#include <linux/highmem.h>
#include <linux/file.h>
#include <linux/writeback.h>
-#include <linux/suspend.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h> /* for try_to_release_page(),
buffer_heads_over_limit */
#include <linux/topology.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
+#include <linux/rwsem.h>
-#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
#include <linux/swapops.h>
+/* possible outcome of pageout() */
+typedef enum {
+ /* failed to write page out, page is locked */
+ PAGE_KEEP,
+ /* move page to the active list, page is locked */
+ PAGE_ACTIVATE,
+ /* page has been sent to the disk successfully, page is unlocked */
+ PAGE_SUCCESS,
+ /* page is clean and locked */
+ PAGE_CLEAN,
+} 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 */
+
+ /* How many pages shrink_cache() should reclaim */
+ int nr_to_reclaim;
+
+ /* Ask shrink_caches, or shrink_zone to scan at this priority */
+ unsigned int priority;
+
+ /* This context's GFP mask */
+ unsigned int gfp_mask;
+
+ int may_writepage;
+};
+
/*
- * From 0 .. 100. Higher means more swappy.
+ * The list of shrinker callbacks used by to apply pressure to
+ * ageable caches.
*/
-int vm_swappiness = 60;
-static long total_memory;
+struct shrinker {
+ shrinker_t shrinker;
+ struct list_head list;
+ int seeks; /* seeks to recreate an obj */
+ long nr; /* objs pending delete */
+};
#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
if ((_page)->lru.prev != _base) { \
struct page *prev; \
\
- prev = lru_to_page(&(_page->lru)); \
+ prev = lru_to_page(&(_page->lru)); \
prefetchw(&prev->_field); \
} \
} while (0)
#endif
/*
- * The list of shrinker callbacks used by to apply pressure to
- * ageable caches.
+ * From 0 .. 100. Higher means more swappy.
*/
-struct shrinker {
- shrinker_t shrinker;
- struct list_head list;
- int seeks; /* seeks to recreate an obj */
- long nr; /* objs pending delete */
-};
+int vm_swappiness = 60;
+static long total_memory;
static LIST_HEAD(shrinker_list);
-static DECLARE_MUTEX(shrinker_sem);
+static DECLARE_RWSEM(shrinker_rwsem);
/*
* Add a shrinker callback to be called from the vm
shrinker->shrinker = theshrinker;
shrinker->seeks = seeks;
shrinker->nr = 0;
- down(&shrinker_sem);
+ down_write(&shrinker_rwsem);
list_add(&shrinker->list, &shrinker_list);
- up(&shrinker_sem);
+ up_write(&shrinker_rwsem);
}
return shrinker;
}
-
EXPORT_SYMBOL(set_shrinker);
/*
*/
void remove_shrinker(struct shrinker *shrinker)
{
- down(&shrinker_sem);
+ down_write(&shrinker_rwsem);
list_del(&shrinker->list);
- up(&shrinker_sem);
+ up_write(&shrinker_rwsem);
kfree(shrinker);
}
-
EXPORT_SYMBOL(remove_shrinker);
-
+
#define SHRINK_BATCH 128
/*
* Call the shrink functions to age shrinkable caches
* slab to avoid swapping.
*
* We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
+ *
+ * `lru_pages' represents the number of on-LRU pages in all the zones which
+ * are eligible for the caller's allocation attempt. It is used for balancing
+ * slab reclaim versus page reclaim.
*/
-static int shrink_slab(unsigned long scanned, unsigned int gfp_mask)
+static int shrink_slab(unsigned long scanned, unsigned int gfp_mask,
+ unsigned long lru_pages)
{
struct shrinker *shrinker;
- long pages;
- if (down_trylock(&shrinker_sem))
+ if (scanned == 0)
+ scanned = SWAP_CLUSTER_MAX;
+
+ if (!down_read_trylock(&shrinker_rwsem))
return 0;
- pages = nr_used_zone_pages();
list_for_each_entry(shrinker, &shrinker_list, list) {
unsigned long long delta;
+ unsigned long total_scan;
delta = (4 * scanned) / shrinker->seeks;
delta *= (*shrinker->shrinker)(0, gfp_mask);
- do_div(delta, pages + 1);
+ do_div(delta, lru_pages + 1);
shrinker->nr += delta;
- if (shrinker->nr > SHRINK_BATCH) {
- long nr_to_scan = shrinker->nr;
-
- shrinker->nr = 0;
- mod_page_state(slabs_scanned, nr_to_scan);
- while (nr_to_scan) {
- long this_scan = nr_to_scan;
-
- if (this_scan > 128)
- this_scan = 128;
- (*shrinker->shrinker)(this_scan, gfp_mask);
- nr_to_scan -= this_scan;
- cond_resched();
- }
+ if (shrinker->nr < 0)
+ shrinker->nr = LONG_MAX; /* It wrapped! */
+
+ total_scan = shrinker->nr;
+ shrinker->nr = 0;
+
+ while (total_scan >= SHRINK_BATCH) {
+ long this_scan = SHRINK_BATCH;
+ int shrink_ret;
+
+ shrink_ret = (*shrinker->shrinker)(this_scan, gfp_mask);
+ if (shrink_ret == -1)
+ break;
+ mod_page_state(slabs_scanned, this_scan);
+ total_scan -= this_scan;
+
+ cond_resched();
}
+
+ shrinker->nr += total_scan;
}
- up(&shrinker_sem);
+ up_read(&shrinker_rwsem);
return 0;
}
-/* Must be called with page's rmap lock held. */
+/* Called without lock on whether page is mapped, so answer is unstable */
static inline int page_mapping_inuse(struct page *page)
{
struct address_space *mapping;
}
/*
- * shrink_list returns the number of reclaimed pages
+ * pageout is called by shrink_list() for each dirty page. Calls ->writepage().
*/
-static int
-shrink_list(struct list_head *page_list, unsigned int gfp_mask,
- int *nr_scanned, int do_writepage)
+static pageout_t pageout(struct page *page, struct address_space *mapping)
+{
+ /*
+ * If the page is dirty, only perform writeback if that write
+ * will be non-blocking. To prevent this allocation from being
+ * stalled by pagecache activity. But note that there may be
+ * stalls if we need to run get_block(). We could test
+ * PagePrivate for that.
+ *
+ * If this process is currently in generic_file_write() against
+ * this page's queue, we can perform writeback even if that
+ * will block.
+ *
+ * If the page is swapcache, write it back even if that would
+ * block, for some throttling. This happens by accident, because
+ * swap_backing_dev_info is bust: it doesn't reflect the
+ * congestion state of the swapdevs. Easy to fix, if needed.
+ * See swapfile.c:page_queue_congested().
+ */
+ if (!is_page_cache_freeable(page))
+ return PAGE_KEEP;
+ if (!mapping)
+ return PAGE_KEEP;
+ if (mapping->a_ops->writepage == NULL)
+ return PAGE_ACTIVATE;
+ if (!may_write_to_queue(mapping->backing_dev_info))
+ return PAGE_KEEP;
+
+ if (clear_page_dirty_for_io(page)) {
+ int res;
+ struct writeback_control wbc = {
+ .sync_mode = WB_SYNC_NONE,
+ .nr_to_write = SWAP_CLUSTER_MAX,
+ .nonblocking = 1,
+ .for_reclaim = 1,
+ };
+
+ SetPageReclaim(page);
+ res = mapping->a_ops->writepage(page, &wbc);
+ if (res < 0)
+ handle_write_error(mapping, page, res);
+ if (res == WRITEPAGE_ACTIVATE) {
+ ClearPageReclaim(page);
+ return PAGE_ACTIVATE;
+ }
+ if (!PageWriteback(page)) {
+ /* synchronous write or broken a_ops? */
+ ClearPageReclaim(page);
+ }
+
+ return PAGE_SUCCESS;
+ }
+
+ return PAGE_CLEAN;
+}
+
+/*
+ * shrink_list adds the number of reclaimed pages to sc->nr_reclaimed
+ */
+static int shrink_list(struct list_head *page_list, struct scan_control *sc)
{
- struct address_space *mapping;
LIST_HEAD(ret_pages);
struct pagevec freed_pvec;
int pgactivate = 0;
- int ret = 0;
+ int reclaimed = 0;
cond_resched();
pagevec_init(&freed_pvec, 1);
while (!list_empty(page_list)) {
+ struct address_space *mapping;
struct page *page;
int may_enter_fs;
int referenced;
+ cond_resched();
+
page = lru_to_page(page_list);
list_del(&page->lru);
if (TestSetPageLocked(page))
goto keep;
+ BUG_ON(PageActive(page));
+
+ sc->nr_scanned++;
/* Double the slab pressure for mapped and swapcache pages */
if (page_mapped(page) || PageSwapCache(page))
- (*nr_scanned)++;
-
- BUG_ON(PageActive(page));
+ sc->nr_scanned++;
if (PageWriteback(page))
goto keep_locked;
- rmap_lock(page);
- referenced = page_referenced(page);
- if (referenced && page_mapping_inuse(page)) {
- /* In active use or really unfreeable. Activate it. */
- rmap_unlock(page);
+ referenced = page_referenced(page, 1, sc->priority <= 0);
+ /* In active use or really unfreeable? Activate it. */
+ if (referenced && page_mapping_inuse(page))
goto activate_locked;
- }
-
- mapping = page_mapping(page);
- may_enter_fs = (gfp_mask & __GFP_FS);
#ifdef CONFIG_SWAP
/*
* Anonymous process memory has backing store?
* Try to allocate it some swap space here.
- *
- * XXX: implement swap clustering ?
*/
if (PageAnon(page) && !PageSwapCache(page)) {
- rmap_unlock(page);
if (!add_to_swap(page))
goto activate_locked;
- rmap_lock(page);
- }
- if (PageSwapCache(page)) {
- mapping = &swapper_space;
- may_enter_fs = (gfp_mask & __GFP_IO);
}
#endif /* CONFIG_SWAP */
+ mapping = page_mapping(page);
+ may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
+ (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
+
/*
* The page is mapped into the page tables of one or more
* processes. Try to unmap it here.
if (page_mapped(page) && mapping) {
switch (try_to_unmap(page)) {
case SWAP_FAIL:
- rmap_unlock(page);
goto activate_locked;
case SWAP_AGAIN:
- rmap_unlock(page);
goto keep_locked;
case SWAP_SUCCESS:
; /* try to free the page below */
}
}
- rmap_unlock(page);
- /*
- * If the page is dirty, only perform writeback if that write
- * will be non-blocking. To prevent this allocation from being
- * stalled by pagecache activity. But note that there may be
- * stalls if we need to run get_block(). We could test
- * PagePrivate for that.
- *
- * If this process is currently in generic_file_write() against
- * this page's queue, we can perform writeback even if that
- * will block.
- *
- * If the page is swapcache, write it back even if that would
- * block, for some throttling. This happens by accident, because
- * swap_backing_dev_info is bust: it doesn't reflect the
- * congestion state of the swapdevs. Easy to fix, if needed.
- * See swapfile.c:page_queue_congested().
- */
if (PageDirty(page)) {
if (referenced)
goto keep_locked;
- if (!is_page_cache_freeable(page))
- goto keep_locked;
- if (!mapping)
- goto keep_locked;
- if (mapping->a_ops->writepage == NULL)
- goto activate_locked;
if (!may_enter_fs)
goto keep_locked;
- if (!may_write_to_queue(mapping->backing_dev_info))
+ if (laptop_mode && !sc->may_writepage)
goto keep_locked;
- if (laptop_mode && !do_writepage)
+
+ /* Page is dirty, try to write it out here */
+ switch(pageout(page, mapping)) {
+ case PAGE_KEEP:
goto keep_locked;
- if (clear_page_dirty_for_io(page)) {
- int res;
- struct writeback_control wbc = {
- .sync_mode = WB_SYNC_NONE,
- .nr_to_write = SWAP_CLUSTER_MAX,
- .nonblocking = 1,
- .for_reclaim = 1,
- };
-
- SetPageReclaim(page);
- res = mapping->a_ops->writepage(page, &wbc);
- if (res < 0)
- handle_write_error(mapping, page, res);
- if (res == WRITEPAGE_ACTIVATE) {
- ClearPageReclaim(page);
- goto activate_locked;
- }
- if (!PageWriteback(page)) {
- /* synchronous write or broken a_ops? */
- ClearPageReclaim(page);
- }
- goto keep;
+ case PAGE_ACTIVATE:
+ goto activate_locked;
+ case PAGE_SUCCESS:
+ if (PageWriteback(page) || PageDirty(page))
+ goto keep;
+ /*
+ * A synchronous write - probably a ramdisk. Go
+ * ahead and try to reclaim the page.
+ */
+ if (TestSetPageLocked(page))
+ goto keep;
+ if (PageDirty(page) || PageWriteback(page))
+ goto keep_locked;
+ mapping = page_mapping(page);
+ case PAGE_CLEAN:
+ ; /* try to free the page below */
}
}
* the pages which were not successfully invalidated in
* truncate_complete_page(). We try to drop those buffers here
* and if that worked, and the page is no longer mapped into
- * process address space (page_count == 0) it can be freed.
+ * process address space (page_count == 1) it can be freed.
* Otherwise, leave the page on the LRU so it is swappable.
*/
if (PagePrivate(page)) {
- if (!try_to_release_page(page, gfp_mask))
+ if (!try_to_release_page(page, sc->gfp_mask))
goto activate_locked;
if (!mapping && page_count(page) == 1)
goto free_it;
free_it:
unlock_page(page);
- ret++;
+ reclaimed++;
if (!pagevec_add(&freed_pvec, page))
__pagevec_release_nonlru(&freed_pvec);
continue;
if (pagevec_count(&freed_pvec))
__pagevec_release_nonlru(&freed_pvec);
mod_page_state(pgactivate, pgactivate);
- return ret;
+ sc->nr_reclaimed += reclaimed;
+ return reclaimed;
}
/*
* a batch of pages and working on them outside the lock. Any pages which were
* not freed will be added back to the LRU.
*
- * shrink_cache() is passed the number of pages to scan and returns the number
- * of pages which were reclaimed.
+ * shrink_cache() adds the number of pages reclaimed to sc->nr_reclaimed
*
* For pagecache intensive workloads, the first loop here is the hottest spot
* in the kernel (apart from the copy_*_user functions).
*/
-static int
-shrink_cache(struct zone *zone, unsigned int gfp_mask,
- int max_scan, int *total_scanned, int do_writepage)
+static void shrink_cache(struct zone *zone, struct scan_control *sc)
{
LIST_HEAD(page_list);
struct pagevec pvec;
- int ret = 0;
+ int max_scan = sc->nr_to_scan;
pagevec_init(&pvec, 1);
if (!TestClearPageLRU(page))
BUG();
list_del(&page->lru);
- if (page_count(page) == 0) {
- /* It is currently in pagevec_release() */
+ if (get_page_testone(page)) {
+ /*
+ * It is being freed elsewhere
+ */
+ __put_page(page);
SetPageLRU(page);
list_add(&page->lru, &zone->inactive_list);
continue;
}
list_add(&page->lru, &page_list);
- page_cache_get(page);
nr_taken++;
}
zone->nr_inactive -= nr_taken;
- zone->pages_scanned += nr_taken;
+ zone->pages_scanned += nr_scan;
spin_unlock_irq(&zone->lru_lock);
if (nr_taken == 0)
mod_page_state_zone(zone, pgscan_kswapd, nr_scan);
else
mod_page_state_zone(zone, pgscan_direct, nr_scan);
- nr_freed = shrink_list(&page_list, gfp_mask,
- total_scanned, do_writepage);
- *total_scanned += nr_taken;
+ nr_freed = shrink_list(&page_list, sc);
if (current_is_kswapd())
mod_page_state(kswapd_steal, nr_freed);
mod_page_state_zone(zone, pgsteal, nr_freed);
-
- ret += nr_freed;
- if (nr_freed <= 0 && list_empty(&page_list))
- goto done;
+ sc->nr_to_reclaim -= nr_freed;
spin_lock_irq(&zone->lru_lock);
/*
spin_unlock_irq(&zone->lru_lock);
done:
pagevec_release(&pvec);
- return ret;
}
/*
* It is safe to rely on PG_active against the non-LRU pages in here because
* nobody will play with that bit on a non-LRU page.
*
- * The downside is that we have to touch page->count against each page.
+ * 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, const int nr_pages_in,
- struct page_state *ps)
+refill_inactive_zone(struct zone *zone, struct scan_control *sc)
{
int pgmoved;
int pgdeactivate = 0;
- int nr_pages = nr_pages_in;
+ int pgscanned = 0;
+ int nr_pages = sc->nr_to_scan;
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 */
lru_add_drain();
pgmoved = 0;
spin_lock_irq(&zone->lru_lock);
- while (nr_pages && !list_empty(&zone->active_list)) {
+ while (pgscanned < nr_pages && !list_empty(&zone->active_list)) {
page = lru_to_page(&zone->active_list);
prefetchw_prev_lru_page(page, &zone->active_list, flags);
if (!TestClearPageLRU(page))
BUG();
list_del(&page->lru);
- if (page_count(page) == 0) {
- /* It is currently in pagevec_release() */
+ if (get_page_testone(page)) {
+ /*
+ * It was already free! release_pages() or put_page()
+ * are about to remove it from the LRU and free it. So
+ * put the refcount back and put the page back on the
+ * LRU
+ */
+ __put_page(page);
SetPageLRU(page);
list_add(&page->lru, &zone->active_list);
} else {
- page_cache_get(page);
list_add(&page->lru, &l_hold);
pgmoved++;
}
- nr_pages--;
+ pgscanned++;
}
+ zone->pages_scanned += pgscanned;
zone->nr_active -= pgmoved;
spin_unlock_irq(&zone->lru_lock);
* mapped memory instead of just pagecache. Work out how much memory
* is mapped.
*/
- mapped_ratio = (ps->nr_mapped * 100) / total_memory;
+ mapped_ratio = (sc->nr_mapped * 100) / total_memory;
/*
* Now decide how much we really want to unmap some pages. The mapped
reclaim_mapped = 1;
while (!list_empty(&l_hold)) {
+ cond_resched();
page = lru_to_page(&l_hold);
list_del(&page->lru);
if (page_mapped(page)) {
- if (!reclaim_mapped) {
- list_add(&page->lru, &l_active);
- continue;
- }
- rmap_lock(page);
- if (page_referenced(page)) {
- rmap_unlock(page);
+ if (!reclaim_mapped ||
+ (total_swap_pages == 0 && PageAnon(page)) ||
+ page_referenced(page, 0, sc->priority <= 0)) {
list_add(&page->lru, &l_active);
continue;
}
- rmap_unlock(page);
- }
- /*
- * FIXME: need to consider page_count(page) here if/when we
- * reap orphaned pages via the LRU (Daniel's locking stuff)
- */
- if (total_swap_pages == 0 && PageAnon(page)) {
- list_add(&page->lru, &l_active);
- continue;
}
list_add(&page->lru, &l_inactive);
}
spin_unlock_irq(&zone->lru_lock);
pagevec_release(&pvec);
- mod_page_state_zone(zone, pgrefill, nr_pages_in - nr_pages);
+ mod_page_state_zone(zone, pgrefill, pgscanned);
mod_page_state(pgdeactivate, pgdeactivate);
}
/*
- * Scan `nr_pages' from this zone. Returns the number of reclaimed pages.
* This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
*/
-static int
-shrink_zone(struct zone *zone, int max_scan, unsigned int gfp_mask,
- int *total_scanned, struct page_state *ps, int do_writepage)
+static void
+shrink_zone(struct zone *zone, struct scan_control *sc)
{
- unsigned long ratio;
- int count;
+ unsigned long nr_active;
+ unsigned long nr_inactive;
/*
- * Try to keep the active list 2/3 of the size of the cache. And
- * make sure that refill_inactive is given a decent number of pages.
- *
- * The "ratio+1" here is important. With pagecache-intensive workloads
- * the inactive list is huge, and `ratio' evaluates to zero all the
- * time. Which pins the active list memory. So we add one to `ratio'
- * just to make sure that the kernel will slowly sift through the
- * active list.
+ * Add one to `nr_to_scan' just to make sure that the kernel will
+ * slowly sift through the active list.
*/
- ratio = (unsigned long)SWAP_CLUSTER_MAX * zone->nr_active /
- ((zone->nr_inactive | 1) * 2);
-
- atomic_add(ratio+1, &zone->nr_scan_active);
- count = atomic_read(&zone->nr_scan_active);
- if (count >= SWAP_CLUSTER_MAX) {
- atomic_set(&zone->nr_scan_active, 0);
- refill_inactive_zone(zone, count, ps);
- }
+ zone->nr_scan_active += (zone->nr_active >> sc->priority) + 1;
+ nr_active = zone->nr_scan_active;
+ if (nr_active >= SWAP_CLUSTER_MAX)
+ zone->nr_scan_active = 0;
+ else
+ nr_active = 0;
+
+ zone->nr_scan_inactive += (zone->nr_inactive >> sc->priority) + 1;
+ nr_inactive = zone->nr_scan_inactive;
+ if (nr_inactive >= SWAP_CLUSTER_MAX)
+ zone->nr_scan_inactive = 0;
+ else
+ nr_inactive = 0;
+
+ sc->nr_to_reclaim = SWAP_CLUSTER_MAX;
+
+ while (nr_active || nr_inactive) {
+ if (nr_active) {
+ sc->nr_to_scan = min(nr_active,
+ (unsigned long)SWAP_CLUSTER_MAX);
+ nr_active -= sc->nr_to_scan;
+ refill_inactive_zone(zone, sc);
+ }
- atomic_add(max_scan, &zone->nr_scan_inactive);
- count = atomic_read(&zone->nr_scan_inactive);
- if (count >= SWAP_CLUSTER_MAX) {
- atomic_set(&zone->nr_scan_inactive, 0);
- return shrink_cache(zone, gfp_mask, count,
- total_scanned, do_writepage);
+ if (nr_inactive) {
+ sc->nr_to_scan = min(nr_inactive,
+ (unsigned long)SWAP_CLUSTER_MAX);
+ nr_inactive -= sc->nr_to_scan;
+ shrink_cache(zone, sc);
+ if (sc->nr_to_reclaim <= 0)
+ break;
+ }
}
- return 0;
}
/*
* If a zone is deemed to be full of pinned pages then just give it a light
* scan then give up on it.
*/
-static int
-shrink_caches(struct zone **zones, int priority, int *total_scanned,
- int gfp_mask, struct page_state *ps, int do_writepage)
+static void
+shrink_caches(struct zone **zones, struct scan_control *sc)
{
- int ret = 0;
int i;
for (i = 0; zones[i] != NULL; i++) {
struct zone *zone = zones[i];
- int max_scan;
- if (zone->free_pages < zone->pages_high)
- zone->temp_priority = priority;
+ if (zone->present_pages == 0)
+ continue;
- if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+ zone->temp_priority = sc->priority;
+ if (zone->prev_priority > sc->priority)
+ zone->prev_priority = sc->priority;
+
+ if (zone->all_unreclaimable && sc->priority != DEF_PRIORITY)
continue; /* Let kswapd poll it */
- max_scan = zone->nr_inactive >> priority;
- ret += shrink_zone(zone, max_scan, gfp_mask,
- total_scanned, ps, do_writepage);
+ shrink_zone(zone, sc);
}
- return ret;
}
/*
*
* If the caller is !__GFP_FS then the probability of a failure is reasonably
* high - the zone may be full of dirty or under-writeback pages, which this
- * caller can't do much about. So for !__GFP_FS callers, we just perform a
- * small LRU walk and if that didn't work out, fail the allocation back to the
- * caller. GFP_NOFS allocators need to know how to deal with it. Kicking
- * bdflush, waiting and retrying will work.
- *
- * This is a fairly lame algorithm - it can result in excessive CPU burning and
- * excessive rotation of the inactive list, which is _supposed_ to be an LRU,
- * yes?
+ * caller can't do much about. We kick pdflush and take explicit naps in the
+ * hope that some of these pages can be written. But if the allocating task
+ * holds filesystem locks which prevent writeout this might not work, and the
+ * allocation attempt will fail.
*/
int try_to_free_pages(struct zone **zones,
unsigned int gfp_mask, unsigned int order)
{
int priority;
int ret = 0;
- int nr_reclaimed = 0;
+ int total_scanned = 0, total_reclaimed = 0;
struct reclaim_state *reclaim_state = current->reclaim_state;
+ struct scan_control sc;
+ unsigned long lru_pages = 0;
int i;
- unsigned long total_scanned = 0;
- int do_writepage = 0;
+
+ sc.gfp_mask = gfp_mask;
+ sc.may_writepage = 0;
inc_page_state(allocstall);
- for (i = 0; zones[i] != 0; i++)
- zones[i]->temp_priority = DEF_PRIORITY;
+ for (i = 0; zones[i] != NULL; i++) {
+ struct zone *zone = zones[i];
- for (priority = DEF_PRIORITY; priority >= 0; priority--) {
- int scanned = 0;
- struct page_state ps;
+ zone->temp_priority = DEF_PRIORITY;
+ lru_pages += zone->nr_active + zone->nr_inactive;
+ }
- get_page_state(&ps);
- nr_reclaimed += shrink_caches(zones, priority, &scanned,
- gfp_mask, &ps, do_writepage);
- shrink_slab(scanned, gfp_mask);
+ 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;
+ shrink_caches(zones, &sc);
+ shrink_slab(sc.nr_scanned, gfp_mask, lru_pages);
if (reclaim_state) {
- nr_reclaimed += reclaim_state->reclaimed_slab;
+ sc.nr_reclaimed += reclaim_state->reclaimed_slab;
reclaim_state->reclaimed_slab = 0;
}
- if (nr_reclaimed >= SWAP_CLUSTER_MAX) {
+ if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) {
ret = 1;
goto out;
}
- if (!(gfp_mask & __GFP_FS))
- break; /* Let the caller handle it */
+ total_scanned += sc.nr_scanned;
+ total_reclaimed += sc.nr_reclaimed;
+
/*
* Try to write back as many pages as we just scanned. This
* tends to cause slow streaming writers to write data to the
* that's undesirable in laptop mode, where we *want* lumpy
* writeout. So in laptop mode, write out the whole world.
*/
- total_scanned += scanned;
if (total_scanned > SWAP_CLUSTER_MAX + SWAP_CLUSTER_MAX/2) {
wakeup_bdflush(laptop_mode ? 0 : total_scanned);
- do_writepage = 1;
+ sc.may_writepage = 1;
}
/* Take a nap, wait for some writeback to complete */
- if (scanned && priority < DEF_PRIORITY - 2)
+ if (sc.nr_scanned && priority < DEF_PRIORITY - 2)
blk_congestion_wait(WRITE, HZ/10);
}
- if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY))
- out_of_memory();
out:
for (i = 0; zones[i] != 0; i++)
zones[i]->prev_priority = zones[i]->temp_priority;
* 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, struct page_state *ps)
+static int balance_pgdat(pg_data_t *pgdat, int nr_pages, int order)
{
int to_free = nr_pages;
+ int all_zones_ok;
int priority;
int i;
+ int total_scanned, total_reclaimed;
struct reclaim_state *reclaim_state = current->reclaim_state;
- unsigned long total_scanned = 0;
- unsigned long total_reclaimed = 0;
- int do_writepage = 0;
+ struct scan_control sc;
+
+loop_again:
+ total_scanned = 0;
+ total_reclaimed = 0;
+ sc.gfp_mask = GFP_KERNEL;
+ sc.may_writepage = 0;
+ sc.nr_mapped = read_page_state(nr_mapped);
inc_page_state(pageoutrun);
zone->temp_priority = DEF_PRIORITY;
}
- for (priority = DEF_PRIORITY; priority; priority--) {
- int all_zones_ok = 1;
+ for (priority = DEF_PRIORITY; priority >= 0; priority--) {
int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
+ unsigned long lru_pages = 0;
+ all_zones_ok = 1;
if (nr_pages == 0) {
/*
for (i = pgdat->nr_zones - 1; i >= 0; i--) {
struct zone *zone = pgdat->node_zones + i;
+ if (zone->present_pages == 0)
+ continue;
+
if (zone->all_unreclaimable &&
priority != DEF_PRIORITY)
continue;
- if (zone->free_pages <= zone->pages_high) {
+ if (!zone_watermark_ok(zone, order,
+ zone->pages_high, 0, 0, 0)) {
end_zone = i;
goto scan;
}
end_zone = pgdat->nr_zones - 1;
}
scan:
+ for (i = 0; i <= end_zone; i++) {
+ struct zone *zone = pgdat->node_zones + i;
+
+ lru_pages += zone->nr_active + zone->nr_inactive;
+ }
+
/*
* Now scan the zone in the dma->highmem direction, stopping
* at the last zone which needs scanning.
*/
for (i = 0; i <= end_zone; i++) {
struct zone *zone = pgdat->node_zones + i;
- int max_scan;
- int reclaimed;
- int scanned = 0;
+
+ if (zone->present_pages == 0)
+ continue;
if (zone->all_unreclaimable && priority != DEF_PRIORITY)
continue;
if (nr_pages == 0) { /* Not software suspend */
- if (zone->free_pages <= zone->pages_high)
+ if (!zone_watermark_ok(zone, order,
+ zone->pages_high, end_zone, 0, 0))
all_zones_ok = 0;
}
zone->temp_priority = priority;
- max_scan = zone->nr_inactive >> priority;
- reclaimed = shrink_zone(zone, max_scan, GFP_KERNEL,
- &scanned, ps, do_writepage);
- total_scanned += scanned;
+ if (zone->prev_priority > priority)
+ zone->prev_priority = priority;
+ sc.nr_scanned = 0;
+ sc.nr_reclaimed = 0;
+ sc.priority = priority;
+ shrink_zone(zone, &sc);
reclaim_state->reclaimed_slab = 0;
- shrink_slab(scanned, GFP_KERNEL);
- reclaimed += reclaim_state->reclaimed_slab;
- total_reclaimed += reclaimed;
- to_free -= reclaimed;
+ shrink_slab(sc.nr_scanned, GFP_KERNEL, lru_pages);
+ sc.nr_reclaimed += reclaim_state->reclaimed_slab;
+ total_reclaimed += sc.nr_reclaimed;
+ total_scanned += sc.nr_scanned;
if (zone->all_unreclaimable)
continue;
- if (zone->pages_scanned > zone->present_pages * 2)
+ if (zone->pages_scanned >= (zone->nr_active +
+ zone->nr_inactive) * 4)
zone->all_unreclaimable = 1;
/*
* If we've done a decent amount of scanning and
*/
if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
total_scanned > total_reclaimed+total_reclaimed/2)
- do_writepage = 1;
+ sc.may_writepage = 1;
}
- if (nr_pages && to_free > 0)
+ if (nr_pages && to_free > total_reclaimed)
continue; /* swsusp: need to do more work */
if (all_zones_ok)
break; /* kswapd: all done */
*/
if (total_scanned && priority < DEF_PRIORITY - 2)
blk_congestion_wait(WRITE, HZ/10);
+
+ /*
+ * We do this so kswapd doesn't build up large priorities for
+ * example when it is freeing in parallel with allocators. It
+ * matches the direct reclaim path behaviour in terms of impact
+ * on zone->*_priority.
+ */
+ if (total_reclaimed >= SWAP_CLUSTER_MAX)
+ break;
}
out:
for (i = 0; i < pgdat->nr_zones; i++) {
zone->prev_priority = zone->temp_priority;
}
+ if (!all_zones_ok) {
+ cond_resched();
+ goto loop_again;
+ }
+
return total_reclaimed;
}
* If there are applications that are active memory-allocators
* (most normal use), this basically shouldn't matter.
*/
-int kswapd(void *p)
+static int kswapd(void *p)
{
+ unsigned long order;
pg_data_t *pgdat = (pg_data_t*)p;
struct task_struct *tsk = current;
DEFINE_WAIT(wait);
*/
tsk->flags |= PF_MEMALLOC|PF_KSWAPD;
+ order = 0;
for ( ; ; ) {
- struct page_state ps;
-
+ unsigned long new_order;
if (current->flags & PF_FREEZE)
refrigerator(PF_FREEZE);
+
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
- schedule();
+ new_order = pgdat->kswapd_max_order;
+ pgdat->kswapd_max_order = 0;
+ if (order < new_order) {
+ /*
+ * Don't sleep if someone wants a larger 'order'
+ * allocation
+ */
+ order = new_order;
+ } else {
+ schedule();
+ order = pgdat->kswapd_max_order;
+ }
finish_wait(&pgdat->kswapd_wait, &wait);
- get_page_state(&ps);
- balance_pgdat(pgdat, 0, &ps);
+
+ balance_pgdat(pgdat, 0, order);
}
+ return 0;
}
/*
* A zone is low on free memory, so wake its kswapd task to service it.
*/
-void wakeup_kswapd(struct zone *zone)
+void wakeup_kswapd(struct zone *zone, int order)
{
- if (zone->free_pages > zone->pages_low)
+ pg_data_t *pgdat;
+
+ if (zone->present_pages == 0)
+ return;
+
+ pgdat = zone->zone_pgdat;
+ if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0, 0))
return;
+ if (pgdat->kswapd_max_order < order)
+ pgdat->kswapd_max_order = order;
if (!waitqueue_active(&zone->zone_pgdat->kswapd_wait))
return;
wake_up_interruptible(&zone->zone_pgdat->kswapd_wait);
current->reclaim_state = &reclaim_state;
for_each_pgdat(pgdat) {
int freed;
- struct page_state ps;
-
- get_page_state(&ps);
- freed = balance_pgdat(pgdat, nr_to_free, &ps);
+ freed = balance_pgdat(pgdat, nr_to_free, 0);
ret += freed;
nr_to_free -= freed;
if (nr_to_free <= 0)
swap_setup();
for_each_pgdat(pgdat)
pgdat->kswapd
- = find_task_by_pid(kernel_thread(kswapd, pgdat, CLONE_KERNEL));
+ = find_task_by_real_pid(kernel_thread(kswapd, pgdat, CLONE_KERNEL));
total_memory = nr_free_pagecache_pages();
hotcpu_notifier(cpu_callback, 0);
return 0;
git://git.onelab.eu / linux-2.6.git / blobdiff