[PATCH v4 2/3] mm, memcg: inline mem_cgroup_{charge/uncharge} to improve disabled memcg config

Suren Baghdasaryan
2021-07-13T01:09:45Z

Inline mem_cgroup_{charge/uncharge} and mem_cgroup_uncharge_list functions
functions to perform mem_cgroup_disabled static key check inline before
calling the main body of the function. This minimizes the memcg overhead
in the pagefault and exit_mmap paths when memcgs are disabled using
cgroup_disable=memory command-line option.
This change results in ~0.4% overhead reduction when running PFT test [1]
comparing {CONFIG_MEMCG=n} against {CONFIG_MEMCG=y, cgroup_disable=memory}
configuration on an 8-core ARM64 Android device.

[1] https://lkml.org/lkml/2006/8/29/294 also used in mmtests suite

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
---
include/linux/memcontrol.h | 28 +++++++++++++++++++++++++---
mm/memcontrol.c | 33 ++++++++++++---------------------
2 files changed, 37 insertions(+), 24 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index bfe5c486f4ad..39fa88051a42 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -693,13 +693,35 @@ static inline bool mem_cgroup_below_min(struct mem_cgroup *memcg)
page_counter_read(&memcg->memory);
}

-int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask);
+int __mem_cgroup_charge(struct page *page, struct mm_struct *mm,
+ gfp_t gfp_mask);
+static inline int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
+ gfp_t gfp_mask)
+{
+ if (mem_cgroup_disabled())
+ return 0;
+ return __mem_cgroup_charge(page, mm, gfp_mask);
+}
+
int mem_cgroup_swapin_charge_page(struct page *page, struct mm_struct *mm,
gfp_t gfp, swp_entry_t entry);
void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry);

-void mem_cgroup_uncharge(struct page *page);
-void mem_cgroup_uncharge_list(struct list_head *page_list);
+void __mem_cgroup_uncharge(struct page *page);
+static inline void mem_cgroup_uncharge(struct page *page)
+{
+ if (mem_cgroup_disabled())
+ return;
+ __mem_cgroup_uncharge(page);
+}
+
+void __mem_cgroup_uncharge_list(struct list_head *page_list);
+static inline void mem_cgroup_uncharge_list(struct list_head *page_list)
+{
+ if (mem_cgroup_disabled())
+ return;
+ __mem_cgroup_uncharge_list(page_list);
+}

void mem_cgroup_migrate(struct page *oldpage, struct page *newpage);

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a228cd51c4bd..6adf50acdbe2 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6701,8 +6701,7 @@ void mem_cgroup_calculate_protection(struct mem_cgroup *root,
atomic_long_read(&parent->memory.children_low_usage)));
}

-static int __mem_cgroup_charge(struct page *page, struct mem_cgroup *memcg,
- gfp_t gfp)
+static int charge_memcg(struct page *page, struct mem_cgroup *memcg, gfp_t gfp)
{
unsigned int nr_pages = thp_nr_pages(page);
int ret;
@@ -6723,7 +6722,7 @@ static int __mem_cgroup_charge(struct page *page, struct mem_cgroup *memcg,
}

/**
- * mem_cgroup_charge - charge a newly allocated page to a cgroup
+ * __mem_cgroup_charge - charge a newly allocated page to a cgroup
* @page: page to charge
* @mm: mm context of the victim
* @gfp_mask: reclaim mode
@@ -6736,16 +6735,14 @@ static int __mem_cgroup_charge(struct page *page, struct mem_cgroup *memcg,
*
* Returns 0 on success. Otherwise, an error code is returned.
*/
-int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask)
+int __mem_cgroup_charge(struct page *page, struct mm_struct *mm,
+ gfp_t gfp_mask)
{
struct mem_cgroup *memcg;
int ret;

- if (mem_cgroup_disabled())
- return 0;
-
memcg = get_mem_cgroup_from_mm(mm);
- ret = __mem_cgroup_charge(page, memcg, gfp_mask);
+ ret = charge_memcg(page, memcg, gfp_mask);
css_put(&memcg->css);

return ret;
@@ -6780,7 +6777,7 @@ int mem_cgroup_swapin_charge_page(struct page *page, struct mm_struct *mm,
memcg = get_mem_cgroup_from_mm(mm);
rcu_read_unlock();

- ret = __mem_cgroup_charge(page, memcg, gfp);
+ ret = charge_memcg(page, memcg, gfp);

css_put(&memcg->css);
return ret;
@@ -6916,18 +6913,15 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug)
}

/**
- * mem_cgroup_uncharge - uncharge a page
+ * __mem_cgroup_uncharge - uncharge a page
* @page: page to uncharge
*
- * Uncharge a page previously charged with mem_cgroup_charge().
+ * Uncharge a page previously charged with __mem_cgroup_charge().
*/
-void mem_cgroup_uncharge(struct page *page)
+void __mem_cgroup_uncharge(struct page *page)
{
struct uncharge_gather ug;

- if (mem_cgroup_disabled())
- return;
-
/* Don't touch page->lru of any random page, pre-check: */
if (!page_memcg(page))
return;
@@ -6938,20 +6932,17 @@ void mem_cgroup_uncharge(struct page *page)
}

/**
- * mem_cgroup_uncharge_list - uncharge a list of page
+ * __mem_cgroup_uncharge_list - uncharge a list of page
* @page_list: list of pages to uncharge
*
* Uncharge a list of pages previously charged with
- * mem_cgroup_charge().
+ * __mem_cgroup_charge().
*/
-void mem_cgroup_uncharge_list(struct list_head *page_list)
+void __mem_cgroup_uncharge_list(struct list_head *page_list)
{
struct uncharge_gather ug;
struct page *page;

- if (mem_cgroup_disabled())
- return;
-
uncharge_gather_clear(&ug);
list_for_each_entry(page, page_list, lru)
uncharge_page(page, &ug);
--
2.32.0.93.g670b81a890-goog