} pageout_t;
struct scan_control {
- /* Ask refill_inactive_zone, or shrink_cache to scan this many pages */
- unsigned long nr_to_scan;
-
/* Incremented by the number of inactive pages that were scanned */
unsigned long nr_scanned;
- /* Incremented by the number of pages reclaimed */
- unsigned long nr_reclaimed;
-
unsigned long nr_mapped; /* From page_state */
- /* Ask shrink_caches, or shrink_zone to scan at this priority */
- unsigned int priority;
-
/* This context's GFP mask */
gfp_t gfp_mask;
int may_writepage;
+ /* Can pages be swapped as part of reclaim? */
+ int may_swap;
+
/* This context's SWAP_CLUSTER_MAX. If freeing memory for
* suspend, we effectively ignore SWAP_CLUSTER_MAX.
* In this context, it doesn't matter that we scan the
*
* Returns the number of slab objects which we shrunk.
*/
-static int shrink_slab(unsigned long scanned, gfp_t gfp_mask,
+unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
unsigned long lru_pages)
{
struct shrinker *shrinker;
- int ret = 0;
+ unsigned long ret = 0;
if (scanned == 0)
scanned = SWAP_CLUSTER_MAX;
static int may_write_to_queue(struct backing_dev_info *bdi)
{
- if (current_is_kswapd())
- return 1;
- if (current_is_pdflush()) /* This is unlikely, but why not... */
+ if (current->flags & PF_SWAPWRITE)
return 1;
if (!bdi_write_congested(bdi))
return 1;
}
/*
- * pageout is called by shrink_list() for each dirty page. Calls ->writepage().
+ * pageout is called by shrink_page_list() for each dirty page.
+ * Calls ->writepage().
*/
static pageout_t pageout(struct page *page, struct address_space *mapping)
{
return PAGE_CLEAN;
}
+static int remove_mapping(struct address_space *mapping, struct page *page)
+{
+ if (!mapping)
+ return 0; /* truncate got there first */
+
+ write_lock_irq(&mapping->tree_lock);
+
+ /*
+ * The non-racy check for busy page. It is critical to check
+ * PageDirty _after_ making sure that the page is freeable and
+ * not in use by anybody. (pagecache + us == 2)
+ */
+ if (unlikely(page_count(page) != 2))
+ goto cannot_free;
+ smp_rmb();
+ if (unlikely(PageDirty(page)))
+ goto cannot_free;
+
+ if (PageSwapCache(page)) {
+ swp_entry_t swap = { .val = page_private(page) };
+ __delete_from_swap_cache(page);
+ write_unlock_irq(&mapping->tree_lock);
+ swap_free(swap);
+ __put_page(page); /* The pagecache ref */
+ return 1;
+ }
+
+ __remove_from_page_cache(page);
+ write_unlock_irq(&mapping->tree_lock);
+ __put_page(page);
+ return 1;
+
+cannot_free:
+ write_unlock_irq(&mapping->tree_lock);
+ return 0;
+}
+
/*
- * shrink_list adds the number of reclaimed pages to sc->nr_reclaimed
+ * shrink_page_list() returns the number of reclaimed pages
*/
-static int shrink_list(struct list_head *page_list, struct scan_control *sc)
+static unsigned long shrink_page_list(struct list_head *page_list,
+ struct scan_control *sc)
{
LIST_HEAD(ret_pages);
struct pagevec freed_pvec;
int pgactivate = 0;
- int reclaimed = 0;
+ unsigned long nr_reclaimed = 0;
cond_resched();
BUG_ON(PageActive(page));
sc->nr_scanned++;
+
+ if (!sc->may_swap && page_mapped(page))
+ goto keep_locked;
+
/* Double the slab pressure for mapped and swapcache pages */
if (page_mapped(page) || PageSwapCache(page))
sc->nr_scanned++;
* Try to allocate it some swap space here.
*/
if (PageAnon(page) && !PageSwapCache(page)) {
- if (!add_to_swap(page))
+ if (!sc->may_swap)
+ goto keep_locked;
+ if (!add_to_swap(page, GFP_ATOMIC))
goto activate_locked;
}
#endif /* CONFIG_SWAP */
* processes. Try to unmap it here.
*/
if (page_mapped(page) && mapping) {
- switch (try_to_unmap(page)) {
+ /*
+ * No unmapping if we do not swap
+ */
+ if (!sc->may_swap)
+ goto keep_locked;
+
+ switch (try_to_unmap(page, 0)) {
case SWAP_FAIL:
goto activate_locked;
case SWAP_AGAIN:
goto keep_locked;
if (!may_enter_fs)
goto keep_locked;
- if (laptop_mode && !sc->may_writepage)
+ if (!sc->may_writepage)
goto keep_locked;
/* Page is dirty, try to write it out here */
goto free_it;
}
- if (!mapping)
- goto keep_locked; /* truncate got there first */
-
- write_lock_irq(&mapping->tree_lock);
-
- /*
- * The non-racy check for busy page. It is critical to check
- * PageDirty _after_ making sure that the page is freeable and
- * not in use by anybody. (pagecache + us == 2)
- */
- if (unlikely(page_count(page) != 2))
- goto cannot_free;
- smp_rmb();
- if (unlikely(PageDirty(page)))
- goto cannot_free;
-
-#ifdef CONFIG_SWAP
- if (PageSwapCache(page)) {
- swp_entry_t swap = { .val = page_private(page) };
- __delete_from_swap_cache(page);
- write_unlock_irq(&mapping->tree_lock);
- swap_free(swap);
- __put_page(page); /* The pagecache ref */
- goto free_it;
- }
-#endif /* CONFIG_SWAP */
-
- __remove_from_page_cache(page);
- write_unlock_irq(&mapping->tree_lock);
- __put_page(page);
+ if (!remove_mapping(mapping, page))
+ goto keep_locked;
free_it:
unlock_page(page);
- reclaimed++;
+ nr_reclaimed++;
if (!pagevec_add(&freed_pvec, page))
__pagevec_release_nonlru(&freed_pvec);
continue;
-cannot_free:
- write_unlock_irq(&mapping->tree_lock);
- goto keep_locked;
-
activate_locked:
SetPageActive(page);
pgactivate++;
if (pagevec_count(&freed_pvec))
__pagevec_release_nonlru(&freed_pvec);
mod_page_state(pgactivate, pgactivate);
- sc->nr_reclaimed += reclaimed;
- return reclaimed;
+ return nr_reclaimed;
+}
+
+#ifdef CONFIG_MIGRATION
+static inline void move_to_lru(struct page *page)
+{
+ list_del(&page->lru);
+ if (PageActive(page)) {
+ /*
+ * lru_cache_add_active checks that
+ * the PG_active bit is off.
+ */
+ ClearPageActive(page);
+ lru_cache_add_active(page);
+ } else {
+ lru_cache_add(page);
+ }
+ put_page(page);
+}
+
+/*
+ * Add isolated pages on the list back to the LRU.
+ *
+ * returns the number of pages put back.
+ */
+unsigned long putback_lru_pages(struct list_head *l)
+{
+ struct page *page;
+ struct page *page2;
+ unsigned long count = 0;
+
+ list_for_each_entry_safe(page, page2, l, lru) {
+ move_to_lru(page);
+ count++;
+ }
+ return count;
+}
+
+/*
+ * Non migratable page
+ */
+int fail_migrate_page(struct page *newpage, struct page *page)
+{
+ return -EIO;
+}
+EXPORT_SYMBOL(fail_migrate_page);
+
+/*
+ * swapout a single page
+ * page is locked upon entry, unlocked on exit
+ */
+static int swap_page(struct page *page)
+{
+ struct address_space *mapping = page_mapping(page);
+
+ if (page_mapped(page) && mapping)
+ if (try_to_unmap(page, 1) != SWAP_SUCCESS)
+ goto unlock_retry;
+
+ if (PageDirty(page)) {
+ /* Page is dirty, try to write it out here */
+ switch(pageout(page, mapping)) {
+ case PAGE_KEEP:
+ case PAGE_ACTIVATE:
+ goto unlock_retry;
+
+ case PAGE_SUCCESS:
+ goto retry;
+
+ case PAGE_CLEAN:
+ ; /* try to free the page below */
+ }
+ }
+
+ if (PagePrivate(page)) {
+ if (!try_to_release_page(page, GFP_KERNEL) ||
+ (!mapping && page_count(page) == 1))
+ goto unlock_retry;
+ }
+
+ if (remove_mapping(mapping, page)) {
+ /* Success */
+ unlock_page(page);
+ return 0;
+ }
+
+unlock_retry:
+ unlock_page(page);
+
+retry:
+ return -EAGAIN;
+}
+EXPORT_SYMBOL(swap_page);
+
+/*
+ * Page migration was first developed in the context of the memory hotplug
+ * project. The main authors of the migration code are:
+ *
+ * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
+ * Hirokazu Takahashi <taka@valinux.co.jp>
+ * Dave Hansen <haveblue@us.ibm.com>
+ * Christoph Lameter <clameter@sgi.com>
+ */
+
+/*
+ * Remove references for a page and establish the new page with the correct
+ * basic settings to be able to stop accesses to the page.
+ */
+int migrate_page_remove_references(struct page *newpage,
+ struct page *page, int nr_refs)
+{
+ struct address_space *mapping = page_mapping(page);
+ struct page **radix_pointer;
+
+ /*
+ * Avoid doing any of the following work if the page count
+ * indicates that the page is in use or truncate has removed
+ * the page.
+ */
+ if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
+ return -EAGAIN;
+
+ /*
+ * Establish swap ptes for anonymous pages or destroy pte
+ * maps for files.
+ *
+ * In order to reestablish file backed mappings the fault handlers
+ * will take the radix tree_lock which may then be used to stop
+ * processses from accessing this page until the new page is ready.
+ *
+ * A process accessing via a swap pte (an anonymous page) will take a
+ * page_lock on the old page which will block the process until the
+ * migration attempt is complete. At that time the PageSwapCache bit
+ * will be examined. If the page was migrated then the PageSwapCache
+ * bit will be clear and the operation to retrieve the page will be
+ * retried which will find the new page in the radix tree. Then a new
+ * direct mapping may be generated based on the radix tree contents.
+ *
+ * If the page was not migrated then the PageSwapCache bit
+ * is still set and the operation may continue.
+ */
+ if (try_to_unmap(page, 1) == SWAP_FAIL)
+ /* A vma has VM_LOCKED set -> Permanent failure */
+ return -EPERM;
+
+ /*
+ * Give up if we were unable to remove all mappings.
+ */
+ if (page_mapcount(page))
+ return -EAGAIN;
+
+ write_lock_irq(&mapping->tree_lock);
+
+ radix_pointer = (struct page **)radix_tree_lookup_slot(
+ &mapping->page_tree,
+ page_index(page));
+
+ if (!page_mapping(page) || page_count(page) != nr_refs ||
+ *radix_pointer != page) {
+ write_unlock_irq(&mapping->tree_lock);
+ return -EAGAIN;
+ }
+
+ /*
+ * Now we know that no one else is looking at the page.
+ *
+ * Certain minimal information about a page must be available
+ * in order for other subsystems to properly handle the page if they
+ * find it through the radix tree update before we are finished
+ * copying the page.
+ */
+ get_page(newpage);
+ newpage->index = page->index;
+ newpage->mapping = page->mapping;
+ if (PageSwapCache(page)) {
+ SetPageSwapCache(newpage);
+ set_page_private(newpage, page_private(page));
+ }
+
+ *radix_pointer = newpage;
+ __put_page(page);
+ write_unlock_irq(&mapping->tree_lock);
+
+ return 0;
+}
+EXPORT_SYMBOL(migrate_page_remove_references);
+
+/*
+ * Copy the page to its new location
+ */
+void migrate_page_copy(struct page *newpage, struct page *page)
+{
+ copy_highpage(newpage, page);
+
+ if (PageError(page))
+ SetPageError(newpage);
+ if (PageReferenced(page))
+ SetPageReferenced(newpage);
+ if (PageUptodate(page))
+ SetPageUptodate(newpage);
+ if (PageActive(page))
+ SetPageActive(newpage);
+ if (PageChecked(page))
+ SetPageChecked(newpage);
+ if (PageMappedToDisk(page))
+ SetPageMappedToDisk(newpage);
+
+ if (PageDirty(page)) {
+ clear_page_dirty_for_io(page);
+ set_page_dirty(newpage);
+ }
+
+ ClearPageSwapCache(page);
+ ClearPageActive(page);
+ ClearPagePrivate(page);
+ set_page_private(page, 0);
+ page->mapping = NULL;
+
+ /*
+ * If any waiters have accumulated on the new page then
+ * wake them up.
+ */
+ if (PageWriteback(newpage))
+ end_page_writeback(newpage);
+}
+EXPORT_SYMBOL(migrate_page_copy);
+
+/*
+ * Common logic to directly migrate a single page suitable for
+ * pages that do not use PagePrivate.
+ *
+ * Pages are locked upon entry and exit.
+ */
+int migrate_page(struct page *newpage, struct page *page)
+{
+ int rc;
+
+ BUG_ON(PageWriteback(page)); /* Writeback must be complete */
+
+ rc = migrate_page_remove_references(newpage, page, 2);
+
+ if (rc)
+ return rc;
+
+ migrate_page_copy(newpage, page);
+
+ /*
+ * Remove auxiliary swap entries and replace
+ * them with real ptes.
+ *
+ * Note that a real pte entry will allow processes that are not
+ * waiting on the page lock to use the new page via the page tables
+ * before the new page is unlocked.
+ */
+ remove_from_swap(newpage);
+ return 0;
+}
+EXPORT_SYMBOL(migrate_page);
+
+/*
+ * migrate_pages
+ *
+ * Two lists are passed to this function. The first list
+ * contains the pages isolated from the LRU to be migrated.
+ * The second list contains new pages that the pages isolated
+ * can be moved to. If the second list is NULL then all
+ * pages are swapped out.
+ *
+ * The function returns after 10 attempts or if no pages
+ * are movable anymore because to has become empty
+ * or no retryable pages exist anymore.
+ *
+ * Return: Number of pages not migrated when "to" ran empty.
+ */
+unsigned long migrate_pages(struct list_head *from, struct list_head *to,
+ struct list_head *moved, struct list_head *failed)
+{
+ unsigned long retry;
+ unsigned long nr_failed = 0;
+ int pass = 0;
+ struct page *page;
+ struct page *page2;
+ int swapwrite = current->flags & PF_SWAPWRITE;
+ int rc;
+
+ if (!swapwrite)
+ current->flags |= PF_SWAPWRITE;
+
+redo:
+ retry = 0;
+
+ list_for_each_entry_safe(page, page2, from, lru) {
+ struct page *newpage = NULL;
+ struct address_space *mapping;
+
+ cond_resched();
+
+ rc = 0;
+ if (page_count(page) == 1)
+ /* page was freed from under us. So we are done. */
+ goto next;
+
+ if (to && list_empty(to))
+ break;
+
+ /*
+ * Skip locked pages during the first two passes to give the
+ * functions holding the lock time to release the page. Later we
+ * use lock_page() to have a higher chance of acquiring the
+ * lock.
+ */
+ rc = -EAGAIN;
+ if (pass > 2)
+ lock_page(page);
+ else
+ if (TestSetPageLocked(page))
+ goto next;
+
+ /*
+ * Only wait on writeback if we have already done a pass where
+ * we we may have triggered writeouts for lots of pages.
+ */
+ if (pass > 0) {
+ wait_on_page_writeback(page);
+ } else {
+ if (PageWriteback(page))
+ goto unlock_page;
+ }
+
+ /*
+ * Anonymous pages must have swap cache references otherwise
+ * the information contained in the page maps cannot be
+ * preserved.
+ */
+ if (PageAnon(page) && !PageSwapCache(page)) {
+ if (!add_to_swap(page, GFP_KERNEL)) {
+ rc = -ENOMEM;
+ goto unlock_page;
+ }
+ }
+
+ if (!to) {
+ rc = swap_page(page);
+ goto next;
+ }
+
+ newpage = lru_to_page(to);
+ lock_page(newpage);
+
+ /*
+ * Pages are properly locked and writeback is complete.
+ * Try to migrate the page.
+ */
+ mapping = page_mapping(page);
+ if (!mapping)
+ goto unlock_both;
+
+ if (mapping->a_ops->migratepage) {
+ /*
+ * Most pages have a mapping and most filesystems
+ * should provide a migration function. Anonymous
+ * pages are part of swap space which also has its
+ * own migration function. This is the most common
+ * path for page migration.
+ */
+ rc = mapping->a_ops->migratepage(newpage, page);
+ goto unlock_both;
+ }
+
+ /*
+ * Default handling if a filesystem does not provide
+ * a migration function. We can only migrate clean
+ * pages so try to write out any dirty pages first.
+ */
+ if (PageDirty(page)) {
+ switch (pageout(page, mapping)) {
+ case PAGE_KEEP:
+ case PAGE_ACTIVATE:
+ goto unlock_both;
+
+ case PAGE_SUCCESS:
+ unlock_page(newpage);
+ goto next;
+
+ case PAGE_CLEAN:
+ ; /* try to migrate the page below */
+ }
+ }
+
+ /*
+ * Buffers are managed in a filesystem specific way.
+ * We must have no buffers or drop them.
+ */
+ if (!page_has_buffers(page) ||
+ try_to_release_page(page, GFP_KERNEL)) {
+ rc = migrate_page(newpage, page);
+ goto unlock_both;
+ }
+
+ /*
+ * On early passes with mapped pages simply
+ * retry. There may be a lock held for some
+ * buffers that may go away. Later
+ * swap them out.
+ */
+ if (pass > 4) {
+ /*
+ * Persistently unable to drop buffers..... As a
+ * measure of last resort we fall back to
+ * swap_page().
+ */
+ unlock_page(newpage);
+ newpage = NULL;
+ rc = swap_page(page);
+ goto next;
+ }
+
+unlock_both:
+ unlock_page(newpage);
+
+unlock_page:
+ unlock_page(page);
+
+next:
+ if (rc == -EAGAIN) {
+ retry++;
+ } else if (rc) {
+ /* Permanent failure */
+ list_move(&page->lru, failed);
+ nr_failed++;
+ } else {
+ if (newpage) {
+ /* Successful migration. Return page to LRU */
+ move_to_lru(newpage);
+ }
+ list_move(&page->lru, moved);
+ }
+ }
+ if (retry && pass++ < 10)
+ goto redo;
+
+ if (!swapwrite)
+ current->flags &= ~PF_SWAPWRITE;
+
+ return nr_failed + retry;
+}
+
+/*
+ * Isolate one page from the LRU lists and put it on the
+ * indicated list with elevated refcount.
+ *
+ * Result:
+ * 0 = page not on LRU list
+ * 1 = page removed from LRU list and added to the specified list.
+ */
+int isolate_lru_page(struct page *page)
+{
+ int ret = 0;
+
+ if (PageLRU(page)) {
+ struct zone *zone = page_zone(page);
+ spin_lock_irq(&zone->lru_lock);
+ if (PageLRU(page)) {
+ ret = 1;
+ get_page(page);
+ ClearPageLRU(page);
+ if (PageActive(page))
+ del_page_from_active_list(zone, page);
+ else
+ del_page_from_inactive_list(zone, page);
+ }
+ spin_unlock_irq(&zone->lru_lock);
+ }
+
+ return ret;
}
+#endif
/*
* zone->lru_lock is heavily contended. Some of the functions that
*
* returns how many pages were moved onto *@dst.
*/
-static int isolate_lru_pages(int nr_to_scan, struct list_head *src,
- struct list_head *dst, int *scanned)
+static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
+ struct list_head *src, struct list_head *dst,
+ unsigned long *scanned)
{
- int nr_taken = 0;
+ unsigned long nr_taken = 0;
struct page *page;
- int scan = 0;
+ unsigned long scan = 0;
while (scan++ < nr_to_scan && !list_empty(src)) {
+ struct list_head *target;
page = lru_to_page(src);
prefetchw_prev_lru_page(page, src, flags);
- if (!TestClearPageLRU(page))
- BUG();
+ BUG_ON(!PageLRU(page));
+
list_del(&page->lru);
- if (get_page_testone(page)) {
+ target = src;
+ if (likely(get_page_unless_zero(page))) {
/*
- * It is being freed elsewhere
+ * 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.
*/
- __put_page(page);
- SetPageLRU(page);
- list_add(&page->lru, src);
- continue;
- } else {
- list_add(&page->lru, dst);
+ ClearPageLRU(page);
+ target = dst;
nr_taken++;
- }
+ } /* else it is being freed elsewhere */
+
+ list_add(&page->lru, target);
}
*scanned = scan;
}
/*
- * shrink_cache() adds the number of pages reclaimed to sc->nr_reclaimed
+ * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
+ * of reclaimed pages
*/
-static void shrink_cache(struct zone *zone, struct scan_control *sc)
+static unsigned long shrink_inactive_list(unsigned long max_scan,
+ struct zone *zone, struct scan_control *sc)
{
LIST_HEAD(page_list);
struct pagevec pvec;
- int max_scan = sc->nr_to_scan;
+ unsigned long nr_scanned = 0;
+ unsigned long nr_reclaimed = 0;
pagevec_init(&pvec, 1);
lru_add_drain();
spin_lock_irq(&zone->lru_lock);
- while (max_scan > 0) {
+ do {
struct page *page;
- int nr_taken;
- int nr_scan;
- int nr_freed;
+ unsigned long nr_taken;
+ unsigned long nr_scan;
+ unsigned long nr_freed;
nr_taken = isolate_lru_pages(sc->swap_cluster_max,
&zone->inactive_list,
if (nr_taken == 0)
goto done;
- max_scan -= nr_scan;
- nr_freed = shrink_list(&page_list, sc);
-
+ nr_scanned += nr_scan;
+ nr_freed = shrink_page_list(&page_list, sc);
+ nr_reclaimed += nr_freed;
local_irq_disable();
if (current_is_kswapd()) {
__mod_page_state_zone(zone, pgscan_kswapd, nr_scan);
*/
while (!list_empty(&page_list)) {
page = lru_to_page(&page_list);
- if (TestSetPageLRU(page))
- BUG();
+ BUG_ON(PageLRU(page));
+ SetPageLRU(page);
list_del(&page->lru);
if (PageActive(page))
add_page_to_active_list(zone, page);
spin_lock_irq(&zone->lru_lock);
}
}
- }
+ } while (nr_scanned < max_scan);
spin_unlock_irq(&zone->lru_lock);
done:
pagevec_release(&pvec);
+ return nr_reclaimed;
}
/*
* The downside is that we have to touch page->_count against each page.
* But we had to alter page->flags anyway.
*/
-static void
-refill_inactive_zone(struct zone *zone, struct scan_control *sc)
+static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
+ struct scan_control *sc)
{
- int pgmoved;
+ unsigned long pgmoved;
int pgdeactivate = 0;
- int pgscanned;
- int nr_pages = sc->nr_to_scan;
+ unsigned long pgscanned;
LIST_HEAD(l_hold); /* The pages which were snipped off */
LIST_HEAD(l_inactive); /* Pages to go onto the inactive_list */
LIST_HEAD(l_active); /* Pages to go onto the active_list */
struct page *page;
struct pagevec pvec;
int reclaim_mapped = 0;
- long mapped_ratio;
- long distress;
- long swap_tendency;
+
+ if (unlikely(sc->may_swap)) {
+ long mapped_ratio;
+ long distress;
+ long swap_tendency;
+
+ /*
+ * `distress' is a measure of how much trouble we're having
+ * reclaiming pages. 0 -> no problems. 100 -> great trouble.
+ */
+ distress = 100 >> zone->prev_priority;
+
+ /*
+ * The point of this algorithm is to decide when to start
+ * reclaiming mapped memory instead of just pagecache. Work out
+ * how much memory
+ * is mapped.
+ */
+ mapped_ratio = (sc->nr_mapped * 100) / total_memory;
+
+ /*
+ * Now decide how much we really want to unmap some pages. The
+ * mapped ratio is downgraded - just because there's a lot of
+ * mapped memory doesn't necessarily mean that page reclaim
+ * isn't succeeding.
+ *
+ * The distress ratio is important - we don't want to start
+ * going oom.
+ *
+ * A 100% value of vm_swappiness overrides this algorithm
+ * altogether.
+ */
+ swap_tendency = mapped_ratio / 2 + distress + vm_swappiness;
+
+ /*
+ * Now use this metric to decide whether to start moving mapped
+ * memory onto the inactive list.
+ */
+ if (swap_tendency >= 100)
+ reclaim_mapped = 1;
+ }
lru_add_drain();
spin_lock_irq(&zone->lru_lock);
zone->nr_active -= pgmoved;
spin_unlock_irq(&zone->lru_lock);
- /*
- * `distress' is a measure of how much trouble we're having reclaiming
- * pages. 0 -> no problems. 100 -> great trouble.
- */
- distress = 100 >> zone->prev_priority;
-
- /*
- * The point of this algorithm is to decide when to start reclaiming
- * mapped memory instead of just pagecache. Work out how much memory
- * is mapped.
- */
- mapped_ratio = (sc->nr_mapped * 100) / total_memory;
-
- /*
- * Now decide how much we really want to unmap some pages. The mapped
- * ratio is downgraded - just because there's a lot of mapped memory
- * doesn't necessarily mean that page reclaim isn't succeeding.
- *
- * The distress ratio is important - we don't want to start going oom.
- *
- * A 100% value of vm_swappiness overrides this algorithm altogether.
- */
- swap_tendency = mapped_ratio / 2 + distress + vm_swappiness;
-
- /*
- * Now use this metric to decide whether to start moving mapped memory
- * onto the inactive list.
- */
- if (swap_tendency >= 100)
- reclaim_mapped = 1;
-
while (!list_empty(&l_hold)) {
cond_resched();
page = lru_to_page(&l_hold);
while (!list_empty(&l_inactive)) {
page = lru_to_page(&l_inactive);
prefetchw_prev_lru_page(page, &l_inactive, flags);
- if (TestSetPageLRU(page))
- BUG();
- if (!TestClearPageActive(page))
- BUG();
+ BUG_ON(PageLRU(page));
+ SetPageLRU(page);
+ BUG_ON(!PageActive(page));
+ ClearPageActive(page);
+
list_move(&page->lru, &zone->inactive_list);
pgmoved++;
if (!pagevec_add(&pvec, page)) {
while (!list_empty(&l_active)) {
page = lru_to_page(&l_active);
prefetchw_prev_lru_page(page, &l_active, flags);
- if (TestSetPageLRU(page))
- BUG();
+ BUG_ON(PageLRU(page));
+ SetPageLRU(page);
BUG_ON(!PageActive(page));
list_move(&page->lru, &zone->active_list);
pgmoved++;
/*
* This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
*/
-static void
-shrink_zone(struct zone *zone, struct scan_control *sc)
+static unsigned long shrink_zone(int priority, struct zone *zone,
+ struct scan_control *sc)
{
unsigned long nr_active;
unsigned long nr_inactive;
+ unsigned long nr_to_scan;
+ unsigned long nr_reclaimed = 0;
atomic_inc(&zone->reclaim_in_progress);
* Add one to `nr_to_scan' just to make sure that the kernel will
* slowly sift through the active list.
*/
- zone->nr_scan_active += (zone->nr_active >> sc->priority) + 1;
+ zone->nr_scan_active += (zone->nr_active >> priority) + 1;
nr_active = zone->nr_scan_active;
if (nr_active >= sc->swap_cluster_max)
zone->nr_scan_active = 0;
else
nr_active = 0;
- zone->nr_scan_inactive += (zone->nr_inactive >> sc->priority) + 1;
+ zone->nr_scan_inactive += (zone->nr_inactive >> priority) + 1;
nr_inactive = zone->nr_scan_inactive;
if (nr_inactive >= sc->swap_cluster_max)
zone->nr_scan_inactive = 0;
while (nr_active || nr_inactive) {
if (nr_active) {
- sc->nr_to_scan = min(nr_active,
+ nr_to_scan = min(nr_active,
(unsigned long)sc->swap_cluster_max);
- nr_active -= sc->nr_to_scan;
- refill_inactive_zone(zone, sc);
+ nr_active -= nr_to_scan;
+ shrink_active_list(nr_to_scan, zone, sc);
}
if (nr_inactive) {
- sc->nr_to_scan = min(nr_inactive,
+ nr_to_scan = min(nr_inactive,
(unsigned long)sc->swap_cluster_max);
- nr_inactive -= sc->nr_to_scan;
- shrink_cache(zone, sc);
+ nr_inactive -= nr_to_scan;
+ nr_reclaimed += shrink_inactive_list(nr_to_scan, zone,
+ sc);
}
}
throttle_vm_writeout();
atomic_dec(&zone->reclaim_in_progress);
+ return nr_reclaimed;
}
/*
* If a zone is deemed to be full of pinned pages then just give it a light
* scan then give up on it.
*/
-static void
-shrink_caches(struct zone **zones, struct scan_control *sc)
+static unsigned long shrink_zones(int priority, struct zone **zones,
+ struct scan_control *sc)
{
+ unsigned long nr_reclaimed = 0;
int i;
for (i = 0; zones[i] != NULL; i++) {
if (!cpuset_zone_allowed(zone, __GFP_HARDWALL))
continue;
- zone->temp_priority = sc->priority;
- if (zone->prev_priority > sc->priority)
- zone->prev_priority = sc->priority;
+ zone->temp_priority = priority;
+ if (zone->prev_priority > priority)
+ zone->prev_priority = priority;
- if (zone->all_unreclaimable && sc->priority != DEF_PRIORITY)
+ if (zone->all_unreclaimable && priority != DEF_PRIORITY)
continue; /* Let kswapd poll it */
- shrink_zone(zone, sc);
+ nr_reclaimed += shrink_zone(priority, zone, sc);
}
+ return nr_reclaimed;
}
/*
* holds filesystem locks which prevent writeout this might not work, and the
* allocation attempt will fail.
*/
-int try_to_free_pages(struct zone **zones, gfp_t gfp_mask)
+unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask)
{
int priority;
int ret = 0;
- int total_scanned = 0, total_reclaimed = 0;
+ unsigned long total_scanned = 0;
+ unsigned long nr_reclaimed = 0;
struct reclaim_state *reclaim_state = current->reclaim_state;
- struct scan_control sc;
unsigned long lru_pages = 0;
int i;
-
- sc.gfp_mask = gfp_mask;
- sc.may_writepage = 0;
+ struct scan_control sc = {
+ .gfp_mask = gfp_mask,
+ .may_writepage = !laptop_mode,
+ .swap_cluster_max = SWAP_CLUSTER_MAX,
+ .may_swap = 1,
+ };
inc_page_state(allocstall);
for (priority = DEF_PRIORITY; priority >= 0; priority--) {
sc.nr_mapped = read_page_state(nr_mapped);
sc.nr_scanned = 0;
- sc.nr_reclaimed = 0;
- sc.priority = priority;
- sc.swap_cluster_max = SWAP_CLUSTER_MAX;
if (!priority)
disable_swap_token();
- shrink_caches(zones, &sc);
+ nr_reclaimed += shrink_zones(priority, zones, &sc);
shrink_slab(sc.nr_scanned, gfp_mask, lru_pages);
if (reclaim_state) {
- sc.nr_reclaimed += reclaim_state->reclaimed_slab;
+ nr_reclaimed += reclaim_state->reclaimed_slab;
reclaim_state->reclaimed_slab = 0;
}
total_scanned += sc.nr_scanned;
- total_reclaimed += sc.nr_reclaimed;
- if (total_reclaimed >= sc.swap_cluster_max) {
+ if (nr_reclaimed >= sc.swap_cluster_max) {
ret = 1;
goto out;
}
* that's undesirable in laptop mode, where we *want* lumpy
* writeout. So in laptop mode, write out the whole world.
*/
- if (total_scanned > sc.swap_cluster_max + sc.swap_cluster_max/2) {
+ if (total_scanned > sc.swap_cluster_max +
+ sc.swap_cluster_max / 2) {
wakeup_pdflush(laptop_mode ? 0 : total_scanned);
sc.may_writepage = 1;
}
* the page allocator fallback scheme to ensure that aging of pages is balanced
* across the zones.
*/
-static int balance_pgdat(pg_data_t *pgdat, int nr_pages, int order)
+static unsigned long balance_pgdat(pg_data_t *pgdat, unsigned long nr_pages,
+ int order)
{
- int to_free = nr_pages;
+ unsigned long to_free = nr_pages;
int all_zones_ok;
int priority;
int i;
- int total_scanned, total_reclaimed;
+ unsigned long total_scanned;
+ unsigned long nr_reclaimed;
struct reclaim_state *reclaim_state = current->reclaim_state;
- struct scan_control sc;
+ struct scan_control sc = {
+ .gfp_mask = GFP_KERNEL,
+ .may_swap = 1,
+ .swap_cluster_max = nr_pages ? nr_pages : SWAP_CLUSTER_MAX,
+ };
loop_again:
total_scanned = 0;
- total_reclaimed = 0;
- sc.gfp_mask = GFP_KERNEL;
- sc.may_writepage = 0;
+ nr_reclaimed = 0;
+ sc.may_writepage = !laptop_mode,
sc.nr_mapped = read_page_state(nr_mapped);
inc_page_state(pageoutrun);
if (zone->prev_priority > priority)
zone->prev_priority = priority;
sc.nr_scanned = 0;
- sc.nr_reclaimed = 0;
- sc.priority = priority;
- sc.swap_cluster_max = nr_pages? nr_pages : SWAP_CLUSTER_MAX;
- atomic_inc(&zone->reclaim_in_progress);
- shrink_zone(zone, &sc);
- atomic_dec(&zone->reclaim_in_progress);
+ nr_reclaimed += shrink_zone(priority, zone, &sc);
reclaim_state->reclaimed_slab = 0;
nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
lru_pages);
- sc.nr_reclaimed += reclaim_state->reclaimed_slab;
- total_reclaimed += sc.nr_reclaimed;
+ nr_reclaimed += reclaim_state->reclaimed_slab;
total_scanned += sc.nr_scanned;
if (zone->all_unreclaimable)
continue;
* even in laptop mode
*/
if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
- total_scanned > total_reclaimed+total_reclaimed/2)
+ total_scanned > nr_reclaimed + nr_reclaimed / 2)
sc.may_writepage = 1;
}
- if (nr_pages && to_free > total_reclaimed)
+ if (nr_pages && to_free > nr_reclaimed)
continue; /* swsusp: need to do more work */
if (all_zones_ok)
break; /* kswapd: all done */
* matches the direct reclaim path behaviour in terms of impact
* on zone->*_priority.
*/
- if ((total_reclaimed >= SWAP_CLUSTER_MAX) && (!nr_pages))
+ if ((nr_reclaimed >= SWAP_CLUSTER_MAX) && !nr_pages)
break;
}
out:
goto loop_again;
}
- return total_reclaimed;
+ return nr_reclaimed;
}
/*
* us from recursively trying to free more memory as we're
* trying to free the first piece of memory in the first place).
*/
- tsk->flags |= PF_MEMALLOC|PF_KSWAPD;
+ tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
order = 0;
for ( ; ; ) {
* Try to free `nr_pages' of memory, system-wide. Returns the number of freed
* pages.
*/
-int shrink_all_memory(int nr_pages)
+unsigned long shrink_all_memory(unsigned long nr_pages)
{
pg_data_t *pgdat;
- int nr_to_free = nr_pages;
- int ret = 0;
+ unsigned long nr_to_free = nr_pages;
+ unsigned long ret = 0;
struct reclaim_state reclaim_state = {
.reclaimed_slab = 0,
};
current->reclaim_state = &reclaim_state;
for_each_pgdat(pgdat) {
- int freed;
+ unsigned long freed;
+
freed = balance_pgdat(pgdat, nr_to_free, 0);
ret += freed;
nr_to_free -= freed;
- if (nr_to_free <= 0)
+ if ((long)nr_to_free <= 0)
break;
}
current->reclaim_state = NULL;
away, we get changed to run anywhere: as the first one comes back,
restore their cpu bindings. */
static int __devinit cpu_callback(struct notifier_block *nfb,
- unsigned long action,
- void *hcpu)
+ unsigned long action, void *hcpu)
{
pg_data_t *pgdat;
cpumask_t mask;
static int __init kswapd_init(void)
{
pg_data_t *pgdat;
+
swap_setup();
- for_each_pgdat(pgdat)
- pgdat->kswapd
- = find_task_by_pid(kernel_thread(kswapd, pgdat, CLONE_KERNEL));
+ for_each_pgdat(pgdat) {
+ pid_t pid;
+
+ pid = kernel_thread(kswapd, pgdat, CLONE_KERNEL);
+ BUG_ON(pid < 0);
+ pgdat->kswapd = find_task_by_pid(pid);
+ }
total_memory = nr_free_pagecache_pages();
hotcpu_notifier(cpu_callback, 0);
return 0;
}
module_init(kswapd_init)
+
+#ifdef CONFIG_NUMA
+/*
+ * Zone reclaim mode
+ *
+ * If non-zero call zone_reclaim when the number of free pages falls below
+ * the watermarks.
+ *
+ * In the future we may add flags to the mode. However, the page allocator
+ * should only have to check that zone_reclaim_mode != 0 before calling
+ * zone_reclaim().
+ */
+int zone_reclaim_mode __read_mostly;
+
+#define RECLAIM_OFF 0
+#define RECLAIM_ZONE (1<<0) /* Run shrink_cache on the zone */
+#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
+#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
+#define RECLAIM_SLAB (1<<3) /* Do a global slab shrink if the zone is out of memory */
+
+/*
+ * Mininum time between zone reclaim scans
+ */
+int zone_reclaim_interval __read_mostly = 30*HZ;
+
+/*
+ * Priority for ZONE_RECLAIM. This determines the fraction of pages
+ * of a node considered for each zone_reclaim. 4 scans 1/16th of
+ * a zone.
+ */
+#define ZONE_RECLAIM_PRIORITY 4
+
+/*
+ * Try to free up some pages from this zone through reclaim.
+ */
+static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
+{
+ const unsigned long nr_pages = 1 << order;
+ struct task_struct *p = current;
+ struct reclaim_state reclaim_state;
+ int priority;
+ unsigned long nr_reclaimed = 0;
+ struct scan_control sc = {
+ .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
+ .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP),
+ .nr_mapped = read_page_state(nr_mapped),
+ .swap_cluster_max = max_t(unsigned long, nr_pages,
+ SWAP_CLUSTER_MAX),
+ .gfp_mask = gfp_mask,
+ };
+
+ disable_swap_token();
+ cond_resched();
+ /*
+ * We need to be able to allocate from the reserves for RECLAIM_SWAP
+ * and we also need to be able to write out pages for RECLAIM_WRITE
+ * and RECLAIM_SWAP.
+ */
+ p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
+ reclaim_state.reclaimed_slab = 0;
+ p->reclaim_state = &reclaim_state;
+
+ /*
+ * Free memory by calling shrink zone with increasing priorities
+ * until we have enough memory freed.
+ */
+ priority = ZONE_RECLAIM_PRIORITY;
+ do {
+ nr_reclaimed += shrink_zone(priority, zone, &sc);
+ priority--;
+ } while (priority >= 0 && nr_reclaimed < nr_pages);
+
+ if (nr_reclaimed < nr_pages && (zone_reclaim_mode & RECLAIM_SLAB)) {
+ /*
+ * shrink_slab does not currently allow us to determine
+ * how many pages were freed in the zone. So we just
+ * shake the slab and then go offnode for a single allocation.
+ *
+ * shrink_slab will free memory on all zones and may take
+ * a long time.
+ */
+ shrink_slab(sc.nr_scanned, gfp_mask, order);
+ }
+
+ p->reclaim_state = NULL;
+ current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
+
+ if (nr_reclaimed == 0)
+ zone->last_unsuccessful_zone_reclaim = jiffies;
+
+ return nr_reclaimed >= nr_pages;
+}
+
+int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
+{
+ cpumask_t mask;
+ int node_id;
+
+ /*
+ * Do not reclaim if there was a recent unsuccessful attempt at zone
+ * reclaim. In that case we let allocations go off node for the
+ * zone_reclaim_interval. Otherwise we would scan for each off-node
+ * page allocation.
+ */
+ if (time_before(jiffies,
+ zone->last_unsuccessful_zone_reclaim + zone_reclaim_interval))
+ return 0;
+
+ /*
+ * Avoid concurrent zone reclaims, do not reclaim in a zone that does
+ * not have reclaimable pages and if we should not delay the allocation
+ * then do not scan.
+ */
+ if (!(gfp_mask & __GFP_WAIT) ||
+ zone->all_unreclaimable ||
+ atomic_read(&zone->reclaim_in_progress) > 0 ||
+ (current->flags & PF_MEMALLOC))
+ return 0;
+
+ /*
+ * Only run zone reclaim on the local zone or on zones that do not
+ * have associated processors. This will favor the local processor
+ * over remote processors and spread off node memory allocations
+ * as wide as possible.
+ */
+ node_id = zone->zone_pgdat->node_id;
+ mask = node_to_cpumask(node_id);
+ if (!cpus_empty(mask) && node_id != numa_node_id())
+ return 0;
+ return __zone_reclaim(zone, gfp_mask, order);
+}
+#endif
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff