datapath: Convert mask list in mask array.

mask caches index of mask in mask_list.  On packet recv OVS
need to traverse mask-list to get cached mask.  Therefore array
is better for retrieving cached mask.  This also allows better
cache replacement algorithm by directly checking mask's existence.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Thomas Graf <tgraf@redhat.com>

diff --git a/datapath/flow.h b/datapath/flow.h
index d05a9f4..2018691 100644 (file)
--- a/datapath/flow.h
+++ b/datapath/flow.h
@@ -127,7 +127,6 @@ 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/datapath/flow_table.c b/datapath/flow_table.c
index cc0eaf2..c8bd9d1 100644 (file)
--- a/datapath/flow_table.c
+++ b/datapath/flow_table.c
@@ -47,6 +47,7 @@
 #include "vlan.h"
 
 #define TBL_MIN_BUCKETS                1024
+#define MASK_ARRAY_SIZE_MIN    16
 #define REHASH_INTERVAL                (10 * 60 * HZ)
 
 #define MC_HASH_SHIFT          8
@@ -211,26 +212,83 @@ static struct table_instance *table_instance_alloc(int new_size)
        return ti;
 }
 
+static void mask_array_rcu_cb(struct rcu_head *rcu)
+{
+       struct mask_array *ma = container_of(rcu, struct mask_array, rcu);
+
+       kfree(ma);
+}
+
+static struct mask_array *tbl_mask_array_alloc(int size)
+{
+       struct mask_array *new;
+
+       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 (old->masks[i])
+                               new->masks[new->count++] = old->masks[i];
+               }
+       }
+       rcu_assign_pointer(tbl->mask_array, new);
+
+       if (old)
+               call_rcu(&old->rcu, mask_array_rcu_cb);
+
+       return 0;
+}
+
 int ovs_flow_tbl_init(struct flow_table *table)
 {
        struct table_instance *ti;
+       struct mask_array *ma;
 
        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) {
-               free_percpu(table->mask_cache);
-               return -ENOMEM;
-       }
+       if (!ti)
+               goto free_mask_array;
 
        rcu_assign_pointer(table->ti, ti);
-       INIT_LIST_HEAD(&table->mask_list);
+       rcu_assign_pointer(table->mask_array, ma);
        table->last_rehash = jiffies;
        table->count = 0;
        return 0;
+
+free_mask_array:
+       kfree((struct mask_array __force *)table->mask_array);
+free_mask_cache:
+       free_percpu(table->mask_cache);
+       return -ENOMEM;
 }
 
 static void flow_tbl_destroy_rcu_cb(struct rcu_head *rcu)
@@ -276,6 +334,7 @@ void ovs_flow_tbl_destroy(struct flow_table *table)
        struct table_instance *ti = (struct table_instance __force *)table->ti;
 
        free_percpu(table->mask_cache);
+       kfree((struct mask_array __force *)table->mask_array);
        table_instance_destroy(ti, false);
 }
 
@@ -457,17 +516,27 @@ static struct sw_flow *masked_flow_lookup(struct table_instance *ti,
 
 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 *n_mask_hit,
+                                  u32 *index)
 {
-       struct sw_flow_mask *mask;
        struct sw_flow *flow;
+       int i;
 
-       list_for_each_entry_rcu(mask, &tbl->mask_list, list) {
-               flow = masked_flow_lookup(ti, key, mask, n_mask_hit);
-               if (flow)  /* Found */
-                       return flow;
+       for (i = 0; i < ma->max; i++) {
+               struct sw_flow_mask *mask;
+
+               mask = rcu_dereference_ovsl(ma->masks[i]);
+               if (mask) {
+                       flow = masked_flow_lookup(ti, key, mask, n_mask_hit);
+                       if (flow) { /* Found */
+                               *index = i;
+                               return flow;
+                       }
+               }
        }
+
        return NULL;
 }
 
@@ -483,6 +552,7 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
                                          u32 skb_hash,
                                          u32 *n_mask_hit)
 {
+       struct mask_array *ma = rcu_dereference_ovsl(tbl->mask_array);
        struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
        struct mask_cache_entry  *entries, *ce, *del;
        struct sw_flow *flow;
@@ -490,8 +560,11 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
        int seg;
 
        *n_mask_hit = 0;
-       if (unlikely(!skb_hash))
-               return flow_lookup(tbl, ti, key, n_mask_hit);
+       if (unlikely(!skb_hash)) {
+               u32 __always_unused mask_index;
+
+               return flow_lookup(tbl, ti, ma, key, n_mask_hit, &mask_index);
+       }
 
        del = NULL;
        entries = this_cpu_ptr(tbl->mask_cache);
@@ -504,36 +577,33 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
 
                if (ce->skb_hash == skb_hash) {
                        struct sw_flow_mask *mask;
-                       int i;
+                       struct sw_flow *flow;
 
-                       i = 0;
-                       list_for_each_entry_rcu(mask, &tbl->mask_list, list) {
-                               if (ce->mask_index == i++) {
-                                       flow = masked_flow_lookup(ti, key, mask,
-                                                                 n_mask_hit);
-                                       if (flow)  /* Found */
-                                               return flow;
+                       mask = rcu_dereference_ovsl(ma->masks[ce->mask_index]);
+                       if (mask) {
+                               flow = masked_flow_lookup(ti, key, mask,
+                                                         n_mask_hit);
+                               if (flow)  /* Found */
+                                       return flow;
 
-                                       break;
-                               }
                        }
                        del = ce;
                        break;
                }
 
-               if (!del || (del->skb_hash && !ce->skb_hash)) {
+               if (!del || (del->skb_hash && !ce->skb_hash) ||
+                   (rcu_dereference_ovsl(ma->masks[del->mask_index]) &&
+                   !rcu_dereference_ovsl(ma->masks[ce->mask_index]))) {
                        del = ce;
                }
 
                hash >>= MC_HASH_SHIFT;
        }
 
-       flow = flow_lookup(tbl, ti, key, n_mask_hit);
-
-       if (flow) {
+       flow = flow_lookup(tbl, ti, ma, key, n_mask_hit, &del->mask_index);
+       if (flow)
                del->skb_hash = skb_hash;
-               del->mask_index = (*n_mask_hit - 1);
-       }
+
        return flow;
 }
 
@@ -541,21 +611,20 @@ 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 __always_unused index;
 
        n_mask_hit = 0;
-       return flow_lookup(tbl, ti, key, &n_mask_hit);
+       return flow_lookup(tbl, ti, ma, key, &n_mask_hit, &index);
 }
 
 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++;
+       struct mask_array *ma;
 
-       return num;
+       ma = rcu_dereference_ovsl(table->mask_array);
+       return ma->count;
 }
 
 static struct table_instance *table_instance_expand(struct table_instance *ti)
@@ -575,7 +644,19 @@ static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
                mask->ref_count--;
 
                if (!mask->ref_count) {
-                       list_del_rcu(&mask->list);
+                       struct mask_array *ma;
+                       int i;
+
+                       ma = ovsl_dereference(tbl->mask_array);
+                       for (i = 0; i < ma->max; i++) {
+                               if (mask == ovsl_dereference(ma->masks[i])) {
+                                       RCU_INIT_POINTER(ma->masks[i], NULL);
+                                       ma->count--;
+                                       goto free;
+                               }
+                       }
+                       BUG();
+free:
                        call_rcu(&mask->rcu, rcu_free_sw_flow_mask_cb);
                }
        }
@@ -620,13 +701,16 @@ 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;
 
-       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;
+               t = ovsl_dereference(ma->masks[i]);
+               if (t && mask_equal(mask, t))
+                       return t;
        }
 
        return NULL;
@@ -637,15 +721,43 @@ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow,
                            struct sw_flow_mask *new)
 {
        struct sw_flow_mask *mask;
+
        mask = flow_mask_find(tbl, new);
        if (!mask) {
+               struct mask_array *ma;
+               int i;
+
                /* Allocate a new mask if none exsits. */
                mask = mask_alloc();
                if (!mask)
                        return -ENOMEM;
+
                mask->key = new->key;
                mask->range = new->range;
-               list_add_tail_rcu(&mask->list, &tbl->mask_list);
+
+               /* Add mask to mask-list. */
+               ma = ovsl_dereference(tbl->mask_array);
+               if (ma->count >= ma->max) {
+                       int err;
+
+                       err = tbl_mask_array_realloc(tbl, ma->max +
+                                                       MASK_ARRAY_SIZE_MIN);
+                       if (err) {
+                               kfree(mask);
+                               return err;
+                       }
+                       ma = ovsl_dereference(tbl->mask_array);
+               }
+               for (i = 0; i < ma->max; i++) {
+                       const struct sw_flow_mask *t;
+
+                       t = ovsl_dereference(ma->masks[i]);
+                       if (!t) {
+                               rcu_assign_pointer(ma->masks[i], mask);
+                               ma->count++;
+                               break;
+                       }
+               }
        } else {
                BUG_ON(!mask->ref_count);
                mask->ref_count++;

diff --git a/datapath/flow_table.h b/datapath/flow_table.h
index 281d1da..ee86953 100644 (file)
--- a/datapath/flow_table.h
+++ b/datapath/flow_table.h
@@ -41,6 +41,12 @@ struct mask_cache_entry {
        u32 mask_index;
 };
 
+struct mask_array {
+       struct rcu_head rcu;
+       int count, max;
+       struct sw_flow_mask __rcu *masks[];
+};
+
 struct table_instance {
        struct flex_array *buckets;
        unsigned int n_buckets;
@@ -53,7 +59,7 @@ struct table_instance {
 struct flow_table {
        struct table_instance __rcu *ti;
        struct mask_cache_entry __percpu *mask_cache;
-       struct list_head mask_list;
+       struct mask_array __rcu *mask_array;
        unsigned long last_rehash;
        unsigned int count;
 };