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SubjectRe: [PATCH v3 1/4] mm: add free_hot_cold_page_list helper
On Fri, 11 Nov 2011, Konstantin Khlebnikov wrote:

> This patch adds helper free_hot_cold_page_list() to free list of 0-order pages.
> It frees pages directly from the list without temporary page-vector.
> It also calls trace_mm_pagevec_free() to simulate pagevec_free() behaviour.
>
> bloat-o-meter:
>
> add/remove: 1/1 grow/shrink: 1/3 up/down: 267/-295 (-28)
> function old new delta
> free_hot_cold_page_list - 264 +264
> get_page_from_freelist 2129 2132 +3
> __pagevec_free 243 239 -4
> split_free_page 380 373 -7
> release_pages 606 510 -96
> free_page_list 188 - -188
>
> v2: Remove list reinititialization.
> v3: Always free pages in reverse order.
> The most recently added struct page, the most likely to be hot.
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>

Acked-by: Hugh Dickins <hughd@google.com>

> ---
> include/linux/gfp.h | 1 +
> mm/page_alloc.c | 13 +++++++++++++
> mm/swap.c | 14 +++-----------
> mm/vmscan.c | 20 +-------------------
> 4 files changed, 18 insertions(+), 30 deletions(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 3a76faf..6562958 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -358,6 +358,7 @@ void *alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask);
> extern void __free_pages(struct page *page, unsigned int order);
> extern void free_pages(unsigned long addr, unsigned int order);
> extern void free_hot_cold_page(struct page *page, int cold);
> +extern void free_hot_cold_page_list(struct list_head *list, int cold);
>
> #define __free_page(page) __free_pages((page), 0)
> #define free_page(addr) free_pages((addr), 0)
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 9dd443d..5093114 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1211,6 +1211,19 @@ out:
> }
>
> /*
> + * Free a list of 0-order pages
> + */
> +void free_hot_cold_page_list(struct list_head *list, int cold)
> +{
> + struct page *page, *next;
> +
> + list_for_each_entry_safe(page, next, list, lru) {
> + trace_mm_pagevec_free(page, cold);
> + free_hot_cold_page(page, cold);
> + }
> +}
> +
> +/*
> * split_page takes a non-compound higher-order page, and splits it into
> * n (1<<order) sub-pages: page[0..n]
> * Each sub-page must be freed individually.
> diff --git a/mm/swap.c b/mm/swap.c
> index a91caf7..67a09a6 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -585,11 +585,10 @@ int lru_add_drain_all(void)
> void release_pages(struct page **pages, int nr, int cold)
> {
> int i;
> - struct pagevec pages_to_free;
> + LIST_HEAD(pages_to_free);
> struct zone *zone = NULL;
> unsigned long uninitialized_var(flags);
>
> - pagevec_init(&pages_to_free, cold);
> for (i = 0; i < nr; i++) {
> struct page *page = pages[i];
>
> @@ -620,19 +619,12 @@ void release_pages(struct page **pages, int nr, int cold)
> del_page_from_lru(zone, page);
> }
>
> - if (!pagevec_add(&pages_to_free, page)) {
> - if (zone) {
> - spin_unlock_irqrestore(&zone->lru_lock, flags);
> - zone = NULL;
> - }
> - __pagevec_free(&pages_to_free);
> - pagevec_reinit(&pages_to_free);
> - }
> + list_add(&page->lru, &pages_to_free);
> }
> if (zone)
> spin_unlock_irqrestore(&zone->lru_lock, flags);
>
> - pagevec_free(&pages_to_free);
> + free_hot_cold_page_list(&pages_to_free, cold);
> }
> EXPORT_SYMBOL(release_pages);
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index a1893c0..f4be53d 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -728,24 +728,6 @@ static enum page_references page_check_references(struct page *page,
> return PAGEREF_RECLAIM;
> }
>
> -static noinline_for_stack void free_page_list(struct list_head *free_pages)
> -{
> - struct pagevec freed_pvec;
> - struct page *page, *tmp;
> -
> - pagevec_init(&freed_pvec, 1);
> -
> - list_for_each_entry_safe(page, tmp, free_pages, lru) {
> - list_del(&page->lru);
> - if (!pagevec_add(&freed_pvec, page)) {
> - __pagevec_free(&freed_pvec);
> - pagevec_reinit(&freed_pvec);
> - }
> - }
> -
> - pagevec_free(&freed_pvec);
> -}
> -
> /*
> * shrink_page_list() returns the number of reclaimed pages
> */
> @@ -1009,7 +991,7 @@ keep_lumpy:
> if (nr_dirty && nr_dirty == nr_congested && scanning_global_lru(sc))
> zone_set_flag(zone, ZONE_CONGESTED);
>
> - free_page_list(&free_pages);
> + free_hot_cold_page_list(&free_pages, 1);
>
> list_splice(&ret_pages, page_list);
> count_vm_events(PGACTIVATE, pgactivate);


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