return PAGE_ACTIVATE;
}
- /*
- * Wait on writeback if requested to. This happens when
- * direct reclaiming a large contiguous area and the
- * first attempt to free a range of pages fails.
- */
- if (PageWriteback(page) &&
- (sc->reclaim_mode & RECLAIM_MODE_SYNC))
- wait_on_page_writeback(page);
-
if (!PageWriteback(page)) {
/* synchronous write or broken a_ops? */
ClearPageReclaim(page);
*/
static unsigned long shrink_page_list(struct list_head *page_list,
struct zone *zone,
- struct scan_control *sc)
+ struct scan_control *sc,
+ int priority,
+ unsigned long *ret_nr_dirty,
+ unsigned long *ret_nr_writeback)
{
LIST_HEAD(ret_pages);
LIST_HEAD(free_pages);
unsigned long nr_dirty = 0;
unsigned long nr_congested = 0;
unsigned long nr_reclaimed = 0;
+ unsigned long nr_writeback = 0;
cond_resched();
(PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
if (PageWriteback(page)) {
+ nr_writeback++;
/*
- * Synchronous reclaim is performed in two passes,
- * first an asynchronous pass over the list to
- * start parallel writeback, and a second synchronous
- * pass to wait for the IO to complete. Wait here
- * for any page for which writeback has already
- * started.
+ * Synchronous reclaim cannot queue pages for
+ * writeback due to the possibility of stack overflow
+ * but if it encounters a page under writeback, wait
+ * for the IO to complete.
*/
if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) &&
may_enter_fs)
if (PageDirty(page)) {
nr_dirty++;
+ /*
+ * Only kswapd can writeback filesystem pages to
+ * avoid risk of stack overflow but do not writeback
+ * unless under significant pressure.
+ */
+ if (page_is_file_cache(page) &&
+ (!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) {
+ inc_zone_page_state(page, NR_VMSCAN_WRITE_SKIP);
+ goto keep_locked;
+ }
+
if (references == PAGEREF_RECLAIM_CLEAN)
goto keep_locked;
if (!may_enter_fs)
list_splice(&ret_pages, page_list);
count_vm_events(PGACTIVATE, pgactivate);
+ *ret_nr_dirty += nr_dirty;
+ *ret_nr_writeback += nr_writeback;
return nr_reclaimed;
}
*
* returns 0 on success, -ve errno on failure.
*/
-int __isolate_lru_page(struct page *page, int mode, int file)
+int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file)
{
+ bool all_lru_mode;
int ret = -EINVAL;
/* Only take pages on the LRU. */
if (!PageLRU(page))
return ret;
+ all_lru_mode = (mode & (ISOLATE_ACTIVE|ISOLATE_INACTIVE)) ==
+ (ISOLATE_ACTIVE|ISOLATE_INACTIVE);
+
/*
* When checking the active state, we need to be sure we are
* dealing with comparible boolean values. Take the logical not
* of each.
*/
- if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
+ if (!all_lru_mode && !PageActive(page) != !(mode & ISOLATE_ACTIVE))
return ret;
- if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file)
+ if (!all_lru_mode && !!page_is_file_cache(page) != file)
return ret;
/*
ret = -EBUSY;
+ if ((mode & ISOLATE_CLEAN) && (PageDirty(page) || PageWriteback(page)))
+ return ret;
+
+ if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))
+ return ret;
+
if (likely(get_page_unless_zero(page))) {
/*
* Be careful not to clear PageLRU until after we're
*/
static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
struct list_head *src, struct list_head *dst,
- unsigned long *scanned, int order, int mode, int file)
+ unsigned long *scanned, int order, isolate_mode_t mode,
+ int file)
{
unsigned long nr_taken = 0;
unsigned long nr_lumpy_taken = 0;
static unsigned long isolate_pages_global(unsigned long nr,
struct list_head *dst,
unsigned long *scanned, int order,
- int mode, struct zone *z,
- int active, int file)
+ isolate_mode_t mode,
+ struct zone *z, int active, int file)
{
int lru = LRU_BASE;
if (active)
}
/*
- * Returns true if the caller should wait to clean dirty/writeback pages.
+ * Returns true if a direct reclaim should wait on pages under writeback.
*
* If we are direct reclaiming for contiguous pages and we do not reclaim
* everything in the list, try again and wait for writeback IO to complete.
if (sc->reclaim_mode & RECLAIM_MODE_SINGLE)
return false;
- /* If we have relaimed everything on the isolated list, no stall */
+ /* If we have reclaimed everything on the isolated list, no stall */
if (nr_freed == nr_taken)
return false;
unsigned long nr_taken;
unsigned long nr_anon;
unsigned long nr_file;
+ unsigned long nr_dirty = 0;
+ unsigned long nr_writeback = 0;
+ isolate_mode_t reclaim_mode = ISOLATE_INACTIVE;
while (unlikely(too_many_isolated(zone, file, sc))) {
congestion_wait(BLK_RW_ASYNC, HZ/10);
}
set_reclaim_mode(priority, sc, false);
+ if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM)
+ reclaim_mode |= ISOLATE_ACTIVE;
+
lru_add_drain();
+
+ if (!sc->may_unmap)
+ reclaim_mode |= ISOLATE_UNMAPPED;
+ if (!sc->may_writepage)
+ reclaim_mode |= ISOLATE_CLEAN;
+
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->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
- ISOLATE_BOTH : ISOLATE_INACTIVE,
- zone, 0, file);
+ nr_taken = isolate_pages_global(nr_to_scan, &page_list,
+ &nr_scanned, sc->order, reclaim_mode, zone, 0, file);
zone->pages_scanned += nr_scanned;
if (current_is_kswapd())
__count_zone_vm_events(PGSCAN_KSWAPD, zone,
__count_zone_vm_events(PGSCAN_DIRECT, zone,
nr_scanned);
} else {
- nr_taken = mem_cgroup_isolate_pages(nr_to_scan,
- &page_list, &nr_scanned, sc->order,
- sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
- ISOLATE_BOTH : ISOLATE_INACTIVE,
- zone, sc->mem_cgroup,
- 0, file);
+ nr_taken = mem_cgroup_isolate_pages(nr_to_scan, &page_list,
+ &nr_scanned, sc->order, reclaim_mode, zone,
+ sc->mem_cgroup, 0, file);
/*
* mem_cgroup_isolate_pages() keeps track of
* scanned pages on its own.
spin_unlock_irq(&zone->lru_lock);
- nr_reclaimed = shrink_page_list(&page_list, zone, sc);
+ nr_reclaimed = shrink_page_list(&page_list, zone, sc, priority,
+ &nr_dirty, &nr_writeback);
/* Check if we should syncronously wait for writeback */
if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
set_reclaim_mode(priority, sc, true);
- nr_reclaimed += shrink_page_list(&page_list, zone, sc);
+ nr_reclaimed += shrink_page_list(&page_list, zone, sc,
+ priority, &nr_dirty, &nr_writeback);
}
local_irq_disable();
putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list);
+ /*
+ * If reclaim is isolating dirty pages under writeback, it implies
+ * that the long-lived page allocation rate is exceeding the page
+ * laundering rate. Either the global limits are not being effective
+ * at throttling processes due to the page distribution throughout
+ * zones or there is heavy usage of a slow backing device. The
+ * only option is to throttle from reclaim context which is not ideal
+ * as there is no guarantee the dirtying process is throttled in the
+ * same way balance_dirty_pages() manages.
+ *
+ * This scales the number of dirty pages that must be under writeback
+ * before throttling depending on priority. It is a simple backoff
+ * function that has the most effect in the range DEF_PRIORITY to
+ * DEF_PRIORITY-2 which is the priority reclaim is considered to be
+ * in trouble and reclaim is considered to be in trouble.
+ *
+ * DEF_PRIORITY 100% isolated pages must be PageWriteback to throttle
+ * DEF_PRIORITY-1 50% must be PageWriteback
+ * DEF_PRIORITY-2 25% must be PageWriteback, kswapd in trouble
+ * ...
+ * DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any
+ * isolated page is PageWriteback
+ */
+ if (nr_writeback && nr_writeback >= (nr_taken >> (DEF_PRIORITY-priority)))
+ wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);
+
trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
zone_idx(zone),
nr_scanned, nr_reclaimed,
struct page *page;
struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
unsigned long nr_rotated = 0;
+ isolate_mode_t reclaim_mode = ISOLATE_ACTIVE;
lru_add_drain();
+
+ if (!sc->may_unmap)
+ reclaim_mode |= ISOLATE_UNMAPPED;
+ if (!sc->may_writepage)
+ reclaim_mode |= ISOLATE_CLEAN;
+
spin_lock_irq(&zone->lru_lock);
if (scanning_global_lru(sc)) {
nr_taken = isolate_pages_global(nr_pages, &l_hold,
&pgscanned, sc->order,
- ISOLATE_ACTIVE, zone,
+ reclaim_mode, zone,
1, file);
zone->pages_scanned += pgscanned;
} else {
nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold,
&pgscanned, sc->order,
- ISOLATE_ACTIVE, zone,
+ reclaim_mode, zone,
sc->mem_cgroup, 1, file);
/*
* mem_cgroup_isolate_pages() keeps track of
enum lru_list l;
int noswap = 0;
bool force_scan = false;
- unsigned long nr_force_scan[2];
- /* kswapd does zone balancing and needs to scan this zone */
+ /*
+ * If the zone or memcg is small, nr[l] can be 0. This
+ * results in no scanning on this priority and a potential
+ * priority drop. Global direct reclaim can go to the next
+ * zone and tends to have no problems. Global kswapd is for
+ * zone balancing and it needs to scan a minimum amount. When
+ * reclaiming for a memcg, a priority drop can cause high
+ * latencies, so it's better to scan a minimum amount there as
+ * well.
+ */
if (scanning_global_lru(sc) && current_is_kswapd())
force_scan = true;
- /* memcg may have small limit and need to avoid priority drop */
if (!scanning_global_lru(sc))
force_scan = true;
fraction[0] = 0;
fraction[1] = 1;
denominator = 1;
- nr_force_scan[0] = 0;
- nr_force_scan[1] = SWAP_CLUSTER_MAX;
goto out;
}
fraction[0] = 1;
fraction[1] = 0;
denominator = 1;
- nr_force_scan[0] = SWAP_CLUSTER_MAX;
- nr_force_scan[1] = 0;
goto out;
}
}
fraction[0] = ap;
fraction[1] = fp;
denominator = ap + fp + 1;
- if (force_scan) {
- unsigned long scan = SWAP_CLUSTER_MAX;
- nr_force_scan[0] = div64_u64(scan * ap, denominator);
- nr_force_scan[1] = div64_u64(scan * fp, denominator);
- }
out:
for_each_evictable_lru(l) {
int file = is_file_lru(l);
scan = zone_nr_lru_pages(zone, sc, l);
if (priority || noswap) {
scan >>= priority;
+ if (!scan && force_scan)
+ scan = SWAP_CLUSTER_MAX;
scan = div64_u64(scan * fraction[file], denominator);
}
-
- /*
- * If zone is small or memcg is small, nr[l] can be 0.
- * This results no-scan on this priority and priority drop down.
- * For global direct reclaim, it can visit next zone and tend
- * not to have problems. For global kswapd, it's for zone
- * balancing and it need to scan a small amounts. When using
- * memcg, priority drop can cause big latency. So, it's better
- * to scan small amount. See may_noscan above.
- */
- if (!scan && force_scan)
- scan = nr_force_scan[file];
nr[l] = scan;
}
}
enum lru_list l;
unsigned long nr_reclaimed, nr_scanned;
unsigned long nr_to_reclaim = sc->nr_to_reclaim;
+ struct blk_plug plug;
restart:
nr_reclaimed = 0;
nr_scanned = sc->nr_scanned;
get_scan_count(zone, sc, nr, priority);
+ blk_start_plug(&plug);
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;
}
+ blk_finish_plug(&plug);
sc->nr_reclaimed += nr_reclaimed;
/*
git.openpandora.org / pandora-kernel.git / blobdiff