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| author | Peter Zijlstra <peterz@infradead.org> | 2019-02-21 17:38:40 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-02-28 09:55:37 +0300 |
| commit | 02e525b2aff1d665f6466e1d123ee4cb69f1d4b0 (patch) | |
| tree | b8ab5cc7bcbe93bcb04a844a4e2352bd62d4679d /include/linux/percpu-rwsem.h | |
| parent | 0614621d89c43ea5b28456c2baf6b0c0e00ca81e (diff) | |
| download | linux-02e525b2aff1d665f6466e1d123ee4cb69f1d4b0.tar.xz | |
locking/percpu-rwsem: Remove preempt_disable variants
Effective revert commit:
87709e28dc7c ("fs/locks: Use percpu_down_read_preempt_disable()")
This is causing major pain for PREEMPT_RT.
Sebastian did a lot of lockperf runs on 2 and 4 node machines with all
preemption modes (PREEMPT=n should be an obvious NOP for this patch
and thus serves as a good control) and no results showed significance
over 2-sigma (the PREEMPT=n results were almost empty at 1-sigma).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
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>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/percpu-rwsem.h')
| -rw-r--r-- | include/linux/percpu-rwsem.h | 24 |
1 files changed, 4 insertions, 20 deletions
diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h index 71b75643c432..03cb4b6f842e 100644 --- a/include/linux/percpu-rwsem.h +++ b/include/linux/percpu-rwsem.h @@ -29,7 +29,7 @@ static struct percpu_rw_semaphore name = { \ extern int __percpu_down_read(struct percpu_rw_semaphore *, int); extern void __percpu_up_read(struct percpu_rw_semaphore *); -static inline void percpu_down_read_preempt_disable(struct percpu_rw_semaphore *sem) +static inline void percpu_down_read(struct percpu_rw_semaphore *sem) { might_sleep(); @@ -47,16 +47,10 @@ static inline void percpu_down_read_preempt_disable(struct percpu_rw_semaphore * __this_cpu_inc(*sem->read_count); if (unlikely(!rcu_sync_is_idle(&sem->rss))) __percpu_down_read(sem, false); /* Unconditional memory barrier */ - barrier(); /* - * The barrier() prevents the compiler from + * The preempt_enable() prevents the compiler from * bleeding the critical section out. */ -} - -static inline void percpu_down_read(struct percpu_rw_semaphore *sem) -{ - percpu_down_read_preempt_disable(sem); preempt_enable(); } @@ -83,13 +77,9 @@ static inline int percpu_down_read_trylock(struct percpu_rw_semaphore *sem) return ret; } -static inline void percpu_up_read_preempt_enable(struct percpu_rw_semaphore *sem) +static inline void percpu_up_read(struct percpu_rw_semaphore *sem) { - /* - * The barrier() prevents the compiler from - * bleeding the critical section out. - */ - barrier(); + preempt_disable(); /* * Same as in percpu_down_read(). */ @@ -102,12 +92,6 @@ static inline void percpu_up_read_preempt_enable(struct percpu_rw_semaphore *sem rwsem_release(&sem->rw_sem.dep_map, 1, _RET_IP_); } -static inline void percpu_up_read(struct percpu_rw_semaphore *sem) -{ - preempt_disable(); - percpu_up_read_preempt_enable(sem); -} - extern void percpu_down_write(struct percpu_rw_semaphore *); extern void percpu_up_write(struct percpu_rw_semaphore *); |