The patch titled
Subject: mm/list_lru: don't pass unnecessary key parameters
has been added to the -mm mm-unstable branch. Its filename is
mm-list_lru-dont-pass-unnecessary-key-parameters.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-list_lru-dont-pass-unnecessary-key-parameters.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kairui Song <kasong@xxxxxxxxxxx>
Subject: mm/list_lru: don't pass unnecessary key parameters
Date: Thu, 26 Sep 2024 01:10:15 +0800
Patch series "Split list_lru lock into per-cgroup scope", v2.
Currently, every list_lru has a per-node lock that protects adding,
deletion, isolation, and reparenting of all list_lru_one instances
belonging to this list_lru on this node. This lock contention is heavy
when multiple cgroups modify the same list_lru.
This can be alleviated by splitting the lock into per-cgroup scope.
To achieve this, this series reworked and optimized the reparenting
process step by step, making it possible to have a stable list_lru_one,
and making it possible to pin the list_lru_one. Then split the lock into
per-cgroup scope.
The result is ~15% performance gain for simple multi-cgroup tar test of
small files, and reduced LOC. See PATCH 5/6 for test details.
This patch (of 6):
When LOCKDEP is not enabled, lock_class_key is an empty struct that is
never used. But the list_lru initialization function still takes a
placeholder pointer as parameter, and the compiler cannot optimize it
because the function is not static and exported.
Remove this parameter and move it inside the list_lru struct. Only use it
when LOCKDEP is enabled. Kernel builds with LOCKDEP will be slightly
larger, while !LOCKDEP builds without it will be slightly smaller (the
common case).
Link: https://lkml.kernel.org/r/20240925171020.32142-1-ryncsn@xxxxxxxxx
Link: https://lkml.kernel.org/r/20240925171020.32142-2-ryncsn@xxxxxxxxx
Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
Cc: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Cc: Waiman Long <longman@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/list_lru.h | 18 +++++++++++++++---
mm/list_lru.c | 9 +++++----
mm/workingset.c | 4 ++--
3 files changed, 22 insertions(+), 9 deletions(-)
--- a/include/linux/list_lru.h~mm-list_lru-dont-pass-unnecessary-key-parameters
+++ a/include/linux/list_lru.h
@@ -56,16 +56,28 @@ struct list_lru {
bool memcg_aware;
struct xarray xa;
#endif
+#ifdef CONFIG_LOCKDEP
+ struct lock_class_key *key;
+#endif
};
void list_lru_destroy(struct list_lru *lru);
int __list_lru_init(struct list_lru *lru, bool memcg_aware,
- struct lock_class_key *key, struct shrinker *shrinker);
+ struct shrinker *shrinker);
#define list_lru_init(lru) \
- __list_lru_init((lru), false, NULL, NULL)
+ __list_lru_init((lru), false, NULL)
#define list_lru_init_memcg(lru, shrinker) \
- __list_lru_init((lru), true, NULL, shrinker)
+ __list_lru_init((lru), true, shrinker)
+
+static inline int list_lru_init_memcg_key(struct list_lru *lru, struct shrinker *shrinker,
+ struct lock_class_key *key)
+{
+#ifdef CONFIG_LOCKDEP
+ lru->key = key;
+#endif
+ return list_lru_init_memcg(lru, shrinker);
+}
int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru,
gfp_t gfp);
--- a/mm/list_lru.c~mm-list_lru-dont-pass-unnecessary-key-parameters
+++ a/mm/list_lru.c
@@ -562,8 +562,7 @@ static void memcg_destroy_list_lru(struc
}
#endif /* CONFIG_MEMCG */
-int __list_lru_init(struct list_lru *lru, bool memcg_aware,
- struct lock_class_key *key, struct shrinker *shrinker)
+int __list_lru_init(struct list_lru *lru, bool memcg_aware, struct shrinker *shrinker)
{
int i;
@@ -583,8 +582,10 @@ int __list_lru_init(struct list_lru *lru
for_each_node(i) {
spin_lock_init(&lru->node[i].lock);
- if (key)
- lockdep_set_class(&lru->node[i].lock, key);
+#ifdef CONFIG_LOCKDEP
+ if (lru->key)
+ lockdep_set_class(&lru->node[i].lock, lru->key);
+#endif
init_one_lru(&lru->node[i].lru);
}
--- a/mm/workingset.c~mm-list_lru-dont-pass-unnecessary-key-parameters
+++ a/mm/workingset.c
@@ -823,8 +823,8 @@ static int __init workingset_init(void)
if (!workingset_shadow_shrinker)
goto err;
- ret = __list_lru_init(&shadow_nodes, true, &shadow_nodes_key,
- workingset_shadow_shrinker);
+ ret = list_lru_init_memcg_key(&shadow_nodes, workingset_shadow_shrinker,
+ &shadow_nodes_key);
if (ret)
goto err_list_lru;
_
Patches currently in -mm which might be from kasong@xxxxxxxxxxx are
mm-list_lru-dont-pass-unnecessary-key-parameters.patch
mm-list_lru-dont-export-list_lru_add.patch
mm-list_lru-code-clean-up-for-reparenting.patch
mm-list_lru-simplify-reparenting-and-initial-allocation.patch
mm-list_lru-split-the-lock-to-per-cgroup-scope.patch
mm-list_lru-simplify-the-list_lru-walk-callback-function.patch
