#include <linux/topology.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
+#include <linux/compaction.h>
#include <linux/notifier.h>
#include <linux/rwsem.h>
#include <linux/delay.h>
#include <linux/memcontrol.h>
#include <linux/delayacct.h>
#include <linux/sysctl.h>
+#include <linux/oom.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
#define CREATE_TRACE_POINTS
#include <trace/events/vmscan.h>
+/*
+ * reclaim_mode determines how the inactive list is shrunk
+ * RECLAIM_MODE_SINGLE: Reclaim only order-0 pages
+ * RECLAIM_MODE_ASYNC: Do not block
+ * RECLAIM_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback
+ * RECLAIM_MODE_LUMPYRECLAIM: For high-order allocations, take a reference
+ * page from the LRU and reclaim all pages within a
+ * naturally aligned range
+ * RECLAIM_MODE_COMPACTION: For high-order allocations, reclaim a number of
+ * order-0 pages and then compact the zone
+ */
+typedef unsigned __bitwise__ reclaim_mode_t;
+#define RECLAIM_MODE_SINGLE ((__force reclaim_mode_t)0x01u)
+#define RECLAIM_MODE_ASYNC ((__force reclaim_mode_t)0x02u)
+#define RECLAIM_MODE_SYNC ((__force reclaim_mode_t)0x04u)
+#define RECLAIM_MODE_LUMPYRECLAIM ((__force reclaim_mode_t)0x08u)
+#define RECLAIM_MODE_COMPACTION ((__force reclaim_mode_t)0x10u)
+
struct scan_control {
/* Incremented by the number of inactive pages that were scanned */
unsigned long nr_scanned;
int order;
/*
- * Intend to reclaim enough contenious memory rather than to reclaim
- * enough amount memory. I.e, it's the mode for high order allocation.
+ * Intend to reclaim enough continuous memory rather than reclaim
+ * enough amount of memory. i.e, mode for high order allocation.
*/
- bool lumpy_reclaim_mode;
+ reclaim_mode_t reclaim_mode;
/* Which cgroup do we reclaim from */
struct mem_cgroup *mem_cgroup;
if (scanned == 0)
scanned = SWAP_CLUSTER_MAX;
- if (!down_read_trylock(&shrinker_rwsem))
- return 1; /* Assume we'll be able to shrink next time */
+ if (!down_read_trylock(&shrinker_rwsem)) {
+ /* Assume we'll be able to shrink next time */
+ ret = 1;
+ goto out;
+ }
list_for_each_entry(shrinker, &shrinker_list, list) {
unsigned long long delta;
shrinker->nr += total_scan;
}
up_read(&shrinker_rwsem);
+out:
+ cond_resched();
return ret;
}
+static void set_reclaim_mode(int priority, struct scan_control *sc,
+ bool sync)
+{
+ reclaim_mode_t syncmode = sync ? RECLAIM_MODE_SYNC : RECLAIM_MODE_ASYNC;
+
+ /*
+ * Initially assume we are entering either lumpy reclaim or
+ * reclaim/compaction.Depending on the order, we will either set the
+ * sync mode or just reclaim order-0 pages later.
+ */
+ if (COMPACTION_BUILD)
+ sc->reclaim_mode = RECLAIM_MODE_COMPACTION;
+ else
+ sc->reclaim_mode = RECLAIM_MODE_LUMPYRECLAIM;
+
+ /*
+ * Avoid using lumpy reclaim or reclaim/compaction if possible by
+ * restricting when its set to either costly allocations or when
+ * under memory pressure
+ */
+ if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
+ sc->reclaim_mode |= syncmode;
+ else if (sc->order && priority < DEF_PRIORITY - 2)
+ sc->reclaim_mode |= syncmode;
+ else
+ sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
+}
+
+static void reset_reclaim_mode(struct scan_control *sc)
+{
+ sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
+}
+
static inline int is_page_cache_freeable(struct page *page)
{
/*
return page_count(page) - page_has_private(page) == 2;
}
-static int may_write_to_queue(struct backing_dev_info *bdi)
+static int may_write_to_queue(struct backing_dev_info *bdi,
+ struct scan_control *sc)
{
if (current->flags & PF_SWAPWRITE)
return 1;
return 1;
if (bdi == current->backing_dev_info)
return 1;
+
+ /* lumpy reclaim for hugepage often need a lot of write */
+ if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
+ return 1;
return 0;
}
unlock_page(page);
}
-/* Request for sync pageout. */
-enum pageout_io {
- PAGEOUT_IO_ASYNC,
- PAGEOUT_IO_SYNC,
-};
-
/* possible outcome of pageout() */
typedef enum {
/* failed to write page out, page is locked */
* Calls ->writepage().
*/
static pageout_t pageout(struct page *page, struct address_space *mapping,
- enum pageout_io sync_writeback)
+ struct scan_control *sc)
{
/*
* If the page is dirty, only perform writeback if that write
}
if (mapping->a_ops->writepage == NULL)
return PAGE_ACTIVATE;
- if (!may_write_to_queue(mapping->backing_dev_info))
+ if (!may_write_to_queue(mapping->backing_dev_info, sc))
return PAGE_KEEP;
if (clear_page_dirty_for_io(page)) {
.nr_to_write = SWAP_CLUSTER_MAX,
.range_start = 0,
.range_end = LLONG_MAX,
- .nonblocking = 1,
.for_reclaim = 1,
};
* direct reclaiming a large contiguous area and the
* first attempt to free a range of pages fails.
*/
- if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC)
+ if (PageWriteback(page) &&
+ (sc->reclaim_mode & RECLAIM_MODE_SYNC))
wait_on_page_writeback(page);
if (!PageWriteback(page)) {
ClearPageReclaim(page);
}
trace_mm_vmscan_writepage(page,
- trace_reclaim_flags(page, sync_writeback));
+ trace_reclaim_flags(page, sc->reclaim_mode));
inc_zone_page_state(page, NR_VMSCAN_WRITE);
return PAGE_SUCCESS;
}
spin_unlock_irq(&mapping->tree_lock);
swapcache_free(swap, page);
} else {
+ void (*freepage)(struct page *);
+
+ freepage = mapping->a_ops->freepage;
+
__remove_from_page_cache(page);
spin_unlock_irq(&mapping->tree_lock);
mem_cgroup_uncharge_cache_page(page);
+
+ if (freepage != NULL)
+ freepage(page);
}
return 1;
referenced_page = TestClearPageReferenced(page);
/* Lumpy reclaim - ignore references */
- if (sc->lumpy_reclaim_mode)
+ if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM)
return PAGEREF_RECLAIM;
/*
}
/* Reclaim if clean, defer dirty pages to writeback */
- if (referenced_page)
+ if (referenced_page && !PageSwapBacked(page))
return PAGEREF_RECLAIM_CLEAN;
return PAGEREF_RECLAIM;
* shrink_page_list() returns the number of reclaimed pages
*/
static unsigned long shrink_page_list(struct list_head *page_list,
- struct scan_control *sc,
- enum pageout_io sync_writeback)
+ struct zone *zone,
+ struct scan_control *sc)
{
LIST_HEAD(ret_pages);
LIST_HEAD(free_pages);
int pgactivate = 0;
+ unsigned long nr_dirty = 0;
+ unsigned long nr_congested = 0;
unsigned long nr_reclaimed = 0;
cond_resched();
goto keep;
VM_BUG_ON(PageActive(page));
+ VM_BUG_ON(page_zone(page) != zone);
sc->nr_scanned++;
* for any page for which writeback has already
* started.
*/
- if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs)
+ if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) &&
+ may_enter_fs)
wait_on_page_writeback(page);
- else
- goto keep_locked;
+ else {
+ unlock_page(page);
+ goto keep_lumpy;
+ }
}
references = page_check_references(page, sc);
}
if (PageDirty(page)) {
+ nr_dirty++;
+
if (references == PAGEREF_RECLAIM_CLEAN)
goto keep_locked;
if (!may_enter_fs)
goto keep_locked;
/* Page is dirty, try to write it out here */
- switch (pageout(page, mapping, sync_writeback)) {
+ switch (pageout(page, mapping, sc)) {
case PAGE_KEEP:
+ nr_congested++;
goto keep_locked;
case PAGE_ACTIVATE:
goto activate_locked;
case PAGE_SUCCESS:
- if (PageWriteback(page) || PageDirty(page))
+ if (PageWriteback(page))
+ goto keep_lumpy;
+ if (PageDirty(page))
goto keep;
+
/*
* A synchronous write - probably a ramdisk. Go
* ahead and try to reclaim the page.
try_to_free_swap(page);
unlock_page(page);
putback_lru_page(page);
+ reset_reclaim_mode(sc);
continue;
activate_locked:
keep_locked:
unlock_page(page);
keep:
+ reset_reclaim_mode(sc);
+keep_lumpy:
list_add(&page->lru, &ret_pages);
VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
}
+ /*
+ * Tag a zone as congested if all the dirty pages encountered were
+ * backed by a congested BDI. In this case, reclaimers should just
+ * back off and wait for congestion to clear because further reclaim
+ * will encounter the same problem
+ */
+ if (nr_dirty == nr_congested && nr_dirty != 0)
+ zone_set_flag(zone, ZONE_CONGESTED);
+
free_page_list(&free_pages);
list_splice(&ret_pages, page_list);
case 0:
list_move(&page->lru, dst);
mem_cgroup_del_lru(page);
- nr_taken++;
+ nr_taken += hpage_nr_pages(page);
break;
case -EBUSY:
/* Check that we have not crossed a zone boundary. */
if (unlikely(page_zone_id(cursor_page) != zone_id))
- continue;
+ break;
/*
* If we don't have enough swap space, reclaiming of
* pointless.
*/
if (nr_swap_pages <= 0 && PageAnon(cursor_page) &&
- !PageSwapCache(cursor_page))
- continue;
+ !PageSwapCache(cursor_page))
+ break;
if (__isolate_lru_page(cursor_page, mode, file) == 0) {
list_move(&cursor_page->lru, dst);
mem_cgroup_del_lru(cursor_page);
- nr_taken++;
+ nr_taken += hpage_nr_pages(page);
nr_lumpy_taken++;
if (PageDirty(cursor_page))
nr_lumpy_dirty++;
scan++;
} else {
- if (mode == ISOLATE_BOTH &&
- page_count(cursor_page))
- nr_lumpy_failed++;
+ /* the page is freed already. */
+ if (!page_count(cursor_page))
+ continue;
+ break;
}
}
+
+ /* If we break out of the loop above, lumpy reclaim failed */
+ if (pfn < end_pfn)
+ nr_lumpy_failed++;
}
*scanned = scan;
struct page *page;
list_for_each_entry(page, page_list, lru) {
+ int numpages = hpage_nr_pages(page);
lru = page_lru_base_type(page);
if (PageActive(page)) {
lru += LRU_ACTIVE;
ClearPageActive(page);
- nr_active++;
+ nr_active += numpages;
}
if (count)
- count[lru]++;
+ count[lru] += numpages;
}
return nr_active;
add_page_to_lru_list(zone, page, lru);
if (is_active_lru(lru)) {
int file = is_file_lru(lru);
- reclaim_stat->recent_rotated[file]++;
+ int numpages = hpage_nr_pages(page);
+ reclaim_stat->recent_rotated[file] += numpages;
}
if (!pagevec_add(&pvec, page)) {
spin_unlock_irq(&zone->lru_lock);
return false;
/* Only stall on lumpy reclaim */
- if (!sc->lumpy_reclaim_mode)
+ if (sc->reclaim_mode & RECLAIM_MODE_SINGLE)
return false;
/* If we have relaimed everything on the isolated list, no stall */
unsigned long nr_scanned;
unsigned long nr_reclaimed = 0;
unsigned long nr_taken;
- unsigned long nr_active;
unsigned long nr_anon;
unsigned long nr_file;
return SWAP_CLUSTER_MAX;
}
-
+ set_reclaim_mode(priority, sc, false);
lru_add_drain();
spin_lock_irq(&zone->lru_lock);
if (scanning_global_lru(sc)) {
nr_taken = isolate_pages_global(nr_to_scan,
&page_list, &nr_scanned, sc->order,
- sc->lumpy_reclaim_mode ?
- ISOLATE_BOTH : ISOLATE_INACTIVE,
+ sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
+ ISOLATE_BOTH : ISOLATE_INACTIVE,
zone, 0, file);
zone->pages_scanned += nr_scanned;
if (current_is_kswapd())
} else {
nr_taken = mem_cgroup_isolate_pages(nr_to_scan,
&page_list, &nr_scanned, sc->order,
- sc->lumpy_reclaim_mode ?
- ISOLATE_BOTH : ISOLATE_INACTIVE,
+ sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
+ ISOLATE_BOTH : ISOLATE_INACTIVE,
zone, sc->mem_cgroup,
0, file);
/*
spin_unlock_irq(&zone->lru_lock);
- nr_reclaimed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
+ nr_reclaimed = shrink_page_list(&page_list, zone, sc);
/* Check if we should syncronously wait for writeback */
if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
- congestion_wait(BLK_RW_ASYNC, HZ/10);
-
- /*
- * The attempt at page out may have made some
- * of the pages active, mark them inactive again.
- */
- nr_active = clear_active_flags(&page_list, NULL);
- count_vm_events(PGDEACTIVATE, nr_active);
-
- nr_reclaimed += shrink_page_list(&page_list, sc, PAGEOUT_IO_SYNC);
+ set_reclaim_mode(priority, sc, true);
+ nr_reclaimed += shrink_page_list(&page_list, zone, sc);
}
local_irq_disable();
__count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list);
+
+ trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
+ zone_idx(zone),
+ nr_scanned, nr_reclaimed,
+ priority,
+ trace_shrink_flags(file, sc->reclaim_mode));
return nr_reclaimed;
}
list_move(&page->lru, &zone->lru[lru].list);
mem_cgroup_add_lru_list(page, lru);
- pgmoved++;
+ pgmoved += hpage_nr_pages(page);
if (!pagevec_add(&pvec, page) || list_empty(list)) {
spin_unlock_irq(&zone->lru_lock);
}
if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) {
- nr_rotated++;
+ nr_rotated += hpage_nr_pages(page);
/*
* Identify referenced, file-backed active pages and
* give them one more trip around the active list. So
spin_unlock_irq(&zone->lru_lock);
}
+#ifdef CONFIG_SWAP
static int inactive_anon_is_low_global(struct zone *zone)
{
unsigned long active, inactive;
{
int low;
+ /*
+ * If we don't have swap space, anonymous page deactivation
+ * is pointless.
+ */
+ if (!total_swap_pages)
+ return 0;
+
if (scanning_global_lru(sc))
low = inactive_anon_is_low_global(zone);
else
low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup);
return low;
}
+#else
+static inline int inactive_anon_is_low(struct zone *zone,
+ struct scan_control *sc)
+{
+ return 0;
+}
+#endif
static int inactive_file_is_low_global(struct zone *zone)
{
}
}
-static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc)
+/*
+ * Reclaim/compaction depends on a number of pages being freed. To avoid
+ * disruption to the system, a small number of order-0 pages continue to be
+ * rotated and reclaimed in the normal fashion. However, by the time we get
+ * back to the allocator and call try_to_compact_zone(), we ensure that
+ * there are enough free pages for it to be likely successful
+ */
+static inline bool should_continue_reclaim(struct zone *zone,
+ unsigned long nr_reclaimed,
+ unsigned long nr_scanned,
+ struct scan_control *sc)
{
+ unsigned long pages_for_compaction;
+ unsigned long inactive_lru_pages;
+
+ /* If not in reclaim/compaction mode, stop */
+ if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION))
+ return false;
+
+ /* Consider stopping depending on scan and reclaim activity */
+ if (sc->gfp_mask & __GFP_REPEAT) {
+ /*
+ * For __GFP_REPEAT allocations, stop reclaiming if the
+ * full LRU list has been scanned and we are still failing
+ * to reclaim pages. This full LRU scan is potentially
+ * expensive but a __GFP_REPEAT caller really wants to succeed
+ */
+ if (!nr_reclaimed && !nr_scanned)
+ return false;
+ } else {
+ /*
+ * For non-__GFP_REPEAT allocations which can presumably
+ * fail without consequence, stop if we failed to reclaim
+ * any pages from the last SWAP_CLUSTER_MAX number of
+ * pages that were scanned. This will return to the
+ * caller faster at the risk reclaim/compaction and
+ * the resulting allocation attempt fails
+ */
+ if (!nr_reclaimed)
+ return false;
+ }
+
/*
- * If we need a large contiguous chunk of memory, or have
- * trouble getting a small set of contiguous pages, we
- * will reclaim both active and inactive pages.
+ * If we have not reclaimed enough pages for compaction and the
+ * inactive lists are large enough, continue reclaiming
*/
- if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
- sc->lumpy_reclaim_mode = 1;
- else if (sc->order && priority < DEF_PRIORITY - 2)
- sc->lumpy_reclaim_mode = 1;
- else
- sc->lumpy_reclaim_mode = 0;
+ pages_for_compaction = (2UL << sc->order);
+ inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) +
+ zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);
+ if (sc->nr_reclaimed < pages_for_compaction &&
+ inactive_lru_pages > pages_for_compaction)
+ return true;
+
+ /* If compaction would go ahead or the allocation would succeed, stop */
+ switch (compaction_suitable(zone, sc->order)) {
+ case COMPACT_PARTIAL:
+ case COMPACT_CONTINUE:
+ return false;
+ default:
+ return true;
+ }
}
/*
unsigned long nr[NR_LRU_LISTS];
unsigned long nr_to_scan;
enum lru_list l;
- unsigned long nr_reclaimed = sc->nr_reclaimed;
+ unsigned long nr_reclaimed, nr_scanned;
unsigned long nr_to_reclaim = sc->nr_to_reclaim;
+restart:
+ nr_reclaimed = 0;
+ nr_scanned = sc->nr_scanned;
get_scan_count(zone, sc, nr, priority);
- set_lumpy_reclaim_mode(priority, sc);
-
while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
nr[LRU_INACTIVE_FILE]) {
for_each_evictable_lru(l) {
if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY)
break;
}
-
- sc->nr_reclaimed = nr_reclaimed;
+ sc->nr_reclaimed += nr_reclaimed;
/*
* Even if we did not try to evict anon pages at all, we want to
* rebalance the anon lru active/inactive ratio.
*/
- if (inactive_anon_is_low(zone, sc) && nr_swap_pages > 0)
+ if (inactive_anon_is_low(zone, sc))
shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
+ /* reclaim/compaction might need reclaim to continue */
+ if (should_continue_reclaim(zone, nr_reclaimed,
+ sc->nr_scanned - nr_scanned, sc))
+ goto restart;
+
throttle_vm_writeout(sc->gfp_mask);
}
* If a zone is deemed to be full of pinned pages then just give it a light
* scan then give up on it.
*/
-static bool shrink_zones(int priority, struct zonelist *zonelist,
+static void shrink_zones(int priority, struct zonelist *zonelist,
struct scan_control *sc)
{
struct zoneref *z;
struct zone *zone;
- bool all_unreclaimable = true;
for_each_zone_zonelist_nodemask(zone, z, zonelist,
gfp_zone(sc->gfp_mask), sc->nodemask) {
}
shrink_zone(priority, zone, sc);
- all_unreclaimable = false;
}
- return all_unreclaimable;
+}
+
+static bool zone_reclaimable(struct zone *zone)
+{
+ return zone->pages_scanned < zone_reclaimable_pages(zone) * 6;
+}
+
+/* All zones in zonelist are unreclaimable? */
+static bool all_unreclaimable(struct zonelist *zonelist,
+ struct scan_control *sc)
+{
+ struct zoneref *z;
+ struct zone *zone;
+
+ for_each_zone_zonelist_nodemask(zone, z, zonelist,
+ gfp_zone(sc->gfp_mask), sc->nodemask) {
+ if (!populated_zone(zone))
+ continue;
+ if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
+ continue;
+ if (!zone->all_unreclaimable)
+ return false;
+ }
+
+ return true;
}
/*
struct scan_control *sc)
{
int priority;
- bool all_unreclaimable;
unsigned long total_scanned = 0;
struct reclaim_state *reclaim_state = current->reclaim_state;
struct zoneref *z;
sc->nr_scanned = 0;
if (!priority)
disable_swap_token();
- all_unreclaimable = shrink_zones(priority, zonelist, sc);
+ shrink_zones(priority, zonelist, sc);
/*
* Don't shrink slabs when reclaiming memory from
* over limit cgroups
/* Take a nap, wait for some writeback to complete */
if (!sc->hibernation_mode && sc->nr_scanned &&
- priority < DEF_PRIORITY - 2)
- congestion_wait(BLK_RW_ASYNC, HZ/10);
+ priority < DEF_PRIORITY - 2) {
+ struct zone *preferred_zone;
+
+ first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
+ &cpuset_current_mems_allowed,
+ &preferred_zone);
+ wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
+ }
}
out:
- /*
- * Now that we've scanned all the zones at this priority level, note
- * that level within the zone so that the next thread which performs
- * scanning of this zone will immediately start out at this priority
- * level. This affects only the decision whether or not to bring
- * mapped pages onto the inactive list.
- */
- if (priority < 0)
- priority = 0;
-
delayacct_freepages_end();
put_mems_allowed();
if (sc->nr_reclaimed)
return sc->nr_reclaimed;
+ /*
+ * As hibernation is going on, kswapd is freezed so that it can't mark
+ * the zone into all_unreclaimable. Thus bypassing all_unreclaimable
+ * check.
+ */
+ if (oom_killer_disabled)
+ return 0;
+
/* top priority shrink_zones still had more to do? don't OOM, then */
- if (scanning_global_lru(sc) && !all_unreclaimable)
+ if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc))
return 1;
return 0;
unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
gfp_t gfp_mask, bool noswap,
unsigned int swappiness,
- struct zone *zone, int nid)
+ struct zone *zone)
{
struct scan_control sc = {
.nr_to_reclaim = SWAP_CLUSTER_MAX,
.order = 0,
.mem_cgroup = mem,
};
- nodemask_t nm = nodemask_of_node(nid);
-
sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
- sc.nodemask = &nm;
trace_mm_vmscan_memcg_softlimit_reclaim_begin(0,
sc.may_writepage,
}
#endif
+/*
+ * pgdat_balanced is used when checking if a node is balanced for high-order
+ * allocations. Only zones that meet watermarks and are in a zone allowed
+ * by the callers classzone_idx are added to balanced_pages. The total of
+ * balanced pages must be at least 25% of the zones allowed by classzone_idx
+ * for the node to be considered balanced. Forcing all zones to be balanced
+ * for high orders can cause excessive reclaim when there are imbalanced zones.
+ * The choice of 25% is due to
+ * o a 16M DMA zone that is balanced will not balance a zone on any
+ * reasonable sized machine
+ * o On all other machines, the top zone must be at least a reasonable
+ * precentage of the middle zones. For example, on 32-bit x86, highmem
+ * would need to be at least 256M for it to be balance a whole node.
+ * Similarly, on x86-64 the Normal zone would need to be at least 1G
+ * to balance a node on its own. These seemed like reasonable ratios.
+ */
+static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
+ int classzone_idx)
+{
+ unsigned long present_pages = 0;
+ int i;
+
+ for (i = 0; i <= classzone_idx; i++)
+ present_pages += pgdat->node_zones[i].present_pages;
+
+ /* A special case here: if zone has no page, we think it's balanced */
+ return balanced_pages >= (present_pages >> 2);
+}
+
/* is kswapd sleeping prematurely? */
-static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
+static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
+ int classzone_idx)
{
int i;
+ unsigned long balanced = 0;
+ bool all_zones_ok = true;
/* If a direct reclaimer woke kswapd within HZ/10, it's premature */
if (remaining)
- return 1;
+ return true;
- /* If after HZ/10, a zone is below the high mark, it's premature */
- for (i = 0; i < pgdat->nr_zones; i++) {
+ /* Check the watermark levels */
+ for (i = 0; i <= classzone_idx; i++) {
struct zone *zone = pgdat->node_zones + i;
if (!populated_zone(zone))
continue;
- if (zone->all_unreclaimable)
+ /*
+ * balance_pgdat() skips over all_unreclaimable after
+ * DEF_PRIORITY. Effectively, it considers them balanced so
+ * they must be considered balanced here as well if kswapd
+ * is to sleep
+ */
+ if (zone->all_unreclaimable) {
+ balanced += zone->present_pages;
continue;
+ }
- if (!zone_watermark_ok(zone, order, high_wmark_pages(zone),
- 0, 0))
- return 1;
+ if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
+ i, 0))
+ all_zones_ok = false;
+ else
+ balanced += zone->present_pages;
}
- return 0;
+ /*
+ * For high-order requests, the balanced zones must contain at least
+ * 25% of the nodes pages for kswapd to sleep. For order-0, all zones
+ * must be balanced
+ */
+ if (order)
+ return !pgdat_balanced(pgdat, balanced, classzone_idx);
+ else
+ return !all_zones_ok;
}
/*
* For kswapd, balance_pgdat() will work across all this node's zones until
* they are all at high_wmark_pages(zone).
*
- * Returns the number of pages which were actually freed.
+ * Returns the final order kswapd was reclaiming at
*
* There is special handling here for zones which are full of pinned pages.
* This can happen if the pages are all mlocked, or if they are all used by
* interoperates with the page allocator fallback scheme to ensure that aging
* of pages is balanced across the zones.
*/
-static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
+static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
+ int *classzone_idx)
{
int all_zones_ok;
+ unsigned long balanced;
int priority;
int i;
+ int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
unsigned long total_scanned;
struct reclaim_state *reclaim_state = current->reclaim_state;
struct scan_control sc = {
count_vm_event(PAGEOUTRUN);
for (priority = DEF_PRIORITY; priority >= 0; priority--) {
- int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
unsigned long lru_pages = 0;
int has_under_min_watermark_zone = 0;
disable_swap_token();
all_zones_ok = 1;
+ balanced = 0;
/*
* Scan in the highmem->dma direction for the highest
shrink_active_list(SWAP_CLUSTER_MAX, zone,
&sc, priority, 0);
- if (!zone_watermark_ok(zone, order,
+ if (!zone_watermark_ok_safe(zone, order,
high_wmark_pages(zone), 0, 0)) {
end_zone = i;
break;
for (i = 0; i <= end_zone; i++) {
struct zone *zone = pgdat->node_zones + i;
int nr_slab;
- int nid, zid;
+ unsigned long balance_gap;
if (!populated_zone(zone))
continue;
sc.nr_scanned = 0;
- nid = pgdat->node_id;
- zid = zone_idx(zone);
/*
* Call soft limit reclaim before calling shrink_zone.
* For now we ignore the return value
*/
- mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask,
- nid, zid);
+ mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask);
+
/*
- * We put equal pressure on every zone, unless one
- * zone has way too many pages free already.
+ * We put equal pressure on every zone, unless
+ * one zone has way too many pages free
+ * already. The "too many pages" is defined
+ * as the high wmark plus a "gap" where the
+ * gap is either the low watermark or 1%
+ * of the zone, whichever is smaller.
*/
- if (!zone_watermark_ok(zone, order,
- 8*high_wmark_pages(zone), end_zone, 0))
+ balance_gap = min(low_wmark_pages(zone),
+ (zone->present_pages +
+ KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
+ KSWAPD_ZONE_BALANCE_GAP_RATIO);
+ if (!zone_watermark_ok_safe(zone, order,
+ high_wmark_pages(zone) + balance_gap,
+ end_zone, 0)) {
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_scanned += sc.nr_scanned;
- if (zone->all_unreclaimable)
- continue;
- if (nr_slab == 0 &&
- zone->pages_scanned >= (zone_reclaimable_pages(zone) * 6))
- zone->all_unreclaimable = 1;
+
+ reclaim_state->reclaimed_slab = 0;
+ nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
+ lru_pages);
+ sc.nr_reclaimed += reclaim_state->reclaimed_slab;
+ total_scanned += sc.nr_scanned;
+
+ if (nr_slab == 0 && !zone_reclaimable(zone))
+ zone->all_unreclaimable = 1;
+ }
+
/*
* If we've done a decent amount of scanning and
* the reclaim ratio is low, start doing writepage
total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
sc.may_writepage = 1;
- if (!zone_watermark_ok(zone, order,
+ if (zone->all_unreclaimable) {
+ if (end_zone && end_zone == i)
+ end_zone--;
+ continue;
+ }
+
+ if (!zone_watermark_ok_safe(zone, order,
high_wmark_pages(zone), end_zone, 0)) {
all_zones_ok = 0;
/*
* means that we have a GFP_ATOMIC allocation
* failure risk. Hurry up!
*/
- if (!zone_watermark_ok(zone, order,
+ if (!zone_watermark_ok_safe(zone, order,
min_wmark_pages(zone), end_zone, 0))
has_under_min_watermark_zone = 1;
+ } else {
+ /*
+ * If a zone reaches its high watermark,
+ * consider it to be no longer congested. It's
+ * possible there are dirty pages backed by
+ * congested BDIs but as pressure is relieved,
+ * spectulatively avoid congestion waits
+ */
+ zone_clear_flag(zone, ZONE_CONGESTED);
+ if (i <= *classzone_idx)
+ balanced += zone->present_pages;
}
}
- if (all_zones_ok)
+ if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
break; /* kswapd: all done */
/*
* OK, kswapd is getting into trouble. Take a nap, then take
break;
}
out:
- if (!all_zones_ok) {
+
+ /*
+ * order-0: All zones must meet high watermark for a balanced node
+ * high-order: Balanced zones must make up at least 25% of the node
+ * for the node to be balanced
+ */
+ if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) {
cond_resched();
try_to_freeze();
goto loop_again;
}
- return sc.nr_reclaimed;
+ /*
+ * If kswapd was reclaiming at a higher order, it has the option of
+ * sleeping without all zones being balanced. Before it does, it must
+ * ensure that the watermarks for order-0 on *all* zones are met and
+ * that the congestion flags are cleared. The congestion flag must
+ * be cleared as kswapd is the only mechanism that clears the flag
+ * and it is potentially going to sleep here.
+ */
+ if (order) {
+ for (i = 0; i <= end_zone; i++) {
+ struct zone *zone = pgdat->node_zones + i;
+
+ if (!populated_zone(zone))
+ continue;
+
+ if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+ continue;
+
+ /* Confirm the zone is balanced for order-0 */
+ if (!zone_watermark_ok(zone, 0,
+ high_wmark_pages(zone), 0, 0)) {
+ order = sc.order = 0;
+ goto loop_again;
+ }
+
+ /* If balanced, clear the congested flag */
+ zone_clear_flag(zone, ZONE_CONGESTED);
+ }
+ }
+
+ /*
+ * Return the order we were reclaiming at so sleeping_prematurely()
+ * makes a decision on the order we were last reclaiming at. However,
+ * if another caller entered the allocator slow path while kswapd
+ * was awake, order will remain at the higher level
+ */
+ *classzone_idx = end_zone;
+ return order;
+}
+
+static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
+{
+ long remaining = 0;
+ DEFINE_WAIT(wait);
+
+ if (freezing(current) || kthread_should_stop())
+ return;
+
+ prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
+
+ /* Try to sleep for a short interval */
+ if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
+ remaining = schedule_timeout(HZ/10);
+ finish_wait(&pgdat->kswapd_wait, &wait);
+ prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
+ }
+
+ /*
+ * After a short sleep, check if it was a premature sleep. If not, then
+ * go fully to sleep until explicitly woken up.
+ */
+ if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
+ trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
+
+ /*
+ * vmstat counters are not perfectly accurate and the estimated
+ * value for counters such as NR_FREE_PAGES can deviate from the
+ * true value by nr_online_cpus * threshold. To avoid the zone
+ * watermarks being breached while under pressure, we reduce the
+ * per-cpu vmstat threshold while kswapd is awake and restore
+ * them before going back to sleep.
+ */
+ set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
+ schedule();
+ set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
+ } else {
+ if (remaining)
+ count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
+ else
+ count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
+ }
+ finish_wait(&pgdat->kswapd_wait, &wait);
}
/*
*/
static int kswapd(void *p)
{
- unsigned long order;
+ unsigned long order, new_order;
+ int classzone_idx, new_classzone_idx;
pg_data_t *pgdat = (pg_data_t*)p;
struct task_struct *tsk = current;
- DEFINE_WAIT(wait);
+
struct reclaim_state reclaim_state = {
.reclaimed_slab = 0,
};
tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
set_freezable();
- order = 0;
+ order = new_order = 0;
+ classzone_idx = new_classzone_idx = pgdat->nr_zones - 1;
for ( ; ; ) {
- unsigned long new_order;
int ret;
- prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
- new_order = pgdat->kswapd_max_order;
- pgdat->kswapd_max_order = 0;
- if (order < new_order) {
+ /*
+ * If the last balance_pgdat was unsuccessful it's unlikely a
+ * new request of a similar or harder type will succeed soon
+ * so consider going to sleep on the basis we reclaimed at
+ */
+ if (classzone_idx >= new_classzone_idx && order == new_order) {
+ new_order = pgdat->kswapd_max_order;
+ new_classzone_idx = pgdat->classzone_idx;
+ pgdat->kswapd_max_order = 0;
+ pgdat->classzone_idx = pgdat->nr_zones - 1;
+ }
+
+ if (order < new_order || classzone_idx > new_classzone_idx) {
/*
* Don't sleep if someone wants a larger 'order'
- * allocation
+ * allocation or has tigher zone constraints
*/
order = new_order;
+ classzone_idx = new_classzone_idx;
} else {
- if (!freezing(current) && !kthread_should_stop()) {
- long remaining = 0;
-
- /* Try to sleep for a short interval */
- if (!sleeping_prematurely(pgdat, order, remaining)) {
- remaining = schedule_timeout(HZ/10);
- finish_wait(&pgdat->kswapd_wait, &wait);
- prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
- }
-
- /*
- * After a short sleep, check if it was a
- * premature sleep. If not, then go fully
- * to sleep until explicitly woken up
- */
- if (!sleeping_prematurely(pgdat, order, remaining)) {
- trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
- schedule();
- } else {
- if (remaining)
- count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
- else
- count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
- }
- }
-
+ kswapd_try_to_sleep(pgdat, order, classzone_idx);
order = pgdat->kswapd_max_order;
+ classzone_idx = pgdat->classzone_idx;
+ pgdat->kswapd_max_order = 0;
+ pgdat->classzone_idx = pgdat->nr_zones - 1;
}
- finish_wait(&pgdat->kswapd_wait, &wait);
ret = try_to_freeze();
if (kthread_should_stop())
*/
if (!ret) {
trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
- balance_pgdat(pgdat, order);
+ order = balance_pgdat(pgdat, order, &classzone_idx);
}
}
return 0;
/*
* A zone is low on free memory, so wake its kswapd task to service it.
*/
-void wakeup_kswapd(struct zone *zone, int order)
+void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
{
pg_data_t *pgdat;
if (!populated_zone(zone))
return;
- pgdat = zone->zone_pgdat;
- if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0))
- return;
- if (pgdat->kswapd_max_order < order)
- pgdat->kswapd_max_order = order;
- trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
return;
+ pgdat = zone->zone_pgdat;
+ if (pgdat->kswapd_max_order < order) {
+ pgdat->kswapd_max_order = order;
+ pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx);
+ }
if (!waitqueue_active(&pgdat->kswapd_wait))
return;
+ if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0))
+ return;
+
+ trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
wake_up_interruptible(&pgdat->kswapd_wait);
}
return 0;
}
+#ifdef CONFIG_NUMA
/*
* per node 'scan_unevictable_pages' attribute. On demand re-scan of
* a specified node's per zone unevictable lists for evictable pages.
{
sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages);
}
-
+#endif
projects / linux-flexiantxendom0-natty.git / blobdiff