This allows plugging-in of different subtable hash-lookup-verify routines, and allows special casing of those functions based on known context (eg: # of bits set) of the specific subtable.
Signed-off-by: Harry van Haaren <harry.van.haa...@intel.com> --- v6: - Implement subtable effort per packet "lookups_match" counter (Ilya) - Remove double newline (Eelco) - Remove doubel * before comments (Eelco) - Reword comments in dpcls_lookup() for clarity (Harry) --- lib/dpif-netdev.c | 135 +++++++++++++++++++++++++++++++--------------- 1 file changed, 93 insertions(+), 42 deletions(-) diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c index 4d6d0c372..e6bdad7ed 100644 --- a/lib/dpif-netdev.c +++ b/lib/dpif-netdev.c @@ -7579,6 +7579,27 @@ dpif_dummy_register(enum dummy_level level) /* Datapath Classifier. */ +/* forward declaration for lookup_func typedef */ +struct dpcls_subtable; + +/* Lookup function for a subtable in the dpcls. This function is called + * by each subtable with an array of packets, and a bitmask of packets to + * perform the lookup on. Using a function pointer gives flexibility to + * optimize the lookup function based on subtable properties and the + * CPU instruction set available at runtime. + */ +typedef uint32_t (*dpcls_subtable_lookup_func)(struct dpcls_subtable *subtable, + uint32_t keys_map, const struct netdev_flow_key *keys[], + struct dpcls_rule **rules); + +/* Prototype for generic lookup func, using same code path as before */ +uint32_t +dpcls_subtable_lookup_generic(struct dpcls_subtable *subtable, + uint32_t keys_map, + const struct netdev_flow_key *keys[], + struct dpcls_rule **rules); + + /* A set of rules that all have the same fields wildcarded. */ struct dpcls_subtable { /* The fields are only used by writers. */ @@ -7588,6 +7609,13 @@ struct dpcls_subtable { struct cmap rules; /* Contains "struct dpcls_rule"s. */ uint32_t hit_cnt; /* Number of match hits in subtable in current optimization interval. */ + + /* the lookup function to use for this subtable. If there is a known + * property of the subtable (eg: only 3 bits of miniflow metadata is + * used for the lookup) then this can point at an optimized version of + * the lookup function for this particular subtable. */ + dpcls_subtable_lookup_func lookup_func; + struct netdev_flow_key mask; /* Wildcards for fields (const). */ /* 'mask' must be the last field, additional space is allocated here. */ }; @@ -7641,6 +7669,10 @@ dpcls_create_subtable(struct dpcls *cls, const struct netdev_flow_key *mask) cmap_init(&subtable->rules); subtable->hit_cnt = 0; netdev_flow_key_clone(&subtable->mask, mask); + + /* decide which hash/lookup/verify function to use */ + subtable->lookup_func = dpcls_subtable_lookup_generic; + cmap_insert(&cls->subtables_map, &subtable->cmap_node, mask->hash); /* Add the new subtable at the end of the pvector (with no hits yet) */ pvector_insert(&cls->subtables, subtable, 0); @@ -7801,6 +7833,53 @@ dpcls_rule_matches_key(const struct dpcls_rule *rule, return true; } +uint32_t +dpcls_subtable_lookup_generic(struct dpcls_subtable *subtable, + uint32_t keys_map, + const struct netdev_flow_key *keys[], + struct dpcls_rule **rules) +{ + int i; + /* Compute hashes for the remaining keys. Each search-key is + * masked with the subtable's mask to avoid hashing the wildcarded + * bits. */ + uint32_t hashes[NETDEV_MAX_BURST]; + ULLONG_FOR_EACH_1(i, keys_map) { + hashes[i] = netdev_flow_key_hash_in_mask(keys[i], + &subtable->mask); + } + + /* Lookup. */ + const struct cmap_node *nodes[NETDEV_MAX_BURST]; + uint32_t found_map = + cmap_find_batch(&subtable->rules, keys_map, hashes, nodes); + /* Check results. When the i-th bit of found_map is set, it means + * that a set of nodes with a matching hash value was found for the + * i-th search-key. Due to possible hash collisions we need to check + * which of the found rules, if any, really matches our masked + * search-key. */ + ULLONG_FOR_EACH_1(i, found_map) { + struct dpcls_rule *rule; + + CMAP_NODE_FOR_EACH (rule, cmap_node, nodes[i]) { + if (OVS_LIKELY(dpcls_rule_matches_key(rule, keys[i]))) { + rules[i] = rule; + /* Even at 20 Mpps the 32-bit hit_cnt cannot wrap + * within one second optimization interval. */ + subtable->hit_cnt++; + goto next; + } + } + /* None of the found rules was a match. Reset the i-th bit to + * keep searching this key in the next subtable. */ + ULLONG_SET0(found_map, i); /* Did not match. */ + next: + ; /* Keep Sparse happy. */ + } + + return found_map; +} + /* For each miniflow in 'keys' performs a classifier lookup writing the result * into the corresponding slot in 'rules'. If a particular entry in 'keys' is * NULL it is skipped. @@ -7819,16 +7898,12 @@ dpcls_lookup(struct dpcls *cls, const struct netdev_flow_key *keys[], /* The received 'cnt' miniflows are the search-keys that will be processed * to find a matching entry into the available subtables. * The number of bits in map_type is equal to NETDEV_MAX_BURST. */ - typedef uint32_t map_type; -#define MAP_BITS (sizeof(map_type) * CHAR_BIT) +#define MAP_BITS (sizeof(uint32_t) * CHAR_BIT) BUILD_ASSERT_DECL(MAP_BITS >= NETDEV_MAX_BURST); struct dpcls_subtable *subtable; - map_type keys_map = TYPE_MAXIMUM(map_type); /* Set all bits. */ - map_type found_map; - uint32_t hashes[MAP_BITS]; - const struct cmap_node *nodes[MAP_BITS]; + uint32_t keys_map = TYPE_MAXIMUM(uint32_t); /* Set all bits. */ if (cnt != MAP_BITS) { keys_map >>= MAP_BITS - cnt; /* Clear extra bits. */ @@ -7845,52 +7920,28 @@ dpcls_lookup(struct dpcls *cls, const struct netdev_flow_key *keys[], * search-key, the search for that key can stop because the rules are * non-overlapping. */ PVECTOR_FOR_EACH (subtable, &cls->subtables) { - int i; + /* call the subtable specific lookup function */ + uint32_t found_map = subtable->lookup_func(subtable, keys_map, + keys, rules); - /* Compute hashes for the remaining keys. Each search-key is - * masked with the subtable's mask to avoid hashing the wildcarded - * bits. */ - ULLONG_FOR_EACH_1(i, keys_map) { - hashes[i] = netdev_flow_key_hash_in_mask(keys[i], - &subtable->mask); - } - /* Lookup. */ - found_map = cmap_find_batch(&subtable->rules, keys_map, hashes, nodes); - /* Check results. When the i-th bit of found_map is set, it means - * that a set of nodes with a matching hash value was found for the - * i-th search-key. Due to possible hash collisions we need to check - * which of the found rules, if any, really matches our masked - * search-key. */ - ULLONG_FOR_EACH_1(i, found_map) { - struct dpcls_rule *rule; + /* Count the number of subtables searched for this packet match. This + * estimates the "spread" of subtables looked at per matched packet */ + uint32_t pkts_matched = __builtin_popcountll(found_map); + lookups_match += pkts_matched * subtable_pos; - CMAP_NODE_FOR_EACH (rule, cmap_node, nodes[i]) { - if (OVS_LIKELY(dpcls_rule_matches_key(rule, keys[i]))) { - rules[i] = rule; - /* Even at 20 Mpps the 32-bit hit_cnt cannot wrap - * within one second optimization interval. */ - subtable->hit_cnt++; - lookups_match += subtable_pos; - goto next; - } - } - /* None of the found rules was a match. Reset the i-th bit to - * keep searching this key in the next subtable. */ - ULLONG_SET0(found_map, i); /* Did not match. */ - next: - ; /* Keep Sparse happy. */ - } - keys_map &= ~found_map; /* Clear the found rules. */ + /* Clear the found rules, and return early if all packets are found */ + keys_map &= ~found_map; if (!keys_map) { if (num_lookups_p) { *num_lookups_p = lookups_match; } - return true; /* All found. */ + return true; } subtable_pos++; } + if (num_lookups_p) { *num_lookups_p = lookups_match; } - return false; /* Some misses. */ + return false; } -- 2.17.1 _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev