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-rw-r--r--mm/compaction.c54
1 files changed, 28 insertions, 26 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index b6984e234fdf..bcce7897e17a 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -384,6 +384,20 @@ static bool suitable_migration_target(struct page *page)
}
/*
+ * 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;
+}
+
+/*
* Based on information in the current compact_control, find blocks
* suitable for isolating free pages from and then isolate them.
*/
@@ -422,17 +436,6 @@ 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;
@@ -474,7 +477,15 @@ static void isolate_freepages(struct zone *zone,
*/
if (isolated) {
high_pfn = max(high_pfn, pfn);
- if (cc->order > 0)
+
+ /*
+ * If the free scanner has wrapped, update
+ * compact_cached_free_pfn to point to the highest
+ * pageblock with free pages. This reduces excessive
+ * scanning of full pageblocks near the end of the
+ * zone
+ */
+ if (cc->order > 0 && cc->wrapped)
zone->compact_cached_free_pfn = high_pfn;
}
}
@@ -484,6 +495,11 @@ static void isolate_freepages(struct zone *zone,
cc->free_pfn = high_pfn;
cc->nr_freepages = nr_freepages;
+
+ /* If compact_cached_free_pfn is reset then set it now */
+ if (cc->order > 0 && !cc->wrapped &&
+ zone->compact_cached_free_pfn == start_free_pfn(zone))
+ zone->compact_cached_free_pfn = high_pfn;
}
/*
@@ -570,20 +586,6 @@ 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)
{