mem_cgroup_threshold_ary->current_threshold points to the last entry
who's threshold is less or equal to usage.
Instead of iterating entries to get the correct index, we can leverage
primary->current_threshold to get it. If the threshold added is less or
equal to usage, current_threshold should increase by one. Otherwise, it
doesn't change.
Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
---
mm/memcontrol.c | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a504616f904a..ce7060907df2 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4161,7 +4161,7 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
struct mem_cgroup_threshold_ary *new;
unsigned long threshold;
unsigned long usage;
- int i, size, ret;
+ int size, ret;
ret = page_counter_memparse(args, "-1", &threshold);
if (ret)
@@ -4193,9 +4193,13 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
new->size = size;
/* Copy thresholds (if any) to new array */
- if (thresholds->primary)
+ if (thresholds->primary) {
memcpy(new->entries, thresholds->primary->entries,
flex_array_size(new, entries, size - 1));
+ new->current_threshold = thresholds->primary->current_threshold;
+ } else {
+ new->current_threshold = -1;
+ }
/* Add new threshold */
new->entries[size - 1].eventfd = eventfd;
@@ -4205,18 +4209,17 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
sort(new->entries, size, sizeof(*new->entries),
compare_thresholds, NULL);
- /* Find current threshold */
- new->current_threshold = -1;
- for (i = 0; i < size; i++) {
- if (new->entries[i].threshold <= usage) {
- /*
- * new->current_threshold will not be used until
- * rcu_assign_pointer(), so it's safe to increment
- * it here.
- */
- ++new->current_threshold;
- } else
- break;
+ /*
+ * If the threshold added here is less or equal to usage, this means
+ * current_threshold need to increase by one.
+ */
+ if (threshold <= usage) {
+ /*
+ * new->current_threshold will not be used until
+ * rcu_assign_pointer(), so it's safe to increment
+ * it here.
+ */
+ new->current_threshold++;
}
/* Free old spare buffer and save old primary buffer as spare */
--
2.33.1
