net: openvswitch: add masks cache hit counter

Add a counter that counts the number of masks cache hits, and
export it through the megaflow netlink statistics.

Reviewed-by: Paolo Abeni <[e-mail]>
Reviewed-by: Tonghao Zhang <[e-mail]>
Signed-off-by: Eelco Chaudron <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/uapi/linux/openvswitch.h

···
 	__u64 n_mask_hit;	 /* Number of masks used for flow lookups. */
 	__u32 n_masks;		 /* Number of masks for the datapath. */
 	__u32 pad0;		 /* Pad for future expension. */
+	__u64 n_cache_hit;       /* Number of cache matches for flow lookups. */
 	__u64 pad1;		 /* Pad for future expension. */
-	__u64 pad2;		 /* Pad for future expension. */
 };
 
 struct ovs_vport_stats {

net/openvswitch/datapath.c

···
 	struct dp_stats_percpu *stats;
 	u64 *stats_counter;
 	u32 n_mask_hit;
+	u32 n_cache_hit;
 	int error;
 
 	stats = this_cpu_ptr(dp->stats_percpu);
 
 	/* Look up flow. */
 	flow = ovs_flow_tbl_lookup_stats(&dp->table, key, skb_get_hash(skb),
-					 &n_mask_hit);
+					 &n_mask_hit, &n_cache_hit);
 	if (unlikely(!flow)) {
 		struct dp_upcall_info upcall;
 
···
 	u64_stats_update_begin(&stats->syncp);
 	(*stats_counter)++;
 	stats->n_mask_hit += n_mask_hit;
+	stats->n_cache_hit += n_cache_hit;
 	u64_stats_update_end(&stats->syncp);
 }
 
···
 		stats->n_missed += local_stats.n_missed;
 		stats->n_lost += local_stats.n_lost;
 		mega_stats->n_mask_hit += local_stats.n_mask_hit;
+		mega_stats->n_cache_hit += local_stats.n_cache_hit;
 	}
 }
 

net/openvswitch/datapath.h

···
  * @n_mask_hit: Number of masks looked up for flow match.
  *   @n_mask_hit / (@n_hit + @n_missed)  will be the average masks looked
  *   up per packet.
+ * @n_cache_hit: The number of received packets that had their mask found using
+ * the mask cache.
  */
 struct dp_stats_percpu {
 	u64 n_hit;
 	u64 n_missed;
 	u64 n_lost;
 	u64 n_mask_hit;
+	u64 n_cache_hit;
 	struct u64_stats_sync syncp;
 };
 

net/openvswitch/flow_table.c

···
 				   struct mask_array *ma,
 				   const struct sw_flow_key *key,
 				   u32 *n_mask_hit,
+				   u32 *n_cache_hit,
 				   u32 *index)
 {
 	u64 *usage_counters = this_cpu_ptr(ma->masks_usage_cntr);
···
 				u64_stats_update_begin(&ma->syncp);
 				usage_counters[*index]++;
 				u64_stats_update_end(&ma->syncp);
+				(*n_cache_hit)++;
 				return flow;
 			}
 		}
···
 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)
+					  u32 *n_mask_hit,
+					  u32 *n_cache_hit)
 {
 	struct mask_array *ma = rcu_dereference(tbl->mask_array);
 	struct table_instance *ti = rcu_dereference(tbl->ti);
···
 	int seg;
 
 	*n_mask_hit = 0;
+	*n_cache_hit = 0;
 	if (unlikely(!skb_hash)) {
 		u32 mask_index = 0;
+		u32 cache = 0;
 
-		return flow_lookup(tbl, ti, ma, key, n_mask_hit, &mask_index);
+		return flow_lookup(tbl, ti, ma, key, n_mask_hit, &cache,
+				   &mask_index);
 	}
 
 	/* Pre and post recirulation flows usually have the same skb_hash
···
 		e = &entries[index];
 		if (e->skb_hash == skb_hash) {
 			flow = flow_lookup(tbl, ti, ma, key, n_mask_hit,
-					   &e->mask_index);
+					   n_cache_hit, &e->mask_index);
 			if (!flow)
 				e->skb_hash = 0;
 			return flow;
···
 	}
 
 	/* Cache miss, do full lookup. */
-	flow = flow_lookup(tbl, ti, ma, key, n_mask_hit, &ce->mask_index);
+	flow = flow_lookup(tbl, ti, ma, key, n_mask_hit, n_cache_hit,
+			   &ce->mask_index);
 	if (flow)
 		ce->skb_hash = skb_hash;
 
+	*n_cache_hit = 0;
 	return flow;
 }
 
···
 	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 __always_unused n_cache_hit;
 	u32 index = 0;
 
-	return flow_lookup(tbl, ti, ma, key, &n_mask_hit, &index);
+	return flow_lookup(tbl, ti, ma, key, &n_mask_hit, &n_cache_hit, &index);
 }
 
 struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl,

net/openvswitch/flow_table.h

···
 struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *,
 					  const struct sw_flow_key *,
 					  u32 skb_hash,
-					  u32 *n_mask_hit);
+					  u32 *n_mask_hit,
+					  u32 *n_cache_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,