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-rw-r--r--mm/compaction.c63
1 files changed, 58 insertions, 5 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 2f42d952853..e78cb968842 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -422,6 +422,17 @@ static void isolate_freepages(struct zone *zone,
pfn -= pageblock_nr_pages) {
unsigned long isolated;
+ /*
+ * Skip ahead if another thread is compacting in the area
+ * simultaneously. If we wrapped around, we can only skip
+ * ahead if zone->compact_cached_free_pfn also wrapped to
+ * above our starting point.
+ */
+ if (cc->order > 0 && (!cc->wrapped ||
+ zone->compact_cached_free_pfn >
+ cc->start_free_pfn))
+ pfn = min(pfn, zone->compact_cached_free_pfn);
+
if (!pfn_valid(pfn))
continue;
@@ -461,8 +472,11 @@ static void isolate_freepages(struct zone *zone,
* looking for free pages, the search will restart here as
* page migration may have returned some pages to the allocator
*/
- if (isolated)
+ if (isolated) {
high_pfn = max(high_pfn, pfn);
+ if (cc->order > 0)
+ zone->compact_cached_free_pfn = high_pfn;
+ }
}
/* split_free_page does not map the pages */
@@ -556,6 +570,20 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
return ISOLATE_SUCCESS;
}
+/*
+ * Returns the start pfn of the last page block in a zone. This is the starting
+ * point for full compaction of a zone. Compaction searches for free pages from
+ * the end of each zone, while isolate_freepages_block scans forward inside each
+ * page block.
+ */
+static unsigned long start_free_pfn(struct zone *zone)
+{
+ unsigned long free_pfn;
+ free_pfn = zone->zone_start_pfn + zone->spanned_pages;
+ free_pfn &= ~(pageblock_nr_pages-1);
+ return free_pfn;
+}
+
static int compact_finished(struct zone *zone,
struct compact_control *cc)
{
@@ -565,8 +593,26 @@ static int compact_finished(struct zone *zone,
if (fatal_signal_pending(current))
return COMPACT_PARTIAL;
- /* Compaction run completes if the migrate and free scanner meet */
- if (cc->free_pfn <= cc->migrate_pfn)
+ /*
+ * A full (order == -1) compaction run starts at the beginning and
+ * end of a zone; it completes when the migrate and free scanner meet.
+ * A partial (order > 0) compaction can start with the free scanner
+ * at a random point in the zone, and may have to restart.
+ */
+ if (cc->free_pfn <= cc->migrate_pfn) {
+ if (cc->order > 0 && !cc->wrapped) {
+ /* We started partway through; restart at the end. */
+ unsigned long free_pfn = start_free_pfn(zone);
+ zone->compact_cached_free_pfn = free_pfn;
+ cc->free_pfn = free_pfn;
+ cc->wrapped = 1;
+ return COMPACT_CONTINUE;
+ }
+ return COMPACT_COMPLETE;
+ }
+
+ /* We wrapped around and ended up where we started. */
+ if (cc->wrapped && cc->free_pfn <= cc->start_free_pfn)
return COMPACT_COMPLETE;
/*
@@ -664,8 +710,15 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
/* Setup to move all movable pages to the end of the zone */
cc->migrate_pfn = zone->zone_start_pfn;
- cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
- cc->free_pfn &= ~(pageblock_nr_pages-1);
+
+ if (cc->order > 0) {
+ /* Incremental compaction. Start where the last one stopped. */
+ cc->free_pfn = zone->compact_cached_free_pfn;
+ cc->start_free_pfn = cc->free_pfn;
+ } else {
+ /* Order == -1 starts at the end of the zone. */
+ cc->free_pfn = start_free_pfn(zone);
+ }
migrate_prep_local();