Thread (20 messages) 20 messages, 5 authors, 2021-07-18

Re: [External] [PATCH v3 2/3] mm, memcg: inline mem_cgroup_{charge/uncharge} to improve disabled memcg config

From: Muchun Song <hidden>
Date: 2021-07-10 11:08:59
Also in: cgroups, lkml

On Sat, Jul 10, 2021 at 8:36 AM Suren Baghdasaryan [off-list ref] wrote:
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 <surenb@google.com>
Reviewed-by: Shakeel Butt <redacted>
Reviewed-by: Muchun Song <redacted>

But some nits below.
quoted hunk ↗ jump to hunk
---
 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().
The comment here also needs to be updated.

mem_cgroup_uncharge() -> __mem_cgroup_uncharge()
quoted hunk ↗ jump to hunk
  */
-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().
Should be __mem_cgroup_charge().

Thanks.
  */
-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
  
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