[GFS2] Replace rgrp "recent list" with mru list

This patch removes the "recent list" which is used during allocation and replaces it with the (already existing) mru list used during deletion. The "recent list" was not a true mru list leading to a number of inefficiencies including a "next" function which made scanning the list an order N^2 operation wrt to the number of list elements. This should increase allocation performance with large numbers of rgrps. Its also a useful preparation and cleanup before some further changes which are planned in this area. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

[GFS2] Replace rgrp "recent list" with mru list
This patch removes the "recent list" which is used during allocation and replaces it with the (already existing) mru list used during deletion. The "recent list" was not a true mru list leading to a number of inefficiencies including a "next" function which made scanning the list an order N^2 operation wrt to the number of list elements. This should increase allocation performance with large numbers of rgrps. Its also a useful preparation and cleanup before some further changes which are planned in this area. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Steven Whitehouse
1 parent 209806aba9
Showing 3 changed files with 12 additions and 99 deletions Side-by-side Diff
fs/gfs2/incore.h
fs/gfs2/ops_fstype.c
fs/gfs2/rgrp.c
@@ -77,7 +77,6 @@
 struct gfs2_rgrpd {
 	struct list_head rd_list;	/* Link with superblock */
 	struct list_head rd_list_mru;
-	struct list_head rd_recent;	/* Recently used rgrps */
 	struct gfs2_glock *rd_gl;	/* Glock for this rgrp */
 	u64 rd_addr;			/* grp block disk address */
 	u64 rd_data0;			/* first data location */
@@ -529,7 +528,6 @@
 	struct mutex sd_rindex_mutex;
 	struct list_head sd_rindex_list;
 	struct list_head sd_rindex_mru_list;
-	struct list_head sd_rindex_recent_list;
 	struct gfs2_rgrpd *sd_rindex_forward;
 	unsigned int sd_rgrps;
  
@@ -64,7 +64,6 @@
 	mutex_init(&sdp->sd_rindex_mutex);
 	INIT_LIST_HEAD(&sdp->sd_rindex_list);
 	INIT_LIST_HEAD(&sdp->sd_rindex_mru_list);
-	INIT_LIST_HEAD(&sdp->sd_rindex_recent_list);
  
 	INIT_LIST_HEAD(&sdp->sd_jindex_list);
 	spin_lock_init(&sdp->sd_jindex_spin);
@@ -371,11 +371,6 @@
  
 	spin_lock(&sdp->sd_rindex_spin);
 	sdp->sd_rindex_forward = NULL;
-	head = &sdp->sd_rindex_recent_list;
-	while (!list_empty(head)) {
-		rgd = list_entry(head->next, struct gfs2_rgrpd, rd_recent);
-		list_del(&rgd->rd_recent);
-	}
 	spin_unlock(&sdp->sd_rindex_spin);
  
 	head = &sdp->sd_rindex_list;
  
  
  
  
  
@@ -945,107 +940,30 @@
 }
  
 /**
- * recent_rgrp_first - get first RG from "recent" list
- * @sdp: The GFS2 superblock
- * @rglast: address of the rgrp used last
- *
- * Returns: The first rgrp in the recent list
- */
-
-static struct gfs2_rgrpd *recent_rgrp_first(struct gfs2_sbd *sdp,
-					    u64 rglast)
-{
-	struct gfs2_rgrpd *rgd;
-
-	spin_lock(&sdp->sd_rindex_spin);
-
-	if (rglast) {
-		list_for_each_entry(rgd, &sdp->sd_rindex_recent_list, rd_recent) {
-			if (rgrp_contains_block(rgd, rglast))
-				goto out;
-		}
-	}
-	rgd = NULL;
-	if (!list_empty(&sdp->sd_rindex_recent_list))
-		rgd = list_entry(sdp->sd_rindex_recent_list.next,
-				 struct gfs2_rgrpd, rd_recent);
-out:
-	spin_unlock(&sdp->sd_rindex_spin);
-	return rgd;
-}
-
-/**
  * recent_rgrp_next - get next RG from "recent" list
  * @cur_rgd: current rgrp
- * @remove:
  *
  * Returns: The next rgrp in the recent list
  */
  
-static struct gfs2_rgrpd *recent_rgrp_next(struct gfs2_rgrpd *cur_rgd,
-					   int remove)
+static struct gfs2_rgrpd *recent_rgrp_next(struct gfs2_rgrpd *cur_rgd)
 {
 	struct gfs2_sbd *sdp = cur_rgd->rd_sbd;
 	struct list_head *head;
 	struct gfs2_rgrpd *rgd;
  
 	spin_lock(&sdp->sd_rindex_spin);
-
-	head = &sdp->sd_rindex_recent_list;
-
-	list_for_each_entry(rgd, head, rd_recent) {
-		if (rgd == cur_rgd) {
-			if (cur_rgd->rd_recent.next != head)
-				rgd = list_entry(cur_rgd->rd_recent.next,
-						 struct gfs2_rgrpd, rd_recent);
-			else
-				rgd = NULL;
-
-			if (remove)
-				list_del(&cur_rgd->rd_recent);
-
-			goto out;
-		}
+	head = &sdp->sd_rindex_mru_list;
+	if (unlikely(cur_rgd->rd_list_mru.next == head)) {
+		spin_unlock(&sdp->sd_rindex_spin);
+		return NULL;
 	}
-
-	rgd = NULL;
-	if (!list_empty(head))
-		rgd = list_entry(head->next, struct gfs2_rgrpd, rd_recent);
-
-out:
+	rgd = list_entry(cur_rgd->rd_list_mru.next, struct gfs2_rgrpd, rd_list_mru);
 	spin_unlock(&sdp->sd_rindex_spin);
 	return rgd;
 }
  
 /**
- * recent_rgrp_add - add an RG to tail of "recent" list
- * @new_rgd: The rgrp to add
- *
- */
-
-static void recent_rgrp_add(struct gfs2_rgrpd *new_rgd)
-{
-	struct gfs2_sbd *sdp = new_rgd->rd_sbd;
-	struct gfs2_rgrpd *rgd;
-	unsigned int count = 0;
-	unsigned int max = sdp->sd_rgrps / gfs2_jindex_size(sdp);
-
-	spin_lock(&sdp->sd_rindex_spin);
-
-	list_for_each_entry(rgd, &sdp->sd_rindex_recent_list, rd_recent) {
-		if (rgd == new_rgd)
-			goto out;
-
-		if (++count >= max)
-			goto out;
-	}
-	list_add_tail(&new_rgd->rd_recent, &sdp->sd_rindex_recent_list);
-
-out:
-	spin_unlock(&sdp->sd_rindex_spin);
-}
-
-/**
  * forward_rgrp_get - get an rgrp to try next from full list
  * @sdp: The GFS2 superblock
  *
  
@@ -1112,10 +1030,8 @@
 	int loops = 0;
 	int error, rg_locked;
  
-	/* Try recently successful rgrps */
+	rgd = gfs2_blk2rgrpd(sdp, ip->i_goal);
  
-	rgd = recent_rgrp_first(sdp, ip->i_goal);
-
 	while (rgd) {
 		rg_locked = 0;
  
  
@@ -1136,11 +1052,9 @@
 				gfs2_glock_dq_uninit(&al->al_rgd_gh);
 			if (inode)
 				return inode;
-			rgd = recent_rgrp_next(rgd, 1);
-			break;
-
+			/* fall through */
 		case GLR_TRYFAILED:
-			rgd = recent_rgrp_next(rgd, 0);
+			rgd = recent_rgrp_next(rgd);
 			break;
  
 		default:
@@ -1199,7 +1113,9 @@
  
 out:
 	if (begin) {
-		recent_rgrp_add(rgd);
+		spin_lock(&sdp->sd_rindex_spin);
+		list_move(&rgd->rd_list_mru, &sdp->sd_rindex_mru_list);
+		spin_unlock(&sdp->sd_rindex_spin);
 		rgd = gfs2_rgrpd_get_next(rgd);
 		if (!rgd)
 			rgd = gfs2_rgrpd_get_first(sdp);
...	...	@@ -77,7 +77,6 @@
77	77	struct gfs2_rgrpd {
78	78	struct list_head rd_list; /* Link with superblock */
79	79	struct list_head rd_list_mru;
80		- struct list_head rd_recent; /* Recently used rgrps */
81	80	struct gfs2_glock rd_gl; / Glock for this rgrp */
82	81	u64 rd_addr; /* grp block disk address */
83	82	u64 rd_data0; /* first data location */
...	...	@@ -529,7 +528,6 @@
529	528	struct mutex sd_rindex_mutex;
530	529	struct list_head sd_rindex_list;
531	530	struct list_head sd_rindex_mru_list;
532		- struct list_head sd_rindex_recent_list;
533	531	struct gfs2_rgrpd *sd_rindex_forward;
534	532	unsigned int sd_rgrps;
535	533
...	...	@@ -64,7 +64,6 @@
64	64	mutex_init(&sdp->sd_rindex_mutex);
65	65	INIT_LIST_HEAD(&sdp->sd_rindex_list);
66	66	INIT_LIST_HEAD(&sdp->sd_rindex_mru_list);
67		- INIT_LIST_HEAD(&sdp->sd_rindex_recent_list);
68	67
69	68	INIT_LIST_HEAD(&sdp->sd_jindex_list);
70	69	spin_lock_init(&sdp->sd_jindex_spin);
...	...	@@ -371,11 +371,6 @@
371	371
372	372	spin_lock(&sdp->sd_rindex_spin);
373	373	sdp->sd_rindex_forward = NULL;
374		- head = &sdp->sd_rindex_recent_list;
375		- while (!list_empty(head)) {
376		- rgd = list_entry(head->next, struct gfs2_rgrpd, rd_recent);
377		- list_del(&rgd->rd_recent);
378		- }
379	374	spin_unlock(&sdp->sd_rindex_spin);
380	375
381	376	head = &sdp->sd_rindex_list;
382	377
383	378
384	379
385	380
386	381
...	...	@@ -945,107 +940,30 @@
945	940	}
946	941
947	942	/**
948		- * recent_rgrp_first - get first RG from "recent" list
949		- * @sdp: The GFS2 superblock
950		- * @rglast: address of the rgrp used last
951		- *
952		- * Returns: The first rgrp in the recent list
953		- */
954		-
955		-static struct gfs2_rgrpd recent_rgrp_first(struct gfs2_sbd sdp,
956		- u64 rglast)
957		-{
958		- struct gfs2_rgrpd *rgd;
959		-
960		- spin_lock(&sdp->sd_rindex_spin);
961		-
962		- if (rglast) {
963		- list_for_each_entry(rgd, &sdp->sd_rindex_recent_list, rd_recent) {
964		- if (rgrp_contains_block(rgd, rglast))
965		- goto out;
966		- }
967		- }
968		- rgd = NULL;
969		- if (!list_empty(&sdp->sd_rindex_recent_list))
970		- rgd = list_entry(sdp->sd_rindex_recent_list.next,
971		- struct gfs2_rgrpd, rd_recent);
972		-out:
973		- spin_unlock(&sdp->sd_rindex_spin);
974		- return rgd;
975		-}
976		-
977		-/**
978	943	* recent_rgrp_next - get next RG from "recent" list
979	944	* @cur_rgd: current rgrp
980		- * @remove:
981	945	*
982	946	* Returns: The next rgrp in the recent list
983	947	*/
984	948
985		-static struct gfs2_rgrpd recent_rgrp_next(struct gfs2_rgrpd cur_rgd,
986		- int remove)
	949	+static struct gfs2_rgrpd recent_rgrp_next(struct gfs2_rgrpd cur_rgd)
987	950	{
988	951	struct gfs2_sbd *sdp = cur_rgd->rd_sbd;
989	952	struct list_head *head;
990	953	struct gfs2_rgrpd *rgd;
991	954
992	955	spin_lock(&sdp->sd_rindex_spin);
993		-
994		- head = &sdp->sd_rindex_recent_list;
995		-
996		- list_for_each_entry(rgd, head, rd_recent) {
997		- if (rgd == cur_rgd) {
998		- if (cur_rgd->rd_recent.next != head)
999		- rgd = list_entry(cur_rgd->rd_recent.next,
1000		- struct gfs2_rgrpd, rd_recent);
1001		- else
1002		- rgd = NULL;
1003		-
1004		- if (remove)
1005		- list_del(&cur_rgd->rd_recent);
1006		-
1007		- goto out;
1008		- }
	956	+ head = &sdp->sd_rindex_mru_list;
	957	+ if (unlikely(cur_rgd->rd_list_mru.next == head)) {
	958	+ spin_unlock(&sdp->sd_rindex_spin);
	959	+ return NULL;
1009	960	}
1010		-
1011		- rgd = NULL;
1012		- if (!list_empty(head))
1013		- rgd = list_entry(head->next, struct gfs2_rgrpd, rd_recent);
1014		-
1015		-out:
	961	+ rgd = list_entry(cur_rgd->rd_list_mru.next, struct gfs2_rgrpd, rd_list_mru);
1016	962	spin_unlock(&sdp->sd_rindex_spin);
1017	963	return rgd;
1018	964	}
1019	965
1020	966	/**
1021		- * recent_rgrp_add - add an RG to tail of "recent" list
1022		- * @new_rgd: The rgrp to add
1023		- *
1024		- */
1025		-
1026		-static void recent_rgrp_add(struct gfs2_rgrpd *new_rgd)
1027		-{
1028		- struct gfs2_sbd *sdp = new_rgd->rd_sbd;
1029		- struct gfs2_rgrpd *rgd;
1030		- unsigned int count = 0;
1031		- unsigned int max = sdp->sd_rgrps / gfs2_jindex_size(sdp);
1032		-
1033		- spin_lock(&sdp->sd_rindex_spin);
1034		-
1035		- list_for_each_entry(rgd, &sdp->sd_rindex_recent_list, rd_recent) {
1036		- if (rgd == new_rgd)
1037		- goto out;
1038		-
1039		- if (++count >= max)
1040		- goto out;
1041		- }
1042		- list_add_tail(&new_rgd->rd_recent, &sdp->sd_rindex_recent_list);
1043		-
1044		-out:
1045		- spin_unlock(&sdp->sd_rindex_spin);
1046		-}
1047		-
1048		-/**
1049	967	* forward_rgrp_get - get an rgrp to try next from full list
1050	968	* @sdp: The GFS2 superblock
1051	969	*
1052	970
...	...	@@ -1112,10 +1030,8 @@
1112	1030	int loops = 0;
1113	1031	int error, rg_locked;
1114	1032
1115		- /* Try recently successful rgrps */
	1033	+ rgd = gfs2_blk2rgrpd(sdp, ip->i_goal);
1116	1034
1117		- rgd = recent_rgrp_first(sdp, ip->i_goal);
1118		-
1119	1035	while (rgd) {
1120	1036	rg_locked = 0;
1121	1037
1122	1038
...	...	@@ -1136,11 +1052,9 @@
1136	1052	gfs2_glock_dq_uninit(&al->al_rgd_gh);
1137	1053	if (inode)
1138	1054	return inode;
1139		- rgd = recent_rgrp_next(rgd, 1);
1140		- break;
1141		-
	1055	+ /* fall through */
1142	1056	case GLR_TRYFAILED:
1143		- rgd = recent_rgrp_next(rgd, 0);
	1057	+ rgd = recent_rgrp_next(rgd);
1144	1058	break;
1145	1059
1146	1060	default:
...	...	@@ -1199,7 +1113,9 @@
1199	1113
1200	1114	out:
1201	1115	if (begin) {
1202		- recent_rgrp_add(rgd);
	1116	+ spin_lock(&sdp->sd_rindex_spin);
	1117	+ list_move(&rgd->rd_list_mru, &sdp->sd_rindex_mru_list);
	1118	+ spin_unlock(&sdp->sd_rindex_spin);
1203	1119	rgd = gfs2_rgrpd_get_next(rgd);
1204	1120	if (!rgd)
1205	1121	rgd = gfs2_rgrpd_get_first(sdp);