---

yaml
---
r: 252041
b: refs/heads/master
c: 889976d
h: refs/heads/master
i:
  252039: 9116d87
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 4e4c941c108eff10844d2b441d96dab44f32f424
+refs/heads/master: 889976dbcb1218119fdd950fb7819084e37d7d37

trunk/include/linux/memcontrol.h

@@ -106,6 +106,7 @@ extern void mem_cgroup_end_migration(struct mem_cgroup *mem,
  */
 int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg);
 int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg);
+int mem_cgroup_select_victim_node(struct mem_cgroup *memcg);
 unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
 				       struct zone *zone,
 				       enum lru_list lru);

trunk/mm/memcontrol.c

@@ -231,6 +231,11 @@ struct mem_cgroup {
 	 * reclaimed from.
 	 */
 	int last_scanned_child;
+	int last_scanned_node;
+#if MAX_NUMNODES > 1
+	nodemask_t	scan_nodes;
+	unsigned long   next_scan_node_update;
+#endif
 	/*
 	 * Should the accounting and control be hierarchical, per subtree?
 	 */
@@ -624,18 +629,27 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
 	preempt_enable();
 }
 
+static unsigned long
+mem_cgroup_get_zonestat_node(struct mem_cgroup *mem, int nid, enum lru_list idx)
+{
+	struct mem_cgroup_per_zone *mz;
+	u64 total = 0;
+	int zid;
+
+	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+		mz = mem_cgroup_zoneinfo(mem, nid, zid);
+		total += MEM_CGROUP_ZSTAT(mz, idx);
+	}
+	return total;
+}
 static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem,
 					enum lru_list idx)
 {
-	int nid, zid;
-	struct mem_cgroup_per_zone *mz;
+	int nid;
 	u64 total = 0;
 
 	for_each_online_node(nid)
-		for (zid = 0; zid < MAX_NR_ZONES; zid++) {
-			mz = mem_cgroup_zoneinfo(mem, nid, zid);
-			total += MEM_CGROUP_ZSTAT(mz, idx);
-		}
+		total += mem_cgroup_get_zonestat_node(mem, nid, idx);
 	return total;
 }
 
@@ -1418,6 +1432,81 @@ mem_cgroup_select_victim(struct mem_cgroup *root_mem)
 	return ret;
 }
 
+#if MAX_NUMNODES > 1
+
+/*
+ * Always updating the nodemask is not very good - even if we have an empty
+ * list or the wrong list here, we can start from some node and traverse all
+ * nodes based on the zonelist. So update the list loosely once per 10 secs.
+ *
+ */
+static void mem_cgroup_may_update_nodemask(struct mem_cgroup *mem)
+{
+	int nid;
+
+	if (time_after(mem->next_scan_node_update, jiffies))
+		return;
+
+	mem->next_scan_node_update = jiffies + 10*HZ;
+	/* make a nodemask where this memcg uses memory from */
+	mem->scan_nodes = node_states[N_HIGH_MEMORY];
+
+	for_each_node_mask(nid, node_states[N_HIGH_MEMORY]) {
+
+		if (mem_cgroup_get_zonestat_node(mem, nid, LRU_INACTIVE_FILE) ||
+		    mem_cgroup_get_zonestat_node(mem, nid, LRU_ACTIVE_FILE))
+			continue;
+
+		if (total_swap_pages &&
+		    (mem_cgroup_get_zonestat_node(mem, nid, LRU_INACTIVE_ANON) ||
+		     mem_cgroup_get_zonestat_node(mem, nid, LRU_ACTIVE_ANON)))
+			continue;
+		node_clear(nid, mem->scan_nodes);
+	}
+}
+
+/*
+ * Selecting a node where we start reclaim from. Because what we need is just
+ * reducing usage counter, start from anywhere is O,K. Considering
+ * memory reclaim from current node, there are pros. and cons.
+ *
+ * Freeing memory from current node means freeing memory from a node which
+ * we'll use or we've used. So, it may make LRU bad. And if several threads
+ * hit limits, it will see a contention on a node. But freeing from remote
+ * node means more costs for memory reclaim because of memory latency.
+ *
+ * Now, we use round-robin. Better algorithm is welcomed.
+ */
+int mem_cgroup_select_victim_node(struct mem_cgroup *mem)
+{
+	int node;
+
+	mem_cgroup_may_update_nodemask(mem);
+	node = mem->last_scanned_node;
+
+	node = next_node(node, mem->scan_nodes);
+	if (node == MAX_NUMNODES)
+		node = first_node(mem->scan_nodes);
+	/*
+	 * We call this when we hit limit, not when pages are added to LRU.
+	 * No LRU may hold pages because all pages are UNEVICTABLE or
+	 * memcg is too small and all pages are not on LRU. In that case,
+	 * we use curret node.
+	 */
+	if (unlikely(node == MAX_NUMNODES))
+		node = numa_node_id();
+
+	mem->last_scanned_node = node;
+	return node;
+}
+
+#else
+int mem_cgroup_select_victim_node(struct mem_cgroup *mem)
+{
+	return 0;
+}
+#endif
+
 /*
  * Scan the hierarchy if needed to reclaim memory. We remember the last child
  * we reclaimed from, so that we don't end up penalizing one child extensively
@@ -4606,6 +4695,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 		res_counter_init(&mem->memsw, NULL);
 	}
 	mem->last_scanned_child = 0;
+	mem->last_scanned_node = MAX_NUMNODES;
 	INIT_LIST_HEAD(&mem->oom_notify);
 
 	if (parent)

trunk/mm/vmscan.c

@@ -2226,6 +2226,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
 {
 	struct zonelist *zonelist;
 	unsigned long nr_reclaimed;
+	int nid;
 	struct scan_control sc = {
 		.may_writepage = !laptop_mode,
 		.may_unmap = 1,
@@ -2242,7 +2243,14 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
 		.gfp_mask = sc.gfp_mask,
 	};
 
-	zonelist = NODE_DATA(numa_node_id())->node_zonelists;
+	/*
+	 * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't
+	 * take care of from where we get pages. So the node where we start the
+	 * scan does not need to be the current node.
+	 */
+	nid = mem_cgroup_select_victim_node(mem_cont);
+
+	zonelist = NODE_DATA(nid)->node_zonelists;
 
 	trace_mm_vmscan_memcg_reclaim_begin(0,
 					    sc.may_writepage,