diff options
| -rw-r--r-- | mm/workingset.c | 44 |
1 files changed, 25 insertions, 19 deletions
diff --git a/mm/workingset.c b/mm/workingset.c index ef556bf1323d..241fa5d6b3b2 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -369,40 +369,46 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker, { unsigned long max_nodes; unsigned long nodes; - unsigned long pages; + unsigned long cache; /* list_lru lock nests inside IRQ-safe mapping->tree_lock */ local_irq_disable(); nodes = list_lru_shrink_count(&shadow_nodes, sc); local_irq_enable(); - if (sc->memcg) { - pages = mem_cgroup_node_nr_lru_pages(sc->memcg, sc->nid, - LRU_ALL_FILE); - } else { - pages = node_page_state(NODE_DATA(sc->nid), NR_ACTIVE_FILE) + - node_page_state(NODE_DATA(sc->nid), NR_INACTIVE_FILE); - } - /* - * Active cache pages are limited to 50% of memory, and shadow - * entries that represent a refault distance bigger than that - * do not have any effect. Limit the number of shadow nodes - * such that shadow entries do not exceed the number of active - * cache pages, assuming a worst-case node population density - * of 1/8th on average. + * Approximate a reasonable limit for the radix tree nodes + * containing shadow entries. We don't need to keep more + * shadow entries than possible pages on the active list, + * since refault distances bigger than that are dismissed. + * + * The size of the active list converges toward 100% of + * overall page cache as memory grows, with only a tiny + * inactive list. Assume the total cache size for that. + * + * Nodes might be sparsely populated, with only one shadow + * entry in the extreme case. Obviously, we cannot keep one + * node for every eligible shadow entry, so compromise on a + * worst-case density of 1/8th. Below that, not all eligible + * refaults can be detected anymore. * * On 64-bit with 7 radix_tree_nodes per page and 64 slots * each, this will reclaim shadow entries when they consume - * ~2% of available memory: + * ~1.8% of available memory: * - * PAGE_SIZE / radix_tree_nodes / node_entries / PAGE_SIZE + * PAGE_SIZE / radix_tree_nodes / node_entries * 8 / PAGE_SIZE */ - max_nodes = pages >> (1 + RADIX_TREE_MAP_SHIFT - 3); + if (sc->memcg) { + cache = mem_cgroup_node_nr_lru_pages(sc->memcg, sc->nid, + LRU_ALL_FILE); + } else { + cache = node_page_state(NODE_DATA(sc->nid), NR_ACTIVE_FILE) + + node_page_state(NODE_DATA(sc->nid), NR_INACTIVE_FILE); + } + max_nodes = cache >> (RADIX_TREE_MAP_SHIFT - 3); if (nodes <= max_nodes) return 0; - return nodes - max_nodes; } |