Commit 6b706e56 authored by Zqiang's avatar Zqiang Committed by Paul E. McKenney
Browse files

rcu/kvfree: Make drain_page_cache() take early return if cache is disabled 



If the rcutree.rcu_min_cached_objs kernel boot parameter is set to zero,
then krcp->page_cache_work will never be triggered to fill page cache.
In addition, the put_cached_bnode() will not fill page cache.  As a
result krcp->bkvcache will always be empty, so there is no need to acquire
krcp->lock to get page from krcp->bkvcache.  This commit therefore makes
drain_page_cache() return immediately if the rcu_min_cached_objs is zero.

Signed-off-by: default avatarZqiang <qiang1.zhang@intel.com>
Reviewed-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 60888b77

kernel/rcu/tree.c

+3 −0
Original line number Diff line number Diff line
@@ -2902,6 +2902,9 @@ drain_page_cache(struct kfree_rcu_cpu *krcp) 
	struct llist_node *page_list, *pos, *n;

	int freed = 0;



	if (!rcu_min_cached_objs)

		return 0;



	raw_spin_lock_irqsave(&krcp->lock, flags);

	page_list = llist_del_all(&krcp->bkvcache);

	WRITE_ONCE(krcp->nr_bkv_objs, 0);