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    Subject[PATCH v6 5/6] mm/swap: implement workingset detection for anonymous LRU
    Date
    From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

    This patch implements workingset detection for anonymous LRU.
    All the infrastructure is implemented by the previous patches so this patch
    just activates the workingset detection by installing/retrieving
    the shadow entry.

    Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    ---
    include/linux/swap.h | 6 ++++++
    mm/memory.c | 11 ++++-------
    mm/swap_state.c | 23 ++++++++++++++++++-----
    mm/vmscan.c | 7 ++++---
    mm/workingset.c | 5 +++--
    5 files changed, 35 insertions(+), 17 deletions(-)

    diff --git a/include/linux/swap.h b/include/linux/swap.h
    index 901da54..9ee78b8 100644
    --- a/include/linux/swap.h
    +++ b/include/linux/swap.h
    @@ -416,6 +416,7 @@ extern struct address_space *swapper_spaces[];
    extern unsigned long total_swapcache_pages(void);
    extern void show_swap_cache_info(void);
    extern int add_to_swap(struct page *page);
    +extern void *get_shadow_from_swap_cache(swp_entry_t entry);
    extern int add_to_swap_cache(struct page *page, swp_entry_t entry,
    gfp_t gfp, void **shadowp);
    extern void __delete_from_swap_cache(struct page *page,
    @@ -575,6 +576,11 @@ static inline int add_to_swap(struct page *page)
    return 0;
    }

    +static inline void *get_shadow_from_swap_cache(swp_entry_t entry)
    +{
    + return NULL;
    +}
    +
    static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
    gfp_t gfp_mask, void **shadowp)
    {
    diff --git a/mm/memory.c b/mm/memory.c
    index f221f96..2411cf57 100644
    --- a/mm/memory.c
    +++ b/mm/memory.c
    @@ -3094,6 +3094,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
    int locked;
    int exclusive = 0;
    vm_fault_t ret = 0;
    + void *shadow = NULL;

    if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
    goto out;
    @@ -3143,13 +3144,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
    if (err)
    goto out_page;

    - /*
    - * XXX: Move to lru_cache_add() when it
    - * supports new vs putback
    - */
    - spin_lock_irq(&page_pgdat(page)->lru_lock);
    - lru_note_cost_page(page);
    - spin_unlock_irq(&page_pgdat(page)->lru_lock);
    + shadow = get_shadow_from_swap_cache(entry);
    + if (shadow)
    + workingset_refault(page, shadow);

    lru_cache_add(page);
    swap_readpage(page, true);
    diff --git a/mm/swap_state.c b/mm/swap_state.c
    index 43c4e3a..90c5bd1 100644
    --- a/mm/swap_state.c
    +++ b/mm/swap_state.c
    @@ -106,6 +106,20 @@ void show_swap_cache_info(void)
    printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
    }

    +void *get_shadow_from_swap_cache(swp_entry_t entry)
    +{
    + struct address_space *address_space = swap_address_space(entry);
    + pgoff_t idx = swp_offset(entry);
    + struct page *page;
    +
    + page = find_get_entry(address_space, idx);
    + if (xa_is_value(page))
    + return page;
    + if (page)
    + put_page(page);
    + return NULL;
    +}
    +
    /*
    * add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
    * but sets SwapCache flag and private instead of mapping and index.
    @@ -405,6 +419,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
    {
    struct swap_info_struct *si;
    struct page *page;
    + void *shadow = NULL;

    *new_page_allocated = false;

    @@ -473,7 +488,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
    __SetPageSwapBacked(page);

    /* May fail (-ENOMEM) if XArray node allocation failed. */
    - if (add_to_swap_cache(page, entry, gfp_mask & GFP_KERNEL, NULL)) {
    + if (add_to_swap_cache(page, entry, gfp_mask & GFP_KERNEL, &shadow)) {
    put_swap_page(page, entry);
    goto fail_unlock;
    }
    @@ -483,10 +498,8 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
    goto fail_unlock;
    }

    - /* XXX: Move to lru_cache_add() when it supports new vs putback */
    - spin_lock_irq(&page_pgdat(page)->lru_lock);
    - lru_note_cost_page(page);
    - spin_unlock_irq(&page_pgdat(page)->lru_lock);
    + if (shadow)
    + workingset_refault(page, shadow);

    /* Caller will initiate read into locked page */
    SetPageWorkingset(page);
    diff --git a/mm/vmscan.c b/mm/vmscan.c
    index 37943bf..eb02d18 100644
    --- a/mm/vmscan.c
    +++ b/mm/vmscan.c
    @@ -859,6 +859,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
    {
    unsigned long flags;
    int refcount;
    + void *shadow = NULL;

    BUG_ON(!PageLocked(page));
    BUG_ON(mapping != page_mapping(page));
    @@ -901,13 +902,13 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
    if (PageSwapCache(page)) {
    swp_entry_t swap = { .val = page_private(page) };
    mem_cgroup_swapout(page, swap);
    - __delete_from_swap_cache(page, swap, NULL);
    + if (reclaimed && !mapping_exiting(mapping))
    + shadow = workingset_eviction(page, target_memcg);
    + __delete_from_swap_cache(page, swap, shadow);
    xa_unlock_irqrestore(&mapping->i_pages, flags);
    put_swap_page(page, swap);
    - workingset_eviction(page, target_memcg);
    } else {
    void (*freepage)(struct page *);
    - void *shadow = NULL;

    freepage = mapping->a_ops->freepage;
    /*
    diff --git a/mm/workingset.c b/mm/workingset.c
    index 8395e60..3769ae6 100644
    --- a/mm/workingset.c
    +++ b/mm/workingset.c
    @@ -353,8 +353,9 @@ void workingset_refault(struct page *page, void *shadow)
    /*
    * Compare the distance to the existing workingset size. We
    * don't activate pages that couldn't stay resident even if
    - * all the memory was available to the page cache. Whether
    - * cache can compete with anon or not depends on having swap.
    + * all the memory was available to the workingset. Whether
    + * workingset competetion need to consider anon or not depends
    + * on having swap.
    */
    workingset_size = lruvec_page_state(eviction_lruvec, NR_ACTIVE_FILE);
    if (mem_cgroup_get_nr_swap_pages(memcg) > 0) {
    --
    2.7.4
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