Re: [PATCH v3 07/21] mm: add lruvec->pages_count

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Thu, 23 Feb 2012 17:52:08 +0400
Konstantin Khlebnikov <khlebnikov@openvz.org> wrote:

> Move lru pages counter from mem_cgroup_per_zone->count[] to lruvec->pages_count[]
> 
> Account pages in all lruvecs, incuding root,
> this isn't a huge overhead, but it greatly simplifies all code.
> 
> Redundant page_lruvec() calls will be optimized in further patches.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>

Hmm, I like this but..a question below.

> ---
>  include/linux/memcontrol.h |   29 --------------
>  include/linux/mm_inline.h  |   15 +++++--
>  include/linux/mmzone.h     |    1 
>  mm/memcontrol.c            |   93 +-------------------------------------------
>  mm/swap.c                  |    7 +--
>  mm/vmscan.c                |   25 +++++++++---
>  6 files changed, 34 insertions(+), 136 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 4822d53..b9d555b 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -63,12 +63,6 @@ extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
>  					gfp_t gfp_mask);
>  
>  struct lruvec *mem_cgroup_zone_lruvec(struct zone *, struct mem_cgroup *);
> -struct lruvec *mem_cgroup_lru_add_list(struct zone *, struct page *,
> -				       enum lru_list);
> -void mem_cgroup_lru_del_list(struct page *, enum lru_list);
> -void mem_cgroup_lru_del(struct page *);
> -struct lruvec *mem_cgroup_lru_move_lists(struct zone *, struct page *,
> -					 enum lru_list, enum lru_list);
>  
>  /* For coalescing uncharge for reducing memcg' overhead*/
>  extern void mem_cgroup_uncharge_start(void);
> @@ -212,29 +206,6 @@ static inline struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
>  	return &zone->lruvec;
>  }
>  
> -static inline struct lruvec *mem_cgroup_lru_add_list(struct zone *zone,
> -						     struct page *page,
> -						     enum lru_list lru)
> -{
> -	return &zone->lruvec;
> -}
> -
> -static inline void mem_cgroup_lru_del_list(struct page *page, enum lru_list lru)
> -{
> -}
> -
> -static inline void mem_cgroup_lru_del(struct page *page)
> -{
> -}
> -
> -static inline struct lruvec *mem_cgroup_lru_move_lists(struct zone *zone,
> -						       struct page *page,
> -						       enum lru_list from,
> -						       enum lru_list to)
> -{
> -	return &zone->lruvec;
> -}
> -
>  static inline struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
>  {
>  	return NULL;
> diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
> index 8415596..daa3d15 100644
> --- a/include/linux/mm_inline.h
> +++ b/include/linux/mm_inline.h
> @@ -24,19 +24,24 @@ static inline int page_is_file_cache(struct page *page)
>  static inline void
>  add_page_to_lru_list(struct zone *zone, struct page *page, enum lru_list lru)
>  {
> -	struct lruvec *lruvec;
> +	struct lruvec *lruvec = page_lruvec(page);
> +	int numpages = hpage_nr_pages(page);
>  
> -	lruvec = mem_cgroup_lru_add_list(zone, page, lru);
>  	list_add(&page->lru, &lruvec->pages_lru[lru]);
> -	__mod_zone_page_state(zone, NR_LRU_BASE + lru, hpage_nr_pages(page));
> +	lruvec->pages_count[lru] += numpages;
> +	__mod_zone_page_state(zone, NR_LRU_BASE + lru, numpages);
>  }
>  
>  static inline void
>  del_page_from_lru_list(struct zone *zone, struct page *page, enum lru_list lru)
>  {
> -	mem_cgroup_lru_del_list(page, lru);
> +	struct lruvec *lruvec = page_lruvec(page);
> +	int numpages = hpage_nr_pages(page);
> +
>  	list_del(&page->lru);
> -	__mod_zone_page_state(zone, NR_LRU_BASE + lru, -hpage_nr_pages(page));
> +	lruvec->pages_count[lru] -= numpages;
> +	VM_BUG_ON((long)lruvec->pages_count[lru] < 0);
> +	__mod_zone_page_state(zone, NR_LRU_BASE + lru, -numpages);
>  }
>  
>  /**
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index be8873a..69b0f31 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -298,6 +298,7 @@ struct zone_reclaim_stat {
>  
>  struct lruvec {
>  	struct list_head	pages_lru[NR_LRU_LISTS];
> +	unsigned long		pages_count[NR_LRU_LISTS];

In this time, you don't put the objects under #ifdef...why ?

How do you handle duplication "the number of pages in LRU" of zone->vm_stat and this ?

Thanks,
-Kame

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