dm zoned: reclaim random zones when idle

When the system is idle we should be starting reclaiming
random zones, too.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-zoned-metadata.c

@@ -1859,15 +1859,20 @@ static void dmz_wait_for_reclaim(struct dmz_metadata *zmd, struct dm_zone *zone)
 /*
  * Select a cache or random write zone for reclaim.
  */
-static struct dm_zone *dmz_get_rnd_zone_for_reclaim(struct dmz_metadata *zmd)
+static struct dm_zone *dmz_get_rnd_zone_for_reclaim(struct dmz_metadata *zmd,
+						    bool idle)
 {
 	struct dm_zone *dzone = NULL;
 	struct dm_zone *zone;
 	struct list_head *zone_list = &zmd->map_rnd_list;
 
 	/* If we have cache zones select from the cache zone list */
-	if (zmd->nr_cache)
+	if (zmd->nr_cache) {
 		zone_list = &zmd->map_cache_list;
+		/* Try to relaim random zones, too, when idle */
+		if (idle && list_empty(zone_list))
+			zone_list = &zmd->map_rnd_list;
+	}
 
 	list_for_each_entry(zone, zone_list, link) {
 		if (dmz_is_buf(zone))
@@ -1901,7 +1906,7 @@ static struct dm_zone *dmz_get_seq_zone_for_reclaim(struct dmz_metadata *zmd)
 /*
  * Select a zone for reclaim.
  */
-struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd)
+struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd, bool idle)
 {
 	struct dm_zone *zone;
 
@@ -1917,7 +1922,7 @@ struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd)
 	if (list_empty(&zmd->reserved_seq_zones_list))
 		zone = dmz_get_seq_zone_for_reclaim(zmd);
 	else
-		zone = dmz_get_rnd_zone_for_reclaim(zmd);
+		zone = dmz_get_rnd_zone_for_reclaim(zmd, idle);
 	dmz_unlock_map(zmd);
 
 	return zone;

drivers/md/dm-zoned-reclaim.c

@@ -284,7 +284,10 @@ static int dmz_reclaim_rnd_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 	int alloc_flags = dmz_nr_cache_zones(zmd) ?
 		DMZ_ALLOC_RND : DMZ_ALLOC_SEQ;
 
-	/* Get a free sequential zone */
+	/* Always use sequential zones to reclaim random zones */
+	if (dmz_is_rnd(dzone))
+		alloc_flags = DMZ_ALLOC_SEQ;
+	/* Get a free random or sequential zone */
 	dmz_lock_map(zmd);
 	szone = dmz_alloc_zone(zmd, alloc_flags | DMZ_ALLOC_RECLAIM);
 	dmz_unlock_map(zmd);
@@ -343,6 +346,14 @@ static void dmz_reclaim_empty(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 	dmz_unlock_flush(zmd);
 }
 
+/*
+ * Test if the target device is idle.
+ */
+static inline int dmz_target_idle(struct dmz_reclaim *zrc)
+{
+	return time_is_before_jiffies(zrc->atime + DMZ_IDLE_PERIOD);
+}
+
 /*
  * Find a candidate zone for reclaim and process it.
  */
@@ -355,7 +366,7 @@ static int dmz_do_reclaim(struct dmz_reclaim *zrc)
 	int ret;
 
 	/* Get a data zone */
-	dzone = dmz_get_zone_for_reclaim(zmd);
+	dzone = dmz_get_zone_for_reclaim(zmd, dmz_target_idle(zrc));
 	if (!dzone)
 		return -EBUSY;
 
@@ -418,14 +429,6 @@ static int dmz_do_reclaim(struct dmz_reclaim *zrc)
 	return 0;
 }
 
-/*
- * Test if the target device is idle.
- */
-static inline int dmz_target_idle(struct dmz_reclaim *zrc)
-{
-	return time_is_before_jiffies(zrc->atime + DMZ_IDLE_PERIOD);
-}
-
 static unsigned int dmz_reclaim_percentage(struct dmz_reclaim *zrc)
 {
 	struct dmz_metadata *zmd = zrc->metadata;
@@ -448,8 +451,13 @@ static unsigned int dmz_reclaim_percentage(struct dmz_reclaim *zrc)
  */
 static bool dmz_should_reclaim(struct dmz_reclaim *zrc, unsigned int p_unmap)
 {
+	unsigned int nr_reclaim = dmz_nr_rnd_zones(zrc->metadata);
+
+	if (dmz_nr_cache_zones(zrc->metadata))
+		nr_reclaim += dmz_nr_cache_zones(zrc->metadata);
+
 	/* Reclaim when idle */
-	if (dmz_target_idle(zrc) && p_unmap < 100)
+	if (dmz_target_idle(zrc) && nr_reclaim)
 		return true;
 
 	/* If there are still plenty of cache zones, do not reclaim */

drivers/md/dm-zoned.h

@@ -240,7 +240,7 @@ static inline bool dmz_is_active(struct dm_zone *zone)
 
 int dmz_lock_zone_reclaim(struct dm_zone *zone);
 void dmz_unlock_zone_reclaim(struct dm_zone *zone);
-struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd);
+struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd, bool idle);
 
 struct dm_zone *dmz_get_chunk_mapping(struct dmz_metadata *zmd,
 				      unsigned int chunk, int op);