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docs: sysctl: convert to ReST
Rename the /proc/sys/ documentation files to ReST, using the README file as a template for an index.rst, adding the other files there via TOC markup. Despite being written on different times with different styles, try to make them somewhat coherent with a similar look and feel, ensuring that they'll look nice as both raw text file and as via the html output produced by the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Mauro Carvalho Chehab
parent
6baec31591
commit
53b9537509
@ -3144,7 +3144,7 @@
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numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
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'node', 'default' can be specified
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This can be set from sysctl after boot.
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See Documentation/sysctl/vm.txt for details.
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See Documentation/sysctl/vm.rst for details.
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ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
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See Documentation/debugging-via-ohci1394.txt for more
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@ -11,7 +11,7 @@ processes address space and many other cool things.
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Linux memory management is a complex system with many configurable
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settings. Most of these settings are available via ``/proc``
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filesystem and can be quired and adjusted using ``sysctl``. These APIs
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are described in Documentation/sysctl/vm.txt and in `man 5 proc`_.
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are described in Documentation/sysctl/vm.rst and in `man 5 proc`_.
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.. _man 5 proc: http://man7.org/linux/man-pages/man5/proc.5.html
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@ -59,7 +59,7 @@ MADV_UNMERGEABLE is applied to a range which was never MADV_MERGEABLE.
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If a region of memory must be split into at least one new MADV_MERGEABLE
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or MADV_UNMERGEABLE region, the madvise may return ENOMEM if the process
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will exceed ``vm.max_map_count`` (see Documentation/sysctl/vm.txt).
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will exceed ``vm.max_map_count`` (see Documentation/sysctl/vm.rst).
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Like other madvise calls, they are intended for use on mapped areas of
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the user address space: they will report ENOMEM if the specified range
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@ -119,7 +119,7 @@ Kernel Pointers
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For printing kernel pointers which should be hidden from unprivileged
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users. The behaviour of %pK depends on the kptr_restrict sysctl - see
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Documentation/sysctl/kernel.txt for more details.
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Documentation/sysctl/kernel.rst for more details.
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Unmodified Addresses
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--------------------
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@ -2287,7 +2287,7 @@ addr_scope_policy - INTEGER
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/proc/sys/net/core/*
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Please see: Documentation/sysctl/net.txt for descriptions of these entries.
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Please see: Documentation/sysctl/net.rst for descriptions of these entries.
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/proc/sys/net/unix/*
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67
Documentation/sysctl/abi.rst
Normal file
67
Documentation/sysctl/abi.rst
Normal file
@ -0,0 +1,67 @@
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================================
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Documentation for /proc/sys/abi/
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================================
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kernel version 2.6.0.test2
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Copyright (c) 2003, Fabian Frederick <ffrederick@users.sourceforge.net>
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For general info: index.rst.
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------------------------------------------------------------------------------
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This path is binary emulation relevant aka personality types aka abi.
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When a process is executed, it's linked to an exec_domain whose
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personality is defined using values available from /proc/sys/abi.
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You can find further details about abi in include/linux/personality.h.
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Here are the files featuring in 2.6 kernel:
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- defhandler_coff
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- defhandler_elf
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- defhandler_lcall7
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- defhandler_libcso
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- fake_utsname
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- trace
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defhandler_coff
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---------------
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defined value:
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PER_SCOSVR3::
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0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS | SHORT_INODE
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defhandler_elf
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--------------
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defined value:
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PER_LINUX::
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0
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defhandler_lcall7
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-----------------
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defined value :
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PER_SVR4::
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0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO,
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defhandler_libsco
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-----------------
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defined value:
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PER_SVR4::
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0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO,
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fake_utsname
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------------
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Unused
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trace
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-----
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Unused
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@ -1,54 +0,0 @@
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Documentation for /proc/sys/abi/* kernel version 2.6.0.test2
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(c) 2003, Fabian Frederick <ffrederick@users.sourceforge.net>
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For general info : README.
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==============================================================
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This path is binary emulation relevant aka personality types aka abi.
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When a process is executed, it's linked to an exec_domain whose
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personality is defined using values available from /proc/sys/abi.
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You can find further details about abi in include/linux/personality.h.
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Here are the files featuring in 2.6 kernel :
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- defhandler_coff
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- defhandler_elf
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- defhandler_lcall7
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- defhandler_libcso
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- fake_utsname
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- trace
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===========================================================
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defhandler_coff:
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defined value :
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PER_SCOSVR3
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0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS | SHORT_INODE
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===========================================================
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defhandler_elf:
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defined value :
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PER_LINUX
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0
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===========================================================
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defhandler_lcall7:
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defined value :
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PER_SVR4
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0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO,
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===========================================================
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defhandler_libsco:
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defined value:
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PER_SVR4
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0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO,
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===========================================================
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fake_utsname:
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Unused
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===========================================================
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trace:
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Unused
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===========================================================
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@ -1,10 +1,16 @@
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Documentation for /proc/sys/fs/* kernel version 2.2.10
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(c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
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(c) 2009, Shen Feng<shen@cn.fujitsu.com>
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===============================
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Documentation for /proc/sys/fs/
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===============================
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For general info and legal blurb, please look in README.
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kernel version 2.2.10
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==============================================================
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Copyright (c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
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Copyright (c) 2009, Shen Feng<shen@cn.fujitsu.com>
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For general info and legal blurb, please look in intro.rst.
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------------------------------------------------------------------------------
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This file contains documentation for the sysctl files in
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/proc/sys/fs/ and is valid for Linux kernel version 2.2.
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@ -16,9 +22,10 @@ system, it is advisable to read both documentation and source
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before actually making adjustments.
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1. /proc/sys/fs
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----------------------------------------------------------
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===============
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Currently, these files are in /proc/sys/fs:
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- aio-max-nr
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- aio-nr
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- dentry-state
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@ -42,9 +49,9 @@ Currently, these files are in /proc/sys/fs:
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- super-max
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- super-nr
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==============================================================
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aio-nr & aio-max-nr:
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aio-nr & aio-max-nr
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-------------------
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aio-nr is the running total of the number of events specified on the
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io_setup system call for all currently active aio contexts. If aio-nr
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@ -52,21 +59,20 @@ reaches aio-max-nr then io_setup will fail with EAGAIN. Note that
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raising aio-max-nr does not result in the pre-allocation or re-sizing
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of any kernel data structures.
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==============================================================
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dentry-state:
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dentry-state
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------------
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From linux/include/linux/dcache.h:
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--------------------------------------------------------------
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struct dentry_stat_t dentry_stat {
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From linux/include/linux/dcache.h::
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struct dentry_stat_t dentry_stat {
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int nr_dentry;
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int nr_unused;
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int age_limit; /* age in seconds */
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int want_pages; /* pages requested by system */
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int nr_negative; /* # of unused negative dentries */
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int dummy; /* Reserved for future use */
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};
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--------------------------------------------------------------
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};
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Dentries are dynamically allocated and deallocated.
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@ -84,9 +90,9 @@ negative dentries which do not map to any files. Instead,
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they help speeding up rejection of non-existing files provided
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by the users.
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==============================================================
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dquot-max & dquot-nr:
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dquot-max & dquot-nr
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--------------------
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The file dquot-max shows the maximum number of cached disk
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quota entries.
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@ -98,9 +104,9 @@ If the number of free cached disk quotas is very low and
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you have some awesome number of simultaneous system users,
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you might want to raise the limit.
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==============================================================
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file-max & file-nr:
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file-max & file-nr
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------------------
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The value in file-max denotes the maximum number of file-
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handles that the Linux kernel will allocate. When you get lots
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@ -119,18 +125,19 @@ used file handles.
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Attempts to allocate more file descriptors than file-max are
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reported with printk, look for "VFS: file-max limit <number>
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reached".
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==============================================================
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nr_open:
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nr_open
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-------
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This denotes the maximum number of file-handles a process can
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allocate. Default value is 1024*1024 (1048576) which should be
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enough for most machines. Actual limit depends on RLIMIT_NOFILE
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resource limit.
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==============================================================
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inode-max, inode-nr & inode-state:
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inode-max, inode-nr & inode-state
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---------------------------------
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As with file handles, the kernel allocates the inode structures
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dynamically, but can't free them yet.
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@ -157,9 +164,9 @@ preshrink is nonzero when the nr_inodes > inode-max and the
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system needs to prune the inode list instead of allocating
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more.
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==============================================================
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overflowgid & overflowuid:
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overflowgid & overflowuid
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-------------------------
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Some filesystems only support 16-bit UIDs and GIDs, although in Linux
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UIDs and GIDs are 32 bits. When one of these filesystems is mounted
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@ -169,18 +176,18 @@ to a fixed value before being written to disk.
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These sysctls allow you to change the value of the fixed UID and GID.
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The default is 65534.
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==============================================================
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pipe-user-pages-hard:
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pipe-user-pages-hard
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--------------------
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Maximum total number of pages a non-privileged user may allocate for pipes.
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Once this limit is reached, no new pipes may be allocated until usage goes
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below the limit again. When set to 0, no limit is applied, which is the default
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setting.
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==============================================================
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pipe-user-pages-soft:
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pipe-user-pages-soft
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--------------------
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Maximum total number of pages a non-privileged user may allocate for pipes
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before the pipe size gets limited to a single page. Once this limit is reached,
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@ -190,9 +197,9 @@ denied until usage goes below the limit again. The default value allows to
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allocate up to 1024 pipes at their default size. When set to 0, no limit is
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applied.
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==============================================================
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protected_fifos:
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protected_fifos
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---------------
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The intent of this protection is to avoid unintentional writes to
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an attacker-controlled FIFO, where a program expected to create a regular
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@ -208,9 +215,9 @@ When set to "2" it also applies to group writable sticky directories.
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This protection is based on the restrictions in Openwall.
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==============================================================
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protected_hardlinks:
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protected_hardlinks
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--------------------
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A long-standing class of security issues is the hardlink-based
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time-of-check-time-of-use race, most commonly seen in world-writable
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@ -228,9 +235,9 @@ already own the source file, or do not have read/write access to it.
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This protection is based on the restrictions in Openwall and grsecurity.
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==============================================================
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protected_regular:
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protected_regular
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-----------------
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This protection is similar to protected_fifos, but it
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avoids writes to an attacker-controlled regular file, where a program
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@ -244,9 +251,9 @@ owned by the owner of the directory.
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When set to "2" it also applies to group writable sticky directories.
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==============================================================
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protected_symlinks:
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protected_symlinks
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------------------
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A long-standing class of security issues is the symlink-based
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time-of-check-time-of-use race, most commonly seen in world-writable
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@ -264,34 +271,38 @@ follower match, or when the directory owner matches the symlink's owner.
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This protection is based on the restrictions in Openwall and grsecurity.
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==============================================================
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suid_dumpable:
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--------------
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This value can be used to query and set the core dump mode for setuid
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or otherwise protected/tainted binaries. The modes are
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0 - (default) - traditional behaviour. Any process which has changed
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privilege levels or is execute only will not be dumped.
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1 - (debug) - all processes dump core when possible. The core dump is
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owned by the current user and no security is applied. This is
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intended for system debugging situations only. Ptrace is unchecked.
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This is insecure as it allows regular users to examine the memory
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contents of privileged processes.
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2 - (suidsafe) - any binary which normally would not be dumped is dumped
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anyway, but only if the "core_pattern" kernel sysctl is set to
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either a pipe handler or a fully qualified path. (For more details
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on this limitation, see CVE-2006-2451.) This mode is appropriate
|
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when administrators are attempting to debug problems in a normal
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environment, and either have a core dump pipe handler that knows
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to treat privileged core dumps with care, or specific directory
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defined for catching core dumps. If a core dump happens without
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a pipe handler or fully qualifid path, a message will be emitted
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to syslog warning about the lack of a correct setting.
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= ========== ===============================================================
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0 (default) traditional behaviour. Any process which has changed
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privilege levels or is execute only will not be dumped.
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1 (debug) all processes dump core when possible. The core dump is
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owned by the current user and no security is applied. This is
|
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intended for system debugging situations only.
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Ptrace is unchecked.
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This is insecure as it allows regular users to examine the
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memory contents of privileged processes.
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2 (suidsafe) any binary which normally would not be dumped is dumped
|
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anyway, but only if the "core_pattern" kernel sysctl is set to
|
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either a pipe handler or a fully qualified path. (For more
|
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details on this limitation, see CVE-2006-2451.) This mode is
|
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appropriate when administrators are attempting to debug
|
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problems in a normal environment, and either have a core dump
|
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pipe handler that knows to treat privileged core dumps with
|
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care, or specific directory defined for catching core dumps.
|
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If a core dump happens without a pipe handler or fully
|
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qualified path, a message will be emitted to syslog warning
|
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about the lack of a correct setting.
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= ========== ===============================================================
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==============================================================
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|
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super-max & super-nr:
|
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super-max & super-nr
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--------------------
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|
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These numbers control the maximum number of superblocks, and
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thus the maximum number of mounted filesystems the kernel
|
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@ -299,33 +310,33 @@ can have. You only need to increase super-max if you need to
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mount more filesystems than the current value in super-max
|
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allows you to.
|
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|
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==============================================================
|
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|
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aio-nr & aio-max-nr:
|
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aio-nr & aio-max-nr
|
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-------------------
|
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|
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aio-nr shows the current system-wide number of asynchronous io
|
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requests. aio-max-nr allows you to change the maximum value
|
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aio-nr can grow to.
|
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|
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==============================================================
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|
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mount-max:
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mount-max
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---------
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|
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This denotes the maximum number of mounts that may exist
|
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in a mount namespace.
|
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|
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==============================================================
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|
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|
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2. /proc/sys/fs/binfmt_misc
|
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----------------------------------------------------------
|
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===========================
|
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|
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Documentation for the files in /proc/sys/fs/binfmt_misc is
|
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in Documentation/admin-guide/binfmt-misc.rst.
|
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|
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|
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3. /proc/sys/fs/mqueue - POSIX message queues filesystem
|
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----------------------------------------------------------
|
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========================================================
|
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|
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|
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The "mqueue" filesystem provides the necessary kernel features to enable the
|
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creation of a user space library that implements the POSIX message queues
|
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@ -356,7 +367,7 @@ the default message size value if attr parameter of mq_open(2) is NULL. If it
|
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exceed msgsize_max, the default value is initialized msgsize_max.
|
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|
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4. /proc/sys/fs/epoll - Configuration options for the epoll interface
|
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--------------------------------------------------------
|
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=====================================================================
|
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|
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This directory contains configuration options for the epoll(7) interface.
|
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|
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@ -371,4 +382,3 @@ Each "watch" costs roughly 90 bytes on a 32bit kernel, and roughly 160 bytes
|
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on a 64bit one.
|
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The current default value for max_user_watches is the 1/32 of the available
|
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low memory, divided for the "watch" cost in bytes.
|
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|
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@ -1,5 +1,12 @@
|
||||
Documentation for /proc/sys/ kernel version 2.2.10
|
||||
(c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
|
||||
:orphan:
|
||||
|
||||
===========================
|
||||
Documentation for /proc/sys
|
||||
===========================
|
||||
|
||||
Copyright (c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
|
||||
|
||||
------------------------------------------------------------------------------
|
||||
|
||||
'Why', I hear you ask, 'would anyone even _want_ documentation
|
||||
for them sysctl files? If anybody really needs it, it's all in
|
||||
@ -12,11 +19,12 @@ have the time or knowledge to read the source code.
|
||||
Furthermore, the programmers who built sysctl have built it to
|
||||
be actually used, not just for the fun of programming it :-)
|
||||
|
||||
==============================================================
|
||||
------------------------------------------------------------------------------
|
||||
|
||||
Legal blurb:
|
||||
|
||||
As usual, there are two main things to consider:
|
||||
|
||||
1. you get what you pay for
|
||||
2. it's free
|
||||
|
||||
@ -35,15 +43,17 @@ stories to: <riel@nl.linux.org>
|
||||
|
||||
Rik van Riel.
|
||||
|
||||
==============================================================
|
||||
--------------------------------------------------------------
|
||||
|
||||
Introduction:
|
||||
Introduction
|
||||
============
|
||||
|
||||
Sysctl is a means of configuring certain aspects of the kernel
|
||||
at run-time, and the /proc/sys/ directory is there so that you
|
||||
don't even need special tools to do it!
|
||||
In fact, there are only four things needed to use these config
|
||||
facilities:
|
||||
|
||||
- a running Linux system
|
||||
- root access
|
||||
- common sense (this is especially hard to come by these days)
|
||||
@ -54,7 +64,9 @@ several (arch-dependent?) subdirs. Each subdir is mainly about
|
||||
one part of the kernel, so you can do configuration on a piece
|
||||
by piece basis, or just some 'thematic frobbing'.
|
||||
|
||||
The subdirs are about:
|
||||
This documentation is about:
|
||||
|
||||
=============== ===============================================================
|
||||
abi/ execution domains & personalities
|
||||
debug/ <empty>
|
||||
dev/ device specific information (eg dev/cdrom/info)
|
||||
@ -70,7 +82,19 @@ sunrpc/ SUN Remote Procedure Call (NFS)
|
||||
vm/ memory management tuning
|
||||
buffer and cache management
|
||||
user/ Per user per user namespace limits
|
||||
=============== ===============================================================
|
||||
|
||||
These are the subdirs I have on my system. There might be more
|
||||
or other subdirs in another setup. If you see another dir, I'd
|
||||
really like to hear about it :-)
|
||||
|
||||
.. toctree::
|
||||
:maxdepth: 1
|
||||
|
||||
abi
|
||||
fs
|
||||
kernel
|
||||
net
|
||||
sunrpc
|
||||
user
|
||||
vm
|
||||
File diff suppressed because it is too large
Load Diff
@ -1,12 +1,25 @@
|
||||
Documentation for /proc/sys/net/*
|
||||
(c) 1999 Terrehon Bowden <terrehon@pacbell.net>
|
||||
Bodo Bauer <bb@ricochet.net>
|
||||
(c) 2000 Jorge Nerin <comandante@zaralinux.com>
|
||||
(c) 2009 Shen Feng <shen@cn.fujitsu.com>
|
||||
================================
|
||||
Documentation for /proc/sys/net/
|
||||
================================
|
||||
|
||||
For general info and legal blurb, please look in README.
|
||||
Copyright
|
||||
|
||||
==============================================================
|
||||
Copyright (c) 1999
|
||||
|
||||
- Terrehon Bowden <terrehon@pacbell.net>
|
||||
- Bodo Bauer <bb@ricochet.net>
|
||||
|
||||
Copyright (c) 2000
|
||||
|
||||
- Jorge Nerin <comandante@zaralinux.com>
|
||||
|
||||
Copyright (c) 2009
|
||||
|
||||
- Shen Feng <shen@cn.fujitsu.com>
|
||||
|
||||
For general info and legal blurb, please look in index.rst.
|
||||
|
||||
------------------------------------------------------------------------------
|
||||
|
||||
This file contains the documentation for the sysctl files in
|
||||
/proc/sys/net
|
||||
@ -17,20 +30,22 @@ see only some of them, depending on your kernel's configuration.
|
||||
|
||||
|
||||
Table : Subdirectories in /proc/sys/net
|
||||
..............................................................................
|
||||
Directory Content Directory Content
|
||||
core General parameter appletalk Appletalk protocol
|
||||
unix Unix domain sockets netrom NET/ROM
|
||||
802 E802 protocol ax25 AX25
|
||||
ethernet Ethernet protocol rose X.25 PLP layer
|
||||
ipv4 IP version 4 x25 X.25 protocol
|
||||
ipx IPX token-ring IBM token ring
|
||||
bridge Bridging decnet DEC net
|
||||
ipv6 IP version 6 tipc TIPC
|
||||
..............................................................................
|
||||
|
||||
========= =================== = ========== ==================
|
||||
Directory Content Directory Content
|
||||
========= =================== = ========== ==================
|
||||
core General parameter appletalk Appletalk protocol
|
||||
unix Unix domain sockets netrom NET/ROM
|
||||
802 E802 protocol ax25 AX25
|
||||
ethernet Ethernet protocol rose X.25 PLP layer
|
||||
ipv4 IP version 4 x25 X.25 protocol
|
||||
ipx IPX token-ring IBM token ring
|
||||
bridge Bridging decnet DEC net
|
||||
ipv6 IP version 6 tipc TIPC
|
||||
========= =================== = ========== ==================
|
||||
|
||||
1. /proc/sys/net/core - Network core options
|
||||
-------------------------------------------------------
|
||||
============================================
|
||||
|
||||
bpf_jit_enable
|
||||
--------------
|
||||
@ -44,6 +59,7 @@ restricted C into a sequence of BPF instructions. After program load
|
||||
through bpf(2) and passing a verifier in the kernel, a JIT will then
|
||||
translate these BPF proglets into native CPU instructions. There are
|
||||
two flavors of JITs, the newer eBPF JIT currently supported on:
|
||||
|
||||
- x86_64
|
||||
- x86_32
|
||||
- arm64
|
||||
@ -55,6 +71,7 @@ two flavors of JITs, the newer eBPF JIT currently supported on:
|
||||
- riscv
|
||||
|
||||
And the older cBPF JIT supported on the following archs:
|
||||
|
||||
- mips
|
||||
- ppc
|
||||
- sparc
|
||||
@ -65,10 +82,11 @@ compile them transparently. Older cBPF JITs can only translate
|
||||
tcpdump filters, seccomp rules, etc, but not mentioned eBPF
|
||||
programs loaded through bpf(2).
|
||||
|
||||
Values :
|
||||
0 - disable the JIT (default value)
|
||||
1 - enable the JIT
|
||||
2 - enable the JIT and ask the compiler to emit traces on kernel log.
|
||||
Values:
|
||||
|
||||
- 0 - disable the JIT (default value)
|
||||
- 1 - enable the JIT
|
||||
- 2 - enable the JIT and ask the compiler to emit traces on kernel log.
|
||||
|
||||
bpf_jit_harden
|
||||
--------------
|
||||
@ -76,10 +94,12 @@ bpf_jit_harden
|
||||
This enables hardening for the BPF JIT compiler. Supported are eBPF
|
||||
JIT backends. Enabling hardening trades off performance, but can
|
||||
mitigate JIT spraying.
|
||||
Values :
|
||||
0 - disable JIT hardening (default value)
|
||||
1 - enable JIT hardening for unprivileged users only
|
||||
2 - enable JIT hardening for all users
|
||||
|
||||
Values:
|
||||
|
||||
- 0 - disable JIT hardening (default value)
|
||||
- 1 - enable JIT hardening for unprivileged users only
|
||||
- 2 - enable JIT hardening for all users
|
||||
|
||||
bpf_jit_kallsyms
|
||||
----------------
|
||||
@ -89,9 +109,11 @@ addresses to the kernel, meaning they neither show up in traces nor
|
||||
in /proc/kallsyms. This enables export of these addresses, which can
|
||||
be used for debugging/tracing. If bpf_jit_harden is enabled, this
|
||||
feature is disabled.
|
||||
|
||||
Values :
|
||||
0 - disable JIT kallsyms export (default value)
|
||||
1 - enable JIT kallsyms export for privileged users only
|
||||
|
||||
- 0 - disable JIT kallsyms export (default value)
|
||||
- 1 - enable JIT kallsyms export for privileged users only
|
||||
|
||||
bpf_jit_limit
|
||||
-------------
|
||||
@ -102,7 +124,7 @@ been surpassed. bpf_jit_limit contains the value of the global limit
|
||||
in bytes.
|
||||
|
||||
dev_weight
|
||||
--------------
|
||||
----------
|
||||
|
||||
The maximum number of packets that kernel can handle on a NAPI interrupt,
|
||||
it's a Per-CPU variable. For drivers that support LRO or GRO_HW, a hardware
|
||||
@ -111,7 +133,7 @@ aggregated packet is counted as one packet in this context.
|
||||
Default: 64
|
||||
|
||||
dev_weight_rx_bias
|
||||
--------------
|
||||
------------------
|
||||
|
||||
RPS (e.g. RFS, aRFS) processing is competing with the registered NAPI poll function
|
||||
of the driver for the per softirq cycle netdev_budget. This parameter influences
|
||||
@ -120,19 +142,22 @@ processing during RX softirq cycles. It is further meant for making current
|
||||
dev_weight adaptable for asymmetric CPU needs on RX/TX side of the network stack.
|
||||
(see dev_weight_tx_bias) It is effective on a per CPU basis. Determination is based
|
||||
on dev_weight and is calculated multiplicative (dev_weight * dev_weight_rx_bias).
|
||||
|
||||
Default: 1
|
||||
|
||||
dev_weight_tx_bias
|
||||
--------------
|
||||
------------------
|
||||
|
||||
Scales the maximum number of packets that can be processed during a TX softirq cycle.
|
||||
Effective on a per CPU basis. Allows scaling of current dev_weight for asymmetric
|
||||
net stack processing needs. Be careful to avoid making TX softirq processing a CPU hog.
|
||||
|
||||
Calculation is based on dev_weight (dev_weight * dev_weight_tx_bias).
|
||||
|
||||
Default: 1
|
||||
|
||||
default_qdisc
|
||||
--------------
|
||||
-------------
|
||||
|
||||
The default queuing discipline to use for network devices. This allows
|
||||
overriding the default of pfifo_fast with an alternative. Since the default
|
||||
@ -144,17 +169,21 @@ which require setting up classes and bandwidths. Note that physical multiqueue
|
||||
interfaces still use mq as root qdisc, which in turn uses this default for its
|
||||
leaves. Virtual devices (like e.g. lo or veth) ignore this setting and instead
|
||||
default to noqueue.
|
||||
|
||||
Default: pfifo_fast
|
||||
|
||||
busy_read
|
||||
----------------
|
||||
---------
|
||||
|
||||
Low latency busy poll timeout for socket reads. (needs CONFIG_NET_RX_BUSY_POLL)
|
||||
Approximate time in us to busy loop waiting for packets on the device queue.
|
||||
This sets the default value of the SO_BUSY_POLL socket option.
|
||||
Can be set or overridden per socket by setting socket option SO_BUSY_POLL,
|
||||
which is the preferred method of enabling. If you need to enable the feature
|
||||
globally via sysctl, a value of 50 is recommended.
|
||||
|
||||
Will increase power usage.
|
||||
|
||||
Default: 0 (off)
|
||||
|
||||
busy_poll
|
||||
@ -167,7 +196,9 @@ For more than that you probably want to use epoll.
|
||||
Note that only sockets with SO_BUSY_POLL set will be busy polled,
|
||||
so you want to either selectively set SO_BUSY_POLL on those sockets or set
|
||||
sysctl.net.busy_read globally.
|
||||
|
||||
Will increase power usage.
|
||||
|
||||
Default: 0 (off)
|
||||
|
||||
rmem_default
|
||||
@ -185,6 +216,7 @@ tstamp_allow_data
|
||||
Allow processes to receive tx timestamps looped together with the original
|
||||
packet contents. If disabled, transmit timestamp requests from unprivileged
|
||||
processes are dropped unless socket option SOF_TIMESTAMPING_OPT_TSONLY is set.
|
||||
|
||||
Default: 1 (on)
|
||||
|
||||
|
||||
@ -250,19 +282,24 @@ randomly generated.
|
||||
Some user space might need to gather its content even if drivers do not
|
||||
provide ethtool -x support yet.
|
||||
|
||||
myhost:~# cat /proc/sys/net/core/netdev_rss_key
|
||||
84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8: ... (52 bytes total)
|
||||
::
|
||||
|
||||
myhost:~# cat /proc/sys/net/core/netdev_rss_key
|
||||
84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8: ... (52 bytes total)
|
||||
|
||||
File contains nul bytes if no driver ever called netdev_rss_key_fill() function.
|
||||
Note:
|
||||
/proc/sys/net/core/netdev_rss_key contains 52 bytes of key,
|
||||
but most drivers only use 40 bytes of it.
|
||||
|
||||
myhost:~# ethtool -x eth0
|
||||
RX flow hash indirection table for eth0 with 8 RX ring(s):
|
||||
0: 0 1 2 3 4 5 6 7
|
||||
RSS hash key:
|
||||
84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8:43:e3:c9:0c:fd:17:55:c2:3a:4d:69:ed:f1:42:89
|
||||
Note:
|
||||
/proc/sys/net/core/netdev_rss_key contains 52 bytes of key,
|
||||
but most drivers only use 40 bytes of it.
|
||||
|
||||
::
|
||||
|
||||
myhost:~# ethtool -x eth0
|
||||
RX flow hash indirection table for eth0 with 8 RX ring(s):
|
||||
0: 0 1 2 3 4 5 6 7
|
||||
RSS hash key:
|
||||
84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8:43:e3:c9:0c:fd:17:55:c2:3a:4d:69:ed:f1:42:89
|
||||
|
||||
netdev_tstamp_prequeue
|
||||
----------------------
|
||||
@ -293,7 +330,7 @@ user space is responsible for creating them if needed.
|
||||
Default : 0 (for compatibility reasons)
|
||||
|
||||
devconf_inherit_init_net
|
||||
----------------------------
|
||||
------------------------
|
||||
|
||||
Controls if a new network namespace should inherit all current
|
||||
settings under /proc/sys/net/{ipv4,ipv6}/conf/{all,default}/. By
|
||||
@ -307,7 +344,7 @@ forced to reset to their default values.
|
||||
Default : 0 (for compatibility reasons)
|
||||
|
||||
2. /proc/sys/net/unix - Parameters for Unix domain sockets
|
||||
-------------------------------------------------------
|
||||
----------------------------------------------------------
|
||||
|
||||
There is only one file in this directory.
|
||||
unix_dgram_qlen limits the max number of datagrams queued in Unix domain
|
||||
@ -315,13 +352,13 @@ socket's buffer. It will not take effect unless PF_UNIX flag is specified.
|
||||
|
||||
|
||||
3. /proc/sys/net/ipv4 - IPV4 settings
|
||||
-------------------------------------------------------
|
||||
-------------------------------------
|
||||
Please see: Documentation/networking/ip-sysctl.txt and ipvs-sysctl.txt for
|
||||
descriptions of these entries.
|
||||
|
||||
|
||||
4. Appletalk
|
||||
-------------------------------------------------------
|
||||
------------
|
||||
|
||||
The /proc/sys/net/appletalk directory holds the Appletalk configuration data
|
||||
when Appletalk is loaded. The configurable parameters are:
|
||||
@ -366,7 +403,7 @@ route flags, and the device the route is using.
|
||||
|
||||
|
||||
5. IPX
|
||||
-------------------------------------------------------
|
||||
------
|
||||
|
||||
The IPX protocol has no tunable values in proc/sys/net.
|
||||
|
||||
@ -391,14 +428,16 @@ gives the destination network, the router node (or Directly) and the network
|
||||
address of the router (or Connected) for internal networks.
|
||||
|
||||
6. TIPC
|
||||
-------------------------------------------------------
|
||||
-------
|
||||
|
||||
tipc_rmem
|
||||
----------
|
||||
---------
|
||||
|
||||
The TIPC protocol now has a tunable for the receive memory, similar to the
|
||||
tcp_rmem - i.e. a vector of 3 INTEGERs: (min, default, max)
|
||||
|
||||
::
|
||||
|
||||
# cat /proc/sys/net/tipc/tipc_rmem
|
||||
4252725 34021800 68043600
|
||||
#
|
||||
@ -409,7 +448,7 @@ is not at this point in time used in any meaningful way, but the triplet is
|
||||
preserved in order to be consistent with things like tcp_rmem.
|
||||
|
||||
named_timeout
|
||||
--------------
|
||||
-------------
|
||||
|
||||
TIPC name table updates are distributed asynchronously in a cluster, without
|
||||
any form of transaction handling. This means that different race scenarios are
|
||||
@ -1,9 +1,14 @@
|
||||
Documentation for /proc/sys/sunrpc/* kernel version 2.2.10
|
||||
(c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
|
||||
===================================
|
||||
Documentation for /proc/sys/sunrpc/
|
||||
===================================
|
||||
|
||||
For general info and legal blurb, please look in README.
|
||||
kernel version 2.2.10
|
||||
|
||||
==============================================================
|
||||
Copyright (c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
|
||||
|
||||
For general info and legal blurb, please look in index.rst.
|
||||
|
||||
------------------------------------------------------------------------------
|
||||
|
||||
This file contains the documentation for the sysctl files in
|
||||
/proc/sys/sunrpc and is valid for Linux kernel version 2.2.
|
||||
@ -1,7 +1,12 @@
|
||||
Documentation for /proc/sys/user/* kernel version 4.9.0
|
||||
(c) 2016 Eric Biederman <ebiederm@xmission.com>
|
||||
=================================
|
||||
Documentation for /proc/sys/user/
|
||||
=================================
|
||||
|
||||
==============================================================
|
||||
kernel version 4.9.0
|
||||
|
||||
Copyright (c) 2016 Eric Biederman <ebiederm@xmission.com>
|
||||
|
||||
------------------------------------------------------------------------------
|
||||
|
||||
This file contains the documentation for the sysctl files in
|
||||
/proc/sys/user.
|
||||
@ -30,37 +35,44 @@ user namespace does not allow a user to escape their current limits.
|
||||
|
||||
Currently, these files are in /proc/sys/user:
|
||||
|
||||
- max_cgroup_namespaces
|
||||
max_cgroup_namespaces
|
||||
=====================
|
||||
|
||||
The maximum number of cgroup namespaces that any user in the current
|
||||
user namespace may create.
|
||||
|
||||
- max_ipc_namespaces
|
||||
max_ipc_namespaces
|
||||
==================
|
||||
|
||||
The maximum number of ipc namespaces that any user in the current
|
||||
user namespace may create.
|
||||
|
||||
- max_mnt_namespaces
|
||||
max_mnt_namespaces
|
||||
==================
|
||||
|
||||
The maximum number of mount namespaces that any user in the current
|
||||
user namespace may create.
|
||||
|
||||
- max_net_namespaces
|
||||
max_net_namespaces
|
||||
==================
|
||||
|
||||
The maximum number of network namespaces that any user in the
|
||||
current user namespace may create.
|
||||
|
||||
- max_pid_namespaces
|
||||
max_pid_namespaces
|
||||
==================
|
||||
|
||||
The maximum number of pid namespaces that any user in the current
|
||||
user namespace may create.
|
||||
|
||||
- max_user_namespaces
|
||||
max_user_namespaces
|
||||
===================
|
||||
|
||||
The maximum number of user namespaces that any user in the current
|
||||
user namespace may create.
|
||||
|
||||
- max_uts_namespaces
|
||||
max_uts_namespaces
|
||||
==================
|
||||
|
||||
The maximum number of user namespaces that any user in the current
|
||||
user namespace may create.
|
||||
@ -1,10 +1,16 @@
|
||||
Documentation for /proc/sys/vm/* kernel version 2.6.29
|
||||
(c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
|
||||
(c) 2008 Peter W. Morreale <pmorreale@novell.com>
|
||||
===============================
|
||||
Documentation for /proc/sys/vm/
|
||||
===============================
|
||||
|
||||
For general info and legal blurb, please look in README.
|
||||
kernel version 2.6.29
|
||||
|
||||
==============================================================
|
||||
Copyright (c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
|
||||
|
||||
Copyright (c) 2008 Peter W. Morreale <pmorreale@novell.com>
|
||||
|
||||
For general info and legal blurb, please look in index.rst.
|
||||
|
||||
------------------------------------------------------------------------------
|
||||
|
||||
This file contains the documentation for the sysctl files in
|
||||
/proc/sys/vm and is valid for Linux kernel version 2.6.29.
|
||||
@ -68,9 +74,9 @@ Currently, these files are in /proc/sys/vm:
|
||||
- watermark_scale_factor
|
||||
- zone_reclaim_mode
|
||||
|
||||
==============================================================
|
||||
|
||||
admin_reserve_kbytes
|
||||
====================
|
||||
|
||||
The amount of free memory in the system that should be reserved for users
|
||||
with the capability cap_sys_admin.
|
||||
@ -97,25 +103,25 @@ On x86_64 this is about 128MB.
|
||||
|
||||
Changing this takes effect whenever an application requests memory.
|
||||
|
||||
==============================================================
|
||||
|
||||
block_dump
|
||||
==========
|
||||
|
||||
block_dump enables block I/O debugging when set to a nonzero value. More
|
||||
information on block I/O debugging is in Documentation/laptops/laptop-mode.rst.
|
||||
|
||||
==============================================================
|
||||
|
||||
compact_memory
|
||||
==============
|
||||
|
||||
Available only when CONFIG_COMPACTION is set. When 1 is written to the file,
|
||||
all zones are compacted such that free memory is available in contiguous
|
||||
blocks where possible. This can be important for example in the allocation of
|
||||
huge pages although processes will also directly compact memory as required.
|
||||
|
||||
==============================================================
|
||||
|
||||
compact_unevictable_allowed
|
||||
===========================
|
||||
|
||||
Available only when CONFIG_COMPACTION is set. When set to 1, compaction is
|
||||
allowed to examine the unevictable lru (mlocked pages) for pages to compact.
|
||||
@ -123,21 +129,22 @@ This should be used on systems where stalls for minor page faults are an
|
||||
acceptable trade for large contiguous free memory. Set to 0 to prevent
|
||||
compaction from moving pages that are unevictable. Default value is 1.
|
||||
|
||||
==============================================================
|
||||
|
||||
dirty_background_bytes
|
||||
======================
|
||||
|
||||
Contains the amount of dirty memory at which the background kernel
|
||||
flusher threads will start writeback.
|
||||
|
||||
Note: dirty_background_bytes is the counterpart of dirty_background_ratio. Only
|
||||
one of them may be specified at a time. When one sysctl is written it is
|
||||
immediately taken into account to evaluate the dirty memory limits and the
|
||||
other appears as 0 when read.
|
||||
Note:
|
||||
dirty_background_bytes is the counterpart of dirty_background_ratio. Only
|
||||
one of them may be specified at a time. When one sysctl is written it is
|
||||
immediately taken into account to evaluate the dirty memory limits and the
|
||||
other appears as 0 when read.
|
||||
|
||||
==============================================================
|
||||
|
||||
dirty_background_ratio
|
||||
======================
|
||||
|
||||
Contains, as a percentage of total available memory that contains free pages
|
||||
and reclaimable pages, the number of pages at which the background kernel
|
||||
@ -145,9 +152,9 @@ flusher threads will start writing out dirty data.
|
||||
|
||||
The total available memory is not equal to total system memory.
|
||||
|
||||
==============================================================
|
||||
|
||||
dirty_bytes
|
||||
===========
|
||||
|
||||
Contains the amount of dirty memory at which a process generating disk writes
|
||||
will itself start writeback.
|
||||
@ -161,18 +168,18 @@ Note: the minimum value allowed for dirty_bytes is two pages (in bytes); any
|
||||
value lower than this limit will be ignored and the old configuration will be
|
||||
retained.
|
||||
|
||||
==============================================================
|
||||
|
||||
dirty_expire_centisecs
|
||||
======================
|
||||
|
||||
This tunable is used to define when dirty data is old enough to be eligible
|
||||
for writeout by the kernel flusher threads. It is expressed in 100'ths
|
||||
of a second. Data which has been dirty in-memory for longer than this
|
||||
interval will be written out next time a flusher thread wakes up.
|
||||
|
||||
==============================================================
|
||||
|
||||
dirty_ratio
|
||||
===========
|
||||
|
||||
Contains, as a percentage of total available memory that contains free pages
|
||||
and reclaimable pages, the number of pages at which a process which is
|
||||
@ -180,9 +187,9 @@ generating disk writes will itself start writing out dirty data.
|
||||
|
||||
The total available memory is not equal to total system memory.
|
||||
|
||||
==============================================================
|
||||
|
||||
dirtytime_expire_seconds
|
||||
========================
|
||||
|
||||
When a lazytime inode is constantly having its pages dirtied, the inode with
|
||||
an updated timestamp will never get chance to be written out. And, if the
|
||||
@ -192,34 +199,39 @@ eventually gets pushed out to disk. This tunable is used to define when dirty
|
||||
inode is old enough to be eligible for writeback by the kernel flusher threads.
|
||||
And, it is also used as the interval to wakeup dirtytime_writeback thread.
|
||||
|
||||
==============================================================
|
||||
|
||||
dirty_writeback_centisecs
|
||||
=========================
|
||||
|
||||
The kernel flusher threads will periodically wake up and write `old' data
|
||||
The kernel flusher threads will periodically wake up and write `old` data
|
||||
out to disk. This tunable expresses the interval between those wakeups, in
|
||||
100'ths of a second.
|
||||
|
||||
Setting this to zero disables periodic writeback altogether.
|
||||
|
||||
==============================================================
|
||||
|
||||
drop_caches
|
||||
===========
|
||||
|
||||
Writing to this will cause the kernel to drop clean caches, as well as
|
||||
reclaimable slab objects like dentries and inodes. Once dropped, their
|
||||
memory becomes free.
|
||||
|
||||
To free pagecache:
|
||||
To free pagecache::
|
||||
|
||||
echo 1 > /proc/sys/vm/drop_caches
|
||||
To free reclaimable slab objects (includes dentries and inodes):
|
||||
|
||||
To free reclaimable slab objects (includes dentries and inodes)::
|
||||
|
||||
echo 2 > /proc/sys/vm/drop_caches
|
||||
To free slab objects and pagecache:
|
||||
|
||||
To free slab objects and pagecache::
|
||||
|
||||
echo 3 > /proc/sys/vm/drop_caches
|
||||
|
||||
This is a non-destructive operation and will not free any dirty objects.
|
||||
To increase the number of objects freed by this operation, the user may run
|
||||
`sync' prior to writing to /proc/sys/vm/drop_caches. This will minimize the
|
||||
`sync` prior to writing to /proc/sys/vm/drop_caches. This will minimize the
|
||||
number of dirty objects on the system and create more candidates to be
|
||||
dropped.
|
||||
|
||||
@ -233,16 +245,16 @@ dropped objects, especially if they were under heavy use. Because of this,
|
||||
use outside of a testing or debugging environment is not recommended.
|
||||
|
||||
You may see informational messages in your kernel log when this file is
|
||||
used:
|
||||
used::
|
||||
|
||||
cat (1234): drop_caches: 3
|
||||
|
||||
These are informational only. They do not mean that anything is wrong
|
||||
with your system. To disable them, echo 4 (bit 2) into drop_caches.
|
||||
|
||||
==============================================================
|
||||
|
||||
extfrag_threshold
|
||||
=================
|
||||
|
||||
This parameter affects whether the kernel will compact memory or direct
|
||||
reclaim to satisfy a high-order allocation. The extfrag/extfrag_index file in
|
||||
@ -254,9 +266,9 @@ implies that the allocation will succeed as long as watermarks are met.
|
||||
The kernel will not compact memory in a zone if the
|
||||
fragmentation index is <= extfrag_threshold. The default value is 500.
|
||||
|
||||
==============================================================
|
||||
|
||||
highmem_is_dirtyable
|
||||
====================
|
||||
|
||||
Available only for systems with CONFIG_HIGHMEM enabled (32b systems).
|
||||
|
||||
@ -274,30 +286,30 @@ OOM killer because some writers (e.g. direct block device writes) can
|
||||
only use the low memory and they can fill it up with dirty data without
|
||||
any throttling.
|
||||
|
||||
==============================================================
|
||||
|
||||
hugetlb_shm_group
|
||||
=================
|
||||
|
||||
hugetlb_shm_group contains group id that is allowed to create SysV
|
||||
shared memory segment using hugetlb page.
|
||||
|
||||
==============================================================
|
||||
|
||||
laptop_mode
|
||||
===========
|
||||
|
||||
laptop_mode is a knob that controls "laptop mode". All the things that are
|
||||
controlled by this knob are discussed in Documentation/laptops/laptop-mode.rst.
|
||||
|
||||
==============================================================
|
||||
|
||||
legacy_va_layout
|
||||
================
|
||||
|
||||
If non-zero, this sysctl disables the new 32-bit mmap layout - the kernel
|
||||
will use the legacy (2.4) layout for all processes.
|
||||
|
||||
==============================================================
|
||||
|
||||
lowmem_reserve_ratio
|
||||
====================
|
||||
|
||||
For some specialised workloads on highmem machines it is dangerous for
|
||||
the kernel to allow process memory to be allocated from the "lowmem"
|
||||
@ -308,7 +320,7 @@ And on large highmem machines this lack of reclaimable lowmem memory
|
||||
can be fatal.
|
||||
|
||||
So the Linux page allocator has a mechanism which prevents allocations
|
||||
which _could_ use highmem from using too much lowmem. This means that
|
||||
which *could* use highmem from using too much lowmem. This means that
|
||||
a certain amount of lowmem is defended from the possibility of being
|
||||
captured into pinned user memory.
|
||||
|
||||
@ -316,39 +328,37 @@ captured into pinned user memory.
|
||||
mechanism will also defend that region from allocations which could use
|
||||
highmem or lowmem).
|
||||
|
||||
The `lowmem_reserve_ratio' tunable determines how aggressive the kernel is
|
||||
The `lowmem_reserve_ratio` tunable determines how aggressive the kernel is
|
||||
in defending these lower zones.
|
||||
|
||||
If you have a machine which uses highmem or ISA DMA and your
|
||||
applications are using mlock(), or if you are running with no swap then
|
||||
you probably should change the lowmem_reserve_ratio setting.
|
||||
|
||||
The lowmem_reserve_ratio is an array. You can see them by reading this file.
|
||||
-
|
||||
% cat /proc/sys/vm/lowmem_reserve_ratio
|
||||
256 256 32
|
||||
-
|
||||
The lowmem_reserve_ratio is an array. You can see them by reading this file::
|
||||
|
||||
% cat /proc/sys/vm/lowmem_reserve_ratio
|
||||
256 256 32
|
||||
|
||||
But, these values are not used directly. The kernel calculates # of protection
|
||||
pages for each zones from them. These are shown as array of protection pages
|
||||
in /proc/zoneinfo like followings. (This is an example of x86-64 box).
|
||||
Each zone has an array of protection pages like this.
|
||||
Each zone has an array of protection pages like this::
|
||||
|
||||
-
|
||||
Node 0, zone DMA
|
||||
pages free 1355
|
||||
min 3
|
||||
low 3
|
||||
high 4
|
||||
Node 0, zone DMA
|
||||
pages free 1355
|
||||
min 3
|
||||
low 3
|
||||
high 4
|
||||
:
|
||||
:
|
||||
numa_other 0
|
||||
protection: (0, 2004, 2004, 2004)
|
||||
numa_other 0
|
||||
protection: (0, 2004, 2004, 2004)
|
||||
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
pagesets
|
||||
cpu: 0 pcp: 0
|
||||
:
|
||||
-
|
||||
pagesets
|
||||
cpu: 0 pcp: 0
|
||||
:
|
||||
|
||||
These protections are added to score to judge whether this zone should be used
|
||||
for page allocation or should be reclaimed.
|
||||
|
||||
@ -359,20 +369,24 @@ not be used because pages_free(1355) is smaller than watermark + protection[2]
|
||||
normal page requirement. If requirement is DMA zone(index=0), protection[0]
|
||||
(=0) is used.
|
||||
|
||||
zone[i]'s protection[j] is calculated by following expression.
|
||||
zone[i]'s protection[j] is calculated by following expression::
|
||||
|
||||
(i < j):
|
||||
zone[i]->protection[j]
|
||||
= (total sums of managed_pages from zone[i+1] to zone[j] on the node)
|
||||
/ lowmem_reserve_ratio[i];
|
||||
(i = j):
|
||||
(should not be protected. = 0;
|
||||
(i > j):
|
||||
(not necessary, but looks 0)
|
||||
(i < j):
|
||||
zone[i]->protection[j]
|
||||
= (total sums of managed_pages from zone[i+1] to zone[j] on the node)
|
||||
/ lowmem_reserve_ratio[i];
|
||||
(i = j):
|
||||
(should not be protected. = 0;
|
||||
(i > j):
|
||||
(not necessary, but looks 0)
|
||||
|
||||
The default values of lowmem_reserve_ratio[i] are
|
||||
|
||||
=== ====================================
|
||||
256 (if zone[i] means DMA or DMA32 zone)
|
||||
32 (others).
|
||||
32 (others)
|
||||
=== ====================================
|
||||
|
||||
As above expression, they are reciprocal number of ratio.
|
||||
256 means 1/256. # of protection pages becomes about "0.39%" of total managed
|
||||
pages of higher zones on the node.
|
||||
@ -381,9 +395,9 @@ If you would like to protect more pages, smaller values are effective.
|
||||
The minimum value is 1 (1/1 -> 100%). The value less than 1 completely
|
||||
disables protection of the pages.
|
||||
|
||||
==============================================================
|
||||
|
||||
max_map_count:
|
||||
==============
|
||||
|
||||
This file contains the maximum number of memory map areas a process
|
||||
may have. Memory map areas are used as a side-effect of calling
|
||||
@ -396,9 +410,9 @@ e.g., up to one or two maps per allocation.
|
||||
|
||||
The default value is 65536.
|
||||
|
||||
=============================================================
|
||||
|
||||
memory_failure_early_kill:
|
||||
==========================
|
||||
|
||||
Control how to kill processes when uncorrected memory error (typically
|
||||
a 2bit error in a memory module) is detected in the background by hardware
|
||||
@ -424,9 +438,9 @@ check handling and depends on the hardware capabilities.
|
||||
|
||||
Applications can override this setting individually with the PR_MCE_KILL prctl
|
||||
|
||||
==============================================================
|
||||
|
||||
memory_failure_recovery
|
||||
=======================
|
||||
|
||||
Enable memory failure recovery (when supported by the platform)
|
||||
|
||||
@ -434,9 +448,9 @@ Enable memory failure recovery (when supported by the platform)
|
||||
|
||||
0: Always panic on a memory failure.
|
||||
|
||||
==============================================================
|
||||
|
||||
min_free_kbytes:
|
||||
min_free_kbytes
|
||||
===============
|
||||
|
||||
This is used to force the Linux VM to keep a minimum number
|
||||
of kilobytes free. The VM uses this number to compute a
|
||||
@ -450,9 +464,9 @@ become subtly broken, and prone to deadlock under high loads.
|
||||
|
||||
Setting this too high will OOM your machine instantly.
|
||||
|
||||
=============================================================
|
||||
|
||||
min_slab_ratio:
|
||||
min_slab_ratio
|
||||
==============
|
||||
|
||||
This is available only on NUMA kernels.
|
||||
|
||||
@ -468,9 +482,9 @@ Note that slab reclaim is triggered in a per zone / node fashion.
|
||||
The process of reclaiming slab memory is currently not node specific
|
||||
and may not be fast.
|
||||
|
||||
=============================================================
|
||||
|
||||
min_unmapped_ratio:
|
||||
min_unmapped_ratio
|
||||
==================
|
||||
|
||||
This is available only on NUMA kernels.
|
||||
|
||||
@ -485,9 +499,9 @@ files and similar are considered.
|
||||
|
||||
The default is 1 percent.
|
||||
|
||||
==============================================================
|
||||
|
||||
mmap_min_addr
|
||||
=============
|
||||
|
||||
This file indicates the amount of address space which a user process will
|
||||
be restricted from mmapping. Since kernel null dereference bugs could
|
||||
@ -498,9 +512,9 @@ security module. Setting this value to something like 64k will allow the
|
||||
vast majority of applications to work correctly and provide defense in depth
|
||||
against future potential kernel bugs.
|
||||
|
||||
==============================================================
|
||||
|
||||
mmap_rnd_bits:
|
||||
mmap_rnd_bits
|
||||
=============
|
||||
|
||||
This value can be used to select the number of bits to use to
|
||||
determine the random offset to the base address of vma regions
|
||||
@ -511,9 +525,9 @@ by the architecture's minimum and maximum supported values.
|
||||
This value can be changed after boot using the
|
||||
/proc/sys/vm/mmap_rnd_bits tunable
|
||||
|
||||
==============================================================
|
||||
|
||||
mmap_rnd_compat_bits:
|
||||
mmap_rnd_compat_bits
|
||||
====================
|
||||
|
||||
This value can be used to select the number of bits to use to
|
||||
determine the random offset to the base address of vma regions
|
||||
@ -525,35 +539,35 @@ architecture's minimum and maximum supported values.
|
||||
This value can be changed after boot using the
|
||||
/proc/sys/vm/mmap_rnd_compat_bits tunable
|
||||
|
||||
==============================================================
|
||||
|
||||
nr_hugepages
|
||||
============
|
||||
|
||||
Change the minimum size of the hugepage pool.
|
||||
|
||||
See Documentation/admin-guide/mm/hugetlbpage.rst
|
||||
|
||||
==============================================================
|
||||
|
||||
nr_hugepages_mempolicy
|
||||
======================
|
||||
|
||||
Change the size of the hugepage pool at run-time on a specific
|
||||
set of NUMA nodes.
|
||||
|
||||
See Documentation/admin-guide/mm/hugetlbpage.rst
|
||||
|
||||
==============================================================
|
||||
|
||||
nr_overcommit_hugepages
|
||||
=======================
|
||||
|
||||
Change the maximum size of the hugepage pool. The maximum is
|
||||
nr_hugepages + nr_overcommit_hugepages.
|
||||
|
||||
See Documentation/admin-guide/mm/hugetlbpage.rst
|
||||
|
||||
==============================================================
|
||||
|
||||
nr_trim_pages
|
||||
=============
|
||||
|
||||
This is available only on NOMMU kernels.
|
||||
|
||||
@ -568,16 +582,17 @@ The default value is 1.
|
||||
|
||||
See Documentation/nommu-mmap.txt for more information.
|
||||
|
||||
==============================================================
|
||||
|
||||
numa_zonelist_order
|
||||
===================
|
||||
|
||||
This sysctl is only for NUMA and it is deprecated. Anything but
|
||||
Node order will fail!
|
||||
|
||||
'where the memory is allocated from' is controlled by zonelists.
|
||||
|
||||
(This documentation ignores ZONE_HIGHMEM/ZONE_DMA32 for simple explanation.
|
||||
you may be able to read ZONE_DMA as ZONE_DMA32...)
|
||||
you may be able to read ZONE_DMA as ZONE_DMA32...)
|
||||
|
||||
In non-NUMA case, a zonelist for GFP_KERNEL is ordered as following.
|
||||
ZONE_NORMAL -> ZONE_DMA
|
||||
@ -585,10 +600,10 @@ This means that a memory allocation request for GFP_KERNEL will
|
||||
get memory from ZONE_DMA only when ZONE_NORMAL is not available.
|
||||
|
||||
In NUMA case, you can think of following 2 types of order.
|
||||
Assume 2 node NUMA and below is zonelist of Node(0)'s GFP_KERNEL
|
||||
Assume 2 node NUMA and below is zonelist of Node(0)'s GFP_KERNEL::
|
||||
|
||||
(A) Node(0) ZONE_NORMAL -> Node(0) ZONE_DMA -> Node(1) ZONE_NORMAL
|
||||
(B) Node(0) ZONE_NORMAL -> Node(1) ZONE_NORMAL -> Node(0) ZONE_DMA.
|
||||
(A) Node(0) ZONE_NORMAL -> Node(0) ZONE_DMA -> Node(1) ZONE_NORMAL
|
||||
(B) Node(0) ZONE_NORMAL -> Node(1) ZONE_NORMAL -> Node(0) ZONE_DMA.
|
||||
|
||||
Type(A) offers the best locality for processes on Node(0), but ZONE_DMA
|
||||
will be used before ZONE_NORMAL exhaustion. This increases possibility of
|
||||
@ -616,9 +631,9 @@ order will be selected.
|
||||
Default order is recommended unless this is causing problems for your
|
||||
system/application.
|
||||
|
||||
==============================================================
|
||||
|
||||
oom_dump_tasks
|
||||
==============
|
||||
|
||||
Enables a system-wide task dump (excluding kernel threads) to be produced
|
||||
when the kernel performs an OOM-killing and includes such information as
|
||||
@ -638,9 +653,9 @@ OOM killer actually kills a memory-hogging task.
|
||||
|
||||
The default value is 1 (enabled).
|
||||
|
||||
==============================================================
|
||||
|
||||
oom_kill_allocating_task
|
||||
========================
|
||||
|
||||
This enables or disables killing the OOM-triggering task in
|
||||
out-of-memory situations.
|
||||
@ -659,9 +674,9 @@ is used in oom_kill_allocating_task.
|
||||
|
||||
The default value is 0.
|
||||
|
||||
==============================================================
|
||||
|
||||
overcommit_kbytes:
|
||||
overcommit_kbytes
|
||||
=================
|
||||
|
||||
When overcommit_memory is set to 2, the committed address space is not
|
||||
permitted to exceed swap plus this amount of physical RAM. See below.
|
||||
@ -670,9 +685,9 @@ Note: overcommit_kbytes is the counterpart of overcommit_ratio. Only one
|
||||
of them may be specified at a time. Setting one disables the other (which
|
||||
then appears as 0 when read).
|
||||
|
||||
==============================================================
|
||||
|
||||
overcommit_memory:
|
||||
overcommit_memory
|
||||
=================
|
||||
|
||||
This value contains a flag that enables memory overcommitment.
|
||||
|
||||
@ -695,17 +710,17 @@ The default value is 0.
|
||||
See Documentation/vm/overcommit-accounting.rst and
|
||||
mm/util.c::__vm_enough_memory() for more information.
|
||||
|
||||
==============================================================
|
||||
|
||||
overcommit_ratio:
|
||||
overcommit_ratio
|
||||
================
|
||||
|
||||
When overcommit_memory is set to 2, the committed address
|
||||
space is not permitted to exceed swap plus this percentage
|
||||
of physical RAM. See above.
|
||||
|
||||
==============================================================
|
||||
|
||||
page-cluster
|
||||
============
|
||||
|
||||
page-cluster controls the number of pages up to which consecutive pages
|
||||
are read in from swap in a single attempt. This is the swap counterpart
|
||||
@ -725,9 +740,9 @@ Lower values mean lower latencies for initial faults, but at the same time
|
||||
extra faults and I/O delays for following faults if they would have been part of
|
||||
that consecutive pages readahead would have brought in.
|
||||
|
||||
=============================================================
|
||||
|
||||
panic_on_oom
|
||||
============
|
||||
|
||||
This enables or disables panic on out-of-memory feature.
|
||||
|
||||
@ -747,14 +762,16 @@ above-mentioned. Even oom happens under memory cgroup, the whole
|
||||
system panics.
|
||||
|
||||
The default value is 0.
|
||||
|
||||
1 and 2 are for failover of clustering. Please select either
|
||||
according to your policy of failover.
|
||||
|
||||
panic_on_oom=2+kdump gives you very strong tool to investigate
|
||||
why oom happens. You can get snapshot.
|
||||
|
||||
=============================================================
|
||||
|
||||
percpu_pagelist_fraction
|
||||
========================
|
||||
|
||||
This is the fraction of pages at most (high mark pcp->high) in each zone that
|
||||
are allocated for each per cpu page list. The min value for this is 8. It
|
||||
@ -770,16 +787,16 @@ The initial value is zero. Kernel does not use this value at boot time to set
|
||||
the high water marks for each per cpu page list. If the user writes '0' to this
|
||||
sysctl, it will revert to this default behavior.
|
||||
|
||||
==============================================================
|
||||
|
||||
stat_interval
|
||||
=============
|
||||
|
||||
The time interval between which vm statistics are updated. The default
|
||||
is 1 second.
|
||||
|
||||
==============================================================
|
||||
|
||||
stat_refresh
|
||||
============
|
||||
|
||||
Any read or write (by root only) flushes all the per-cpu vm statistics
|
||||
into their global totals, for more accurate reports when testing
|
||||
@ -790,24 +807,26 @@ as 0) and "fails" with EINVAL if any are found, with a warning in dmesg.
|
||||
(At time of writing, a few stats are known sometimes to be found negative,
|
||||
with no ill effects: errors and warnings on these stats are suppressed.)
|
||||
|
||||
==============================================================
|
||||
|
||||
numa_stat
|
||||
=========
|
||||
|
||||
This interface allows runtime configuration of numa statistics.
|
||||
|
||||
When page allocation performance becomes a bottleneck and you can tolerate
|
||||
some possible tool breakage and decreased numa counter precision, you can
|
||||
do:
|
||||
do::
|
||||
|
||||
echo 0 > /proc/sys/vm/numa_stat
|
||||
|
||||
When page allocation performance is not a bottleneck and you want all
|
||||
tooling to work, you can do:
|
||||
tooling to work, you can do::
|
||||
|
||||
echo 1 > /proc/sys/vm/numa_stat
|
||||
|
||||
==============================================================
|
||||
|
||||
swappiness
|
||||
==========
|
||||
|
||||
This control is used to define how aggressive the kernel will swap
|
||||
memory pages. Higher values will increase aggressiveness, lower values
|
||||
@ -817,9 +836,9 @@ than the high water mark in a zone.
|
||||
|
||||
The default value is 60.
|
||||
|
||||
==============================================================
|
||||
|
||||
unprivileged_userfaultfd
|
||||
========================
|
||||
|
||||
This flag controls whether unprivileged users can use the userfaultfd
|
||||
system calls. Set this to 1 to allow unprivileged users to use the
|
||||
@ -828,9 +847,9 @@ privileged users (with SYS_CAP_PTRACE capability).
|
||||
|
||||
The default value is 1.
|
||||
|
||||
==============================================================
|
||||
|
||||
- user_reserve_kbytes
|
||||
user_reserve_kbytes
|
||||
===================
|
||||
|
||||
When overcommit_memory is set to 2, "never overcommit" mode, reserve
|
||||
min(3% of current process size, user_reserve_kbytes) of free memory.
|
||||
@ -846,10 +865,9 @@ Any subsequent attempts to execute a command will result in
|
||||
|
||||
Changing this takes effect whenever an application requests memory.
|
||||
|
||||
==============================================================
|
||||
|
||||
vfs_cache_pressure
|
||||
------------------
|
||||
==================
|
||||
|
||||
This percentage value controls the tendency of the kernel to reclaim
|
||||
the memory which is used for caching of directory and inode objects.
|
||||
@ -867,9 +885,9 @@ performance impact. Reclaim code needs to take various locks to find freeable
|
||||
directory and inode objects. With vfs_cache_pressure=1000, it will look for
|
||||
ten times more freeable objects than there are.
|
||||
|
||||
=============================================================
|
||||
|
||||
watermark_boost_factor:
|
||||
watermark_boost_factor
|
||||
======================
|
||||
|
||||
This factor controls the level of reclaim when memory is being fragmented.
|
||||
It defines the percentage of the high watermark of a zone that will be
|
||||
@ -887,9 +905,9 @@ fragmentation events that occurred in the recent past. If this value is
|
||||
smaller than a pageblock then a pageblocks worth of pages will be reclaimed
|
||||
(e.g. 2MB on 64-bit x86). A boost factor of 0 will disable the feature.
|
||||
|
||||
=============================================================
|
||||
|
||||
watermark_scale_factor:
|
||||
watermark_scale_factor
|
||||
======================
|
||||
|
||||
This factor controls the aggressiveness of kswapd. It defines the
|
||||
amount of memory left in a node/system before kswapd is woken up and
|
||||
@ -905,20 +923,22 @@ that the number of free pages kswapd maintains for latency reasons is
|
||||
too small for the allocation bursts occurring in the system. This knob
|
||||
can then be used to tune kswapd aggressiveness accordingly.
|
||||
|
||||
==============================================================
|
||||
|
||||
zone_reclaim_mode:
|
||||
zone_reclaim_mode
|
||||
=================
|
||||
|
||||
Zone_reclaim_mode allows someone to set more or less aggressive approaches to
|
||||
reclaim memory when a zone runs out of memory. If it is set to zero then no
|
||||
zone reclaim occurs. Allocations will be satisfied from other zones / nodes
|
||||
in the system.
|
||||
|
||||
This is value ORed together of
|
||||
This is value OR'ed together of
|
||||
|
||||
1 = Zone reclaim on
|
||||
2 = Zone reclaim writes dirty pages out
|
||||
4 = Zone reclaim swaps pages
|
||||
= ===================================
|
||||
1 Zone reclaim on
|
||||
2 Zone reclaim writes dirty pages out
|
||||
4 Zone reclaim swaps pages
|
||||
= ===================================
|
||||
|
||||
zone_reclaim_mode is disabled by default. For file servers or workloads
|
||||
that benefit from having their data cached, zone_reclaim_mode should be
|
||||
@ -942,5 +962,3 @@ of other processes running on other nodes will not be affected.
|
||||
Allowing regular swap effectively restricts allocations to the local
|
||||
node unless explicitly overridden by memory policies or cpuset
|
||||
configurations.
|
||||
|
||||
============ End of Document =================================
|
||||
@ -439,7 +439,7 @@ Compacting MLOCKED Pages
|
||||
|
||||
The unevictable LRU can be scanned for compactable regions and the default
|
||||
behavior is to do so. /proc/sys/vm/compact_unevictable_allowed controls
|
||||
this behavior (see Documentation/sysctl/vm.txt). Once scanning of the
|
||||
this behavior (see Documentation/sysctl/vm.rst). Once scanning of the
|
||||
unevictable LRU is enabled, the work of compaction is mostly handled by
|
||||
the page migration code and the same work flow as described in MIGRATING
|
||||
MLOCKED PAGES will apply.
|
||||
|
||||
@ -372,7 +372,7 @@ const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
|
||||
/**
|
||||
* print_tainted - return a string to represent the kernel taint state.
|
||||
*
|
||||
* For individual taint flag meanings, see Documentation/sysctl/kernel.txt
|
||||
* For individual taint flag meanings, see Documentation/sysctl/kernel.rst
|
||||
*
|
||||
* The string is overwritten by the next call to print_tainted(),
|
||||
* but is always NULL terminated.
|
||||
|
||||
@ -8,7 +8,7 @@
|
||||
/*
|
||||
* This file contains the default values for the operation of the
|
||||
* Linux VM subsystem. Fine-tuning documentation can be found in
|
||||
* Documentation/sysctl/vm.txt.
|
||||
* Documentation/sysctl/vm.rst.
|
||||
* Started 18.12.91
|
||||
* Swap aging added 23.2.95, Stephen Tweedie.
|
||||
* Buffermem limits added 12.3.98, Rik van Riel.
|
||||
|
||||
Loading…
Reference in New Issue
Block a user