string: do not export memweight() to userspace

[pandora-kernel.git] / mm / compaction.c

diff --git a/mm/compaction.c b/mm/compaction.c
index 2f42d95..e78cb96 100644 (file)
--- 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();