![Minchan Kim](/assets/img/avatar_default.png)
invalidate_mapping_pages is very big hint to reclaimer. It means user
doesn't want to use the page any more. So in order to prevent working set
page eviction, this patch move the page into tail of inactive list by
PG_reclaim.
Please, remember that pages in inactive list are working set as well as
active list. If we don't move pages into inactive list's tail, pages near
by tail of inactive list can be evicted although we have a big clue about
useless pages. It's totally bad.
Now PG_readahead/PG_reclaim is shared. fe3cba17
added ClearPageReclaim
into clear_page_dirty_for_io for preventing fast reclaiming readahead
marker page.
In this series, PG_reclaim is used by invalidated page, too. If VM find
the page is invalidated and it's dirty, it sets PG_reclaim to reclaim
asap. Then, when the dirty page will be writeback,
clear_page_dirty_for_io will clear PG_reclaim unconditionally. It
disturbs this serie's goal.
I think it's okay to clear PG_readahead when the page is dirty, not
writeback time. So this patch moves ClearPageReadahead. In v4,
ClearPageReadahead in set_page_dirty has a problem which is reported by
Steven Barrett. It's due to compound page. Some driver(ex, audio) calls
set_page_dirty with compound page which isn't on LRU. but my patch does
ClearPageRelcaim on compound page. In non-CONFIG_PAGEFLAGS_EXTENDED, it
breaks PageTail flag.
I think it doesn't affect THP and pass my test with THP enabling but Cced
Andrea for double check.
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reported-by: Steven Barrett <damentz@liquorix.net>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
749 lines
19 KiB
C
749 lines
19 KiB
C
/*
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* linux/mm/swap.c
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*
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*/
|
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/*
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* This file contains the default values for the operation of the
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* Linux VM subsystem. Fine-tuning documentation can be found in
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* Documentation/sysctl/vm.txt.
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* Started 18.12.91
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* Swap aging added 23.2.95, Stephen Tweedie.
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* Buffermem limits added 12.3.98, Rik van Riel.
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*/
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/kernel_stat.h>
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#include <linux/swap.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/pagevec.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/mm_inline.h>
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#include <linux/buffer_head.h> /* for try_to_release_page() */
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#include <linux/percpu_counter.h>
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#include <linux/percpu.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/backing-dev.h>
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#include <linux/memcontrol.h>
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#include <linux/gfp.h>
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#include "internal.h"
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/* How many pages do we try to swap or page in/out together? */
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int page_cluster;
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static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
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static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
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static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
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/*
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* This path almost never happens for VM activity - pages are normally
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* freed via pagevecs. But it gets used by networking.
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*/
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static void __page_cache_release(struct page *page)
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{
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if (PageLRU(page)) {
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unsigned long flags;
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struct zone *zone = page_zone(page);
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spin_lock_irqsave(&zone->lru_lock, flags);
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VM_BUG_ON(!PageLRU(page));
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__ClearPageLRU(page);
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del_page_from_lru(zone, page);
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spin_unlock_irqrestore(&zone->lru_lock, flags);
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}
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}
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static void __put_single_page(struct page *page)
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{
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__page_cache_release(page);
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free_hot_cold_page(page, 0);
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}
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static void __put_compound_page(struct page *page)
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{
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compound_page_dtor *dtor;
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__page_cache_release(page);
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dtor = get_compound_page_dtor(page);
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(*dtor)(page);
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}
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static void put_compound_page(struct page *page)
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{
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if (unlikely(PageTail(page))) {
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/* __split_huge_page_refcount can run under us */
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struct page *page_head = page->first_page;
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smp_rmb();
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/*
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* If PageTail is still set after smp_rmb() we can be sure
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* that the page->first_page we read wasn't a dangling pointer.
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* See __split_huge_page_refcount() smp_wmb().
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*/
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if (likely(PageTail(page) && get_page_unless_zero(page_head))) {
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unsigned long flags;
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/*
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* Verify that our page_head wasn't converted
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* to a a regular page before we got a
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* reference on it.
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*/
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if (unlikely(!PageHead(page_head))) {
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/* PageHead is cleared after PageTail */
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smp_rmb();
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VM_BUG_ON(PageTail(page));
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goto out_put_head;
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}
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/*
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* Only run compound_lock on a valid PageHead,
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* after having it pinned with
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* get_page_unless_zero() above.
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*/
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smp_mb();
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/* page_head wasn't a dangling pointer */
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flags = compound_lock_irqsave(page_head);
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if (unlikely(!PageTail(page))) {
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/* __split_huge_page_refcount run before us */
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compound_unlock_irqrestore(page_head, flags);
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VM_BUG_ON(PageHead(page_head));
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out_put_head:
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if (put_page_testzero(page_head))
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__put_single_page(page_head);
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out_put_single:
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if (put_page_testzero(page))
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__put_single_page(page);
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return;
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}
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VM_BUG_ON(page_head != page->first_page);
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/*
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* We can release the refcount taken by
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* get_page_unless_zero now that
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* split_huge_page_refcount is blocked on the
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* compound_lock.
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*/
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if (put_page_testzero(page_head))
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VM_BUG_ON(1);
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/* __split_huge_page_refcount will wait now */
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VM_BUG_ON(atomic_read(&page->_count) <= 0);
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atomic_dec(&page->_count);
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VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
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compound_unlock_irqrestore(page_head, flags);
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if (put_page_testzero(page_head)) {
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if (PageHead(page_head))
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__put_compound_page(page_head);
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else
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__put_single_page(page_head);
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}
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} else {
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/* page_head is a dangling pointer */
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VM_BUG_ON(PageTail(page));
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goto out_put_single;
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}
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} else if (put_page_testzero(page)) {
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if (PageHead(page))
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__put_compound_page(page);
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else
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__put_single_page(page);
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}
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}
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void put_page(struct page *page)
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{
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if (unlikely(PageCompound(page)))
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put_compound_page(page);
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else if (put_page_testzero(page))
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__put_single_page(page);
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}
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EXPORT_SYMBOL(put_page);
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/**
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* put_pages_list() - release a list of pages
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* @pages: list of pages threaded on page->lru
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*
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* Release a list of pages which are strung together on page.lru. Currently
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* used by read_cache_pages() and related error recovery code.
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*/
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void put_pages_list(struct list_head *pages)
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{
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while (!list_empty(pages)) {
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struct page *victim;
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victim = list_entry(pages->prev, struct page, lru);
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list_del(&victim->lru);
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page_cache_release(victim);
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}
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}
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EXPORT_SYMBOL(put_pages_list);
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/*
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* pagevec_move_tail() must be called with IRQ disabled.
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* Otherwise this may cause nasty races.
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*/
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static void pagevec_move_tail(struct pagevec *pvec)
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{
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int i;
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int pgmoved = 0;
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struct zone *zone = NULL;
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for (i = 0; i < pagevec_count(pvec); i++) {
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struct page *page = pvec->pages[i];
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struct zone *pagezone = page_zone(page);
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if (pagezone != zone) {
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if (zone)
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spin_unlock(&zone->lru_lock);
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zone = pagezone;
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spin_lock(&zone->lru_lock);
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}
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if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
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enum lru_list lru = page_lru_base_type(page);
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list_move_tail(&page->lru, &zone->lru[lru].list);
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mem_cgroup_rotate_reclaimable_page(page);
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pgmoved++;
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}
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}
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if (zone)
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spin_unlock(&zone->lru_lock);
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__count_vm_events(PGROTATED, pgmoved);
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release_pages(pvec->pages, pvec->nr, pvec->cold);
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pagevec_reinit(pvec);
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}
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/*
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* Writeback is about to end against a page which has been marked for immediate
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* reclaim. If it still appears to be reclaimable, move it to the tail of the
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* inactive list.
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*/
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void rotate_reclaimable_page(struct page *page)
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{
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if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
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!PageUnevictable(page) && PageLRU(page)) {
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struct pagevec *pvec;
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unsigned long flags;
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page_cache_get(page);
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local_irq_save(flags);
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pvec = &__get_cpu_var(lru_rotate_pvecs);
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if (!pagevec_add(pvec, page))
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pagevec_move_tail(pvec);
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local_irq_restore(flags);
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}
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}
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static void update_page_reclaim_stat(struct zone *zone, struct page *page,
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int file, int rotated)
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{
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struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat;
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struct zone_reclaim_stat *memcg_reclaim_stat;
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memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page);
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reclaim_stat->recent_scanned[file]++;
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if (rotated)
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reclaim_stat->recent_rotated[file]++;
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if (!memcg_reclaim_stat)
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return;
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memcg_reclaim_stat->recent_scanned[file]++;
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if (rotated)
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memcg_reclaim_stat->recent_rotated[file]++;
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}
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/*
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* FIXME: speed this up?
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*/
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void activate_page(struct page *page)
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{
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struct zone *zone = page_zone(page);
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spin_lock_irq(&zone->lru_lock);
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if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
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int file = page_is_file_cache(page);
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int lru = page_lru_base_type(page);
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del_page_from_lru_list(zone, page, lru);
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SetPageActive(page);
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lru += LRU_ACTIVE;
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add_page_to_lru_list(zone, page, lru);
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__count_vm_event(PGACTIVATE);
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update_page_reclaim_stat(zone, page, file, 1);
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}
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spin_unlock_irq(&zone->lru_lock);
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}
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/*
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* Mark a page as having seen activity.
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*
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* inactive,unreferenced -> inactive,referenced
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* inactive,referenced -> active,unreferenced
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* active,unreferenced -> active,referenced
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*/
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void mark_page_accessed(struct page *page)
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{
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if (!PageActive(page) && !PageUnevictable(page) &&
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PageReferenced(page) && PageLRU(page)) {
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activate_page(page);
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ClearPageReferenced(page);
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} else if (!PageReferenced(page)) {
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SetPageReferenced(page);
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}
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}
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EXPORT_SYMBOL(mark_page_accessed);
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void __lru_cache_add(struct page *page, enum lru_list lru)
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{
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struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];
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page_cache_get(page);
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if (!pagevec_add(pvec, page))
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____pagevec_lru_add(pvec, lru);
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put_cpu_var(lru_add_pvecs);
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}
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EXPORT_SYMBOL(__lru_cache_add);
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/**
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* lru_cache_add_lru - add a page to a page list
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* @page: the page to be added to the LRU.
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* @lru: the LRU list to which the page is added.
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*/
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void lru_cache_add_lru(struct page *page, enum lru_list lru)
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{
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if (PageActive(page)) {
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VM_BUG_ON(PageUnevictable(page));
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ClearPageActive(page);
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} else if (PageUnevictable(page)) {
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VM_BUG_ON(PageActive(page));
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ClearPageUnevictable(page);
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}
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VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page));
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__lru_cache_add(page, lru);
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}
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/**
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* add_page_to_unevictable_list - add a page to the unevictable list
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* @page: the page to be added to the unevictable list
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*
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* Add page directly to its zone's unevictable list. To avoid races with
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* tasks that might be making the page evictable, through eg. munlock,
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* munmap or exit, while it's not on the lru, we want to add the page
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* while it's locked or otherwise "invisible" to other tasks. This is
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* difficult to do when using the pagevec cache, so bypass that.
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*/
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void add_page_to_unevictable_list(struct page *page)
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{
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struct zone *zone = page_zone(page);
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spin_lock_irq(&zone->lru_lock);
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SetPageUnevictable(page);
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SetPageLRU(page);
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add_page_to_lru_list(zone, page, LRU_UNEVICTABLE);
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spin_unlock_irq(&zone->lru_lock);
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}
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|
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/*
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* If the page can not be invalidated, it is moved to the
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* inactive list to speed up its reclaim. It is moved to the
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* head of the list, rather than the tail, to give the flusher
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* threads some time to write it out, as this is much more
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* effective than the single-page writeout from reclaim.
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*
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* If the page isn't page_mapped and dirty/writeback, the page
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* could reclaim asap using PG_reclaim.
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*
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* 1. active, mapped page -> none
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* 2. active, dirty/writeback page -> inactive, head, PG_reclaim
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* 3. inactive, mapped page -> none
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* 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
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* 5. inactive, clean -> inactive, tail
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* 6. Others -> none
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*
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* In 4, why it moves inactive's head, the VM expects the page would
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* be write it out by flusher threads as this is much more effective
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* than the single-page writeout from reclaim.
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*/
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static void lru_deactivate(struct page *page, struct zone *zone)
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{
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int lru, file;
|
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bool active;
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|
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if (!PageLRU(page))
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return;
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|
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/* Some processes are using the page */
|
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if (page_mapped(page))
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return;
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active = PageActive(page);
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file = page_is_file_cache(page);
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lru = page_lru_base_type(page);
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del_page_from_lru_list(zone, page, lru + active);
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ClearPageActive(page);
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ClearPageReferenced(page);
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add_page_to_lru_list(zone, page, lru);
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|
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if (PageWriteback(page) || PageDirty(page)) {
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/*
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* PG_reclaim could be raced with end_page_writeback
|
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* It can make readahead confusing. But race window
|
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* is _really_ small and it's non-critical problem.
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*/
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SetPageReclaim(page);
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} else {
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/*
|
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* The page's writeback ends up during pagevec
|
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* We moves tha page into tail of inactive.
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*/
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list_move_tail(&page->lru, &zone->lru[lru].list);
|
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mem_cgroup_rotate_reclaimable_page(page);
|
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__count_vm_event(PGROTATED);
|
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}
|
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|
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if (active)
|
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__count_vm_event(PGDEACTIVATE);
|
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update_page_reclaim_stat(zone, page, file, 0);
|
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}
|
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|
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static void ____pagevec_lru_deactivate(struct pagevec *pvec)
|
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{
|
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int i;
|
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struct zone *zone = NULL;
|
|
|
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for (i = 0; i < pagevec_count(pvec); i++) {
|
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struct page *page = pvec->pages[i];
|
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struct zone *pagezone = page_zone(page);
|
|
|
|
if (pagezone != zone) {
|
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if (zone)
|
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spin_unlock_irq(&zone->lru_lock);
|
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zone = pagezone;
|
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spin_lock_irq(&zone->lru_lock);
|
|
}
|
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lru_deactivate(page, zone);
|
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}
|
|
if (zone)
|
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spin_unlock_irq(&zone->lru_lock);
|
|
|
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release_pages(pvec->pages, pvec->nr, pvec->cold);
|
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pagevec_reinit(pvec);
|
|
}
|
|
|
|
|
|
/*
|
|
* Drain pages out of the cpu's pagevecs.
|
|
* Either "cpu" is the current CPU, and preemption has already been
|
|
* disabled; or "cpu" is being hot-unplugged, and is already dead.
|
|
*/
|
|
static void drain_cpu_pagevecs(int cpu)
|
|
{
|
|
struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu);
|
|
struct pagevec *pvec;
|
|
int lru;
|
|
|
|
for_each_lru(lru) {
|
|
pvec = &pvecs[lru - LRU_BASE];
|
|
if (pagevec_count(pvec))
|
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____pagevec_lru_add(pvec, lru);
|
|
}
|
|
|
|
pvec = &per_cpu(lru_rotate_pvecs, cpu);
|
|
if (pagevec_count(pvec)) {
|
|
unsigned long flags;
|
|
|
|
/* No harm done if a racing interrupt already did this */
|
|
local_irq_save(flags);
|
|
pagevec_move_tail(pvec);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
pvec = &per_cpu(lru_deactivate_pvecs, cpu);
|
|
if (pagevec_count(pvec))
|
|
____pagevec_lru_deactivate(pvec);
|
|
}
|
|
|
|
/**
|
|
* deactivate_page - forcefully deactivate a page
|
|
* @page: page to deactivate
|
|
*
|
|
* This function hints the VM that @page is a good reclaim candidate,
|
|
* for example if its invalidation fails due to the page being dirty
|
|
* or under writeback.
|
|
*/
|
|
void deactivate_page(struct page *page)
|
|
{
|
|
if (likely(get_page_unless_zero(page))) {
|
|
struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
|
|
|
|
if (!pagevec_add(pvec, page))
|
|
____pagevec_lru_deactivate(pvec);
|
|
put_cpu_var(lru_deactivate_pvecs);
|
|
}
|
|
}
|
|
|
|
void lru_add_drain(void)
|
|
{
|
|
drain_cpu_pagevecs(get_cpu());
|
|
put_cpu();
|
|
}
|
|
|
|
static void lru_add_drain_per_cpu(struct work_struct *dummy)
|
|
{
|
|
lru_add_drain();
|
|
}
|
|
|
|
/*
|
|
* Returns 0 for success
|
|
*/
|
|
int lru_add_drain_all(void)
|
|
{
|
|
return schedule_on_each_cpu(lru_add_drain_per_cpu);
|
|
}
|
|
|
|
/*
|
|
* Batched page_cache_release(). Decrement the reference count on all the
|
|
* passed pages. If it fell to zero then remove the page from the LRU and
|
|
* free it.
|
|
*
|
|
* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
|
|
* for the remainder of the operation.
|
|
*
|
|
* The locking in this function is against shrink_inactive_list(): we recheck
|
|
* the page count inside the lock to see whether shrink_inactive_list()
|
|
* grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
|
|
* will free it.
|
|
*/
|
|
void release_pages(struct page **pages, int nr, int cold)
|
|
{
|
|
int i;
|
|
struct pagevec 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];
|
|
|
|
if (unlikely(PageCompound(page))) {
|
|
if (zone) {
|
|
spin_unlock_irqrestore(&zone->lru_lock, flags);
|
|
zone = NULL;
|
|
}
|
|
put_compound_page(page);
|
|
continue;
|
|
}
|
|
|
|
if (!put_page_testzero(page))
|
|
continue;
|
|
|
|
if (PageLRU(page)) {
|
|
struct zone *pagezone = page_zone(page);
|
|
|
|
if (pagezone != zone) {
|
|
if (zone)
|
|
spin_unlock_irqrestore(&zone->lru_lock,
|
|
flags);
|
|
zone = pagezone;
|
|
spin_lock_irqsave(&zone->lru_lock, flags);
|
|
}
|
|
VM_BUG_ON(!PageLRU(page));
|
|
__ClearPageLRU(page);
|
|
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);
|
|
}
|
|
}
|
|
if (zone)
|
|
spin_unlock_irqrestore(&zone->lru_lock, flags);
|
|
|
|
pagevec_free(&pages_to_free);
|
|
}
|
|
EXPORT_SYMBOL(release_pages);
|
|
|
|
/*
|
|
* The pages which we're about to release may be in the deferred lru-addition
|
|
* queues. That would prevent them from really being freed right now. That's
|
|
* OK from a correctness point of view but is inefficient - those pages may be
|
|
* cache-warm and we want to give them back to the page allocator ASAP.
|
|
*
|
|
* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
|
|
* and __pagevec_lru_add_active() call release_pages() directly to avoid
|
|
* mutual recursion.
|
|
*/
|
|
void __pagevec_release(struct pagevec *pvec)
|
|
{
|
|
lru_add_drain();
|
|
release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
|
|
pagevec_reinit(pvec);
|
|
}
|
|
|
|
EXPORT_SYMBOL(__pagevec_release);
|
|
|
|
/* used by __split_huge_page_refcount() */
|
|
void lru_add_page_tail(struct zone* zone,
|
|
struct page *page, struct page *page_tail)
|
|
{
|
|
int active;
|
|
enum lru_list lru;
|
|
const int file = 0;
|
|
struct list_head *head;
|
|
|
|
VM_BUG_ON(!PageHead(page));
|
|
VM_BUG_ON(PageCompound(page_tail));
|
|
VM_BUG_ON(PageLRU(page_tail));
|
|
VM_BUG_ON(!spin_is_locked(&zone->lru_lock));
|
|
|
|
SetPageLRU(page_tail);
|
|
|
|
if (page_evictable(page_tail, NULL)) {
|
|
if (PageActive(page)) {
|
|
SetPageActive(page_tail);
|
|
active = 1;
|
|
lru = LRU_ACTIVE_ANON;
|
|
} else {
|
|
active = 0;
|
|
lru = LRU_INACTIVE_ANON;
|
|
}
|
|
update_page_reclaim_stat(zone, page_tail, file, active);
|
|
if (likely(PageLRU(page)))
|
|
head = page->lru.prev;
|
|
else
|
|
head = &zone->lru[lru].list;
|
|
__add_page_to_lru_list(zone, page_tail, lru, head);
|
|
} else {
|
|
SetPageUnevictable(page_tail);
|
|
add_page_to_lru_list(zone, page_tail, LRU_UNEVICTABLE);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Add the passed pages to the LRU, then drop the caller's refcount
|
|
* on them. Reinitialises the caller's pagevec.
|
|
*/
|
|
void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
|
|
{
|
|
int i;
|
|
struct zone *zone = NULL;
|
|
|
|
VM_BUG_ON(is_unevictable_lru(lru));
|
|
|
|
for (i = 0; i < pagevec_count(pvec); i++) {
|
|
struct page *page = pvec->pages[i];
|
|
struct zone *pagezone = page_zone(page);
|
|
int file;
|
|
int active;
|
|
|
|
if (pagezone != zone) {
|
|
if (zone)
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
zone = pagezone;
|
|
spin_lock_irq(&zone->lru_lock);
|
|
}
|
|
VM_BUG_ON(PageActive(page));
|
|
VM_BUG_ON(PageUnevictable(page));
|
|
VM_BUG_ON(PageLRU(page));
|
|
SetPageLRU(page);
|
|
active = is_active_lru(lru);
|
|
file = is_file_lru(lru);
|
|
if (active)
|
|
SetPageActive(page);
|
|
update_page_reclaim_stat(zone, page, file, active);
|
|
add_page_to_lru_list(zone, page, lru);
|
|
}
|
|
if (zone)
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
release_pages(pvec->pages, pvec->nr, pvec->cold);
|
|
pagevec_reinit(pvec);
|
|
}
|
|
|
|
EXPORT_SYMBOL(____pagevec_lru_add);
|
|
|
|
/*
|
|
* Try to drop buffers from the pages in a pagevec
|
|
*/
|
|
void pagevec_strip(struct pagevec *pvec)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < pagevec_count(pvec); i++) {
|
|
struct page *page = pvec->pages[i];
|
|
|
|
if (page_has_private(page) && trylock_page(page)) {
|
|
if (page_has_private(page))
|
|
try_to_release_page(page, 0);
|
|
unlock_page(page);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* pagevec_lookup - gang pagecache lookup
|
|
* @pvec: Where the resulting pages are placed
|
|
* @mapping: The address_space to search
|
|
* @start: The starting page index
|
|
* @nr_pages: The maximum number of pages
|
|
*
|
|
* pagevec_lookup() will search for and return a group of up to @nr_pages pages
|
|
* in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
|
|
* reference against the pages in @pvec.
|
|
*
|
|
* The search returns a group of mapping-contiguous pages with ascending
|
|
* indexes. There may be holes in the indices due to not-present pages.
|
|
*
|
|
* pagevec_lookup() returns the number of pages which were found.
|
|
*/
|
|
unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
|
|
pgoff_t start, unsigned nr_pages)
|
|
{
|
|
pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
|
|
return pagevec_count(pvec);
|
|
}
|
|
|
|
EXPORT_SYMBOL(pagevec_lookup);
|
|
|
|
unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
|
|
pgoff_t *index, int tag, unsigned nr_pages)
|
|
{
|
|
pvec->nr = find_get_pages_tag(mapping, index, tag,
|
|
nr_pages, pvec->pages);
|
|
return pagevec_count(pvec);
|
|
}
|
|
|
|
EXPORT_SYMBOL(pagevec_lookup_tag);
|
|
|
|
/*
|
|
* Perform any setup for the swap system
|
|
*/
|
|
void __init swap_setup(void)
|
|
{
|
|
unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
|
|
|
|
#ifdef CONFIG_SWAP
|
|
bdi_init(swapper_space.backing_dev_info);
|
|
#endif
|
|
|
|
/* Use a smaller cluster for small-memory machines */
|
|
if (megs < 16)
|
|
page_cluster = 2;
|
|
else
|
|
page_cluster = 3;
|
|
/*
|
|
* Right now other parts of the system means that we
|
|
* _really_ don't want to cluster much more
|
|
*/
|
|
}
|