[PATCH v8 4/8] mm: Provide a new count_objcg_events() API for batch event updates.

From: Kanchana P Sridhar
Date: Fri Sep 27 2024 - 22:16:59 EST


With the introduction of zswap_store() swapping out large folios,
we need to efficiently update the objcg's memcg events once per
successfully stored folio. For instance, the 'ZSWPOUT' event needs
to be incremented by folio_nr_pages().

Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@xxxxxxxxx>
---
include/linux/memcontrol.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 15c2716f9aa3..f47fd00c5eea 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1778,6 +1778,21 @@ static inline void count_objcg_event(struct obj_cgroup *objcg,
rcu_read_unlock();
}

+static inline void count_objcg_events(struct obj_cgroup *objcg,
+ enum vm_event_item idx,
+ unsigned long count)
+{
+ struct mem_cgroup *memcg;
+
+ if (!memcg_kmem_online())
+ return;
+
+ rcu_read_lock();
+ memcg = obj_cgroup_memcg(objcg);
+ count_memcg_events(memcg, idx, count);
+ rcu_read_unlock();
+}
+
#else
static inline bool mem_cgroup_kmem_disabled(void)
{
@@ -1834,6 +1849,11 @@ static inline void count_objcg_event(struct obj_cgroup *objcg,
{
}

+static inline void count_objcg_events(struct obj_cgroup *objcg,
+ enum vm_event_item idx,
+ unsigned long count)
+{
+}
#endif /* CONFIG_MEMCG */

#if defined(CONFIG_MEMCG) && defined(CONFIG_ZSWAP)
--
2.27.0