Re: [PATCH v4 4/7] Reclaim invalidated page ASAP

[Johannes Weiner <hannes@cmpxchg.org>]

On Mon, Dec 06, 2010 at 02:29:12AM +0900, Minchan Kim wrote:
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -275,26 +275,59 @@ void add_page_to_unevictable_list(struct page *page)
>   * head of the list, rather than the tail, to give the flusher
>   * threads some time to write it out, as this is much more
>   * effective than the single-page writeout from reclaim.
> + *
> + * If the page isn't page_mapped and dirty/writeback, the page
> + * could reclaim asap using PG_reclaim.
> + *
> + * 1. active, mapped page -> none
> + * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
> + * 3. inactive, mapped page -> none
> + * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim

         inactive, clean -> inactive, tail

> + * 5. Others -> none
> + *
> + * In 4, why it moves inactive's head, the VM expects the page would
> + * be write it out by flusher threads as this is much more effective
> + * than the single-page writeout from reclaim.
>   */
>  static void lru_deactivate(struct page *page, struct zone *zone)
>  {
>  	int lru, file;
> +	bool active;
>  
> -	if (!PageLRU(page) || !PageActive(page))
> +	if (!PageLRU(page))
>  		return;
>  
>  	/* Some processes are using the page */
>  	if (page_mapped(page))
>  		return;
>  
> +	active = PageActive(page);
> +
>  	file = page_is_file_cache(page);
>  	lru = page_lru_base_type(page);
> -	del_page_from_lru_list(zone, page, lru + LRU_ACTIVE);
> +	del_page_from_lru_list(zone, page, lru + active);
>  	ClearPageActive(page);
>  	ClearPageReferenced(page);
>  	add_page_to_lru_list(zone, page, lru);
> -	__count_vm_event(PGDEACTIVATE);
>
> +	if (PageWriteback(page) || PageDirty(page)) {
> +		/*
> +		 * PG_reclaim could be raced with end_page_writeback
> +		 * It can make readahead confusing.  But race window
> +		 * is _really_ small and  it's non-critical problem.
> +		 */
> +		SetPageReclaim(page);
> +	} else {
> +		/*
> +		 * The page's writeback ends up during pagevec
> +		 * We moves tha page into tail of inactive.
> +		 */
> +		list_move_tail(&page->lru, &zone->lru[lru].list);
> +		mem_cgroup_rotate_reclaimable_page(page);

I think you also need to increase PGROTATED here.

Other than that,
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>