared (shmem/tmpfs) memory backed by
huge pages.
+
"Shared_Hugetlb" and "Private_Hugetlb" show the ammounts 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
@@ -489,36 +511,39 @@ does not take into account swapped out page of underlying shmem objects.
"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
- ar - architecture specific flag
- 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
+"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
+ ar architecture specific flag
+ 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
+ == =======================================
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
@@ -531,6 +556,7 @@ 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:
@@ -544,9 +570,9 @@ 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
+- 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
@@ -558,20 +584,25 @@ 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
+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
+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
+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
+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:
+current value::
+
> echo 5 > /proc/PID/clear_refs
Any other value written to /proc/PID/clear_refs will have no effect.
@@ -584,30 +615,33 @@ 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
+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.
@@ -621,81 +655,83 @@ the running kernel. The files used to obtain this information are contained in
system. It depends on the kernel configuration and the loaded modules, which
files are there, and which are missing.
-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
- locks Kernel locks
- meminfo Memory info
- misc Miscellaneous
- modules List of loaded modules
- mounts Mounted filesystems
- net Networking info (see text)
+.. 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
+ 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
-..............................................................................
+ 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
+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):
+output of a SMP machine)::
- > cat /proc/interrupts
+ > cat /proc/interrupts
- CPU0 CPU1
+ CPU0 CPU1
0: 1243498 1214548 IO-APIC-edge timer
1: 8949 8958 IO-APIC-edge keyboard
2: 0 0 XT-PIC cascade
@@ -708,8 +744,8 @@ output of a SMP machine):
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
+ NMI: 2457961 2457959
+ LOC: 2457882 2457881
ERR: 2155
NMI is incremented in this case because every timer interrupt generates a NMI
@@ -726,21 +762,25 @@ 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
+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
+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
+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
+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.
@@ -756,7 +796,8 @@ 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
+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
@@ -764,20 +805,20 @@ For example
smp_affinity
smp_affinity is a bitmask, in which you can specify which CPUs can handle the
-IRQ, you can set it by doing:
+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:
+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:
+a cpu range instead of a bitmask::
> cat /proc/irq/0/smp_affinity_list
1024-1031
@@ -810,46 +851,46 @@ 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
+ > 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 ...
+ 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
+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...
+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
+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.
@@ -870,59 +911,63 @@ 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:
+meminfo
+~~~~~~~
Provides information about distribution and utilization of memory. This
varies by architecture and compile options. 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
+::
+
+ > 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
+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.
@@ -930,69 +975,99 @@ MemAvailable: An estimate of how much memory is available for starting new
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
+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
+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
+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
+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
+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
+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
+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
+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
+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
+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
+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
+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: NFS pages sent to the server, but not yet committed to stable
+NFS_Unstable
+ NFS pages sent to the server, but not yet 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'),
+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]
+
+ 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.
+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
@@ -1005,21 +1080,25 @@ Committed_AS: The amount of memory presently allocated on the system.
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
+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:
+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)
@@ -1029,49 +1108,54 @@ on the kind of 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:
+ ========== ===================================================
+
+::
+
+ > 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
+::
+
+ > 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
@@ -1083,7 +1167,7 @@ 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:
+IDE devices::
> cat /proc/ide/drivers
ide-cdrom version 4.53
@@ -1094,57 +1178,61 @@ subdirectories. These are named ide0, ide1 and so on. Each of these
directories contains the files shown in table 1-6.
-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
-..............................................................................
+.. 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 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
+.. 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
@@ -1155,67 +1243,70 @@ 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 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 1-9: Network info in /proc/net
-..............................................................................
- File Content
- arp Kernel ARP table
- dev network devices with statistics
+.. 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
-..............................................................................
+ 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
+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/.
@@ -1228,62 +1319,62 @@ many times the slaves link has failed.
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:
+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
+ >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)
+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
@@ -1296,18 +1387,20 @@ number (0,1,2,...).
These directories contain the four files shown in Table 1-10.
-Table 1-10: Files in /proc/parport
-..............................................................................
- File Content
- autoprobe Any IEEE-1284 device ID information that has been acquired.
+.. 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.
+ 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).
-..............................................................................
+ number or none).
+ ========= ====================================================================
1.7 TTY info in /proc/tty
-------------------------
@@ -1317,29 +1410,31 @@ directory /proc/tty.You'll find entries for drivers and line disciplines in
this directory, as shown in Table 1-11.
-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
-..............................................................................
+.. 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
+/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
@@ -1347,7 +1442,7 @@ To see which tty's are currently in use, you can simply look into the file
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:
+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
@@ -1372,6 +1467,7 @@ second). The meanings of the columns are as follows, from left to right:
- 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 io, another task will be scheduled on this CPU.
@@ -1379,6 +1475,7 @@ second). The meanings of the columns are as follows, from left to right:
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
@@ -1422,18 +1519,19 @@ Information about mounted ext4 file systems can be found in
/proc/fs/ext4/dm-0). The files in each per-device directory are shown
in Table 1-12, below.
-Table 1-12: Files in /proc/fs/ext4/<devname>
-..............................................................................
- File Content
+.. table:: Table 1-12: Files in /proc/fs/ext4/<devname>
+
+ ============== ==========================================================
+ File Content
mb_groups details of multiblock allocator buddy cache of free blocks
-..............................................................................
+ ============== ==========================================================
2.0 /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:
+/dev/console, you may simply look into the file /proc/consoles::
> cat /proc/consoles
tty0 -WU (ECp) 4:7
@@ -1441,41 +1539,45 @@ To see which character device lines are currently used for the system console
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
++--------------------+-------------------------------------------------------+
+| 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
-------------------------------------------------------------------------------
+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
@@ -1503,19 +1605,18 @@ 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
-------------------------------------------------------------------------------
+
+Chapter 3: Per-process Parameters
+=================================
3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
--------------------------------------------------------------------------------
@@ -1588,26 +1689,28 @@ process should be killed in an out-of-memory situation.
This file contains IO statistics for each running process
Example
--------
+~~~~~~~
+
+::
-test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
-[1] 3828
+ 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
+ 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
@@ -1618,7 +1721,7 @@ pagecache)
wchar
------
+^^^^^
I/O counter: chars written
The number of bytes which this task has caused, or shall cause to be written
@@ -1626,7 +1729,7 @@ 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()
@@ -1634,7 +1737,7 @@ and pread().
syscw
------
+^^^^^
I/O counter: write syscalls
Attempt to count the number of write I/O operations, i.e. syscalls like
@@ -1642,7 +1745,7 @@ write() and pwrite().
read_bytes
-----------
+^^^^^^^^^^
I/O counter: bytes read
Attempt to count the number of bytes which this process really did cause to
@@ -1652,7 +1755,7 @@ 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
@@ -1660,7 +1763,7 @@ 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
@@ -1673,12 +1776,11 @@ from the truncating task's write_bytes, but there is information loss in doing
that.
-Note
-----
+.. 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.
+ 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
@@ -1698,12 +1800,13 @@ 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)
+ effective only if the bit 2 is cleared)
- (bit 5) hugetlb private memory
- (bit 6) hugetlb shared memory
- (bit 7) DAX private memory
@@ -1719,13 +1822,13 @@ 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.
+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:
+For example::
$ echo 0x7 > /proc/self/coredump_filter
$ ./some_program
@@ -1733,35 +1836,37 @@ For example:
3.5 /proc/<pid>/mountinfo - Information about mounts
--------------------------------------------------------
-This file contains lines of the form:
+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) (7) (8) (9) (10) (11)
+ 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
+ (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
-(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
-(7) optional fields: zero or more fields of the form "tag[:value]"
-(8) separator: marks the end of the optional fields
-(9) filesystem type: name of filesystem of the form "type[.subtype]"
-(10) mount source: filesystem specific information or "none"
-(11) super options: per super block options
+ (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
+ (7) optional fields: zero or more fields of the form "tag[:value]"
+ (8) separator: marks the end of the optional fields
+ (9) filesystem type: name of filesystem of the form "type[.subtype]"
+ (10) mount source: filesystem specific information or "none"
+ (11) 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
+================ ==============================================================
+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.
+.. [#] 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:
@@ -1804,77 +1909,86 @@ 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].
-A typical output is
+A typical output is::
pos: 0
flags: 0100002
mnt_id: 19
-All locks associated with a file descriptor are shown in its fdinfo too.
+All locks associated with a file descriptor are shown in its fdinfo too::
-lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF
+ 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
- ~~~~~~~~~~~~~
+Eventfd files
+~~~~~~~~~~~~~
+
+::
+
pos: 0
flags: 04002
mnt_id: 9
eventfd-count: 5a
- where 'eventfd-count' is hex value of a counter.
+where 'eventfd-count' is hex value of a counter.
+
+Signalfd files
+~~~~~~~~~~~~~~
+
+::
- Signalfd files
- ~~~~~~~~~~~~~~
pos: 0
flags: 04002
mnt_id: 9
sigmask: 0000000000000200
- where 'sigmask' is hex value of the signal mask associated
- with a file.
+where 'sigmask' is hex value of the signal mask associated
+with a file.
+
+Epoll files
+~~~~~~~~~~~
+
+::
- Epoll files
- ~~~~~~~~~~~
pos: 0
flags: 02
mnt_id: 9
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].
+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.
+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
+Fsnotify files
+~~~~~~~~~~~~~~
+For inotify files the format is the following::
pos: 0
flags: 02000000
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, ie 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].
+where 'wd' is a watch descriptor in decimal form, ie 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 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 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.
+If there is no inotify mark attached yet the 'inotify' line will be omitted.
- For fanotify files the format is
+For fanotify files the format is::
pos: 0
flags: 02
@@ -1883,20 +1997,22 @@ pair provide additional information particular to the objects they represent.
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', '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 in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask'
- does provide information about flags and mask used in fanotify_mark
- call [see fsnotify manpage for details].
+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', '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 in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask'
+does 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.
- 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
+~~~~~~~~~~~~~
- Timerfd files
- ~~~~~~~~~~~~~
+::
pos: 0
flags: 02
@@ -1907,18 +2023,18 @@ pair provide additional information particular to the objects they represent.
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 exiration.
- '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.
+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 exiration.
+'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.
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:
+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
@@ -1976,17 +2092,22 @@ 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:
- ------------------
+~~~~~~~~~~~~~~~~~~~~~
+
+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
@@ -2010,17 +2131,18 @@ x86 specific entries:
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.
-------------------------------------------------------------------------------
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.
+ ========= ========================================================
hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories
(default).