From: Tonghao Zhang <xiangxia.m....@gmail.com>

The full looking up on flow table traverses all mask array.
If mask-array is too large, the number of invalid flow-mask
increase, performance will be drop.

This patch optimizes mask-array operation:

* Inserting, insert it [ma->count- 1] directly.
* Removing, only change last and current mask point, and free current mask.
* Looking up, full looking up will break if mask is NULL.

Signed-off-by: Tonghao Zhang <xiangxia.m....@gmail.com>
---
 net/openvswitch/flow_table.c | 93 ++++++++++++++++++++++----------------------
 1 file changed, 46 insertions(+), 47 deletions(-)

diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
index e59fac5..2d74d74 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -546,7 +546,7 @@ static struct sw_flow *flow_lookup(struct flow_table *tbl,
 
                mask = rcu_dereference_ovsl(ma->masks[i]);
                if (!mask)
-                       continue;
+                       break;
 
                flow = masked_flow_lookup(ti, key, mask, n_mask_hit);
                if (flow) { /* Found */
@@ -712,21 +712,31 @@ static struct table_instance 
*table_instance_expand(struct table_instance *ti,
        return table_instance_rehash(ti, ti->n_buckets * 2, ufid);
 }
 
-static void tbl_mask_array_delete_mask(struct mask_array *ma,
-                                      struct sw_flow_mask *mask)
+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;
 
        /* Remove the deleted mask pointers from the array */
-       for (i = 0; i < ma->max; i++) {
-               if (mask == ovsl_dereference(ma->masks[i])) {
-                       RCU_INIT_POINTER(ma->masks[i], NULL);
-                       ma->count--;
-                       kfree_rcu(mask, rcu);
-                       return;
-               }
+       for (i = 0; i < ma->count; i++) {
+               if (mask == ovsl_dereference(ma->masks[i]))
+                       goto found;
        }
+
        BUG();
+       return;
+
+found:
+       rcu_assign_pointer(ma->masks[i], ma->masks[ma->count -1]);
+       RCU_INIT_POINTER(ma->masks[ma->count -1], NULL);
+       ma->count--;
+       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. */
@@ -740,17 +750,8 @@ static void flow_mask_remove(struct flow_table *tbl, 
struct sw_flow_mask *mask)
                BUG_ON(!mask->ref_count);
                mask->ref_count--;
 
-               if (!mask->ref_count) {
-                       struct mask_array *ma;
-
-                       ma = ovsl_dereference(tbl->mask_array);
-                       tbl_mask_array_delete_mask(ma, mask);
-
-                       /* 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);
-               }
+               if (!mask->ref_count)
+                       tbl_mask_array_del_mask(tbl, mask);
        }
 }
 
@@ -814,6 +815,27 @@ static struct sw_flow_mask *flow_mask_find(const struct 
flow_table *tbl,
        return NULL;
 }
 
+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;
+
+       if (ma->count >= ma->max) {
+               err = tbl_mask_array_realloc(tbl, ma->max +
+                                             MASK_ARRAY_SIZE_MIN);
+               if (err)
+                       return err;
+       }
+
+       BUG_ON(ovsl_dereference(ma->masks[ma->count]));
+
+       rcu_assign_pointer(ma->masks[ma->count], new);
+       ma->count++;
+
+       return 0;
+}
+
 /* Add 'mask' into the mask list, if it is not already there. */
 static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow,
                            const struct sw_flow_mask *new)
@@ -822,9 +844,6 @@ static int flow_mask_insert(struct flow_table *tbl, struct 
sw_flow *flow,
 
        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)
@@ -833,29 +852,9 @@ static int flow_mask_insert(struct flow_table *tbl, struct 
sw_flow *flow,
                mask->range = new->range;
 
                /* 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;
-                       }
+               if (tbl_mask_array_add_mask(tbl, mask)) {
+                       kfree(mask);
+                       return -ENOMEM;
                }
        } else {
                BUG_ON(!mask->ref_count);
-- 
1.8.3.1

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