[RFC][PATCH 5/6] fix inactive_ratio under hierarchy

From: KAMEZAWA Hiroyuki
Date: Tue Dec 09 2008 - 06:11:30 EST



From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>

After lru updates for memcg, followint test easily see OOM.
and memory-reclaim speed was very bad.

mkdir /opt/cgroup/xxx
echo 1 > /opt/cgroup/xxx/memory.use_hierarchy
mkdir /opt/cgroup/xxx/01
mkdir /opt/cgroup/xxx/02
echo 40M > /opt/cgroup/xxx/memory.limit_in_bytes

Run task under group 01 or 02.

This is because calclation of inactive_ratio doesn't handle hierarchy.
In above, 01 and 02's inactive_ratio = 65535 and inactive list will be
empty.

This patch tries to set 01 and 02 's inactive ration to appropriate value
under hierarchy. inactive_ratio is adjusted to the minimum limit found in
upwards in hierarchy.


ex)In following tree,
/opt/cgroup/01 limit=1G
/opt/cgroup/01/A limit=500M
/opt/cgroup/01/A/B limit=unlimited
/opt/cgroup/01/A/C limit=50M
/opt/cgroup/01/Z limit=700M


/opt/cgroup/01's inactive_ratio is calculated by limit of 1G.
/opt/cgroup/01/A's inactive_ratio is calculated by limit of 500M
/opt/cgroup/01/A/B's inactive_ratio is calculated by limit of 500M.
/opt/cgroup/01/A/C's inactive_ratio is calculated by limit of 50M.
/opt/cgroup/01's inactive_ratio is calculated by limit of 700M.


Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxx>

mm/memcontrol.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 64 insertions(+), 7 deletions(-)

---
Index: mmotm-2.6.28-Dec08/mm/memcontrol.c
===================================================================
--- mmotm-2.6.28-Dec08.orig/mm/memcontrol.c
+++ mmotm-2.6.28-Dec08/mm/memcontrol.c
@@ -1382,20 +1382,73 @@ int mem_cgroup_shrink_usage(struct mm_st
* page_alloc.c::setup_per_zone_inactive_ratio().
* it describe more detail.
*/
-static void mem_cgroup_set_inactive_ratio(struct mem_cgroup *memcg)
+static int __mem_cgroup_inactive_ratio(unsigned long long gb)
{
- unsigned int gb, ratio;
+ unsigned int ratio;

- gb = res_counter_read_u64(&memcg->res, RES_LIMIT) >> 30;
+ gb = gb >> 30;
if (gb)
ratio = int_sqrt(10 * gb);
else
ratio = 1;

- memcg->inactive_ratio = ratio;
+ return ratio;
+}
+
+
+static void mem_cgroup_update_inactive_ratio(struct mem_cgroup *memcg)
+{
+ struct cgroup *cur;
+ struct mem_cgroup *root_memcg, *tmp;
+ unsigned long long min_limit, limit;
+ int depth, nextid, rootid, found, ratio;
+
+ if (!memcg->use_hierarchy) {
+ limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
+ memcg->inactive_ratio = __mem_cgroup_inactive_ratio(limit);
+ return;
+ }

+ cur = memcg->css.cgroup;
+ min_limit = res_counter_read_u64(&tmp->res, RES_LIMIT);
+
+ /* go up to root cgroup and find min limit.*/
+ while (cur->parent != NULL) {
+ tmp = mem_cgroup_from_cont(cur);
+ if (!tmp->use_hierarchy)
+ break;
+ limit = res_counter_read_u64(&tmp->res, RES_LIMIT);
+ if (limit < min_limit)
+ limit = min_limit;
+ cur = cur->parent;
+ }
+ /* new inactive ratio for this hierarchy */
+ ratio = __mem_cgroup_inactive_ratio(min_limit);
+
+ /*
+ * update inactive ratio under this.
+ * all children's inactive_ratio will be updated.
+ */
+ cur = memcg->css.cgroup;
+ rootid = cgroup_id(cur);
+ depth = cgroup_depth(cur);
+ nextid = 0;
+ rcu_read_lock();
+ while (1) {
+ cur = cgroup_get_next(nextid, rootid, depth, &found);
+ if (!cur)
+ break;
+ if (!cgroup_is_removed(cur)) {
+ tmp = mem_cgroup_from_cont(cur);
+ tmp->inactive_ratio = ratio;
+ }
+ nextid = found + 1;
+ }
+ rcu_read_unlock();
}

+
+
static DEFINE_MUTEX(set_limit_mutex);

static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
@@ -1435,8 +1488,11 @@ static int mem_cgroup_resize_limit(struc
if (!progress) retry_count--;
}

- if (!ret)
- mem_cgroup_set_inactive_ratio(memcg);
+ if (!ret) {
+ mutex_lock(&set_limit_mutex);
+ mem_cgroup_update_inactive_ratio(memcg);
+ mutex_unlock(&set_limit_mutex);
+ }

return ret;
}
@@ -2081,11 +2137,12 @@ mem_cgroup_create(struct cgroup_subsys *
if (parent && parent->use_hierarchy) {
res_counter_init(&mem->res, &parent->res);
res_counter_init(&mem->memsw, &parent->memsw);
+ /* min_limit under hierarchy is unchanged.*/
+ mem->inactive_ratio = parent->inactive_ratio;
} else {
res_counter_init(&mem->res, NULL);
res_counter_init(&mem->memsw, NULL);
}
- mem_cgroup_set_inactive_ratio(mem);
mem->last_scanned_child = 0;
mem->scan_age = 0;
spin_lock_init(&mem->reclaim_param_lock);

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