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>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 93090b2..1fb28c5 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -356,6 +356,9 @@
*/
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 @@
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 @@
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 @@
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",