[PATCH v2] mm: compaction: refactor compact_node()

[Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>]

Refactor compact_node() to handle both proactive and synchronous compact
memory, which cleanups code a bit.

Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
v2: 
- drop proactive_compact_node() and add comments for compact_node()
  suggested by Andrew 

 mm/compaction.c | 65 ++++++++++++++++---------------------------------
 1 file changed, 21 insertions(+), 44 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index e63a4ee7e029..de882ecb61c5 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2885,25 +2885,27 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
 }
 
 /*
- * Compact all zones within a node till each zone's fragmentation score
- * reaches within proactive compaction thresholds (as determined by the
- * proactiveness tunable).
+ * compact_node() - compact all zones within a node
+ * @pgdat: The node page data
+ * @proactive: Whether the compaction is proactive
  *
- * It is possible that the function returns before reaching score targets
- * due to various back-off conditions, such as, contention on per-node or
- * per-zone locks.
+ * For proactive compaction, compact till each zone's fragmentation score
+ * reaches within proactive compaction thresholds (as determined by the
+ * proactiveness tunable), it is possible that the function returns before
+ * reaching score targets due to various back-off conditions, such as,
+ * contention on per-node or per-zone locks.
  */
-static void proactive_compact_node(pg_data_t *pgdat)
+static void compact_node(pg_data_t *pgdat, bool proactive)
 {
 	int zoneid;
 	struct zone *zone;
 	struct compact_control cc = {
 		.order = -1,
-		.mode = MIGRATE_SYNC_LIGHT,
+		.mode = proactive ? MIGRATE_SYNC_LIGHT : MIGRATE_SYNC,
 		.ignore_skip_hint = true,
 		.whole_zone = true,
 		.gfp_mask = GFP_KERNEL,
-		.proactive_compaction = true,
+		.proactive_compaction = proactive,
 	};
 
 	for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
@@ -2915,41 +2917,16 @@ static void proactive_compact_node(pg_data_t *pgdat)
 
 		compact_zone(&cc, NULL);
 
-		count_compact_events(KCOMPACTD_MIGRATE_SCANNED,
-				     cc.total_migrate_scanned);
-		count_compact_events(KCOMPACTD_FREE_SCANNED,
-				     cc.total_free_scanned);
-	}
-}
-
-/* Compact all zones within a node */
-static void compact_node(int nid)
-{
-	pg_data_t *pgdat = NODE_DATA(nid);
-	int zoneid;
-	struct zone *zone;
-	struct compact_control cc = {
-		.order = -1,
-		.mode = MIGRATE_SYNC,
-		.ignore_skip_hint = true,
-		.whole_zone = true,
-		.gfp_mask = GFP_KERNEL,
-	};
-
-
-	for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
-
-		zone = &pgdat->node_zones[zoneid];
-		if (!populated_zone(zone))
-			continue;
-
-		cc.zone = zone;
-
-		compact_zone(&cc, NULL);
+		if (proactive) {
+			count_compact_events(KCOMPACTD_MIGRATE_SCANNED,
+					     cc.total_migrate_scanned);
+			count_compact_events(KCOMPACTD_FREE_SCANNED,
+					     cc.total_free_scanned);
+		}
 	}
 }
 
-/* Compact all nodes in the system */
+/* Compact all zones of all nodes in the system */
 static void compact_nodes(void)
 {
 	int nid;
@@ -2958,7 +2935,7 @@ static void compact_nodes(void)
 	lru_add_drain_all();
 
 	for_each_online_node(nid)
-		compact_node(nid);
+		compact_node(NODE_DATA(nid), false);
 }
 
 static int compaction_proactiveness_sysctl_handler(struct ctl_table *table, int write,
@@ -3020,7 +2997,7 @@ static ssize_t compact_store(struct device *dev,
 		/* Flush pending updates to the LRU lists */
 		lru_add_drain_all();
 
-		compact_node(nid);
+		compact_node(NODE_DATA(nid), false);
 	}
 
 	return count;
@@ -3229,7 +3206,7 @@ static int kcompactd(void *p)
 			unsigned int prev_score, score;
 
 			prev_score = fragmentation_score_node(pgdat);
-			proactive_compact_node(pgdat);
+			compact_node(pgdat, true);
 			score = fragmentation_score_node(pgdat);
 			/*
 			 * Defer proactive compaction if the fragmentation
-- 
2.27.0