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dpif-netdev: Implement function pointers/subtable

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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.haaren@intel.com>
Tested-by: Malvika Gupta <malvika.gupta@arm.com>
Acked-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>
This commit is contained in:
Harry van Haaren
2019-07-18 14:03:02 +01:00
committed by Ian Stokes
parent 300ac0e184
commit aadede3dda
1 changed files with 96 additions and 42 deletions
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138
lib/dpif-netdev.c
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@@ -7683,6 +7683,28 @@ 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. */
@@ -7692,6 +7714,13 @@ 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. */
};
@@ -7751,6 +7780,10 @@ 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);
@@ -7911,6 +7944,55 @@ 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;
uint32_t found_map;
/* 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];
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.
@@ -7929,16 +8011,12 @@ 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. */
@@ -7946,6 +8024,7 @@ dpcls_lookup(struct dpcls *cls, const struct netdev_flow_key *keys[],
memset(rules, 0, cnt * sizeof *rules);
int lookups_match = 0, subtable_pos = 1;
uint32_t found_map;
/* The Datapath classifier - aka dpcls - is composed of subtables.
* Subtables are dynamically created as needed when new rules are inserted.
@@ -7955,52 +8034,27 @@ 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. */
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 = count_1bits(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;
}