Commit Graph

70 Commits

Author SHA1 Message Date
Nicolai Hähnle 27bd57aa81 locking/ww_mutex/Documentation: Update the design document
Document the invariants we maintain for the wait list of ww_mutexes.

Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-13-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:55 +01:00
Peter Zijlstra d32cdbfb0b locking/lglock: Remove lglock implementation
It is now unused, remove it before someone else thinks its a good idea
to use this.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-09-22 15:25:56 +02:00
Eric Engestrom 1d4093d3b3 locking/Documentation/lockdep: Fix spelling mistakes
Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1461566229-4717-2-git-send-email-eric@engestrom.ch
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-28 10:40:57 +02:00
Linus Torvalds d63a978865 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking changes from Ingo Molnar:
 "The main changes in this cycle were:

   - More gradual enhancements to atomic ops: new atomic*_read_ctrl()
     ops, synchronize atomic_{read,set}() ordering requirements between
     architectures, add atomic_long_t bitops.  (Peter Zijlstra)

   - Add _{relaxed|acquire|release}() variants for inc/dec atomics and
     use them in various locking primitives: mutex, rtmutex, mcs, rwsem.
     This enables weakly ordered architectures (such as arm64) to make
     use of more locking related optimizations.  (Davidlohr Bueso)

   - Implement atomic[64]_{inc,dec}_relaxed() on ARM.  (Will Deacon)

   - Futex kernel data cache footprint micro-optimization.  (Rasmus
     Villemoes)

   - pvqspinlock runtime overhead micro-optimization.  (Waiman Long)

   - misc smaller fixlets"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ARM, locking/atomics: Implement _relaxed variants of atomic[64]_{inc,dec}
  locking/rwsem: Use acquire/release semantics
  locking/mcs: Use acquire/release semantics
  locking/rtmutex: Use acquire/release semantics
  locking/mutex: Use acquire/release semantics
  locking/asm-generic: Add _{relaxed|acquire|release}() variants for inc/dec atomics
  atomic: Implement atomic_read_ctrl()
  atomic, arch: Audit atomic_{read,set}()
  atomic: Add atomic_long_t bitops
  futex: Force hot variables into a single cache line
  locking/pvqspinlock: Kick the PV CPU unconditionally when _Q_SLOW_VAL
  locking/osq: Relax atomic semantics
  locking/qrwlock: Rename ->lock to ->wait_lock
  locking/Documentation/lockstat: Fix typo - lokcing -> locking
  locking/atomics, cmpxchg: Privatize the inclusion of asm/cmpxchg.h
2015-11-03 16:10:43 -08:00
Davidlohr Bueso 095777c417 locktorture: Support rtmutex torturing
Real time mutexes is one of the few general primitives
that we do not have in locktorture. Address this -- a few
considerations:

o To spice things up, enable competing thread(s) to become
rt, such that we can stress different prio boosting paths
in the rtmutex code. Introduce a ->task_boost callback,
only used by rtmutex-torturer. Tasks will boost/deboost
around every 50k (arbitrarily) lock/unlock operations.

o Hold times are similar to what we have for other locks:
only occasionally having longer hold times (per ~200k ops).
So we roughly do two full rt boost+deboosting ops with
short hold times.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-10-06 11:24:40 -07:00
Stephen Boyd e58cdf585a locking/Documentation/lockstat: Fix typo - lokcing -> locking
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Kosina <trivial@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1441842398-25063-1-git-send-email-sboyd@codeaurora.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-09-18 09:27:28 +02:00
Linus Torvalds 73b4f63aeb Documentation changes for 3.20
Highlights this time around include:
 
  - A thrashing of SubmittingPatches to bring it out of the "send everything
    to Linus" era of kernel development.
 
  - A new document on completions from Nicholas McGuire
 
  - Lots of typo fixes, formatting improvements, corrections, build fixes,
    and more.
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Merge tag 'docs-for-linus' of git://git.lwn.net/linux-2.6

Pull documentation updates from Jonathan Corbet:
 "Highlights this time around include:

   - A thrashing of SubmittingPatches to bring it out of the "send
     everything to Linus" era of kernel development.

   - A new document on completions from Nicholas McGuire

   - Lots of typo fixes, formatting improvements, corrections, build
     fixes, and more"

* tag 'docs-for-linus' of git://git.lwn.net/linux-2.6: (35 commits)
  Documentation: Fix the wrong command `echo -1 > set_ftrace_pid` for cleaning the filter.
  can-doc: Fixed a wrong filepath in can.txt
  Documentation: Fix trivial typo in comment.
  kgdb,docs: Fix typo and minor style issues
  Documentation: add description for FTRACE probe status
  doc: brief user documentation for completion
  Documentation/misc-devices/mei: Fix indentation of embedded code.
  Documentation/misc-devices/mei: Fix indentation of enumeration.
  Documentation/misc-devices/mei: Fix spacing around parentheses.
  Documentation/misc-devices/mei: Fix formatting of headings.
  Documentation: devicetree: Fix double words in Doumentation/devicetree
  Documentation: mm: Fix typo in vm.txt
  lockstat: Add documentation on contention and contenting points
  Documentation: fix blackfin gptimers-example build errors
  Fixes column alignment in table of contents entry 1.9 in Documentation/filesystems/proc.txt
  CodingStyle: enable emacs display of trailing whitespace
  DocBook: Do not exceed argument list limit
  gpio: board.txt: Fix the gpio name example
  Documentation/SubmittingPatches: unify whitespace/tabs for the DCO
  MAINTAINERS: Add the docs-next git tree to the maintainer entry
  ...
2015-02-11 13:03:11 -08:00
Daniel Wagner 7b7e1b7b7f lockstat: Add documentation on contention and contenting points
Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2015-01-28 15:13:10 -07:00
SeongJae Park a97af339c8 locking/Documentation: Update code path
lockdep code has been moved from kernel/ to kernel/locking/ by commit
8eddac3f10 ("locking: Move the lockdep
code to kernel/locking/"). But, path to lockdep code in document was not
updated.

This commit updates the path.

Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1421176921-27688-1-git-send-email-sj38.park@gmail.com
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-01-16 09:09:21 +01:00
Henrik Austad 8ea8f3eb9c Update of Documentation/00-INDEX
Added files
- hsi.txt was added by 3a8ab8af (HSI: Add some general description for
  the HSI subsystem)
- lzo.txt was added by d98a0526 (lzo: document part of the encoding)
- xillybus.txt was added by 7051924f (xillybus: Move out of staging)
- mailbox.txt was added by 15320fbc (add documentation for mailbox
  framework)

Moved files
- xommit 214e0aed (Move locking related docs into Documentation/locking/):
  * lockdep-design.txt
  * lockstat.txt
  * mutex-design.txt
  * rt-mutex-design.txt
  * rt-mutex.txt
  * spinlocks.txt
  * ww-mutex-design.txt
- kselftest.txt was moved by 3c415707 (kselftest: Move the docs to the
  Documentation dir)

CC: Davidlohr Bueso <davidlohr@hp.com>
CC: Willy Tarreau <w@1wt.eu>
CC: Randy Dunlap <rdunlap@infradead.org>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: Sebastian Reichel <sre@kernel.org>
CC: Eli Billauer <eli.billauer@gmail.com>
CC: Jonathan Corbet <corbet@lwn.net>
CC: Jiri Kosina <trivial@kernel.org>
CC: linux-doc@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Cc: Tim Bird <tim.bird@sonymobile.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>

Signed-off-by: Henrik Austad <henrik@austad.us>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2014-12-29 15:27:54 -07:00
Linus Torvalds 9c37f95936 Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking tree changes from Ingo Molnar:
 "Two changes: a documentation update and a ticket locks live lock fix"

* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/ticketlock: Fix spin_unlock_wait() livelock
  locking/lglocks: Add documentation of current lglocks implementation
2014-12-09 19:59:22 -08:00
Nicholas Mc Guire 9fd7fc34cf locking/lglocks: Add documentation of current lglocks implementation
Local/global locks are currently not documented anywhere other
than in an somewhat out-of-date LWN article - this is an attempt
to document the current state of lglocks.

This patch is against linux-next 3.18.0-rc6

Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Carsten Emde <c.emde@osadl.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20141208083326.GA29895@opentech.at
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-12-08 09:55:00 +01:00
Linus Torvalds 6d5f0ebfc0 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core locking updates from Ingo Molnar:
 "The main updates in this cycle were:

   - mutex MCS refactoring finishing touches: improve comments, refactor
     and clean up code, reduce debug data structure footprint, etc.

   - qrwlock finishing touches: remove old code, self-test updates.

   - small rwsem optimization

   - various smaller fixes/cleanups"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/lockdep: Revert qrwlock recusive stuff
  locking/rwsem: Avoid double checking before try acquiring write lock
  locking/rwsem: Move EXPORT_SYMBOL() lines to follow function definition
  locking/rwlock, x86: Delete unused asm/rwlock.h and rwlock.S
  locking/rwlock, x86: Clean up asm/spinlock*.h to remove old rwlock code
  locking/semaphore: Resolve some shadow warnings
  locking/selftest: Support queued rwlock
  locking/lockdep: Restrict the use of recursive read_lock() with qrwlock
  locking/spinlocks: Always evaluate the second argument of spin_lock_nested()
  locking/Documentation: Update locking/mutex-design.txt disadvantages
  locking/Documentation: Move locking related docs into Documentation/locking/
  locking/mutexes: Use MUTEX_SPIN_ON_OWNER when appropriate
  locking/mutexes: Refactor optimistic spinning code
  locking/mcs: Remove obsolete comment
  locking/mutexes: Document quick lock release when unlocking
  locking/mutexes: Standardize arguments in lock/unlock slowpaths
  locking: Remove deprecated smp_mb__() barriers
2014-10-13 15:51:40 +02:00
Davidlohr Bueso e34191fad8 locktorture: Support rwlocks
Add a "rw_lock" torture test to stress kernel rwlocks and their irq
variant. Reader critical regions are 5x longer than writers. As such
a similar ratio of lock acquisitions is seen in the statistics. In the
case of massive contention, both hold the lock for 1/10 of a second.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-30 00:10:00 -07:00
Davidlohr Bueso 4a3b427f0b locktorture: Support rwsems
We can easily do so with our new reader lock support. Just an arbitrary
design default: readers have higher (5x) critical region latencies than
writers: 50 ms and 10 ms, respectively.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:36 -07:00
Davidlohr Bueso 4f6332c1dc locktorture: Add infrastructure for torturing read locks
Most of it is based on what we already have for writers. This allows
readers to be very independent (and thus configurable), enabling
future module parameters to control things such as rw distribution.
Furthermore, readers have their own delaying function, allowing us
to test different rw critical region latencies, and stress locking
internals. Similarly, statistics, for now will only serve for the
number of lock acquisitions -- as opposed to writers, readers have
no failure detection.

In addition, introduce a new nreaders_stress module parameter. The
default number of readers will be the same number of writers threads.
Writer threads are interleaved with readers. Documentation is updated,
respectively.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:07 -07:00
Davidlohr Bueso 42ddc75ddd locktorture: Support mutexes
Add a "mutex_lock" torture test. The main difference with the already
existing spinlock tests is that the latency of the critical region
is much larger. We randomly delay for (arbitrarily) either 500 ms or,
otherwise, 25 ms. While this can considerably reduce the amount of
writes compared to non blocking locks, if run long enough it can have
the same torturous effect. Furthermore it is more representative of
mutex hold times and can stress better things like thrashing.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:40:59 -07:00
Davidlohr Bueso cdf26bb10b locktorture: Add documentation
Just like Documentation/RCU/torture.txt, begin a document for the
locktorture module. This module is still pretty green, so I have
just added some specific sections to the doc (general desc, params,
usage, etc.). Further development should update the file.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
[ paulmck: Apply Randy Dunlap review comments. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:39:13 -07:00
Davidlohr Bueso 0a7cbf9abe locking/Documentation: Update locking/mutex-design.txt disadvantages
Fortunately Jason was able to reduce some of the overhead we
had introduced in the original rwsem optimistic spinning -
an it is now the same size as mutexes. Update the documentation
accordingly.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: aswin@hp.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Link: http://lkml.kernel.org/r/1406752916-3341-7-git-send-email-davidlohr@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-08-13 10:32:04 +02:00
Davidlohr Bueso 214e0aed63 locking/Documentation: Move locking related docs into Documentation/locking/
Specifically:
  Documentation/locking/lockdep-design.txt
  Documentation/locking/lockstat.txt
  Documentation/locking/mutex-design.txt
  Documentation/locking/rt-mutex-design.txt
  Documentation/locking/rt-mutex.txt
  Documentation/locking/spinlocks.txt
  Documentation/locking/ww-mutex-design.txt

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: jason.low2@hp.com
Cc: aswin@hp.com
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Mason <clm@fb.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Josef Bacik <jbacik@fusionio.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lubomir Rintel <lkundrak@v3.sk>
Cc: Masanari Iida <standby24x7@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: fengguang.wu@intel.com
Link: http://lkml.kernel.org/r/1406752916-3341-6-git-send-email-davidlohr@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-08-13 10:32:03 +02:00