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percpu-rwsem: use synchronize_sched_expedited 

Use synchronize_sched_expedited() instead of synchronize_sched()
to improve mount speed.

This patch improves mount time from 0.500s to 0.013s for Jeff's
test-case.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-and-tested-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mikulas Patocka 2012-11-27 22:59:52 -05:00 committed by Linus Torvalds
parent e23739b4ad
commit 4b05a1c74d
1 changed files with 2 additions and 2 deletions
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4
include/linux/percpu-rwsem.h
View File

@ -13,7 +13,7 @@ struct percpu_rw_semaphore {
};
#define light_mb() barrier()
#define heavy_mb() synchronize_sched()
#define heavy_mb() synchronize_sched_expedited()
static inline void percpu_down_read(struct percpu_rw_semaphore *p)
{
@ -51,7 +51,7 @@ static inline void percpu_down_write(struct percpu_rw_semaphore *p)
{
mutex_lock(&p->mtx);
p->locked = true;
synchronize_sched(); /* make sure that all readers exit the rcu_read_lock_sched region */
synchronize_sched_expedited(); /* make sure that all readers exit the rcu_read_lock_sched region */
while (__percpu_count(p->counters))
msleep(1);
heavy_mb(); /* C, between read of p->counter and write to data, paired with B */