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Message-ID: <BANLkTi=UGNJKhFDZwuQK7Oopk7p=Pz=NYQ@mail.gmail.com>
Date: Wed, 27 Apr 2011 13:20:00 +0900
From: Minchan Kim <minchan.kim@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
Christoph Lameter <cl@...ux.com>,
Johannes Weiner <jweiner@...hat.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Minchan Kim <minchan.kim@...il.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: [RFC 6/8] In order putback lru core
On Wed, Apr 27, 2011 at 1:25 AM, Minchan Kim <minchan.kim@...il.com> wrote:
> This patch defines new APIs to putback the page into previous position of LRU.
> The idea is simple.
>
> When we try to putback the page into lru list and if friends(prev, next) of the pages
> still is nearest neighbor, we can insert isolated page into prev's next instead of
> head of LRU list. So it keeps LRU history without losing the LRU information.
>
> Before :
> LRU POV : H - P1 - P2 - P3 - P4 -T
>
> Isolate P3 :
> LRU POV : H - P1 - P2 - P4 - T
>
> Putback P3 :
> if (P2->next == P4)
> putback(P3, P2);
> So,
> LRU POV : H - P1 - P2 - P3 - P4 -T
>
> For implement, we defines new structure pages_lru which remebers
> both lru friend pages of isolated one and handling functions.
>
> But this approach has a problem on contiguous pages.
> In this case, my idea can not work since friend pages are isolated, too.
> It means prev_page->next == next_page always is false and both pages are not
> LRU any more at that time. It's pointed out by Rik at LSF/MM summit.
> So for solving the problem, I can change the idea.
> I think we don't need both friend(prev, next) pages relation but
> just consider either prev or next page that it is still same LRU.
> Worset case in this approach, prev or next page is free and allocate new
> so it's in head of LRU and our isolated page is located on next of head.
> But it's almost same situation with current problem. So it doesn't make worse
> than now and it would be rare. But in this version, I implement based on idea
> discussed at LSF/MM. If my new idea makes sense, I will change it.
>
> Any comment?
>
> Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> Cc: Mel Gorman <mgorman@...e.de>
> Cc: Rik van Riel <riel@...hat.com>
> Cc: Andrea Arcangeli <aarcange@...hat.com>
> Signed-off-by: Minchan Kim <minchan.kim@...il.com>
> ---
> include/linux/migrate.h | 2 +
> include/linux/mm_types.h | 7 ++++
> include/linux/swap.h | 4 ++-
> mm/compaction.c | 3 +-
> mm/internal.h | 2 +
> mm/memcontrol.c | 2 +-
> mm/migrate.c | 36 +++++++++++++++++++++
> mm/swap.c | 2 +-
> mm/vmscan.c | 79 +++++++++++++++++++++++++++++++++++++++++++--
> 9 files changed, 129 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index e39aeec..3aa5ab6 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -9,6 +9,7 @@ typedef struct page *new_page_t(struct page *, unsigned long private, int **);
> #ifdef CONFIG_MIGRATION
> #define PAGE_MIGRATION 1
>
> +extern void putback_pages_lru(struct list_head *l);
> extern void putback_lru_pages(struct list_head *l);
> extern int migrate_page(struct address_space *,
> struct page *, struct page *);
> @@ -33,6 +34,7 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping,
> #else
> #define PAGE_MIGRATION 0
>
> +static inline void putback_pages_lru(struct list_head *l) {}
> static inline void putback_lru_pages(struct list_head *l) {}
> static inline int migrate_pages(struct list_head *l, new_page_t x,
> unsigned long private, bool offlining,
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index ca01ab2..35e80fb 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -102,6 +102,13 @@ struct page {
> #endif
> };
>
> +/* This structure is used for keeping LRU ordering of isolated page */
> +struct pages_lru {
> + struct page *page; /* isolated page */
> + struct page *prev_page; /* previous page of isolate page as LRU order */
> + struct page *next_page; /* next page of isolate page as LRU order */
> + struct list_head lru;
> +};
> /*
> * A region containing a mapping of a non-memory backed file under NOMMU
> * conditions. These are held in a global tree and are pinned by the VMAs that
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index baef4ad..4ad0a0c 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -227,6 +227,8 @@ extern void rotate_reclaimable_page(struct page *page);
> extern void deactivate_page(struct page *page);
> extern void swap_setup(void);
>
> +extern void update_page_reclaim_stat(struct zone *zone, struct page *page,
> + int file, int rotated);
> extern void add_page_to_unevictable_list(struct page *page);
>
> /**
> @@ -260,7 +262,7 @@ extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
> struct zone *zone,
> unsigned long *nr_scanned);
> extern int __isolate_lru_page(struct page *page, int mode, int file,
> - int not_dirty, int not_mapped);
> + int not_dirty, int not_mapped, struct pages_lru *pages_lru);
> extern unsigned long shrink_all_memory(unsigned long nr_pages);
> extern int vm_swappiness;
> extern int remove_mapping(struct address_space *mapping, struct page *page);
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 653b02b..c453000 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -335,7 +335,8 @@ static unsigned long isolate_migratepages(struct zone *zone,
> }
>
> /* Try isolate the page */
> - if (__isolate_lru_page(page, ISOLATE_BOTH, 0, !cc->sync, 0) != 0)
> + if (__isolate_lru_page(page, ISOLATE_BOTH, 0,
> + !cc->sync, 0, NULL) != 0)
> continue;
>
> VM_BUG_ON(PageTransCompound(page));
> diff --git a/mm/internal.h b/mm/internal.h
> index d071d38..3c8182c 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -43,6 +43,8 @@ extern unsigned long highest_memmap_pfn;
> * in mm/vmscan.c:
> */
> extern int isolate_lru_page(struct page *page);
> +extern bool keep_lru_order(struct pages_lru *pages_lru);
> +extern void putback_page_to_lru(struct page *page, struct list_head *head);
> extern void putback_lru_page(struct page *page);
>
> /*
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 471e7fd..92a9046 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1193,7 +1193,7 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
> continue;
>
> scan++;
> - ret = __isolate_lru_page(page, mode, file, 0, 0);
> + ret = __isolate_lru_page(page, mode, file, 0, 0, NULL);
> switch (ret) {
> case 0:
> list_move(&page->lru, dst);
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 819d233..9cfb63b 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -85,6 +85,42 @@ void putback_lru_pages(struct list_head *l)
> }
>
> /*
> + * This function is almost same iwth putback_lru_pages.
> + * The difference is that function receives struct pages_lru list
> + * and if possible, we add pages into original position of LRU
> + * instead of LRU's head.
> + */
> +void putback_pages_lru(struct list_head *l)
> +{
> + struct pages_lru *isolated_page;
> + struct pages_lru *isolated_page2;
> + struct page *page;
> +
> + list_for_each_entry_safe(isolated_page, isolated_page2, l, lru) {
> + struct zone *zone;
> + page = isolated_page->page;
> + list_del(&isolated_page->lru);
> +
> + dec_zone_page_state(page, NR_ISOLATED_ANON +
> + page_is_file_cache(page));
> +
> + zone = page_zone(page);
> + spin_lock_irq(&zone->lru_lock);
> + if (keep_lru_order(isolated_page)) {
> + putback_page_to_lru(page, &isolated_page->prev_page->lru);
> + spin_unlock_irq(&zone->lru_lock);
> + }
> + else {
> + spin_unlock_irq(&zone->lru_lock);
> + putback_lru_page(page);
> + }
> +
> + kfree(isolated_page);
> + }
> +}
> +
> +
> +/*
> * Restore a potential migration pte to a working pte entry
> */
> static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
> diff --git a/mm/swap.c b/mm/swap.c
> index a83ec5a..0cb15b7 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -252,7 +252,7 @@ void rotate_reclaimable_page(struct page *page)
> }
> }
>
> -static void update_page_reclaim_stat(struct zone *zone, struct page *page,
> +void update_page_reclaim_stat(struct zone *zone, struct page *page,
> int file, int rotated)
> {
> struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat;
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 5196f0c..06a7c9b 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -550,6 +550,58 @@ int remove_mapping(struct address_space *mapping, struct page *page)
> return 0;
> }
>
> +/* zone->lru_lock must be hold */
> +bool keep_lru_order(struct pages_lru *pages_lru)
> +{
> + bool ret = false;
> + struct page *prev, *next;
> +
> + if (!pages_lru->prev_page)
> + return ret;
> +
> + prev = pages_lru->prev_page;
> + next = pages_lru->next_page;
> +
> + if (!PageLRU(prev) || !PageLRU(next))
> + return ret;
> +
> + if (prev->lru.next == &next->lru)
> + ret = true;
> +
> + if (unlikely(PageUnevictable(prev)))
> + ret = false;
> +
> + return ret;
> +}
> +
> +/**
> + * putback_page_to_lru - put isolated @page onto @head
> + * @page: page to be put back to appropriate lru list
> + * @head: lru position to be put back
> + *
> + * Insert previously isolated @page to appropriate position of lru list
> + * zone->lru_lock must be hold.
> + */
> +void putback_page_to_lru(struct page *page, struct list_head *head)
> +{
> + int lru, active, file;
> + struct zone *zone = page_zone(page);
> + struct page *prev_page = container_of(head, struct page, lru);
> +
> + lru = page_lru(prev_page);
> + active = is_active_lru(lru);
> + file = is_file_lru(lru);
> +
> + if (active)
> + SetPageActive(page);
> + else
> + ClearPageActive(page);
> +
> + update_page_reclaim_stat(zone, page, file, active);
> + SetPageLRU(page);
> + __add_page_to_lru_list(zone, page, lru, head);
> +}
> +
> /**
> * putback_lru_page - put previously isolated page onto appropriate LRU list's head
> * @page: page to be put back to appropriate lru list
> @@ -959,8 +1011,8 @@ keep_lumpy:
> * not_mapped: page should be not mapped
> * returns 0 on success, -ve errno on failure.
> */
> -int __isolate_lru_page(struct page *page, int mode, int file,
> - int not_dirty, int not_mapped)
> +int __isolate_lru_page(struct page *page, int mode, int file, int not_dirty,
> + int not_mapped, struct pages_lru *pages_lru)
> {
> int ret = -EINVAL;
>
> @@ -996,12 +1048,31 @@ int __isolate_lru_page(struct page *page, int mode, int file,
> ret = -EBUSY;
>
> if (likely(get_page_unless_zero(page))) {
> + struct zone *zone = page_zone(page);
> + enum lru_list l = page_lru(page);
> /*
> * Be careful not to clear PageLRU until after we're
> * sure the page is not being freed elsewhere -- the
> * page release code relies on it.
> */
> ClearPageLRU(page);
> +
> + if (!pages_lru)
> + goto skip;
> +
> + pages_lru->page = page;
> + if (&zone->lru[l].list == pages_lru->lru.prev ||
> + &zone->lru[l].list == pages_lru->lru.next) {
> + pages_lru->prev_page = NULL;
> + pages_lru->next_page = NULL;
> + goto skip;
> + }
While I was refactoring the code, I might got sleep.
It should be following as,
@@ -1071,8 +1072,8 @@ int __isolate_lru_page(struct page *page, int
mode, int file, int not_dirty,
goto skip;
pages_lru->page = page;
- if (&zone->lru[l].list == pages_lru->lru.prev ||
- &zone->lru[l].list == pages_lru->lru.next) {
+ if (&zone->lru[l].list == page->lru.prev ||
+ &zone->lru[l].list == page->lru.next) {
pages_lru->prev_page = NULL;
pages_lru->next_page = NULL;
goto skip;
--
Kind regards,
Minchan Kim
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