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2017-10-19Documentation: fix locking rt-mutex doc refsTom Saeger1-1/+1
Signed-off-by: Tom Saeger <tom.saeger@oracle.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-09-04Merge branch 'linus' into locking/core, to fix up conflictsIngo Molnar2-359/+131
Conflicts: mm/page_alloc.c Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-24rtmutex: update rt-mutexAlex Shi1-32/+26
The rtmutex remove a pending owner bit in in rt_mutex::owner, in commit 8161239a8bcc ("rtmutex: Simplify PI algorithm and make highest prio task get lock") But the document was changed accordingly. Updating it to a meaningful state. BTW, as 'Steven Rostedt' mentioned: There is still technically a "Pending Owner", it's just not called that anymore. The pending owner happens to be the top_waiter of a lock that has no owner and has been woken up to grab the lock. Signed-off-by: Alex Shi <alex.shi@linaro.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> To: linux-doc@vger.kernel.org To: linux-kernel@vger.kernel.org To: Jonathan Corbet <corbet@lwn.net> To: Ingo Molnar <mingo@redhat.com> To: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-08-24rtmutex: update rt-mutex-designAlex Shi1-327/+105
The rt-mutex-design documents didn't gotten meaningful update from its first version. Even after owner's pending bit was removed in commit 8161239a8bcc ("rtmutex: Simplify PI algorithm and make highest prio task get lock") and priority list 'plist' changed to rbtree. And Peter Zijlstra did some clean up and fix for deadline task changes on tip tree. So update it to latest code and make it meaningful. Steven Rostedt and Sebastian Siewior gave much of comments and input in this doc. Thanks! Signed-off-by: Alex Shi <alex.shi@linaro.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> To: linux-doc@vger.kernel.org To: linux-kernel@vger.kernel.org To: Jonathan Corbet <corbet@lwn.net> To: Ingo Molnar <mingo@redhat.com> To: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-08-10locking/lockdep: Add 'crossrelease' feature documentationByungchul Park1-0/+874
This document describes the concept of crossrelease feature. Signed-off-by: Byungchul Park <byungchul.park@lge.com> 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: akpm@linux-foundation.org Cc: boqun.feng@gmail.com Cc: kernel-team@lge.com Cc: kirill@shutemov.name Cc: npiggin@gmail.com Cc: walken@google.com Cc: willy@infradead.org Link: http://lkml.kernel.org/r/1502089981-21272-15-git-send-email-byungchul.park@lge.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14locking/ww_mutex/Documentation: Update the design documentNicolai Hähnle1-4/+8
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>
2016-09-22locking/lglock: Remove lglock implementationPeter Zijlstra1-166/+0
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>
2016-04-28locking/Documentation/lockdep: Fix spelling mistakesEric Engestrom1-2/+2
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>
2015-11-03Merge branch 'locking-core-for-linus' of ↵Linus Torvalds1-1/+1
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
2015-10-06locktorture: Support rtmutex torturingDavidlohr Bueso1-0/+3
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>
2015-09-18locking/Documentation/lockstat: Fix typo - lokcing -> lockingStephen Boyd1-1/+1
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>
2015-02-11Merge tag 'docs-for-linus' of git://git.lwn.net/linux-2.6Linus Torvalds2-0/+21
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 ...
2015-01-28lockstat: Add documentation on contention and contenting pointsDaniel Wagner1-0/+5
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>
2015-01-16locking/Documentation: Update code pathSeongJae Park1-1/+1
lockdep code has been moved from kernel/ to kernel/locking/ by commit 8eddac3f103736163f49255bcb109edadea167f6 ("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>
2014-12-29Update of Documentation/00-INDEXHenrik Austad1-0/+16
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>
2014-12-09Merge branch 'core-locking-for-linus' of ↵Linus Torvalds1-0/+166
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
2014-12-08locking/lglocks: Add documentation of current lglocks implementationNicholas Mc Guire1-0/+166
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>
2014-10-13Merge branch 'locking-core-for-linus' of ↵Linus Torvalds7-0/+1992
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
2014-09-30locktorture: Support rwlocksDavidlohr Bueso1-0/+5
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>
2014-09-16locktorture: Support rwsemsDavidlohr Bueso1-0/+2
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>
2014-09-16locktorture: Add infrastructure for torturing read locksDavidlohr Bueso1-4/+12
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>
2014-09-16locktorture: Support mutexesDavidlohr Bueso1-0/+2
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>
2014-09-16locktorture: Add documentationDavidlohr Bueso1-0/+130
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>
2014-08-13locking/Documentation: Update locking/mutex-design.txt disadvantagesDavidlohr Bueso1-3/+3
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>
2014-08-13locking/Documentation: Move locking related docs into Documentation/locking/Davidlohr Bueso7-0/+1992
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>
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