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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: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
Shaohua Li 2013-11-14 15:16:17 +11:00 committed by NeilBrown
parent 566c09c534
commit 4bda556aea
2 changed files with 8 additions and 1 deletions
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8
drivers/md/raid5.c
View File

@ -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",

1
drivers/md/raid5.h
View File

@ -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;