Merge branch 'optimize-openvswitch-flow-looking-up'

Tonghao Zhang says:

====================
optimize openvswitch flow looking up

This series patch optimize openvswitch for performance or simplify
codes.

Patch 1, 2, 4: Port Pravin B Shelar patches to
linux upstream with little changes.

Patch 5, 6, 7: Optimize the flow looking up and
simplify the flow hash.

Patch 8, 9: are bugfix.

The performance test is on Intel Xeon E5-2630 v4.
The test topology is show as below:

+-----------------------------------+
|   +---------------------------+   |
|   | eth0   ovs-switch    eth1 |   | Host0
|   +---------------------------+   |
+-----------------------------------+
      ^                       |
      |                       |
      |                       |
      |                       |
      |                       v
+-----+----+             +----+-----+
| netperf  | Host1       | netserver| Host2
+----------+             +----------+

We use netperf send the 64B packets, and insert 255+ flow-mask:
$ ovs-dpctl add-flow ovs-switch "in_port(1),eth(dst=00:01:00:00:00:00/ff:ff:ff:ff:ff:01),eth_type(0x0800),ipv4(frag=no)" 2
...
$ ovs-dpctl add-flow ovs-switch "in_port(1),eth(dst=00:ff:00:00:00:00/ff:ff:ff:ff:ff:ff),eth_type(0x0800),ipv4(frag=no)" 2
$
$ netperf -t UDP_STREAM -H 2.2.2.200 -l 40 -- -m 18

* Without series patch, throughput 8.28Mbps
* With series patch, throughput 46.05Mbps

v6:
some coding style fixes

v5:
rewrite patch 8, release flow-mask when freeing flow

v4:
access ma->count with READ_ONCE/WRITE_ONCE API. More information,
see patch 5 comments.

v3:
update ma point when realloc mask_array in patch 5

v2:
simplify codes. e.g. use kfree_rcu instead of call_rcu
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 361 insertions, 105 deletions

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index d8c364d637b1..2088619c03f0 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -227,7 +227,8 @@ void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key)
 	stats = this_cpu_ptr(dp->stats_percpu);
 
 	/* Look up flow. */
-	flow = ovs_flow_tbl_lookup_stats(&dp->table, key, &n_mask_hit);
+	flow = ovs_flow_tbl_lookup_stats(&dp->table, key, skb_get_hash(skb),
+					 &n_mask_hit);
 	if (unlikely(!flow)) {
 		struct dp_upcall_info upcall;
 
@@ -1575,6 +1576,31 @@ static int ovs_dp_change(struct datapath *dp, struct nlattr *a[])
 	return 0;
 }
 
+static int ovs_dp_stats_init(struct datapath *dp)
+{
+	dp->stats_percpu = netdev_alloc_pcpu_stats(struct dp_stats_percpu);
+	if (!dp->stats_percpu)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int ovs_dp_vport_init(struct datapath *dp)
+{
+	int i;
+
+	dp->ports = kmalloc_array(DP_VPORT_HASH_BUCKETS,
+				  sizeof(struct hlist_head),
+				  GFP_KERNEL);
+	if (!dp->ports)
+		return -ENOMEM;
+
+	for (i = 0; i < DP_VPORT_HASH_BUCKETS; i++)
+		INIT_HLIST_HEAD(&dp->ports[i]);
+
+	return 0;
+}
+
 static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 {
 	struct nlattr **a = info->attrs;
@@ -1583,7 +1609,7 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	struct datapath *dp;
 	struct vport *vport;
 	struct ovs_net *ovs_net;
-	int err, i;
+	int err;
 
 	err = -EINVAL;
 	if (!a[OVS_DP_ATTR_NAME] || !a[OVS_DP_ATTR_UPCALL_PID])
@@ -1596,35 +1622,26 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	err = -ENOMEM;
 	dp = kzalloc(sizeof(*dp), GFP_KERNEL);
 	if (dp == NULL)
-		goto err_free_reply;
+		goto err_destroy_reply;
 
 	ovs_dp_set_net(dp, sock_net(skb->sk));
 
 	/* Allocate table. */
 	err = ovs_flow_tbl_init(&dp->table);
 	if (err)
-		goto err_free_dp;
+		goto err_destroy_dp;
 
-	dp->stats_percpu = netdev_alloc_pcpu_stats(struct dp_stats_percpu);
-	if (!dp->stats_percpu) {
-		err = -ENOMEM;
+	err = ovs_dp_stats_init(dp);
+	if (err)
 		goto err_destroy_table;
-	}
-
-	dp->ports = kmalloc_array(DP_VPORT_HASH_BUCKETS,
-				  sizeof(struct hlist_head),
-				  GFP_KERNEL);
-	if (!dp->ports) {
-		err = -ENOMEM;
-		goto err_destroy_percpu;
-	}
 
-	for (i = 0; i < DP_VPORT_HASH_BUCKETS; i++)
-		INIT_HLIST_HEAD(&dp->ports[i]);
+	err = ovs_dp_vport_init(dp);
+	if (err)
+		goto err_destroy_stats;
 
 	err = ovs_meters_init(dp);
 	if (err)
-		goto err_destroy_ports_array;
+		goto err_destroy_ports;
 
 	/* Set up our datapath device. */
 	parms.name = nla_data(a[OVS_DP_ATTR_NAME]);
@@ -1656,6 +1673,7 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 				ovs_dp_reset_user_features(skb, info);
 		}
 
+		ovs_unlock();
 		goto err_destroy_meters;
 	}
 
@@ -1672,17 +1690,16 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	return 0;
 
 err_destroy_meters:
-	ovs_unlock();
 	ovs_meters_exit(dp);
-err_destroy_ports_array:
+err_destroy_ports:
 	kfree(dp->ports);
-err_destroy_percpu:
+err_destroy_stats:
 	free_percpu(dp->stats_percpu);
 err_destroy_table:
 	ovs_flow_tbl_destroy(&dp->table);
-err_free_dp:
+err_destroy_dp:
 	kfree(dp);
-err_free_reply:
+err_destroy_reply:
 	kfree_skb(reply);
 err:
 	return err;
diff --git a/net/openvswitch/flow.h b/net/openvswitch/flow.h
index b830d5ff7af4..8080518ca5f2 100644
--- a/net/openvswitch/flow.h
+++ b/net/openvswitch/flow.h
@@ -166,7 +166,6 @@ struct sw_flow_key_range {
 struct sw_flow_mask {
 	int ref_count;
 	struct rcu_head rcu;
-	struct list_head list;
 	struct sw_flow_key_range range;
 	struct sw_flow_key key;
 };
diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
index cf3582c5ed70..5904e93e5765 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -34,8 +34,13 @@
 #include <net/ndisc.h>
 
 #define TBL_MIN_BUCKETS		1024
+#define MASK_ARRAY_SIZE_MIN	16
 #define REHASH_INTERVAL		(10 * 60 * HZ)
 
+#define MC_HASH_SHIFT		8
+#define MC_HASH_ENTRIES		(1u << MC_HASH_SHIFT)
+#define MC_HASH_SEGS		((sizeof(uint32_t) * 8) / MC_HASH_SHIFT)
+
 static struct kmem_cache *flow_cache;
 struct kmem_cache *flow_stats_cache __read_mostly;
 
@@ -164,14 +169,133 @@ static struct table_instance *table_instance_alloc(int new_size)
 	return ti;
 }
 
+static struct mask_array *tbl_mask_array_alloc(int size)
+{
+	struct mask_array *new;
+
+	size = max(MASK_ARRAY_SIZE_MIN, size);
+	new = kzalloc(sizeof(struct mask_array) +
+		      sizeof(struct sw_flow_mask *) * size, GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	new->count = 0;
+	new->max = size;
+
+	return new;
+}
+
+static int tbl_mask_array_realloc(struct flow_table *tbl, int size)
+{
+	struct mask_array *old;
+	struct mask_array *new;
+
+	new = tbl_mask_array_alloc(size);
+	if (!new)
+		return -ENOMEM;
+
+	old = ovsl_dereference(tbl->mask_array);
+	if (old) {
+		int i;
+
+		for (i = 0; i < old->max; i++) {
+			if (ovsl_dereference(old->masks[i]))
+				new->masks[new->count++] = old->masks[i];
+		}
+	}
+
+	rcu_assign_pointer(tbl->mask_array, new);
+	kfree_rcu(old, rcu);
+
+	return 0;
+}
+
+static int tbl_mask_array_add_mask(struct flow_table *tbl,
+				   struct sw_flow_mask *new)
+{
+	struct mask_array *ma = ovsl_dereference(tbl->mask_array);
+	int err, ma_count = READ_ONCE(ma->count);
+
+	if (ma_count >= ma->max) {
+		err = tbl_mask_array_realloc(tbl, ma->max +
+					      MASK_ARRAY_SIZE_MIN);
+		if (err)
+			return err;
+
+		ma = ovsl_dereference(tbl->mask_array);
+	}
+
+	BUG_ON(ovsl_dereference(ma->masks[ma_count]));
+
+	rcu_assign_pointer(ma->masks[ma_count], new);
+	WRITE_ONCE(ma->count, ma_count +1);
+
+	return 0;
+}
+
+static void tbl_mask_array_del_mask(struct flow_table *tbl,
+				    struct sw_flow_mask *mask)
+{
+	struct mask_array *ma = ovsl_dereference(tbl->mask_array);
+	int i, ma_count = READ_ONCE(ma->count);
+
+	/* Remove the deleted mask pointers from the array */
+	for (i = 0; i < ma_count; i++) {
+		if (mask == ovsl_dereference(ma->masks[i]))
+			goto found;
+	}
+
+	BUG();
+	return;
+
+found:
+	WRITE_ONCE(ma->count, ma_count -1);
+
+	rcu_assign_pointer(ma->masks[i], ma->masks[ma_count -1]);
+	RCU_INIT_POINTER(ma->masks[ma_count -1], NULL);
+
+	kfree_rcu(mask, rcu);
+
+	/* Shrink the mask array if necessary. */
+	if (ma->max >= (MASK_ARRAY_SIZE_MIN * 2) &&
+	    ma_count <= (ma->max / 3))
+		tbl_mask_array_realloc(tbl, ma->max / 2);
+}
+
+/* Remove 'mask' from the mask list, if it is not needed any more. */
+static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
+{
+	if (mask) {
+		/* ovs-lock is required to protect mask-refcount and
+		 * mask list.
+		 */
+		ASSERT_OVSL();
+		BUG_ON(!mask->ref_count);
+		mask->ref_count--;
+
+		if (!mask->ref_count)
+			tbl_mask_array_del_mask(tbl, mask);
+	}
+}
+
 int ovs_flow_tbl_init(struct flow_table *table)
 {
 	struct table_instance *ti, *ufid_ti;
+	struct mask_array *ma;
 
-	ti = table_instance_alloc(TBL_MIN_BUCKETS);
+	table->mask_cache = __alloc_percpu(sizeof(struct mask_cache_entry) *
+					   MC_HASH_ENTRIES,
+					   __alignof__(struct mask_cache_entry));
+	if (!table->mask_cache)
+		return -ENOMEM;
 
+	ma = tbl_mask_array_alloc(MASK_ARRAY_SIZE_MIN);
+	if (!ma)
+		goto free_mask_cache;
+
+	ti = table_instance_alloc(TBL_MIN_BUCKETS);
 	if (!ti)
-		return -ENOMEM;
+		goto free_mask_array;
 
 	ufid_ti = table_instance_alloc(TBL_MIN_BUCKETS);
 	if (!ufid_ti)
@@ -179,7 +303,7 @@ int ovs_flow_tbl_init(struct flow_table *table)
 
 	rcu_assign_pointer(table->ti, ti);
 	rcu_assign_pointer(table->ufid_ti, ufid_ti);
-	INIT_LIST_HEAD(&table->mask_list);
+	rcu_assign_pointer(table->mask_array, ma);
 	table->last_rehash = jiffies;
 	table->count = 0;
 	table->ufid_count = 0;
@@ -187,6 +311,10 @@ int ovs_flow_tbl_init(struct flow_table *table)
 
 free_ti:
 	__table_instance_destroy(ti);
+free_mask_array:
+	kfree(ma);
+free_mask_cache:
+	free_percpu(table->mask_cache);
 	return -ENOMEM;
 }
 
@@ -197,7 +325,28 @@ static void flow_tbl_destroy_rcu_cb(struct rcu_head *rcu)
 	__table_instance_destroy(ti);
 }
 
-static void table_instance_destroy(struct table_instance *ti,
+static void table_instance_flow_free(struct flow_table *table,
+				  struct table_instance *ti,
+				  struct table_instance *ufid_ti,
+				  struct sw_flow *flow,
+				  bool count)
+{
+	hlist_del_rcu(&flow->flow_table.node[ti->node_ver]);
+	if (count)
+		table->count--;
+
+	if (ovs_identifier_is_ufid(&flow->id)) {
+		hlist_del_rcu(&flow->ufid_table.node[ufid_ti->node_ver]);
+
+		if (count)
+			table->ufid_count--;
+	}
+
+	flow_mask_remove(table, flow->mask);
+}
+
+static void table_instance_destroy(struct flow_table *table,
+				   struct table_instance *ti,
 				   struct table_instance *ufid_ti,
 				   bool deferred)
 {
@@ -214,13 +363,12 @@ static void table_instance_destroy(struct table_instance *ti,
 		struct sw_flow *flow;
 		struct hlist_head *head = &ti->buckets[i];
 		struct hlist_node *n;
-		int ver = ti->node_ver;
-		int ufid_ver = ufid_ti->node_ver;
 
-		hlist_for_each_entry_safe(flow, n, head, flow_table.node[ver]) {
-			hlist_del_rcu(&flow->flow_table.node[ver]);
-			if (ovs_identifier_is_ufid(&flow->id))
-				hlist_del_rcu(&flow->ufid_table.node[ufid_ver]);
+		hlist_for_each_entry_safe(flow, n, head,
+					  flow_table.node[ti->node_ver]) {
+
+			table_instance_flow_free(table, ti, ufid_ti,
+						 flow, false);
 			ovs_flow_free(flow, deferred);
 		}
 	}
@@ -243,7 +391,9 @@ void ovs_flow_tbl_destroy(struct flow_table *table)
 	struct table_instance *ti = rcu_dereference_raw(table->ti);
 	struct table_instance *ufid_ti = rcu_dereference_raw(table->ufid_ti);
 
-	table_instance_destroy(ti, ufid_ti, false);
+	free_percpu(table->mask_cache);
+	kfree_rcu(rcu_dereference_raw(table->mask_array), rcu);
+	table_instance_destroy(table, ti, ufid_ti, false);
 }
 
 struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *ti,
@@ -359,7 +509,7 @@ int ovs_flow_tbl_flush(struct flow_table *flow_table)
 	flow_table->count = 0;
 	flow_table->ufid_count = 0;
 
-	table_instance_destroy(old_ti, old_ufid_ti, true);
+	table_instance_destroy(flow_table, old_ti, old_ufid_ti, true);
 	return 0;
 
 err_free_ti:
@@ -370,13 +520,10 @@ err_free_ti:
 static u32 flow_hash(const struct sw_flow_key *key,
 		     const struct sw_flow_key_range *range)
 {
-	int key_start = range->start;
-	int key_end = range->end;
-	const u32 *hash_key = (const u32 *)((const u8 *)key + key_start);
-	int hash_u32s = (key_end - key_start) >> 2;
+	const u32 *hash_key = (const u32 *)((const u8 *)key + range->start);
 
 	/* Make sure number of hash bytes are multiple of u32. */
-	BUILD_BUG_ON(sizeof(long) % sizeof(u32));
+	int hash_u32s = range_n_bytes(range) >> 2;
 
 	return jhash2(hash_key, hash_u32s, 0);
 }
@@ -425,7 +572,8 @@ static bool ovs_flow_cmp_unmasked_key(const struct sw_flow *flow,
 
 static struct sw_flow *masked_flow_lookup(struct table_instance *ti,
 					  const struct sw_flow_key *unmasked,
-					  const struct sw_flow_mask *mask)
+					  const struct sw_flow_mask *mask,
+					  u32 *n_mask_hit)
 {
 	struct sw_flow *flow;
 	struct hlist_head *head;
@@ -435,6 +583,8 @@ static struct sw_flow *masked_flow_lookup(struct table_instance *ti,
 	ovs_flow_mask_key(&masked_key, unmasked, false, mask);
 	hash = flow_hash(&masked_key, &mask->range);
 	head = find_bucket(ti, hash);
+	(*n_mask_hit)++;
+
 	hlist_for_each_entry_rcu(flow, head, flow_table.node[ti->node_ver]) {
 		if (flow->mask == mask && flow->flow_table.hash == hash &&
 		    flow_cmp_masked_key(flow, &masked_key, &mask->range))
@@ -443,46 +593,147 @@ static struct sw_flow *masked_flow_lookup(struct table_instance *ti,
 	return NULL;
 }
 
-struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
-				    const struct sw_flow_key *key,
-				    u32 *n_mask_hit)
+/* Flow lookup does full lookup on flow table. It starts with
+ * mask from index passed in *index.
+ */
+static struct sw_flow *flow_lookup(struct flow_table *tbl,
+				   struct table_instance *ti,
+				   struct mask_array *ma,
+				   const struct sw_flow_key *key,
+				   u32 *n_mask_hit,
+				   u32 *index)
 {
-	struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
+	struct sw_flow *flow;
 	struct sw_flow_mask *mask;
+	int i;
+
+	if (likely(*index < ma->max)) {
+		mask = rcu_dereference_ovsl(ma->masks[*index]);
+		if (mask) {
+			flow = masked_flow_lookup(ti, key, mask, n_mask_hit);
+			if (flow)
+				return flow;
+		}
+	}
+
+	for (i = 0; i < ma->max; i++)  {
+
+		if (i == *index)
+			continue;
+
+		mask = rcu_dereference_ovsl(ma->masks[i]);
+		if (unlikely(!mask))
+			break;
+
+		flow = masked_flow_lookup(ti, key, mask, n_mask_hit);
+		if (flow) { /* Found */
+			*index = i;
+			return flow;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * mask_cache maps flow to probable mask. This cache is not tightly
+ * coupled cache, It means updates to  mask list can result in inconsistent
+ * cache entry in mask cache.
+ * This is per cpu cache and is divided in MC_HASH_SEGS segments.
+ * In case of a hash collision the entry is hashed in next segment.
+ * */
+struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
+					  const struct sw_flow_key *key,
+					  u32 skb_hash,
+					  u32 *n_mask_hit)
+{
+	struct mask_array *ma = rcu_dereference(tbl->mask_array);
+	struct table_instance *ti = rcu_dereference(tbl->ti);
+	struct mask_cache_entry *entries, *ce;
 	struct sw_flow *flow;
+	u32 hash;
+	int seg;
 
 	*n_mask_hit = 0;
-	list_for_each_entry_rcu(mask, &tbl->mask_list, list) {
-		(*n_mask_hit)++;
-		flow = masked_flow_lookup(ti, key, mask);
-		if (flow)  /* Found */
+	if (unlikely(!skb_hash)) {
+		u32 mask_index = 0;
+
+		return flow_lookup(tbl, ti, ma, key, n_mask_hit, &mask_index);
+	}
+
+	/* Pre and post recirulation flows usually have the same skb_hash
+	 * value. To avoid hash collisions, rehash the 'skb_hash' with
+	 * 'recirc_id'.  */
+	if (key->recirc_id)
+		skb_hash = jhash_1word(skb_hash, key->recirc_id);
+
+	ce = NULL;
+	hash = skb_hash;
+	entries = this_cpu_ptr(tbl->mask_cache);
+
+	/* Find the cache entry 'ce' to operate on. */
+	for (seg = 0; seg < MC_HASH_SEGS; seg++) {
+		int index = hash & (MC_HASH_ENTRIES - 1);
+		struct mask_cache_entry *e;
+
+		e = &entries[index];
+		if (e->skb_hash == skb_hash) {
+			flow = flow_lookup(tbl, ti, ma, key, n_mask_hit,
+					   &e->mask_index);
+			if (!flow)
+				e->skb_hash = 0;
 			return flow;
+		}
+
+		if (!ce || e->skb_hash < ce->skb_hash)
+			ce = e;  /* A better replacement cache candidate. */
+
+		hash >>= MC_HASH_SHIFT;
 	}
-	return NULL;
+
+	/* Cache miss, do full lookup. */
+	flow = flow_lookup(tbl, ti, ma, key, n_mask_hit, &ce->mask_index);
+	if (flow)
+		ce->skb_hash = skb_hash;
+
+	return flow;
 }
 
 struct sw_flow *ovs_flow_tbl_lookup(struct flow_table *tbl,
 				    const struct sw_flow_key *key)
 {
+	struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
+	struct mask_array *ma = rcu_dereference_ovsl(tbl->mask_array);
 	u32 __always_unused n_mask_hit;
+	u32 index = 0;
 
-	return ovs_flow_tbl_lookup_stats(tbl, key, &n_mask_hit);
+	return flow_lookup(tbl, ti, ma, key, &n_mask_hit, &index);
 }
 
 struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl,
 					  const struct sw_flow_match *match)
 {
-	struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
-	struct sw_flow_mask *mask;
-	struct sw_flow *flow;
+	struct mask_array *ma = ovsl_dereference(tbl->mask_array);
+	int i;
 
 	/* Always called under ovs-mutex. */
-	list_for_each_entry(mask, &tbl->mask_list, list) {
-		flow = masked_flow_lookup(ti, match->key, mask);
+	for (i = 0; i < ma->max; i++) {
+		struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
+		u32 __always_unused n_mask_hit;
+		struct sw_flow_mask *mask;
+		struct sw_flow *flow;
+
+		mask = ovsl_dereference(ma->masks[i]);
+		if (!mask)
+			continue;
+
+		flow = masked_flow_lookup(ti, match->key, mask, &n_mask_hit);
 		if (flow && ovs_identifier_is_key(&flow->id) &&
-		    ovs_flow_cmp_unmasked_key(flow, match))
+		    ovs_flow_cmp_unmasked_key(flow, match)) {
 			return flow;
+		}
 	}
+
 	return NULL;
 }
 
@@ -528,13 +779,8 @@ struct sw_flow *ovs_flow_tbl_lookup_ufid(struct flow_table *tbl,
 
 int ovs_flow_tbl_num_masks(const struct flow_table *table)
 {
-	struct sw_flow_mask *mask;
-	int num = 0;
-
-	list_for_each_entry(mask, &table->mask_list, list)
-		num++;
-
-	return num;
+	struct mask_array *ma = rcu_dereference_ovsl(table->mask_array);
+	return READ_ONCE(ma->count);
 }
 
 static struct table_instance *table_instance_expand(struct table_instance *ti,
@@ -543,24 +789,6 @@ static struct table_instance *table_instance_expand(struct table_instance *ti,
 	return table_instance_rehash(ti, ti->n_buckets * 2, ufid);
 }
 
-/* Remove 'mask' from the mask list, if it is not needed any more. */
-static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
-{
-	if (mask) {
-		/* ovs-lock is required to protect mask-refcount and
-		 * mask list.
-		 */
-		ASSERT_OVSL();
-		BUG_ON(!mask->ref_count);
-		mask->ref_count--;
-
-		if (!mask->ref_count) {
-			list_del_rcu(&mask->list);
-			kfree_rcu(mask, rcu);
-		}
-	}
-}
-
 /* Must be called with OVS mutex held. */
 void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow *flow)
 {
@@ -568,17 +796,7 @@ void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow *flow)
 	struct table_instance *ufid_ti = ovsl_dereference(table->ufid_ti);
 
 	BUG_ON(table->count == 0);
-	hlist_del_rcu(&flow->flow_table.node[ti->node_ver]);
-	table->count--;
-	if (ovs_identifier_is_ufid(&flow->id)) {
-		hlist_del_rcu(&flow->ufid_table.node[ufid_ti->node_ver]);
-		table->ufid_count--;
-	}
-
-	/* RCU delete the mask. 'flow->mask' is not NULLed, as it should be
-	 * accessible as long as the RCU read lock is held.
-	 */
-	flow_mask_remove(table, flow->mask);
+	table_instance_flow_free(table, ti, ufid_ti, flow, true);
 }
 
 static struct sw_flow_mask *mask_alloc(void)
@@ -606,13 +824,16 @@ static bool mask_equal(const struct sw_flow_mask *a,
 static struct sw_flow_mask *flow_mask_find(const struct flow_table *tbl,
 					   const struct sw_flow_mask *mask)
 {
-	struct list_head *ml;
+	struct mask_array *ma;
+	int i;
+
+	ma = ovsl_dereference(tbl->mask_array);
+	for (i = 0; i < ma->max; i++) {
+		struct sw_flow_mask *t;
+		t = ovsl_dereference(ma->masks[i]);
 
-	list_for_each(ml, &tbl->mask_list) {
-		struct sw_flow_mask *m;
-		m = container_of(ml, struct sw_flow_mask, list);
-		if (mask_equal(mask, m))
-			return m;
+		if (t && mask_equal(mask, t))
+			return t;
 	}
 
 	return NULL;
@@ -623,6 +844,7 @@ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow,
 			    const struct sw_flow_mask *new)
 {
 	struct sw_flow_mask *mask;
+
 	mask = flow_mask_find(tbl, new);
 	if (!mask) {
 		/* Allocate a new mask if none exsits. */
@@ -631,7 +853,12 @@ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow,
 			return -ENOMEM;
 		mask->key = new->key;
 		mask->range = new->range;
-		list_add_rcu(&mask->list, &tbl->mask_list);
+
+		/* Add mask to mask-list. */
+		if (tbl_mask_array_add_mask(tbl, mask)) {
+			kfree(mask);
+			return -ENOMEM;
+		}
 	} else {
 		BUG_ON(!mask->ref_count);
 		mask->ref_count++;
diff --git a/net/openvswitch/flow_table.h b/net/openvswitch/flow_table.h
index bc52045b63ff..8a5cea6ae111 100644
--- a/net/openvswitch/flow_table.h
+++ b/net/openvswitch/flow_table.h
@@ -22,6 +22,17 @@
 
 #include "flow.h"
 
+struct mask_cache_entry {
+	u32 skb_hash;
+	u32 mask_index;
+};
+
+struct mask_array {
+	struct rcu_head rcu;
+	int count, max;
+	struct sw_flow_mask __rcu *masks[];
+};
+
 struct table_instance {
 	struct hlist_head *buckets;
 	unsigned int n_buckets;
@@ -34,7 +45,8 @@ struct table_instance {
 struct flow_table {
 	struct table_instance __rcu *ti;
 	struct table_instance __rcu *ufid_ti;
-	struct list_head mask_list;
+	struct mask_cache_entry __percpu *mask_cache;
+	struct mask_array __rcu *mask_array;
 	unsigned long last_rehash;
 	unsigned int count;
 	unsigned int ufid_count;
@@ -60,8 +72,9 @@ int  ovs_flow_tbl_num_masks(const struct flow_table *table);
 struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *table,
 				       u32 *bucket, u32 *idx);
 struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *,
-				    const struct sw_flow_key *,
-				    u32 *n_mask_hit);
+					  const struct sw_flow_key *,
+					  u32 skb_hash,
+					  u32 *n_mask_hit);
 struct sw_flow *ovs_flow_tbl_lookup(struct flow_table *,
 				    const struct sw_flow_key *);
 struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl,