[RFC] memory controller : backgorund reclaim and avoid excessive locking [5/5] lazy page_cgroup freeing

[YAMAMOTO Takashi]

> +	/*
> +	 * For lazy freeing (not GC)
> +	 */
> +	struct {
> +		struct mem_cgroup_per_zone *mz;
> +		int			num;
> +#define GARBAGE_MAXSIZE		(16)
> +		struct page_cgroup	*vec[GARBAGE_MAXSIZE];
> +	} garbage[NR_CPUS];
>  };

i think you want to dedicate cache lines.

> @@ -176,12 +185,14 @@ struct page_cgroup {
>  	struct list_head lru;		/* per cgroup LRU list */
>  	struct page *page;
>  	struct mem_cgroup *mem_cgroup;
> +	struct mem_cgroup_per_zone *mz;	/* now belongs to...*/

is this for performance?

> @@ -408,10 +427,12 @@ static void __mem_cgroup_move_lists(stru
>  	if (active) {
>  		MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_ACTIVE) += 1;
>  		pc->flags |= PAGE_CGROUP_FLAG_ACTIVE;
> +		pc->mz = mz;
>  		list_move(&pc->lru, &mz->active_list);
>  	} else {
>  		MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_INACTIVE) += 1;
>  		pc->flags &= ~PAGE_CGROUP_FLAG_ACTIVE;
> +		pc->mz = mz;
>  		list_move(&pc->lru, &mz->inactive_list);
>  	}
>  }

isn't pc->mz already assigned by __mem_cgroup_add_list?

> @@ -1050,11 +1114,15 @@ mem_cgroup_force_empty_list(struct mem_c
>  	if (list_empty(list))
>  		return;
>  retry:
> +	all_free_garbages(mem);
>  	count = FORCE_UNCHARGE_BATCH;
>  	spin_lock_irqsave(&mz->lru_lock, flags);
>  
>  	while (--count && !list_empty(list)) {
>  		pc = list_entry(list->prev, struct page_cgroup, lru);
> +		/* If there are still garbage, exit and retry */
> +		if (pc->flags & PAGE_CGROUP_FLAG_GARBAGE)
> +			break;

i think mem_cgroup_isolate_pages needs a similar check.

YAMAMOTO Takashi