madv MADV_FREE indicate pages are 'lazyfree'. They are still anonymous pages, but they can be freed without pageout. To destinguish them against normal anonymous pages, we clear their SwapBacked flag.
MADV_FREE pages could be freed without pageout, so they pretty much like used once file pages. For such pages, we'd like to reclaim them once there is memory pressure. Also it might be unfair reclaiming MADV_FREE pages always before used once file pages and we definitively want to reclaim the pages before other anonymous and file pages. To speed up MADV_FREE pages reclaim, we put the pages into LRU_INACTIVE_FILE list. The rationale is LRU_INACTIVE_FILE list is tiny nowadays and should be full of used once file pages. Reclaiming MADV_FREE pages will not have much interfere of anonymous and active file pages. And the inactive file pages and MADV_FREE pages will be reclaimed according to their age, so we don't reclaim too many MADV_FREE pages too. Putting the MADV_FREE pages into LRU_INACTIVE_FILE_LIST also means we can reclaim the pages without swap support. This idea is suggested by Johannes. This patch doesn't move MADV_FREE pages to LRU_INACTIVE_FILE list yet to avoid bisect failure, next patch will do it. The patch is based on Minchan's original patch. Cc: Michal Hocko <mho...@suse.com> Cc: Minchan Kim <minc...@kernel.org> Cc: Hugh Dickins <hu...@google.com> Cc: Rik van Riel <r...@redhat.com> Cc: Mel Gorman <mgor...@techsingularity.net> Cc: Andrew Morton <a...@linux-foundation.org> Suggested-by: Johannes Weiner <han...@cmpxchg.org> Signed-off-by: Shaohua Li <s...@fb.com> --- include/linux/swap.h | 2 +- include/linux/vm_event_item.h | 2 +- mm/huge_memory.c | 3 --- mm/madvise.c | 2 -- mm/swap.c | 50 ++++++++++++++++++++++++------------------- mm/vmstat.c | 1 + 6 files changed, 31 insertions(+), 29 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 45e91dd..486494e 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -279,7 +279,7 @@ extern void lru_add_drain_cpu(int cpu); extern void lru_add_drain_all(void); extern void rotate_reclaimable_page(struct page *page); extern void deactivate_file_page(struct page *page); -extern void deactivate_page(struct page *page); +extern void mark_page_lazyfree(struct page *page); extern void swap_setup(void); extern void add_page_to_unevictable_list(struct page *page); diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h index 6aa1b6c..94e58da 100644 --- a/include/linux/vm_event_item.h +++ b/include/linux/vm_event_item.h @@ -25,7 +25,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, FOR_ALL_ZONES(PGALLOC), FOR_ALL_ZONES(ALLOCSTALL), FOR_ALL_ZONES(PGSCAN_SKIP), - PGFREE, PGACTIVATE, PGDEACTIVATE, + PGFREE, PGACTIVATE, PGDEACTIVATE, PGLAZYFREE, PGFAULT, PGMAJFAULT, PGLAZYFREED, PGREFILL, diff --git a/mm/huge_memory.c b/mm/huge_memory.c index cf9fb46..3b7ee0c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1562,9 +1562,6 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, ClearPageDirty(page); unlock_page(page); - if (PageActive(page)) - deactivate_page(page); - if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, tlb->fullmm); diff --git a/mm/madvise.c b/mm/madvise.c index dc5927c..61e10b1 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -411,8 +411,6 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, ptent = pte_mkold(ptent); ptent = pte_mkclean(ptent); set_pte_at(mm, addr, pte, ptent); - if (PageActive(page)) - deactivate_page(page); tlb_remove_tlb_entry(tlb, pte, addr); } } diff --git a/mm/swap.c b/mm/swap.c index c4910f1..c4fb4b9 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -46,7 +46,7 @@ int page_cluster; static DEFINE_PER_CPU(struct pagevec, lru_add_pvec); static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs); -static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); +static DEFINE_PER_CPU(struct pagevec, lru_lazyfree_pvecs); #ifdef CONFIG_SMP static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs); #endif @@ -561,20 +561,26 @@ static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec, } -static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec, +static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec, void *arg) { - if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) { - int file = page_is_file_cache(page); - int lru = page_lru_base_type(page); + if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) && + !PageUnevictable(page)) { + bool active = PageActive(page); - del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE); + del_page_from_lru_list(page, lruvec, LRU_INACTIVE_ANON + active); ClearPageActive(page); ClearPageReferenced(page); - add_page_to_lru_list(page, lruvec, lru); + /* + * lazyfree pages are clean anonymous pages. They have + * SwapBacked flag cleared to distinguish normal anonymous + * pages + */ + ClearPageSwapBacked(page); + add_page_to_lru_list(page, lruvec, LRU_INACTIVE_FILE); - __count_vm_event(PGDEACTIVATE); - update_page_reclaim_stat(lruvec, file, 0); + __count_vm_events(PGLAZYFREE, hpage_nr_pages(page)); + update_page_reclaim_stat(lruvec, 1, 0); } } @@ -604,9 +610,9 @@ void lru_add_drain_cpu(int cpu) if (pagevec_count(pvec)) pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL); - pvec = &per_cpu(lru_deactivate_pvecs, cpu); + pvec = &per_cpu(lru_lazyfree_pvecs, cpu); if (pagevec_count(pvec)) - pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); + pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL); activate_page_drain(cpu); } @@ -638,22 +644,22 @@ void deactivate_file_page(struct page *page) } /** - * deactivate_page - deactivate a page + * mark_page_lazyfree - make an anon page lazyfree * @page: page to deactivate * - * deactivate_page() moves @page to the inactive list if @page was on the active - * list and was not an unevictable page. This is done to accelerate the reclaim - * of @page. + * mark_page_lazyfree() moves @page to the inactive file list. + * This is done to accelerate the reclaim of @page. */ -void deactivate_page(struct page *page) -{ - if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) { - struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs); +void mark_page_lazyfree(struct page *page) + { + if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) && + !PageUnevictable(page)) { + struct pagevec *pvec = &get_cpu_var(lru_lazyfree_pvecs); get_page(page); if (!pagevec_add(pvec, page) || PageCompound(page)) - pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); - put_cpu_var(lru_deactivate_pvecs); + pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL); + put_cpu_var(lru_lazyfree_pvecs); } } @@ -704,7 +710,7 @@ void lru_add_drain_all(void) if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) || pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) || pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) || - pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) || + pagevec_count(&per_cpu(lru_lazyfree_pvecs, cpu)) || need_activate_page_drain(cpu)) { INIT_WORK(work, lru_add_drain_per_cpu); queue_work_on(cpu, lru_add_drain_wq, work); diff --git a/mm/vmstat.c b/mm/vmstat.c index 69f9aff..7774196 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -992,6 +992,7 @@ const char * const vmstat_text[] = { "pgfree", "pgactivate", "pgdeactivate", + "pglazyfree", "pgfault", "pgmajfault", -- 2.9.3