diff mbox series

[v2,1/5] mm: memcontrol: introduce obj_cgroup_{un}charge_page

Message ID 20210303055917.66054-2-songmuchun@bytedance.com (mailing list archive)
State New
Headers show
Series Use obj_cgroup APIs to charge kmem pages | expand

Commit Message

Muchun Song March 3, 2021, 5:59 a.m. UTC
We know that the unit of slab object charging is bytes, the unit of
kmem page charging is PAGE_SIZE. If we want to reuse obj_cgroup APIs
to charge the kmem pages, we should pass PAGE_SIZE (as third parameter)
to obj_cgroup_charge(). Because the size is already PAGE_SIZE, we can
skip touch the objcg stock. And obj_cgroup_{un}charge_page() are
introduced to charge in units of page level.

In the later patch, we also can reuse those two helpers to charge or
uncharge a number of kernel pages to a object cgroup. This is just
a code movement without any functional changes.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 mm/memcontrol.c | 46 +++++++++++++++++++++++++++++++---------------
 1 file changed, 31 insertions(+), 15 deletions(-)

Comments

Roman Gushchin March 5, 2021, 6:56 p.m. UTC | #1
On Wed, Mar 03, 2021 at 01:59:13PM +0800, Muchun Song wrote:
> We know that the unit of slab object charging is bytes, the unit of
> kmem page charging is PAGE_SIZE. If we want to reuse obj_cgroup APIs
> to charge the kmem pages, we should pass PAGE_SIZE (as third parameter)
> to obj_cgroup_charge(). Because the size is already PAGE_SIZE, we can
> skip touch the objcg stock. And obj_cgroup_{un}charge_page() are
> introduced to charge in units of page level.
> 
> In the later patch, we also can reuse those two helpers to charge or
> uncharge a number of kernel pages to a object cgroup. This is just
> a code movement without any functional changes.
> 
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>

This patch looks good to me, even as a standalone refactoring.
Please, rename obj_cgroup_charge_page() to obj_cgroup_charge_pages()
and the same with uncharge. It's because _page suffix usually means
we're dealing with a physical page (e.g. struct page * as an argument),
here it's not the case.

Please, add my Acked-by: Roman Gushchin <guro@fb.com>
after the renaming.

Thank you!

> ---
>  mm/memcontrol.c | 46 +++++++++++++++++++++++++++++++---------------
>  1 file changed, 31 insertions(+), 15 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 845eec01ef9d..faae16def127 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3056,6 +3056,34 @@ static void memcg_free_cache_id(int id)
>  	ida_simple_remove(&memcg_cache_ida, id);
>  }
>  
> +static inline void obj_cgroup_uncharge_page(struct obj_cgroup *objcg,
> +					    unsigned int nr_pages)
> +{
> +	rcu_read_lock();
> +	__memcg_kmem_uncharge(obj_cgroup_memcg(objcg), nr_pages);
> +	rcu_read_unlock();
> +}
> +
> +static int obj_cgroup_charge_page(struct obj_cgroup *objcg, gfp_t gfp,
> +				  unsigned int nr_pages)
> +{
> +	struct mem_cgroup *memcg;
> +	int ret;
> +
> +	rcu_read_lock();
> +retry:
> +	memcg = obj_cgroup_memcg(objcg);
> +	if (unlikely(!css_tryget(&memcg->css)))
> +		goto retry;
> +	rcu_read_unlock();
> +
> +	ret = __memcg_kmem_charge(memcg, gfp, nr_pages);
> +
> +	css_put(&memcg->css);
> +
> +	return ret;
> +}
> +
>  /**
>   * __memcg_kmem_charge: charge a number of kernel pages to a memcg
>   * @memcg: memory cgroup to charge
> @@ -3180,11 +3208,8 @@ static void drain_obj_stock(struct memcg_stock_pcp *stock)
>  		unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT;
>  		unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1);
>  
> -		if (nr_pages) {
> -			rcu_read_lock();
> -			__memcg_kmem_uncharge(obj_cgroup_memcg(old), nr_pages);
> -			rcu_read_unlock();
> -		}
> +		if (nr_pages)
> +			obj_cgroup_uncharge_page(old, nr_pages);
>  
>  		/*
>  		 * The leftover is flushed to the centralized per-memcg value.
> @@ -3242,7 +3267,6 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes)
>  
>  int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
>  {
> -	struct mem_cgroup *memcg;
>  	unsigned int nr_pages, nr_bytes;
>  	int ret;
>  
> @@ -3259,24 +3283,16 @@ int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
>  	 * refill_obj_stock(), called from this function or
>  	 * independently later.
>  	 */
> -	rcu_read_lock();
> -retry:
> -	memcg = obj_cgroup_memcg(objcg);
> -	if (unlikely(!css_tryget(&memcg->css)))
> -		goto retry;
> -	rcu_read_unlock();
> -
>  	nr_pages = size >> PAGE_SHIFT;
>  	nr_bytes = size & (PAGE_SIZE - 1);
>  
>  	if (nr_bytes)
>  		nr_pages += 1;
>  
> -	ret = __memcg_kmem_charge(memcg, gfp, nr_pages);
> +	ret = obj_cgroup_charge_page(objcg, gfp, nr_pages);
>  	if (!ret && nr_bytes)
>  		refill_obj_stock(objcg, PAGE_SIZE - nr_bytes);
>  
> -	css_put(&memcg->css);
>  	return ret;
>  }
>  
> -- 
> 2.11.0
>
Muchun Song March 6, 2021, 5:26 a.m. UTC | #2
On Sat, Mar 6, 2021 at 2:56 AM Roman Gushchin <guro@fb.com> wrote:
>
> On Wed, Mar 03, 2021 at 01:59:13PM +0800, Muchun Song wrote:
> > We know that the unit of slab object charging is bytes, the unit of
> > kmem page charging is PAGE_SIZE. If we want to reuse obj_cgroup APIs
> > to charge the kmem pages, we should pass PAGE_SIZE (as third parameter)
> > to obj_cgroup_charge(). Because the size is already PAGE_SIZE, we can
> > skip touch the objcg stock. And obj_cgroup_{un}charge_page() are
> > introduced to charge in units of page level.
> >
> > In the later patch, we also can reuse those two helpers to charge or
> > uncharge a number of kernel pages to a object cgroup. This is just
> > a code movement without any functional changes.
> >
> > Signed-off-by: Muchun Song <songmuchun@bytedance.com>
>
> This patch looks good to me, even as a standalone refactoring.
> Please, rename obj_cgroup_charge_page() to obj_cgroup_charge_pages()
> and the same with uncharge. It's because _page suffix usually means
> we're dealing with a physical page (e.g. struct page * as an argument),
> here it's not the case.

Make sense.

>
> Please, add my Acked-by: Roman Gushchin <guro@fb.com>
> after the renaming.

Will do. Thanks for your review.

>
> Thank you!
>
> > ---
> >  mm/memcontrol.c | 46 +++++++++++++++++++++++++++++++---------------
> >  1 file changed, 31 insertions(+), 15 deletions(-)
> >
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 845eec01ef9d..faae16def127 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -3056,6 +3056,34 @@ static void memcg_free_cache_id(int id)
> >       ida_simple_remove(&memcg_cache_ida, id);
> >  }
> >
> > +static inline void obj_cgroup_uncharge_page(struct obj_cgroup *objcg,
> > +                                         unsigned int nr_pages)
> > +{
> > +     rcu_read_lock();
> > +     __memcg_kmem_uncharge(obj_cgroup_memcg(objcg), nr_pages);
> > +     rcu_read_unlock();
> > +}
> > +
> > +static int obj_cgroup_charge_page(struct obj_cgroup *objcg, gfp_t gfp,
> > +                               unsigned int nr_pages)
> > +{
> > +     struct mem_cgroup *memcg;
> > +     int ret;
> > +
> > +     rcu_read_lock();
> > +retry:
> > +     memcg = obj_cgroup_memcg(objcg);
> > +     if (unlikely(!css_tryget(&memcg->css)))
> > +             goto retry;
> > +     rcu_read_unlock();
> > +
> > +     ret = __memcg_kmem_charge(memcg, gfp, nr_pages);
> > +
> > +     css_put(&memcg->css);
> > +
> > +     return ret;
> > +}
> > +
> >  /**
> >   * __memcg_kmem_charge: charge a number of kernel pages to a memcg
> >   * @memcg: memory cgroup to charge
> > @@ -3180,11 +3208,8 @@ static void drain_obj_stock(struct memcg_stock_pcp *stock)
> >               unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT;
> >               unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1);
> >
> > -             if (nr_pages) {
> > -                     rcu_read_lock();
> > -                     __memcg_kmem_uncharge(obj_cgroup_memcg(old), nr_pages);
> > -                     rcu_read_unlock();
> > -             }
> > +             if (nr_pages)
> > +                     obj_cgroup_uncharge_page(old, nr_pages);
> >
> >               /*
> >                * The leftover is flushed to the centralized per-memcg value.
> > @@ -3242,7 +3267,6 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes)
> >
> >  int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
> >  {
> > -     struct mem_cgroup *memcg;
> >       unsigned int nr_pages, nr_bytes;
> >       int ret;
> >
> > @@ -3259,24 +3283,16 @@ int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
> >        * refill_obj_stock(), called from this function or
> >        * independently later.
> >        */
> > -     rcu_read_lock();
> > -retry:
> > -     memcg = obj_cgroup_memcg(objcg);
> > -     if (unlikely(!css_tryget(&memcg->css)))
> > -             goto retry;
> > -     rcu_read_unlock();
> > -
> >       nr_pages = size >> PAGE_SHIFT;
> >       nr_bytes = size & (PAGE_SIZE - 1);
> >
> >       if (nr_bytes)
> >               nr_pages += 1;
> >
> > -     ret = __memcg_kmem_charge(memcg, gfp, nr_pages);
> > +     ret = obj_cgroup_charge_page(objcg, gfp, nr_pages);
> >       if (!ret && nr_bytes)
> >               refill_obj_stock(objcg, PAGE_SIZE - nr_bytes);
> >
> > -     css_put(&memcg->css);
> >       return ret;
> >  }
> >
> > --
> > 2.11.0
> >
diff mbox series

Patch

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 845eec01ef9d..faae16def127 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3056,6 +3056,34 @@  static void memcg_free_cache_id(int id)
 	ida_simple_remove(&memcg_cache_ida, id);
 }
 
+static inline void obj_cgroup_uncharge_page(struct obj_cgroup *objcg,
+					    unsigned int nr_pages)
+{
+	rcu_read_lock();
+	__memcg_kmem_uncharge(obj_cgroup_memcg(objcg), nr_pages);
+	rcu_read_unlock();
+}
+
+static int obj_cgroup_charge_page(struct obj_cgroup *objcg, gfp_t gfp,
+				  unsigned int nr_pages)
+{
+	struct mem_cgroup *memcg;
+	int ret;
+
+	rcu_read_lock();
+retry:
+	memcg = obj_cgroup_memcg(objcg);
+	if (unlikely(!css_tryget(&memcg->css)))
+		goto retry;
+	rcu_read_unlock();
+
+	ret = __memcg_kmem_charge(memcg, gfp, nr_pages);
+
+	css_put(&memcg->css);
+
+	return ret;
+}
+
 /**
  * __memcg_kmem_charge: charge a number of kernel pages to a memcg
  * @memcg: memory cgroup to charge
@@ -3180,11 +3208,8 @@  static void drain_obj_stock(struct memcg_stock_pcp *stock)
 		unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT;
 		unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1);
 
-		if (nr_pages) {
-			rcu_read_lock();
-			__memcg_kmem_uncharge(obj_cgroup_memcg(old), nr_pages);
-			rcu_read_unlock();
-		}
+		if (nr_pages)
+			obj_cgroup_uncharge_page(old, nr_pages);
 
 		/*
 		 * The leftover is flushed to the centralized per-memcg value.
@@ -3242,7 +3267,6 @@  static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes)
 
 int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
 {
-	struct mem_cgroup *memcg;
 	unsigned int nr_pages, nr_bytes;
 	int ret;
 
@@ -3259,24 +3283,16 @@  int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
 	 * refill_obj_stock(), called from this function or
 	 * independently later.
 	 */
-	rcu_read_lock();
-retry:
-	memcg = obj_cgroup_memcg(objcg);
-	if (unlikely(!css_tryget(&memcg->css)))
-		goto retry;
-	rcu_read_unlock();
-
 	nr_pages = size >> PAGE_SHIFT;
 	nr_bytes = size & (PAGE_SIZE - 1);
 
 	if (nr_bytes)
 		nr_pages += 1;
 
-	ret = __memcg_kmem_charge(memcg, gfp, nr_pages);
+	ret = obj_cgroup_charge_page(objcg, gfp, nr_pages);
 	if (!ret && nr_bytes)
 		refill_obj_stock(objcg, PAGE_SIZE - nr_bytes);
 
-	css_put(&memcg->css);
 	return ret;
 }