13 Oct, 2014
1 commit
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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
30 Sep, 2014
1 commit
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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
Signed-off-by: Paul E. McKenney
17 Sep, 2014
4 commits
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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
Signed-off-by: Paul E. McKenney -
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
Signed-off-by: Paul E. McKenney -
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
Signed-off-by: Paul E. McKenney -
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
[ paulmck: Apply Randy Dunlap review comments. ]
Signed-off-by: Paul E. McKenney
13 Aug, 2014
2 commits
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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
Acked-by: Jason Low
Signed-off-by: Peter Zijlstra
Cc: aswin@hp.com
Cc: Linus Torvalds
Cc: Randy Dunlap
Link: http://lkml.kernel.org/r/1406752916-3341-7-git-send-email-davidlohr@hp.com
Signed-off-by: Ingo Molnar -
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.txtSigned-off-by: Davidlohr Bueso
Acked-by: Randy Dunlap
Signed-off-by: Peter Zijlstra
Cc: jason.low2@hp.com
Cc: aswin@hp.com
Cc: Alexei Starovoitov
Cc: Al Viro
Cc: Andrew Morton
Cc: Chris Mason
Cc: Dan Streetman
Cc: David Airlie
Cc: Davidlohr Bueso
Cc: David S. Miller
Cc: Greg Kroah-Hartman
Cc: Heiko Carstens
Cc: Jason Low
Cc: Josef Bacik
Cc: Kees Cook
Cc: Linus Torvalds
Cc: Lubomir Rintel
Cc: Masanari Iida
Cc: Paul E. McKenney
Cc: Randy Dunlap
Cc: Tim Chen
Cc: Vineet Gupta
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
