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-rw-r--r--mm/compaction.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index f61f779..9583e19 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -35,6 +35,8 @@ struct compact_control {
unsigned long nr_anon;
unsigned long nr_file;
+ unsigned int order; /* order a direct compactor needs */
+ int migratetype; /* MOVABLE, RECLAIMABLE etc */
struct zone *zone;
};
@@ -341,6 +343,9 @@ static void update_nr_listpages(struct compact_control *cc)
static int compact_finished(struct zone *zone,
struct compact_control *cc)
{
+ unsigned int order;
+ unsigned long watermark = low_wmark_pages(zone) + (1 << cc->order);
+
if (fatal_signal_pending(current))
return COMPACT_PARTIAL;
@@ -348,6 +353,24 @@ static int compact_finished(struct zone *zone,
if (cc->free_pfn <= cc->migrate_pfn)
return COMPACT_COMPLETE;
+ /* Compaction run is not finished if the watermark is not met */
+ if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
+ return COMPACT_CONTINUE;
+
+ if (cc->order == -1)
+ return COMPACT_CONTINUE;
+
+ /* Direct compactor: Is a suitable page free? */
+ for (order = cc->order; order < MAX_ORDER; order++) {
+ /* Job done if page is free of the right migratetype */
+ if (!list_empty(&zone->free_area[order].free_list[cc->migratetype]))
+ return COMPACT_PARTIAL;
+
+ /* Job done if allocation would set block type */
+ if (order >= pageblock_order && zone->free_area[order].nr_free)
+ return COMPACT_PARTIAL;
+ }
+
return COMPACT_CONTINUE;
}
@@ -394,6 +417,99 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
return ret;
}
+static unsigned long compact_zone_order(struct zone *zone,
+ int order, gfp_t gfp_mask)
+{
+ struct compact_control cc = {
+ .nr_freepages = 0,
+ .nr_migratepages = 0,
+ .order = order,
+ .migratetype = allocflags_to_migratetype(gfp_mask),
+ .zone = zone,
+ };
+ INIT_LIST_HEAD(&cc.freepages);
+ INIT_LIST_HEAD(&cc.migratepages);
+
+ return compact_zone(zone, &cc);
+}
+
+/**
+ * try_to_compact_pages - Direct compact to satisfy a high-order allocation
+ * @zonelist: The zonelist used for the current allocation
+ * @order: The order of the current allocation
+ * @gfp_mask: The GFP mask of the current allocation
+ * @nodemask: The allowed nodes to allocate from
+ *
+ * This is the main entry point for direct page compaction.
+ */
+unsigned long try_to_compact_pages(struct zonelist *zonelist,
+ int order, gfp_t gfp_mask, nodemask_t *nodemask)
+{
+ enum zone_type high_zoneidx = gfp_zone(gfp_mask);
+ int may_enter_fs = gfp_mask & __GFP_FS;
+ int may_perform_io = gfp_mask & __GFP_IO;
+ unsigned long watermark;
+ struct zoneref *z;
+ struct zone *zone;
+ int rc = COMPACT_SKIPPED;
+
+ /*
+ * Check whether it is worth even starting compaction. The order check is
+ * made because an assumption is made that the page allocator can satisfy
+ * the "cheaper" orders without taking special steps
+ */
+ if (order <= PAGE_ALLOC_COSTLY_ORDER || !may_enter_fs || !may_perform_io)
+ return rc;
+
+ count_vm_event(COMPACTSTALL);
+
+ /* Compact each zone in the list */
+ for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
+ nodemask) {
+ int fragindex;
+ int status;
+
+ /*
+ * Watermarks for order-0 must be met for compaction. Note
+ * the 2UL. This is because during migration, copies of
+ * pages need to be allocated and for a short time, the
+ * footprint is higher
+ */
+ watermark = low_wmark_pages(zone) + (2UL << order);
+ if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
+ continue;
+
+ /*
+ * fragmentation index determines if allocation failures are
+ * due to low memory or external fragmentation
+ *
+ * index of -1 implies allocations might succeed depending
+ * on watermarks
+ * index towards 0 implies failure is due to lack of memory
+ * index towards 1000 implies failure is due to fragmentation
+ *
+ * Only compact if a failure would be due to fragmentation.
+ */
+ fragindex = fragmentation_index(zone, order);
+ if (fragindex >= 0 && fragindex <= 500)
+ continue;
+
+ if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0)) {
+ rc = COMPACT_PARTIAL;
+ break;
+ }
+
+ status = compact_zone_order(zone, order, gfp_mask);
+ rc = max(status, rc);
+
+ if (zone_watermark_ok(zone, order, watermark, 0, 0))
+ break;
+ }
+
+ return rc;
+}
+
+
/* Compact all zones within a node */
static int compact_node(int nid)
{
@@ -412,6 +528,7 @@ static int compact_node(int nid)
struct compact_control cc = {
.nr_freepages = 0,
.nr_migratepages = 0,
+ .order = -1,
};
zone = &pgdat->node_zones[zoneid];
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