(2012/09/06 14:16), Minchan Kim wrote:
> The page allocator caches the pageblock information in page->private while
> it is in the PCP freelists but this is overwritten with the order of the
> page when freed to the buddy allocator. This patch stores the migratetype
> of the page in the page->index field so that it is available at all times
> when the page remain in free_list.
>
sounds reasonable.
> This patch adds a new call site in __free_pages_ok so it might be
> overhead a bit but it's for high order allocation.
> So I believe damage isn't hurt.
>
> * from v1
> * Fix move_freepages's migratetype - Mel
> * Add more kind explanation in description - Mel
>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Hmm, page->index is valid only when the page is the head of buddy chunk ?
Anyway,
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> ---
> include/linux/mm.h | 4 ++--
> mm/page_alloc.c | 7 +++++--
> 2 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 84d1663f..68f9e8d 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -240,13 +240,13 @@ struct inode;
> /* It's valid only if the page is free path or free_list */
> static inline void set_freepage_migratetype(struct page *page, int migratetype)
> {
> - set_page_private(page, migratetype);
> + page->index = migratetype;
> }
>
> /* It's valid only if the page is free path or free_list */
> static inline int get_freepage_migratetype(struct page *page)
> {
> - return page_private(page);
> + return page->index;
> }
>
> /*
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index f5ba236..8531fa3 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -723,6 +723,7 @@ static void __free_pages_ok(struct page *page, unsigned int order)
> {
> unsigned long flags;
> int wasMlocked = __TestClearPageMlocked(page);
> + int migratetype;
>
> if (!free_pages_prepare(page, order))
> return;
> @@ -731,8 +732,9 @@ static void __free_pages_ok(struct page *page, unsigned int order)
> if (unlikely(wasMlocked))
> free_page_mlock(page);
> __count_vm_events(PGFREE, 1 << order);
> - free_one_page(page_zone(page), page, order,
> - get_pageblock_migratetype(page));
> + migratetype = get_pageblock_migratetype(page);
> + set_freepage_migratetype(page, migratetype);
> + free_one_page(page_zone(page), page, order, migratetype);
> local_irq_restore(flags);
> }
>
> @@ -952,6 +954,7 @@ static int move_freepages(struct zone *zone,
> order = page_order(page);
> list_move(&page->lru,
> &zone->free_area[order].free_list[migratetype]);
> + set_freepage_migratetype(page, migratetype);
> page += 1 << order;
> pages_moved += 1 << order;
> }
>
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