Commit 4bda556a authored by Shaohua Li's avatar Shaohua Li Committed by NeilBrown
Browse files

raid5: relieve lock contention in get_active_stripe() 



track empty inactive list count, so md_raid5_congested() can use it to make
decision.

Signed-off-by: default avatarShaohua Li <shli@fusionio.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 566c09c5

drivers/md/raid5.c

+7 −1
Original line number Diff line number Diff line
@@ -356,6 +356,9 @@ static void release_inactive_stripe_list(struct r5conf *conf, 
		 */

		if (!list_empty_careful(list)) {

			spin_lock_irqsave(conf->hash_locks + hash, flags);

			if (list_empty(conf->inactive_list + hash) &&

			    !list_empty(list))

				atomic_dec(&conf->empty_inactive_list_nr);

			list_splice_tail_init(list, conf->inactive_list + hash);

			do_wakeup = true;

			spin_unlock_irqrestore(conf->hash_locks + hash, flags);
@@ -477,6 +480,8 @@ static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash) 
	remove_hash(sh);

	atomic_inc(&conf->active_stripes);

	BUG_ON(hash != sh->hash_lock_index);

	if (list_empty(conf->inactive_list + hash))

		atomic_inc(&conf->empty_inactive_list_nr);

out:

	return sh;

}
@@ -4059,7 +4064,7 @@ int md_raid5_congested(struct mddev *mddev, int bits) 
		return 1;

	if (conf->quiesce)

		return 1;

	if (atomic_read(&conf->active_stripes) == conf->max_nr_stripes)

	if (atomic_read(&conf->empty_inactive_list_nr))

		return 1;



	return 0;
@@ -5750,6 +5755,7 @@ static struct r5conf *setup_conf(struct mddev *mddev) 


	memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +

		 max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;

	atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);

	if (grow_stripes(conf, NR_STRIPES)) {

		printk(KERN_ERR

		       "md/raid:%s: couldn't allocate %dkB for buffers\n",

drivers/md/raid5.h

+1 −0
Original line number Diff line number Diff line
@@ -475,6 +475,7 @@ struct r5conf { 
	 */

	atomic_t		active_stripes;

	struct list_head	inactive_list[NR_STRIPE_HASH_LOCKS];

	atomic_t		empty_inactive_list_nr;

	struct llist_head	released_stripes;

	wait_queue_head_t	wait_for_stripe;

	wait_queue_head_t	wait_for_overlap;