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Commit 4b05a1c7 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Linus Torvalds
Browse files

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: default avatarMikulas Patocka <mpatocka@redhat.com>
Reported-and-tested-by: default avatarJeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e23739b4

include/linux/percpu-rwsem.h

+2 −2
Original line number Diff line number Diff line
@@ -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 */