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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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