#include "dpif-netdev-perf.h"
#include "dpif-provider.h"
#include "flow.h"
+#include "ovs-thread.h"
#include "packets.h"
#include "pvector.h"
-/* Returns a hash value for the bits of 'key' where there are 1-bits in
- * 'mask'. */
-static inline uint32_t
-netdev_flow_key_hash_in_mask(const struct netdev_flow_key *key,
- const struct netdev_flow_key *mask)
+VLOG_DEFINE_THIS_MODULE(dpif_lookup_generic);
+
+/* Lookup functions below depends on the internal structure of flowmap. */
+BUILD_ASSERT_DECL(FLOWMAP_UNITS == 2);
+
+struct block_array {
+ uint32_t count; /* Number of items allocated in 'blocks' */
+ uint64_t blocks[];
+};
+
+DEFINE_PER_THREAD_MALLOCED_DATA(struct block_array *, block_array);
+
+static inline uint64_t *
+get_blocks_scratch(uint32_t required_count)
{
- const uint64_t *p = miniflow_get_values(&mask->mf);
- uint32_t hash = 0;
- uint64_t value;
+ struct block_array *array = block_array_get();
- NETDEV_FLOW_KEY_FOR_EACH_IN_FLOWMAP (value, key, mask->mf.map) {
- hash = hash_add64(hash, value & *p);
- p++;
+ /* Check if this thread already has a large enough array allocated.
+ * This is a predictable and unlikely branch, as it occurs only once at
+ * startup, or if a subtable with higher block count is added.
+ */
+ if (OVS_UNLIKELY(!array || array->count < required_count)) {
+ array = xrealloc(array, sizeof *array +
+ (required_count * sizeof array->blocks[0]));
+ array->count = required_count;
+ block_array_set_unsafe(array);
+ VLOG_DBG("Block array resized to %"PRIu32, required_count);
}
- return hash_finish(hash, (p - miniflow_get_values(&mask->mf)) * 8);
+ return &array->blocks[0];
}
-uint32_t
-dpcls_subtable_lookup_generic(struct dpcls_subtable *subtable,
- uint32_t keys_map,
- const struct netdev_flow_key *keys[],
- struct dpcls_rule **rules)
+static inline void
+netdev_flow_key_flatten_unit(const uint64_t *pkt_blocks,
+ const uint64_t *tbl_blocks,
+ const uint64_t *mf_masks,
+ uint64_t *blocks_scratch,
+ const uint64_t pkt_mf_bits,
+ const uint32_t count)
{
- int i;
- uint32_t found_map;
+ uint32_t i;
+
+ for (i = 0; i < count; i++) {
+ uint64_t mf_mask = mf_masks[i];
+ /* Calculate the block index for the packet metadata. */
+ uint64_t idx_bits = mf_mask & pkt_mf_bits;
+ const uint32_t pkt_idx = count_1bits(idx_bits);
+
+ /* Check if the packet has the subtable miniflow bit set. If yes, the
+ * block at the above pkt_idx will be stored, otherwise it is masked
+ * out to be zero.
+ */
+ uint64_t pkt_has_mf_bit = (mf_mask + 1) & pkt_mf_bits;
+ uint64_t no_bit = ((!pkt_has_mf_bit) > 0) - 1;
+
+ /* Mask packet block by table block, and mask to zero if packet
+ * doesn't actually contain this block of metadata.
+ */
+ blocks_scratch[i] = pkt_blocks[pkt_idx] & tbl_blocks[i] & no_bit;
+ }
+}
+
+/* This function takes a packet, and subtable and writes an array of uint64_t
+ * blocks. The blocks contain the metadata that the subtable matches on, in
+ * the same order as the subtable, allowing linear iteration over the blocks.
+ *
+ * To calculate the blocks contents, the netdev_flow_key_flatten_unit function
+ * is called twice, once for each "unit" of the miniflow. This call can be
+ * inlined by the compiler for performance.
+ *
+ * Note that the u0_count and u1_count variables can be compile-time constants,
+ * allowing the loop in the inlined flatten_unit() function to be compile-time
+ * unrolled, or possibly removed totally by unrolling by the loop iterations.
+ * The compile time optimizations enabled by this design improves performance.
+ */
+static inline void
+netdev_flow_key_flatten(const struct netdev_flow_key *key,
+ const struct netdev_flow_key *mask,
+ const uint64_t *mf_masks,
+ uint64_t *blocks_scratch,
+ const uint32_t u0_count,
+ const uint32_t u1_count)
+{
+ /* Load mask from subtable, mask with packet mf, popcount to get idx. */
+ const uint64_t *pkt_blocks = miniflow_get_values(&key->mf);
+ const uint64_t *tbl_blocks = miniflow_get_values(&mask->mf);
+
+ /* Packet miniflow bits to be masked by pre-calculated mf_masks. */
+ const uint64_t pkt_bits_u0 = key->mf.map.bits[0];
+ const uint32_t pkt_bits_u0_pop = count_1bits(pkt_bits_u0);
+ const uint64_t pkt_bits_u1 = key->mf.map.bits[1];
+
+ /* Unit 0 flattening */
+ netdev_flow_key_flatten_unit(&pkt_blocks[0],
+ &tbl_blocks[0],
+ &mf_masks[0],
+ &blocks_scratch[0],
+ pkt_bits_u0,
+ u0_count);
+
+ /* Unit 1 flattening:
+ * Move the pointers forward in the arrays based on u0 offsets, NOTE:
+ * 1) pkt blocks indexed by actual popcount of u0, which is NOT always
+ * the same as the amount of bits set in the subtable.
+ * 2) mf_masks, tbl_block and blocks_scratch are all "flat" arrays, so
+ * the index is always u0_count.
+ */
+ netdev_flow_key_flatten_unit(&pkt_blocks[pkt_bits_u0_pop],
+ &tbl_blocks[u0_count],
+ &mf_masks[u0_count],
+ &blocks_scratch[u0_count],
+ pkt_bits_u1,
+ u1_count);
+}
+
+/* Compares a rule and the blocks representing a key, returns 1 on a match. */
+static inline uint64_t
+netdev_rule_matches_key(const struct dpcls_rule *rule,
+ const uint32_t mf_bits_total,
+ const uint64_t *blocks_scratch)
+{
+ const uint64_t *keyp = miniflow_get_values(&rule->flow.mf);
+ const uint64_t *maskp = miniflow_get_values(&rule->mask->mf);
+ uint64_t not_match = 0;
+
+ for (int i = 0; i < mf_bits_total; i++) {
+ not_match |= (blocks_scratch[i] & maskp[i]) != keyp[i];
+ }
- /* Compute hashes for the remaining keys. Each search-key is
- * masked with the subtable's mask to avoid hashing the wildcarded
- * bits. */
+ /* Invert result to show match as 1. */
+ return !not_match;
+}
+
+/* Const prop version of the function: note that mf bits total and u0 are
+ * explicitly passed in here, while they're also available at runtime from the
+ * subtable pointer. By making them compile time, we enable the compiler to
+ * unroll loops and flatten out code-sequences based on the knowledge of the
+ * mf_bits_* compile time values. This results in improved performance.
+ *
+ * Note: this function is marked with ALWAYS_INLINE to ensure the compiler
+ * inlines the below code, and then uses the compile time constants to make
+ * specialized versions of the runtime code. Without ALWAYS_INLINE, the
+ * compiler might decide to not inline, and performance will suffer.
+ */
+static inline uint32_t ALWAYS_INLINE
+lookup_generic_impl(struct dpcls_subtable *subtable,
+ uint32_t keys_map,
+ const struct netdev_flow_key *keys[],
+ struct dpcls_rule **rules,
+ const uint32_t bit_count_u0,
+ const uint32_t bit_count_u1)
+{
+ const uint32_t n_pkts = count_1bits(keys_map);
+ ovs_assert(NETDEV_MAX_BURST >= n_pkts);
uint32_t hashes[NETDEV_MAX_BURST];
+
+ const uint32_t bit_count_total = bit_count_u0 + bit_count_u1;
+ const uint32_t block_count_required = bit_count_total * NETDEV_MAX_BURST;
+ uint64_t *mf_masks = subtable->mf_masks;
+ int i;
+
+ /* Blocks scratch is an optimization to re-use the same packet miniflow
+ * block data when doing rule-verify. This reduces work done during lookup
+ * and hence improves performance. The blocks_scratch array is stored as a
+ * thread local variable, as each thread requires its own blocks memory.
+ */
+ uint64_t *blocks_scratch = get_blocks_scratch(block_count_required);
+
+ /* Flatten the packet metadata into the blocks_scratch[] using subtable. */
+ ULLONG_FOR_EACH_1 (i, keys_map) {
+ netdev_flow_key_flatten(keys[i],
+ &subtable->mask,
+ mf_masks,
+ &blocks_scratch[i * bit_count_total],
+ bit_count_u0,
+ bit_count_u1);
+ }
+
+ /* Hash the now linearized blocks of packet metadata. */
ULLONG_FOR_EACH_1 (i, keys_map) {
- hashes[i] = netdev_flow_key_hash_in_mask(keys[i], &subtable->mask);
+ uint64_t *block_ptr = &blocks_scratch[i * bit_count_total];
+ uint32_t hash = hash_add_words64(0, block_ptr, bit_count_total);
+ hashes[i] = hash_finish(hash, bit_count_total * 8);
}
- /* Lookup. */
+ /* Lookup: this returns a bitmask of packets where the hash table had
+ * an entry for the given hash key. Presence of a hash key does not
+ * guarantee matching the key, as there can be hash collisions.
+ */
+ uint32_t found_map;
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. */
+ /* Verify that packet actually matched rule. If not found, a hash
+ * collision has taken place, so continue searching with the next node.
+ */
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]))) {
+ const uint32_t cidx = i * bit_count_total;
+ uint32_t match = netdev_rule_matches_key(rule, bit_count_total,
+ &blocks_scratch[cidx]);
+
+ if (OVS_LIKELY(match)) {
rules[i] = rule;
- /* Even at 20 Mpps the 32-bit hit_cnt cannot wrap
- * within one second optimization interval. */
subtable->hit_cnt++;
goto next;
}
return found_map;
}
+
+/* Generic lookup function that uses runtime provided mf bits for iterating. */
+uint32_t
+dpcls_subtable_lookup_generic(struct dpcls_subtable *subtable,
+ uint32_t keys_map,
+ const struct netdev_flow_key *keys[],
+ struct dpcls_rule **rules)
+{
+ return lookup_generic_impl(subtable, keys_map, keys, rules,
+ subtable->mf_bits_set_unit0,
+ subtable->mf_bits_set_unit1);
+}
dpcls_subtable_destroy_cb(struct dpcls_subtable *subtable)
{
cmap_destroy(&subtable->rules);
+ ovsrcu_postpone(free, subtable->mf_masks);
ovsrcu_postpone(free, subtable);
}
subtable->hit_cnt = 0;
netdev_flow_key_clone(&subtable->mask, mask);
- /* Decide which hash/lookup/verify function to use. */
+ /* The count of bits in the mask defines the space required for masks.
+ * Then call gen_masks() to create the appropriate masks, avoiding the cost
+ * of doing runtime calculations. */
+ uint32_t unit0 = count_1bits(mask->mf.map.bits[0]);
+ uint32_t unit1 = count_1bits(mask->mf.map.bits[1]);
+ subtable->mf_bits_set_unit0 = unit0;
+ subtable->mf_bits_set_unit1 = unit1;
+ subtable->mf_masks = xmalloc(sizeof(uint64_t) * (unit0 + unit1));
+ netdev_flow_key_gen_masks(mask, subtable->mf_masks, unit0, unit1);
+
+ /* Assign the generic lookup - this works with any miniflow fingerprint. */
subtable->lookup_func = dpcls_subtable_lookup_generic;
cmap_insert(&cls->subtables_map, &subtable->cmap_node, mask->hash);
}
}
+/* Inner loop for mask generation of a unit, see netdev_flow_key_gen_masks. */
+static inline void
+netdev_flow_key_gen_mask_unit(uint64_t iter,
+ const uint64_t count,
+ uint64_t *mf_masks)
+{
+ int i;
+ for (i = 0; i < count; i++) {
+ uint64_t lowest_bit = (iter & -iter);
+ iter &= ~lowest_bit;
+ mf_masks[i] = (lowest_bit - 1);
+ }
+ /* Checks that count has covered all bits in the iter bitmap. */
+ ovs_assert(iter == 0);
+}
+
+/* Generate a mask for each block in the miniflow, based on the bits set. This
+ * allows easily masking packets with the generated array here, without
+ * calculations. This replaces runtime-calculating the masks.
+ * @param key The table to generate the mf_masks for
+ * @param mf_masks Pointer to a u64 array of at least *mf_bits* in size
+ * @param mf_bits_total Number of bits set in the whole miniflow (both units)
+ * @param mf_bits_unit0 Number of bits set in unit0 of the miniflow
+ */
+void
+netdev_flow_key_gen_masks(const struct netdev_flow_key *tbl,
+ uint64_t *mf_masks,
+ const uint32_t mf_bits_u0,
+ const uint32_t mf_bits_u1)
+{
+ uint64_t iter_u0 = tbl->mf.map.bits[0];
+ uint64_t iter_u1 = tbl->mf.map.bits[1];
+
+ netdev_flow_key_gen_mask_unit(iter_u0, mf_bits_u0, &mf_masks[0]);
+ netdev_flow_key_gen_mask_unit(iter_u1, mf_bits_u1, &mf_masks[mf_bits_u0]);
+}
+
/* Returns true if 'target' satisfies 'key' in 'mask', that is, if each 1-bit
* in 'mask' the values in 'key' and 'target' are the same. */
bool
BUILD_ASSERT_DECL(MAP_BITS >= NETDEV_MAX_BURST);
struct dpcls_subtable *subtable;
-
uint32_t keys_map = TYPE_MAXIMUM(uint32_t); /* Set all bits. */
if (cnt != MAP_BITS) {
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