block,elevator: use new hashtable implementation

Switch elevator to use the new hashtable implementation. This reduces the amount of generic unrelated code in the elevator. This also removes the dymanic allocation of the hash table. The size of the table is constant so there's no point in paying the price of an extra dereference when accessing it. This patch depends on d9b482c ("hashtable: introduce a small and naive hashtable") which was merged in v3.6. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>

block,elevator: use new hashtable implementation
Switch elevator to use the new hashtable implementation. This reduces the amount of generic unrelated code in the elevator. This also removes the dymanic allocation of the hash table. The size of the table is constant so there's no point in paying the price of an extra dereference when accessing it. This patch depends on d9b482c ("hashtable: introduce a small and naive hashtable") which was merged in v3.6. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Sasha Levin · Jens Axboe
1 parent 9931faca02
Showing 3 changed files with 9 additions and 21 deletions Side-by-side Diff
block/blk.h
block/elevator.c
include/linux/elevator.h
@@ -61,7 +61,7 @@
 /*
  * Internal elevator interface
  */
-#define ELV_ON_HASH(rq)		(!hlist_unhashed(&(rq)->hash))
+#define ELV_ON_HASH(rq) hash_hashed(&(rq)->hash)
  
 void blk_insert_flush(struct request *rq);
 void blk_abort_flushes(struct request_queue *q);
@@ -46,11 +46,6 @@
 /*
  * Merge hash stuff.
  */
-static const int elv_hash_shift = 6;
-#define ELV_HASH_BLOCK(sec)	((sec) >> 3)
-#define ELV_HASH_FN(sec)	\
-		(hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift))
-#define ELV_HASH_ENTRIES	(1 << elv_hash_shift)
 #define rq_hash_key(rq)		(blk_rq_pos(rq) + blk_rq_sectors(rq))
  
 /*
@@ -142,7 +137,6 @@
 				  struct elevator_type *e)
 {
 	struct elevator_queue *eq;
-	int i;
  
 	eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node);
 	if (unlikely(!eq))
  
@@ -151,15 +145,8 @@
 	eq->type = e;
 	kobject_init(&eq->kobj, &elv_ktype);
 	mutex_init(&eq->sysfs_lock);
+	hash_init(eq->hash);
  
-	eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES,
-					GFP_KERNEL, q->node);
-	if (!eq->hash)
-		goto err;
-
-	for (i = 0; i < ELV_HASH_ENTRIES; i++)
-		INIT_HLIST_HEAD(&eq->hash[i]);
-
 	return eq;
 err:
 	kfree(eq);
@@ -173,7 +160,6 @@
  
 	e = container_of(kobj, struct elevator_queue, kobj);
 	elevator_put(e->type);
-	kfree(e->hash);
 	kfree(e);
 }
  
@@ -240,7 +226,7 @@
  
 static inline void __elv_rqhash_del(struct request *rq)
 {
-	hlist_del_init(&rq->hash);
+	hash_del(&rq->hash);
 }
  
 static void elv_rqhash_del(struct request_queue *q, struct request *rq)
@@ -254,7 +240,7 @@
 	struct elevator_queue *e = q->elevator;
  
 	BUG_ON(ELV_ON_HASH(rq));
-	hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]);
+	hash_add(e->hash, &rq->hash, rq_hash_key(rq));
 }
  
 static void elv_rqhash_reposition(struct request_queue *q, struct request *rq)
  
@@ -266,11 +252,10 @@
 static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset)
 {
 	struct elevator_queue *e = q->elevator;
-	struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)];
 	struct hlist_node *entry, *next;
 	struct request *rq;
  
-	hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) {
+	hash_for_each_possible_safe(e->hash, rq, entry, next, hash, offset) {
 		BUG_ON(!ELV_ON_HASH(rq));
  
 		if (unlikely(!rq_mergeable(rq))) {
@@ -2,6 +2,7 @@
 #define _LINUX_ELEVATOR_H
  
 #include <linux/percpu.h>
+#include <linux/hashtable.h>
  
 #ifdef CONFIG_BLOCK
  
@@ -96,6 +97,8 @@
 	struct list_head list;
 };
  
+#define ELV_HASH_BITS 6
+
 /*
  * each queue has an elevator_queue associated with it
  */
  
@@ -105,8 +108,8 @@
 	void *elevator_data;
 	struct kobject kobj;
 	struct mutex sysfs_lock;
-	struct hlist_head *hash;
 	unsigned int registered:1;
+	DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
 };
  
 /*
...	...	@@ -61,7 +61,7 @@
61	61	/*
62	62	* Internal elevator interface
63	63	*/
64		-#define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash))
	64	+#define ELV_ON_HASH(rq) hash_hashed(&(rq)->hash)
65	65
66	66	void blk_insert_flush(struct request *rq);
67	67	void blk_abort_flushes(struct request_queue *q);
...	...	@@ -46,11 +46,6 @@
46	46	/*
47	47	* Merge hash stuff.
48	48	*/
49		-static const int elv_hash_shift = 6;
50		-#define ELV_HASH_BLOCK(sec) ((sec) >> 3)
51		-#define ELV_HASH_FN(sec) \
52		- (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift))
53		-#define ELV_HASH_ENTRIES (1 << elv_hash_shift)
54	49	#define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
55	50
56	51	/*
...	...	@@ -142,7 +137,6 @@
142	137	struct elevator_type *e)
143	138	{
144	139	struct elevator_queue *eq;
145		- int i;
146	140
147	141	eq = kmalloc_node(sizeof(*eq), GFP_KERNEL \| __GFP_ZERO, q->node);
148	142	if (unlikely(!eq))
149	143
...	...	@@ -151,15 +145,8 @@
151	145	eq->type = e;
152	146	kobject_init(&eq->kobj, &elv_ktype);
153	147	mutex_init(&eq->sysfs_lock);
	148	+ hash_init(eq->hash);
154	149
155		- eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES,
156		- GFP_KERNEL, q->node);
157		- if (!eq->hash)
158		- goto err;
159		-
160		- for (i = 0; i < ELV_HASH_ENTRIES; i++)
161		- INIT_HLIST_HEAD(&eq->hash[i]);
162		-
163	150	return eq;
164	151	err:
165	152	kfree(eq);
...	...	@@ -173,7 +160,6 @@
173	160
174	161	e = container_of(kobj, struct elevator_queue, kobj);
175	162	elevator_put(e->type);
176		- kfree(e->hash);
177	163	kfree(e);
178	164	}
179	165
...	...	@@ -240,7 +226,7 @@
240	226
241	227	static inline void __elv_rqhash_del(struct request *rq)
242	228	{
243		- hlist_del_init(&rq->hash);
	229	+ hash_del(&rq->hash);
244	230	}
245	231
246	232	static void elv_rqhash_del(struct request_queue q, struct request rq)
...	...	@@ -254,7 +240,7 @@
254	240	struct elevator_queue *e = q->elevator;
255	241
256	242	BUG_ON(ELV_ON_HASH(rq));
257		- hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]);
	243	+ hash_add(e->hash, &rq->hash, rq_hash_key(rq));
258	244	}
259	245
260	246	static void elv_rqhash_reposition(struct request_queue q, struct request rq)
261	247
...	...	@@ -266,11 +252,10 @@
266	252	static struct request elv_rqhash_find(struct request_queue q, sector_t offset)
267	253	{
268	254	struct elevator_queue *e = q->elevator;
269		- struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)];
270	255	struct hlist_node entry, next;
271	256	struct request *rq;
272	257
273		- hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) {
	258	+ hash_for_each_possible_safe(e->hash, rq, entry, next, hash, offset) {
274	259	BUG_ON(!ELV_ON_HASH(rq));
275	260
276	261	if (unlikely(!rq_mergeable(rq))) {
...	...	@@ -2,6 +2,7 @@
2	2	#define _LINUX_ELEVATOR_H
3	3
4	4	#include <linux/percpu.h>
	5	+#include <linux/hashtable.h>
5	6
6	7	#ifdef CONFIG_BLOCK
7	8
...	...	@@ -96,6 +97,8 @@
96	97	struct list_head list;
97	98	};
98	99
	100	+#define ELV_HASH_BITS 6
	101	+
99	102	/*
100	103	* each queue has an elevator_queue associated with it
101	104	*/
102	105
...	...	@@ -105,8 +108,8 @@
105	108	void *elevator_data;
106	109	struct kobject kobj;
107	110	struct mutex sysfs_lock;
108		- struct hlist_head *hash;
109	111	unsigned int registered:1;
	112	+ DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
110	113	};
111	114
112	115	/*