linux-toradex.git/kernel/locking/Makefile, branch v3.17-rc6

locking/rwlocks: Introduce 'qrwlocks' - fair, queued rwlocks

2014-06-06T05:58:28+00:00

This rwlock uses the arch_spin_lock_t as a waitqueue, and assuming the
arch_spin_lock_t is a fair lock (ticket,mcs etc..) the resulting
rwlock is a fair lock.

It fits in the same 8 bytes as the regular rwlock_t by folding the
reader and writer count into a single integer, using the remaining 4
bytes for the arch_spinlock_t.

Architectures that can single-copy adress bytes can optimize
queue_write_unlock() with a 0 write to the LSB (the write count).

Performance as measured by Davidlohr Bueso (rwlock_t -> qrwlock_t):

 +--------------+-------------+---------------+
 |   Workload   |   #users    |     delta     |
 +--------------+-------------+---------------+
 | alltests     | > 1400      | -4.83%        |
 | custom       | 0-100,> 100 | +1.43%,-1.57% |
 | high_systime | > 1000      | -2.61         |
 | shared       | all         | +0.32         |
 +--------------+-------------+---------------+

http://www.stgolabs.net/qrwlock-stuff/aim7-results-vs-rwsem_optsin/

Signed-off-by: Waiman Long 
[peterz: near complete rewrite]
Signed-off-by: Peter Zijlstra 
Cc: Arnd Bergmann 
Cc: Linus Torvalds 
Cc: "Paul E.McKenney" 
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-gac1nnl3wvs2ij87zv2xkdzq@git.kernel.org
Signed-off-by: Ingo Molnar

lglock: map to spinlock when !CONFIG_SMP

2014-04-07T23:36:14+00:00

When the system has only one CPU, lglock is effectively a spinlock; map
it directly to spinlock to eliminate the indirection and duplicate code.

In addition to removing overhead, this drops 1.6k of code with a
defconfig modified to have !CONFIG_SMP, and 1.1k with a minimal config.

Signed-off-by: Josh Triplett 
Cc: Rusty Russell 
Cc: Michal Marek 
Cc: Thomas Gleixner 
Cc: David Howells 
Cc: "H. Peter Anvin" 
Cc: Nick Piggin 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2014-03-31T18:05:24+00:00

Pull RCU updates from Ingo Molnar:
 "Main changes:

   - Torture-test changes, including refactoring of rcutorture and
     introduction of a vestigial locktorture.

   - Real-time latency fixes.

   - Documentation updates.

   - Miscellaneous fixes"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits)
  rcu: Provide grace-period piggybacking API
  rcu: Ensure kernel/rcu/rcu.h can be sourced/used stand-alone
  rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.c
  notifier: Substitute rcu_access_pointer() for rcu_dereference_raw()
  Documentation/memory-barriers.txt: Clarify release/acquire ordering
  rcutorture: Save kvm.sh output to log
  rcutorture: Add a lock_busted to test the test
  rcutorture: Place kvm-test-1-run.sh output into res directory
  rcutorture: Rename TREE_RCU-Kconfig.txt
  locktorture: Add kvm-recheck.sh plug-in for locktorture
  rcutorture: Gracefully handle NULL cleanup hooks
  locktorture: Add vestigial locktorture configuration
  rcutorture: Introduce "rcu" directory level underneath configs
  rcutorture: Rename kvm-test-1-rcu.sh
  rcutorture: Remove RCU dependencies from ver_functions.sh API
  rcutorture: Create CFcommon file for common Kconfig parameters
  rcutorture: Create config files for scripted test-the-test testing
  rcutorture: Add an rcu_busted to test the test
  locktorture: Add a lock-torture kernel module
  rcutorture: Abstract kvm-recheck.sh
  ...

locking/mutexes: Introduce cancelable MCS lock for adaptive spinning

2014-03-11T11:14:56+00:00

Since we want a task waiting for a mutex_lock() to go to sleep and
reschedule on need_resched() we must be able to abort the
mcs_spin_lock() around the adaptive spin.

Therefore implement a cancelable mcs lock.

Signed-off-by: Peter Zijlstra 
Cc: chegu_vinod@hp.com
Cc: paulmck@linux.vnet.ibm.com
Cc: Waiman.Long@hp.com
Cc: torvalds@linux-foundation.org
Cc: tglx@linutronix.de
Cc: riel@redhat.com
Cc: akpm@linux-foundation.org
Cc: davidlohr@hp.com
Cc: hpa@zytor.com
Cc: andi@firstfloor.org
Cc: aswin@hp.com
Cc: scott.norton@hp.com
Cc: Jason Low 
Link: http://lkml.kernel.org/n/tip-62hcl5wxydmjzd182zhvk89m@git.kernel.org
Signed-off-by: Ingo Molnar

locktorture: Add a lock-torture kernel module

2014-02-23T17:04:29+00:00

This commit adds the locking counterpart to rcutorture.

Signed-off-by: Paul E. McKenney 
[ paulmck: Make n_lock_torture_errors and torture_spinlock static
  as suggested by Fengguang Wu. ]
Reviewed-by: Josh Triplett

locking: Move the percpu-rwsem code to kernel/locking/

2013-11-06T08:24:22+00:00

Suggested-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-52bjmtty46we26hbfd9sc9iy@git.kernel.org
Signed-off-by: Ingo Molnar

locking: Move the lglocks code to kernel/locking/

2013-11-06T08:24:20+00:00

Suggested-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-amd6pg1mif6tikbyktfvby3y@git.kernel.org
Signed-off-by: Ingo Molnar

locking: Move the rwsem code to kernel/locking/

2013-11-06T08:24:18+00:00

Notably: changed lib/rwsem* targets from lib- to obj-, no idea about
the ramifications of that.

Suggested-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-g0kynfh5feriwc6p3h6kpbw6@git.kernel.org
Signed-off-by: Ingo Molnar

locking: Move the rtmutex code to kernel/locking/

2013-11-06T08:23:59+00:00

Suggested-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-p9ijt8div0hwldexwfm4nlhj@git.kernel.org
[ Fixed build failure in kernel/rcu/tree_plugin.h. ]
Signed-off-by: Ingo Molnar

locking: Move the semaphore core to kernel/locking/

2013-11-06T06:55:22+00:00

Suggested-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-vmw5sf6vzmua1z6nx1cg69h2@git.kernel.org
Signed-off-by: Ingo Molnar