netdev_flow_key is a miniflow with the following constraints:
1) It is used only inside dpif-netdev.c.
2) It always has inline values.
3) It contains only miniflows created by miniflow_extract().
Therefore, by using these new functions instead of the miniflow_* ones, we get
the following (performance related) benefits:
- Because of (1) the functions can be inlined.
- Because of (2) and (3) the netdev_flow_key can be treated as POD.
Specifically, because of (3), we can do comparisons with memcmp, since if the
map is different the miniflow must be different.
Signed-off-by: Daniele Di Proietto <ddiproie...@vmware.com>
---
lib/dpif-netdev.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 62 insertions(+), 6 deletions(-)
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 869fb55..112cd5a 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -87,7 +87,7 @@ static struct shash dp_netdevs OVS_GUARDED_BY(dp_netdev_mutex)
static struct vlog_rate_limit upcall_rl = VLOG_RATE_LIMIT_INIT(600, 600);
-/* Stores a miniflow */
+/* Stores a miniflow with inline values */
/* There are fields in the flow structure that we never use. Therefore we can
* save a few words of memory */
@@ -1133,6 +1133,59 @@ static bool dp_netdev_flow_ref(struct dp_netdev_flow
*flow)
return ovs_refcount_try_ref_rcu(&flow->ref_cnt);
}
+/* netdev_flow_key utilities.
+ *
+ * netdev_flow_key is basically a miniflow. We use these functions
+ * (netdev_flow_key_clone, netdev_flow_key_equal, ...) instead of the miniflow
+ * functions (miniflow_clone_inline, miniflow_equal, ...), because:
+ *
+ * - Since we are dealing exclusively with miniflows created by
+ * miniflow_extract(), if the map is different the miniflow is different.
+ * Therefore we can be faster by comparing the map and the miniflow in a
+ * single memcmp().
+ * _ netdev_flow_key's miniflow has always inline values.
+ * - These functions can be inlined by the compiler.
+ *
+ * The following assertions make sure that what we're doing with miniflow is
+ * safe
+ */
+BUILD_ASSERT_DECL(offsetof(struct miniflow, inline_values)
+ == sizeof(uint64_t));
+BUILD_ASSERT_DECL(offsetof(struct netdev_flow_key, flow) == 0);
+
+static inline struct netdev_flow_key *
+miniflow_to_netdev_flow_key(const struct miniflow *mf)
+{
+ return (struct netdev_flow_key *) CONST_CAST(struct miniflow *, mf);
+}
+
+/* Given the number of bits set in the miniflow map, returns the size of the
+ * netdev_flow key */
+static inline uint32_t
+netdev_flow_key_size(uint32_t flow_u32s)
+{
+ return MINIFLOW_VALUES_SIZE(flow_u32s)
+ + offsetof(struct miniflow, inline_values);
+}
+
+/* Used to compare 'netdev_flow_key's (miniflows) in the exact match cache. */
+static inline bool
+netdev_flow_key_equal(const struct netdev_flow_key *a,
+ const struct netdev_flow_key *b)
+{
+ uint32_t size = count_1bits(a->flow.map);
+
+ return !memcmp(a, b, netdev_flow_key_size(size));
+}
+
+static inline void
+netdev_flow_key_clone(struct netdev_flow_key *dst,
+ const struct netdev_flow_key *src,
+ uint32_t size)
+{
+ memcpy(dst, src, netdev_flow_key_size(size));
+}
+
static inline bool
emc_entry_alive(struct emc_entry *ce)
{
@@ -1150,7 +1203,7 @@ emc_clear_entry(struct emc_entry *ce)
static inline void
emc_change_entry(struct emc_entry *ce, struct dp_netdev_flow *flow,
- const struct miniflow *mf, uint32_t hash)
+ const struct netdev_flow_key *mf, uint32_t hash)
{
if (ce->flow != flow) {
if (ce->flow) {
@@ -1164,7 +1217,7 @@ emc_change_entry(struct emc_entry *ce, struct
dp_netdev_flow *flow,
}
}
if (mf) {
- miniflow_clone_inline(&ce->mf.flow, mf, count_1bits(mf->map));
+ netdev_flow_key_clone(&ce->mf, mf, count_1bits(mf->flow.map));
ce->hash = hash;
}
}
@@ -1178,7 +1231,8 @@ emc_insert(struct emc_cache *cache, const struct miniflow
*mf, uint32_t hash,
EMC_FOR_EACH_POS_WITH_HASH(cache, current_entry, hash) {
if (current_entry->hash == hash
- && miniflow_equal(¤t_entry->mf.flow, mf)) {
+ && netdev_flow_key_equal(¤t_entry->mf,
+ miniflow_to_netdev_flow_key(mf))) {
/* We found the entry with the 'mf' miniflow */
emc_change_entry(current_entry, flow, NULL, 0);
@@ -1197,7 +1251,8 @@ emc_insert(struct emc_cache *cache, const struct miniflow
*mf, uint32_t hash,
/* We didn't find the miniflow in the cache.
* The 'to_be_replaced' entry is where the new flow will be stored */
- emc_change_entry(to_be_replaced, flow, mf, hash);
+ emc_change_entry(to_be_replaced, flow, miniflow_to_netdev_flow_key(mf),
+ hash);
}
static inline struct dp_netdev_flow *
@@ -1207,7 +1262,8 @@ emc_lookup(struct emc_cache *cache, const struct miniflow
*mf, uint32_t hash)
EMC_FOR_EACH_POS_WITH_HASH(cache, current_entry, hash) {
if (current_entry->hash == hash && emc_entry_alive(current_entry)
- && miniflow_equal(¤t_entry->mf.flow, mf)) {
+ && netdev_flow_key_equal(¤t_entry->mf,
+ miniflow_to_netdev_flow_key(mf))) {
/* We found the entry with the 'mf' miniflow */
return current_entry->flow;
--
2.1.0.rc1
_______________________________________________
dev mailing list
dev@openvswitch.org
http://openvswitch.org/mailman/listinfo/dev
