On Mon, Jul 12, 2021 at 12:15 AM Michal Hocko [off-list ref] wrote:

On Fri 09-07-21 17:36:25, Suren Baghdasaryan wrote:

quoted

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
comparing {CONFIG_MEMCG=n} against {CONFIG_MEMCG=y, cgroup_disable=memory}
configurationon on an 8-core ARM64 Android device.

Signed-off-by: Suren Baghdasaryan <redacted>
Reviewed-by: Shakeel Butt <redacted>

With doc updated as suggested by Muchun Song
Acked-by: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>

Thanks! Will fix the comment and post v4 later today.

Thanks!

quoted

---
 include/linux/memcontrol.h | 28 +++++++++++++++++++++++++---
 mm/memcontrol.c            | 29 ++++++++++-------------------
 2 files changed, 35 insertions(+), 22 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..cdaf7003b43d 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().
  */
-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().
  */
-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

--
Michal Hocko
SUSE Labs