Commit Graph

47 Commits

Author SHA1 Message Date
Borislav Petkov
15ce51f55e Documentation/no_hz: Introduce "dyntick-idle mode" before using it
The CONFIG_NO_HZ_IDLE paragraph is using "dyntick-idle mode" before
having defined it while the definition comes a couple of paragraphs
later.

That is leaving the reader with scratching head what that dyntick-idle
mode might be. Pull its definition up so that it is clear.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20210914203355.21360-1-bp@alien8.de
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-09-27 11:31:11 -06:00
Randy Dunlap
9e255e2b9a Documentation: drop optional BOMs
A few of the Documentation .rst files begin with a Unicode
byte order mark (BOM). The BOM may signify endianess for
16-bit or 32-bit encodings or indicate that the text stream
is indeed Unicode. We don't need it for either of those uses.
It may also interfere with (confuse) some software.

Since we don't need it and its use is optional, just delete
the uses of it in Documentation/.

https://en.wikipedia.org/wiki/Byte_order_mark

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Link: https://lore.kernel.org/r/20210506231907.14359-1-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-05-10 15:17:34 -06:00
Joe Perches
05a5f51ca5 Documentation: Replace lkml.org links with lore
Replace the lkml.org links with lore to better use a single source
that's more likely to stay available long-term.

Done by bash script:

cvt_lkml_to_lore ()
{
    tmpfile=$(mktemp ./.cvt_links.XXXXXXX)

    header=$(echo $1 | sed 's@/lkml/@/lkml/headers/@')

    wget -qO - $header > $tmpfile
    if [[ $? == 0 ]] ; then
	link=$(grep -i '^Message-Id:' $tmpfile | head -1 | \
		   sed -r -e 's/^\s*Message-Id:\s*<\s*//' -e  's/\s*>\s*$//' -e 's@^@https://lore.kernel.org/r/@')
	#    echo "testlink: $link"
	if [ -n "$link" ] ; then
	    wget -qO - $link > /dev/null
	    if [[ $? == 0 ]] ; then
		echo $link
	    fi
	fi
    fi

    rm -f $tmpfile
}

git grep -P -o "\bhttps?://(?:www.)?lkml.org/lkml[\/\w]+" $@ |
    while read line ; do
	echo $line
	file=$(echo $line | cut -f1 -d':')
	link=$(echo $line | cut -f2- -d':')
	newlink=$(cvt_lkml_to_lore $link)
	if [[ -n "$newlink" ]] ; then
	    sed -i -e "s#\b$link\b#$newlink#" $file
	fi
    done

Link: https://lore.kernel.org/patchwork/patch/1265849/#1462688
Signed-off-by: Joe Perches <joe@perches.com>
Link: https://lore.kernel.org/r/77cdb7f32cfb087955bfc3600b86c40bed5d4104.camel@perches.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-01-11 12:47:38 -07:00
Julia Lawall
61ebd0d0ae docs: timers: drop documentation about LB_BIAS
The LB_BIAS feature was removed in commit 1c1b8a7b03 ("sched/fair:
Replace source_load() & target_load() with weighted_cpuload()"), so drop
the mention that it is disabled in the no_hz case.

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

Link: https://lore.kernel.org/r/1595088518-28116-1-git-send-email-Julia.Lawall@inria.fr
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-07-23 14:32:44 -06:00
Heiner Kallweit
c6af13d334 timer: add fsleep for flexible sleeping
Sleeping for a certain amount of time requires use of different
functions, depending on the time period.
Documentation/timers/timers-howto.rst explains when to use which
function, and also checkpatch checks for some potentially
problematic cases.

So let's create a helper that automatically chooses the appropriate
sleep function -> fsleep(), for flexible sleeping

If the delay is a constant, then the compiler should be able to ensure
that the new helper doesn't create overhead. If the delay is not
constant, then the new helper can save some code.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-05-06 17:03:34 -07:00
Mauro Carvalho Chehab
113094f743 docs: add some directories to the main documentation index
The contents of those directories were orphaned at the documentation
body.

While those directories could likely be moved to be inside some guide,
I'm opting to just adding their indexes to the main one, removing the
:orphan: and adding the SPDX header.

For the drivers, the rationale is that the documentation contains
a mix of Kernelspace, uAPI and admin-guide. So, better to keep them on
separate directories, as we've be doing with similar subsystem-specific
docs that were not split yet.

For the others, well... I'm too lazy to do the move. Also, it
seems to make sense to keep at least some of those at the main
dir (like kbuild, for example). In any case, a latter patch
could do the move.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
2019-07-15 11:03:03 -03:00
Mauro Carvalho Chehab
458f69ef36 docs: timers: convert docs to ReST and rename to *.rst
The conversion here is really trivial: just a bunch of title
markups and very few puntual changes is enough to make it to
be parsed by Sphinx and generate a nice html.

The conversion is actually:
  - add blank lines and identation in order to identify paragraphs;
  - fix tables markups;
  - add some lists markups;
  - mark literal blocks;
  - adjust title markups.

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>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-14 14:31:48 -06:00
George Sofianos
3203561d6d Docs: Correct /proc/stat path
The documentation for dynamic ticks in high resolution timers uses an
incorrect path for /proc/stat - fix it.

Signed-off-by: George Sofianos <gsf.greece@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-02-22 08:50:17 -07:00
Henrik Austad
a7ddcea58a Drop all 00-INDEX files from Documentation/
This is a respin with a wider audience (all that get_maintainer returned)
and I know this spams a *lot* of people. Not sure what would be the correct
way, so my apologies for ruining your inbox.

The 00-INDEX files are supposed to give a summary of all files present
in a directory, but these files are horribly out of date and their
usefulness is brought into question. Often a simple "ls" would reveal
the same information as the filenames are generally quite descriptive as
a short introduction to what the file covers (it should not surprise
anyone what Documentation/sched/sched-design-CFS.txt covers)

A few years back it was mentioned that these files were no longer really
needed, and they have since then grown further out of date, so perhaps
it is time to just throw them out.

A short status yields the following _outdated_ 00-INDEX files, first
counter is files listed in 00-INDEX but missing in the directory, last
is files present but not listed in 00-INDEX.

List of outdated 00-INDEX:
Documentation: (4/10)
Documentation/sysctl: (0/1)
Documentation/timers: (1/0)
Documentation/blockdev: (3/1)
Documentation/w1/slaves: (0/1)
Documentation/locking: (0/1)
Documentation/devicetree: (0/5)
Documentation/power: (1/1)
Documentation/powerpc: (0/5)
Documentation/arm: (1/0)
Documentation/x86: (0/9)
Documentation/x86/x86_64: (1/1)
Documentation/scsi: (4/4)
Documentation/filesystems: (2/9)
Documentation/filesystems/nfs: (0/2)
Documentation/cgroup-v1: (0/2)
Documentation/kbuild: (0/4)
Documentation/spi: (1/0)
Documentation/virtual/kvm: (1/0)
Documentation/scheduler: (0/2)
Documentation/fb: (0/1)
Documentation/block: (0/1)
Documentation/networking: (6/37)
Documentation/vm: (1/3)

Then there are 364 subdirectories in Documentation/ with several files that
are missing 00-INDEX alltogether (and another 120 with a single file and no
00-INDEX).

I don't really have an opinion to whether or not we /should/ have 00-INDEX,
but the above 00-INDEX should either be removed or be kept up to date. If
we should keep the files, I can try to keep them updated, but I rather not
if we just want to delete them anyway.

As a starting point, remove all index-files and references to 00-INDEX and
see where the discussion is going.

Signed-off-by: Henrik Austad <henrik@austad.us>
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Just-do-it-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: [Almost everybody else]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-09-09 15:08:58 -06:00
Siddaraju DH
9e7c758ec4 timekeeping.txt: Correct maxCount of n-bit binary counter
A n-bit binary counter can count a maximum of 2^n events and the count
value ranges from 0 to (2^n)-1

Signed-off-by: Siddaraju DH <siddarajudh@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-07-23 09:33:06 -06:00
Paul E. McKenney
a7c8655b07 sched/isolation: Eliminate NO_HZ_FULL_ALL
Commit 6f1982fedd ("sched/isolation: Handle the nohz_full= parameter")
broke CONFIG_NO_HZ_FULL_ALL=y kernels.  This breakage is due to the code
under CONFIG_NO_HZ_FULL_ALL failing to invoke the shiny new housekeeping
functions.  This means that rcutorture scenario TREE04 now emits RCU CPU
stall warnings due to the RCU grace-period kthreads not being awakened
at a time of their choosing, or perhaps even not at all:

[   27.731422] rcu_bh kthread starved for 21001 jiffies! g18446744073709551369 c18446744073709551368 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x402 ->cpu=3
[   27.731423] rcu_bh          I14936     9      2 0x80080000
[   27.731435] Call Trace:
[   27.731440]  __schedule+0x31a/0x6d0
[   27.731442]  schedule+0x31/0x80
[   27.731446]  schedule_timeout+0x15a/0x320
[   27.731453]  ? call_timer_fn+0x130/0x130
[   27.731457]  rcu_gp_kthread+0x66c/0xea0
[   27.731458]  ? rcu_gp_kthread+0x66c/0xea0

Because no one has complained about CONFIG_NO_HZ_FULL_ALL=y being broken,
I hypothesize that no one is in fact using it, other than rcutorture.
This commit therefore eliminates CONFIG_NO_HZ_FULL_ALL and updates
rcutorture's config files to instead use the nohz_full= kernel parameter
to put the desired CPUs into nohz_full mode.

Fixes: 6f1982fedd ("sched/isolation: Handle the nohz_full= parameter")

Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
2018-02-15 15:40:37 -08:00
stephen lu
44e9f09936 docs: highres: fix broken urls
Some urls is invalid. I find alternative urls.

Signed-off-by: stephen lu <lumotuwe@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-09-26 14:58:23 -06:00
Paul E. McKenney
44c65ff2e3 rcu: Eliminate NOCBs CPU-state Kconfig options
The CONFIG_RCU_NOCB_CPU_ALL, CONFIG_RCU_NOCB_CPU_NONE, and
CONFIG_RCU_NOCB_CPU_ZERO Kconfig options are used only in testing and
are redundant with the rcu_nocbs= boot parameter.  This commit therefore
removes these three Kconfig options and adjusts the rcutorture scripts
to use the boot parameter instead.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-06-08 18:52:43 -07:00
Kees Cook
dfb4357da6 time: Remove CONFIG_TIMER_STATS
Currently CONFIG_TIMER_STATS exposes process information across namespaces:

kernel/time/timer_list.c print_timer():

        SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);

/proc/timer_list:

 #11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570

Given that the tracer can give the same information, this patch entirely
removes CONFIG_TIMER_STATS.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: linux-doc@vger.kernel.org
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Xing Gao <xgao01@email.wm.edu>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jessica Frazelle <me@jessfraz.com>
Cc: kernel-hardening@lists.openwall.com
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Michal Marek <mmarek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Cc: Arjan van de Ven <arjan@linux.intel.com>
Link: http://lkml.kernel.org/r/20170208192659.GA32582@beast
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-02-10 11:15:08 +01:00
Shuah Khan
f59c668c0b Doc: update 00-INDEX files to reflect the runnable code move
Update 00-INDEX files with the current file list to reflect the runnable
code move.

Acked-by: Michal Marek <mmarek@suse.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
2016-10-10 07:12:09 -06:00
Shuah Khan
155fe001c6 samples: move timers example code from Documentation
Move timers examples to samples and remove it from Documentation
Makefile. Create a new Makefile to build timers. It can be built
from top level directory or from timers directory:

Run make -C samples/timers or cd samples/timers; make

Acked-by: Jonathan Corbet <corbet@lwn.net>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
2016-09-23 11:51:58 -06:00
Kees Cook
08559657b2 Documentation: fix common spelling mistakes
This fixes several spelling mistakes in the Documentation/ tree, which
are caught by checkpatch.pl's spell checking.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2016-04-28 07:51:59 -06:00
Cao jin
ac86db349e hrtimers: doc cleanup
It has:
a tense correction(led->leads);
a typo(unevitably->inevitably);

Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2016-04-28 07:13:10 -06:00
Linus Torvalds
37aa7319cd Merge tag 'docs-for-linus' of git://git.lwn.net/linux
Pul documentation update from Jon Corbet:
 "Another relatively boring cycle for the docs tree: typo fixes,
  translation updates, etc"

* tag 'docs-for-linus' of git://git.lwn.net/linux:
  modsign: Fix documentation on module signing enforcement parameter.
  Doc: nfs: Fix typos in Documentation/filesystems/nfs
  Documentation: kselftest: Remove duplicate word
  doc: fix grammar
  Documentation: Howto: Fixed subtitles style
  Doc: ARM: Fix a typo in clksrc-change-registers.awk
  Documentation/ko_KR: update maintainer information
  Documentation: Fix int/unsigned int comparison
  Documentation: Chinese translation of arm64/silicon-errata.txt
  Documentation:Update Documentation/zh_CN/arm64/booting.txt
  Documentation: HOWTO: remove obsolete info about regression postings
  Doc: ja_JP: Fix a typo in HOWTO
  Doc: i2c: Fix typo in Documentation/i2c
  Doc: DocBook: Fix a typo in device-drivers.tmpl
  Remove "arch" usage in Documentation/features/list-arch.sh
  README: cosmetic fixes
  Documentation/CodingStyle: add space before parenthesis in example macro
  SubmittingPatches: fix spelling of "git send-email"
2016-03-17 12:09:35 -07:00
Mahesh Khanwalkar
f0cd147e61 Documentation: Fix int/unsigned int comparison
Signed int - unsigned int comparison fixed in mpssd, prctl, ptp, and
timers in Documentation. In places where 'int argc' and 'const char
**argv' are not used, they are replaced with void

Documentation/mic/mpssd/mpssd.c: Fixed comparison in sum_iovec_len and
disp_iovec

Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c: main signature
changed to void, as parameters 'argc' and 'argv' are never used

Documentation/prctl/disable-tsc-on-off-stress-test.c: main signature
changed to void

Documentation/prctl/disable-tsc-test.c: main signature changed to void

Documentation/ptp/testptp.c: Sign comparison fix
Documentation/timers/hpet_example.c: Sign comparision fix

Signed-off-by: Mahesh Khanwalkar <maheshkhanwalkar@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2016-02-17 14:09:43 -07:00
Michael S. Tsirkin
4e7f9df258 hpet: Drop stale URLs
Looks like the HPET spec at intel.com got moved.
It isn't hard to find so drop the link, just mention
the revision assumed.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/1455145462-3877-1-git-send-email-mst@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-17 09:39:56 +01:00
Paul E. McKenney
c25197841e documentation: Update NO_HZ_FULL interaction with POSIX timers
POSIX timers are no longer starved on adaptive-ticks CPUs.  Instead, they
prevent affected CPUs from entering adaptive-ticks mode.  This commit
therefore updates the NO_HZ.txt documentation.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-02-26 11:57:29 -08:00
Peter Foley
c5e2a7e012 Documentation: update .gitignore files
Add some missing files to .gitignore.
Push Documentation/.gitignore down into subdirectories.

Signed-off-by: Peter Foley <pefoley2@pefoley.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2014-09-26 11:02:59 +02:00
Peter Foley
df68a01014 Documentation: use subdir-y to avoid unnecessary built-in.o files
Change the Documentation makefiles from obj-m to subdir-y
to avoid generating unnecessary built-in.o files since nothing
in Documentation/ is ever linked in to vmlinux.

Signed-off-by: Peter Foley <pefoley2@pefoley.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2014-09-26 11:02:55 +02:00
Linus Walleij
7806f60e1d clocksource: document some basic timekeeping concepts
This adds some documentation about clock sources, clock events,
the weak sched_clock() function and delay timers that answers
questions that repeatedly arise on the mailing lists.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Colin Cross <ccross@google.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23 15:07:13 -07:00