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-rw-r--r--include/linux/compaction.h15
-rw-r--r--include/linux/mmzone.h3
-rw-r--r--mm/compaction.c50
-rw-r--r--mm/page_alloc.c1
-rw-r--r--mm/vmscan.c8
5 files changed, 60 insertions, 17 deletions
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 0e38a1d..6ecb6dc 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -24,6 +24,7 @@ extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
int order, gfp_t gfp_mask, nodemask_t *mask,
bool sync, bool *contended, struct page **page);
extern int compact_pgdat(pg_data_t *pgdat, int order);
+extern void reset_isolation_suitable(pg_data_t *pgdat);
extern unsigned long compaction_suitable(struct zone *zone, int order);
/* Do not skip compaction more than 64 times */
@@ -61,6 +62,16 @@ static inline bool compaction_deferred(struct zone *zone, int order)
return zone->compact_considered < defer_limit;
}
+/* Returns true if restarting compaction after many failures */
+static inline bool compaction_restarting(struct zone *zone, int order)
+{
+ if (order < zone->compact_order_failed)
+ return false;
+
+ return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
+ zone->compact_considered >= 1UL << zone->compact_defer_shift;
+}
+
#else
static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
int order, gfp_t gfp_mask, nodemask_t *nodemask,
@@ -74,6 +85,10 @@ static inline int compact_pgdat(pg_data_t *pgdat, int order)
return COMPACT_CONTINUE;
}
+static inline void reset_isolation_suitable(pg_data_t *pgdat)
+{
+}
+
static inline unsigned long compaction_suitable(struct zone *zone, int order)
{
return COMPACT_SKIPPED;
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index c8b3abc..d240efa 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -370,7 +370,8 @@ struct zone {
spinlock_t lock;
int all_unreclaimable; /* All pages pinned */
#if defined CONFIG_COMPACTION || defined CONFIG_CMA
- unsigned long compact_blockskip_expire;
+ /* Set to true when the PG_migrate_skip bits should be cleared */
+ bool compact_blockskip_flush;
/* pfns where compaction scanners should start */
unsigned long compact_cached_free_pfn;
diff --git a/mm/compaction.c b/mm/compaction.c
index f94cbc0..d8187f9 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -66,24 +66,15 @@ static inline bool isolation_suitable(struct compact_control *cc,
* should be skipped for page isolation when the migrate and free page scanner
* meet.
*/
-static void reset_isolation_suitable(struct zone *zone)
+static void __reset_isolation_suitable(struct zone *zone)
{
unsigned long start_pfn = zone->zone_start_pfn;
unsigned long end_pfn = zone->zone_start_pfn + zone->spanned_pages;
unsigned long pfn;
- /*
- * Do not reset more than once every five seconds. If allocations are
- * failing sufficiently quickly to allow this to happen then continually
- * scanning for compaction is not going to help. The choice of five
- * seconds is arbitrary but will mitigate excessive scanning.
- */
- if (time_before(jiffies, zone->compact_blockskip_expire))
- return;
-
zone->compact_cached_migrate_pfn = start_pfn;
zone->compact_cached_free_pfn = end_pfn;
- zone->compact_blockskip_expire = jiffies + (HZ * 5);
+ zone->compact_blockskip_flush = false;
/* Walk the zone and mark every pageblock as suitable for isolation */
for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
@@ -102,9 +93,24 @@ static void reset_isolation_suitable(struct zone *zone)
}
}
+void reset_isolation_suitable(pg_data_t *pgdat)
+{
+ int zoneid;
+
+ for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
+ struct zone *zone = &pgdat->node_zones[zoneid];
+ if (!populated_zone(zone))
+ continue;
+
+ /* Only flush if a full compaction finished recently */
+ if (zone->compact_blockskip_flush)
+ __reset_isolation_suitable(zone);
+ }
+}
+
/*
* If no pages were isolated then mark this pageblock to be skipped in the
- * future. The information is later cleared by reset_isolation_suitable().
+ * future. The information is later cleared by __reset_isolation_suitable().
*/
static void update_pageblock_skip(struct compact_control *cc,
struct page *page, unsigned long nr_isolated,
@@ -820,7 +826,15 @@ static int compact_finished(struct zone *zone,
/* Compaction run completes if the migrate and free scanner meet */
if (cc->free_pfn <= cc->migrate_pfn) {
- reset_isolation_suitable(cc->zone);
+ /*
+ * Mark that the PG_migrate_skip information should be cleared
+ * by kswapd when it goes to sleep. kswapd does not set the
+ * flag itself as the decision to be clear should be directly
+ * based on an allocation request.
+ */
+ if (!current_is_kswapd())
+ zone->compact_blockskip_flush = true;
+
return COMPACT_COMPLETE;
}
@@ -943,9 +957,13 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
zone->compact_cached_migrate_pfn = cc->migrate_pfn;
}
- /* Clear pageblock skip if there are numerous alloc failures */
- if (zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT)
- reset_isolation_suitable(zone);
+ /*
+ * Clear pageblock skip if there were failures recently and compaction
+ * is about to be retried after being deferred. kswapd does not do
+ * this reset as it'll reset the cached information when going to sleep.
+ */
+ if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
+ __reset_isolation_suitable(zone);
migrate_prep_local();
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 44c5604..b97cf12 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2172,6 +2172,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
preferred_zone, migratetype);
if (page) {
got_page:
+ preferred_zone->compact_blockskip_flush = false;
preferred_zone->compact_considered = 0;
preferred_zone->compact_defer_shift = 0;
if (order >= preferred_zone->compact_order_failed)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1ee4b69..b010efc 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2895,6 +2895,14 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
*/
set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
+ /*
+ * Compaction records what page blocks it recently failed to
+ * isolate pages from and skips them in the future scanning.
+ * When kswapd is going to sleep, it is reasonable to assume
+ * that pages and compaction may succeed so reset the cache.
+ */
+ reset_isolation_suitable(pgdat);
+
if (!kthread_should_stop())
schedule();
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