diff options
| author | Waiman Long | 2013-04-17 15:23:11 -0400 |
|---|---|---|
| committer | Ingo Molnar | 2013-04-19 09:33:34 +0200 |
| commit | 41fcb9f230bf773656d1768b73000ef720bf00c3 (patch) | |
| tree | dd87697f88e28825668ed4c342824929b4d7070c /kernel/sched | |
| parent | 8184004ed7a0bc9538f5e825615c29fc52466bab (diff) | |
mutex: Move mutex spinning code from sched/core.c back to mutex.c
As mentioned by Ingo, the SCHED_FEAT_OWNER_SPIN scheduler
feature bit was really just an early hack to make with/without
mutex-spinning testable. So it is no longer necessary.
This patch removes the SCHED_FEAT_OWNER_SPIN feature bit and
move the mutex spinning code from kernel/sched/core.c back to
kernel/mutex.c which is where they should belong.
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Chandramouleeswaran Aswin <aswin@hp.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Norton Scott J <scott.norton@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1366226594-5506-2-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/core.c | 45 | ||||
| -rw-r--r-- | kernel/sched/features.h | 7 |
2 files changed, 0 insertions, 52 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7f12624a393c..b37a22b99e0e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2997,51 +2997,6 @@ void __sched schedule_preempt_disabled(void) preempt_disable(); } -#ifdef CONFIG_MUTEX_SPIN_ON_OWNER - -static inline bool owner_running(struct mutex *lock, struct task_struct *owner) -{ - if (lock->owner != owner) - return false; - - /* - * Ensure we emit the owner->on_cpu, dereference _after_ checking - * lock->owner still matches owner, if that fails, owner might - * point to free()d memory, if it still matches, the rcu_read_lock() - * ensures the memory stays valid. - */ - barrier(); - - return owner->on_cpu; -} - -/* - * Look out! "owner" is an entirely speculative pointer - * access and not reliable. - */ -int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner) -{ - if (!sched_feat(OWNER_SPIN)) - return 0; - - rcu_read_lock(); - while (owner_running(lock, owner)) { - if (need_resched()) - break; - - arch_mutex_cpu_relax(); - } - rcu_read_unlock(); - - /* - * We break out the loop above on need_resched() and when the - * owner changed, which is a sign for heavy contention. Return - * success only when lock->owner is NULL. - */ - return lock->owner == NULL; -} -#endif - #ifdef CONFIG_PREEMPT /* * this is the entry point to schedule() from in-kernel preemption diff --git a/kernel/sched/features.h b/kernel/sched/features.h index 1ad1d2b5395f..99399f8e4799 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -46,13 +46,6 @@ SCHED_FEAT(DOUBLE_TICK, false) SCHED_FEAT(LB_BIAS, true) /* - * Spin-wait on mutex acquisition when the mutex owner is running on - * another cpu -- assumes that when the owner is running, it will soon - * release the lock. Decreases scheduling overhead. - */ -SCHED_FEAT(OWNER_SPIN, true) - -/* * Decrement CPU power based on time not spent running tasks */ SCHED_FEAT(NONTASK_POWER, true) |