If tcache is empty we can bail out immediately from tcache_cleancache_[get_page, invalidate_page,invalidate_inode](). As a fast way of identifying empty tcache this patch adds global atomic counter of tcache nodes.
https://jira.sw.ru/browse/PSBM-56475 Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> --- mm/tcache.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/mm/tcache.c b/mm/tcache.c index cec5a4e..00e15d6 100644 --- a/mm/tcache.c +++ b/mm/tcache.c @@ -98,6 +98,8 @@ struct tcache_pool { struct tcache_pool_nodeinfo nodeinfo[0]; }; +static atomic_t nr_tcache_nodes; + /* * Tcache nodes correspond to inodes. A node is created automatically when a * new page is added to the cache (cleancache_put_page) and destroyed either @@ -561,6 +563,7 @@ retry: node->pool = pool; node->key = *key; atomic_long_inc(&pool->nr_nodes); + atomic_inc(&nr_tcache_nodes); __tcache_insert_node(&tree->root, node, rb_link, rb_parent); } spin_unlock_irqrestore(&tree->lock, flags); @@ -590,6 +593,7 @@ static void tcache_node_release_fn(struct kref *kref) __tcache_delete_node(&tree->root, node); spin_unlock(&tree->lock); + atomic_dec(&nr_tcache_nodes); atomic_long_dec(&node->pool->nr_nodes); kfree(node); } @@ -1168,6 +1172,9 @@ static int tcache_cleancache_get_page(int pool_id, struct tcache_node *node; struct page *cache_page = NULL; + if (!atomic_read(&nr_tcache_nodes)) + return -1; + node = tcache_get_node_and_pool(pool_id, &key, false); if (node) { cache_page = tcache_detach_page(node, index, true); @@ -1192,6 +1199,9 @@ static void tcache_cleancache_invalidate_page(int pool_id, struct tcache_node *node; struct page *page; + if (!atomic_read(&nr_tcache_nodes)) + return; + node = tcache_get_node_and_pool(pool_id, &key, false); if (node) { page = tcache_detach_page(node, index, false); @@ -1206,6 +1216,9 @@ static void tcache_cleancache_invalidate_inode(int pool_id, { struct tcache_pool *pool; + if (!atomic_read(&nr_tcache_nodes)) + return; + pool = tcache_get_pool(pool_id); if (pool) { tcache_invalidate_node(pool, &key); -- 2.7.3 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel