memcg: use CSS ID
Assigning CSS ID for each memcg and use css_get_next() for scanning hierarchy.
Assume folloing tree.
group_A (ID=3)
/01 (ID=4)
/0A (ID=7)
/02 (ID=10)
group_B (ID=5)
and task in group_A/01/0A hits limit at group_A.
reclaim will be done in following order (round-robin).
group_A(3) -> group_A/01 (4) -> group_A/01/0A (7) -> group_A/02(10)
-> group_A -> .....
Round robin by ID. The last visited cgroup is recorded and restart
from it when it start reclaim again.
(More smart algorithm can be implemented..)
No cgroup_mutex or hierarchy_mutex is required.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8ffec67..61fd959 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -95,6 +95,15 @@
return ret;
}
+static s64 mem_cgroup_local_usage(struct mem_cgroup_stat *stat)
+{
+ s64 ret;
+
+ ret = mem_cgroup_read_stat(stat, MEM_CGROUP_STAT_CACHE);
+ ret += mem_cgroup_read_stat(stat, MEM_CGROUP_STAT_RSS);
+ return ret;
+}
+
/*
* per-zone information in memory controller.
*/
@@ -154,9 +163,9 @@
/*
* While reclaiming in a hiearchy, we cache the last child we
- * reclaimed from. Protected by hierarchy_mutex
+ * reclaimed from.
*/
- struct mem_cgroup *last_scanned_child;
+ int last_scanned_child;
/*
* Should the accounting and control be hierarchical, per subtree?
*/
@@ -629,103 +638,6 @@
#define mem_cgroup_from_res_counter(counter, member) \
container_of(counter, struct mem_cgroup, member)
-/*
- * This routine finds the DFS walk successor. This routine should be
- * called with hierarchy_mutex held
- */
-static struct mem_cgroup *
-__mem_cgroup_get_next_node(struct mem_cgroup *curr, struct mem_cgroup *root_mem)
-{
- struct cgroup *cgroup, *curr_cgroup, *root_cgroup;
-
- curr_cgroup = curr->css.cgroup;
- root_cgroup = root_mem->css.cgroup;
-
- if (!list_empty(&curr_cgroup->children)) {
- /*
- * Walk down to children
- */
- cgroup = list_entry(curr_cgroup->children.next,
- struct cgroup, sibling);
- curr = mem_cgroup_from_cont(cgroup);
- goto done;
- }
-
-visit_parent:
- if (curr_cgroup == root_cgroup) {
- /* caller handles NULL case */
- curr = NULL;
- goto done;
- }
-
- /*
- * Goto next sibling
- */
- if (curr_cgroup->sibling.next != &curr_cgroup->parent->children) {
- cgroup = list_entry(curr_cgroup->sibling.next, struct cgroup,
- sibling);
- curr = mem_cgroup_from_cont(cgroup);
- goto done;
- }
-
- /*
- * Go up to next parent and next parent's sibling if need be
- */
- curr_cgroup = curr_cgroup->parent;
- goto visit_parent;
-
-done:
- return curr;
-}
-
-/*
- * Visit the first child (need not be the first child as per the ordering
- * of the cgroup list, since we track last_scanned_child) of @mem and use
- * that to reclaim free pages from.
- */
-static struct mem_cgroup *
-mem_cgroup_get_next_node(struct mem_cgroup *root_mem)
-{
- struct cgroup *cgroup;
- struct mem_cgroup *orig, *next;
- bool obsolete;
-
- /*
- * Scan all children under the mem_cgroup mem
- */
- mutex_lock(&mem_cgroup_subsys.hierarchy_mutex);
-
- orig = root_mem->last_scanned_child;
- obsolete = mem_cgroup_is_obsolete(orig);
-
- if (list_empty(&root_mem->css.cgroup->children)) {
- /*
- * root_mem might have children before and last_scanned_child
- * may point to one of them. We put it later.
- */
- if (orig)
- VM_BUG_ON(!obsolete);
- next = NULL;
- goto done;
- }
-
- if (!orig || obsolete) {
- cgroup = list_first_entry(&root_mem->css.cgroup->children,
- struct cgroup, sibling);
- next = mem_cgroup_from_cont(cgroup);
- } else
- next = __mem_cgroup_get_next_node(orig, root_mem);
-
-done:
- if (next)
- mem_cgroup_get(next);
- root_mem->last_scanned_child = next;
- if (orig)
- mem_cgroup_put(orig);
- mutex_unlock(&mem_cgroup_subsys.hierarchy_mutex);
- return (next) ? next : root_mem;
-}
-
static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
{
if (do_swap_account) {
@@ -755,46 +667,79 @@
}
/*
- * Dance down 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 based on its position in the children list.
+ * Visit the first child (need not be the first child as per the ordering
+ * of the cgroup list, since we track last_scanned_child) of @mem and use
+ * that to reclaim free pages from.
+ */
+static struct mem_cgroup *
+mem_cgroup_select_victim(struct mem_cgroup *root_mem)
+{
+ struct mem_cgroup *ret = NULL;
+ struct cgroup_subsys_state *css;
+ int nextid, found;
+
+ if (!root_mem->use_hierarchy) {
+ css_get(&root_mem->css);
+ ret = root_mem;
+ }
+
+ while (!ret) {
+ rcu_read_lock();
+ nextid = root_mem->last_scanned_child + 1;
+ css = css_get_next(&mem_cgroup_subsys, nextid, &root_mem->css,
+ &found);
+ if (css && css_tryget(css))
+ ret = container_of(css, struct mem_cgroup, css);
+
+ rcu_read_unlock();
+ /* Updates scanning parameter */
+ spin_lock(&root_mem->reclaim_param_lock);
+ if (!css) {
+ /* this means start scan from ID:1 */
+ root_mem->last_scanned_child = 0;
+ } else
+ root_mem->last_scanned_child = found;
+ spin_unlock(&root_mem->reclaim_param_lock);
+ }
+
+ return ret;
+}
+
+/*
+ * 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
+ * based on its position in the children list.
*
* root_mem is the original ancestor that we've been reclaim from.
+ *
+ * We give up and return to the caller when we visit root_mem twice.
+ * (other groups can be removed while we're walking....)
*/
static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
gfp_t gfp_mask, bool noswap)
{
- struct mem_cgroup *next_mem;
- int ret = 0;
+ struct mem_cgroup *victim;
+ int ret, total = 0;
+ int loop = 0;
- /*
- * Reclaim unconditionally and don't check for return value.
- * We need to reclaim in the current group and down the tree.
- * One might think about checking for children before reclaiming,
- * but there might be left over accounting, even after children
- * have left.
- */
- ret += try_to_free_mem_cgroup_pages(root_mem, gfp_mask, noswap,
- get_swappiness(root_mem));
- if (mem_cgroup_check_under_limit(root_mem))
- return 1; /* indicate reclaim has succeeded */
- if (!root_mem->use_hierarchy)
- return ret;
-
- next_mem = mem_cgroup_get_next_node(root_mem);
-
- while (next_mem != root_mem) {
- if (mem_cgroup_is_obsolete(next_mem)) {
- next_mem = mem_cgroup_get_next_node(root_mem);
+ while (loop < 2) {
+ victim = mem_cgroup_select_victim(root_mem);
+ if (victim == root_mem)
+ loop++;
+ if (!mem_cgroup_local_usage(&victim->stat)) {
+ /* this cgroup's local usage == 0 */
+ css_put(&victim->css);
continue;
}
- ret += try_to_free_mem_cgroup_pages(next_mem, gfp_mask, noswap,
- get_swappiness(next_mem));
+ /* we use swappiness of local cgroup */
+ ret = try_to_free_mem_cgroup_pages(victim, gfp_mask, noswap,
+ get_swappiness(victim));
+ css_put(&victim->css);
+ total += ret;
if (mem_cgroup_check_under_limit(root_mem))
- return 1; /* indicate reclaim has succeeded */
- next_mem = mem_cgroup_get_next_node(root_mem);
+ return 1 + total;
}
- return ret;
+ return total;
}
bool mem_cgroup_oom_called(struct task_struct *task)
@@ -1324,8 +1269,8 @@
res_counter_uncharge(&mem->res, PAGE_SIZE);
if (do_swap_account && (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT))
res_counter_uncharge(&mem->memsw, PAGE_SIZE);
-
mem_cgroup_charge_statistics(mem, pc, false);
+
ClearPageCgroupUsed(pc);
/*
* pc->mem_cgroup is not cleared here. It will be accessed when it's
@@ -2178,6 +2123,8 @@
{
int node;
+ free_css_id(&mem_cgroup_subsys, &mem->css);
+
for_each_node_state(node, N_POSSIBLE)
free_mem_cgroup_per_zone_info(mem, node);
@@ -2228,11 +2175,12 @@
mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
{
struct mem_cgroup *mem, *parent;
+ long error = -ENOMEM;
int node;
mem = mem_cgroup_alloc();
if (!mem)
- return ERR_PTR(-ENOMEM);
+ return ERR_PTR(error);
for_each_node_state(node, N_POSSIBLE)
if (alloc_mem_cgroup_per_zone_info(mem, node))
@@ -2260,7 +2208,7 @@
res_counter_init(&mem->res, NULL);
res_counter_init(&mem->memsw, NULL);
}
- mem->last_scanned_child = NULL;
+ mem->last_scanned_child = 0;
spin_lock_init(&mem->reclaim_param_lock);
if (parent)
@@ -2269,7 +2217,7 @@
return &mem->css;
free_out:
__mem_cgroup_free(mem);
- return ERR_PTR(-ENOMEM);
+ return ERR_PTR(error);
}
static int mem_cgroup_pre_destroy(struct cgroup_subsys *ss,
@@ -2284,12 +2232,7 @@
struct cgroup *cont)
{
struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
- struct mem_cgroup *last_scanned_child = mem->last_scanned_child;
- if (last_scanned_child) {
- VM_BUG_ON(!mem_cgroup_is_obsolete(last_scanned_child));
- mem_cgroup_put(last_scanned_child);
- }
mem_cgroup_put(mem);
}
@@ -2328,6 +2271,7 @@
.populate = mem_cgroup_populate,
.attach = mem_cgroup_move_task,
.early_init = 0,
+ .use_id = 1,
};
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
