hash: modify lookup bulk pipeline
authorByron Marohn <byron.marohn@intel.com>
Tue, 4 Oct 2016 23:25:15 +0000 (00:25 +0100)
committerThomas Monjalon <thomas.monjalon@6wind.com>
Wed, 5 Oct 2016 10:10:49 +0000 (12:10 +0200)
This patch replaces the pipelined rte_hash lookup mechanism with a
loop-and-jump model, which performs significantly better,
especially for smaller table sizes and smaller table occupancies.

Signed-off-by: Byron Marohn <byron.marohn@intel.com>
Signed-off-by: Saikrishna Edupuganti <saikrishna.edupuganti@intel.com>
Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Sameh Gobriel <sameh.gobriel@intel.com>
lib/librte_hash/rte_cuckoo_hash.c
lib/librte_hash/rte_cuckoo_hash.h

index d762f36..3324b17 100644 (file)
@@ -914,44 +914,8 @@ rte_hash_get_key_with_position(const struct rte_hash *h, const int32_t position,
        return 0;
 }
 
-/* Lookup bulk stage 0: Prefetch input key */
 static inline void
-lookup_stage0(unsigned *idx, uint64_t *lookup_mask,
-               const void * const *keys)
-{
-       *idx = __builtin_ctzl(*lookup_mask);
-       if (*lookup_mask == 0)
-               *idx = 0;
-
-       rte_prefetch0(keys[*idx]);
-       *lookup_mask &= ~(1llu << *idx);
-}
-
-/*
- * Lookup bulk stage 1: Calculate primary/secondary hashes
- * and prefetch primary/secondary buckets
- */
-static inline void
-lookup_stage1(unsigned idx, hash_sig_t *prim_hash, hash_sig_t *sec_hash,
-               const struct rte_hash_bucket **primary_bkt,
-               const struct rte_hash_bucket **secondary_bkt,
-               hash_sig_t *hash_vals, const void * const *keys,
-               const struct rte_hash *h)
-{
-       *prim_hash = rte_hash_hash(h, keys[idx]);
-       hash_vals[idx] = *prim_hash;
-       *sec_hash = rte_hash_secondary_hash(*prim_hash);
-
-       *primary_bkt = &h->buckets[*prim_hash & h->bucket_bitmask];
-       *secondary_bkt = &h->buckets[*sec_hash & h->bucket_bitmask];
-
-       rte_prefetch0(*primary_bkt);
-       rte_prefetch0(*secondary_bkt);
-}
-
-static inline void
-compare_signatures(unsigned int *prim_hash_matches,
-                       unsigned int *sec_hash_matches,
+compare_signatures(uint32_t *prim_hash_matches, uint32_t *sec_hash_matches,
                        const struct rte_hash_bucket *prim_bkt,
                        const struct rte_hash_bucket *sec_bkt,
                        hash_sig_t prim_hash, hash_sig_t sec_hash,
@@ -962,11 +926,11 @@ compare_signatures(unsigned int *prim_hash_matches,
        switch (sig_cmp_fn) {
 #ifdef RTE_MACHINE_CPUFLAG_AVX2
        case RTE_HASH_COMPARE_AVX2:
-               *prim_hash_matches |= _mm256_movemask_ps((__m256)_mm256_cmpeq_epi32(
+               *prim_hash_matches = _mm256_movemask_ps((__m256)_mm256_cmpeq_epi32(
                                _mm256_load_si256(
                                        (__m256i const *)prim_bkt->sig_current),
                                _mm256_set1_epi32(prim_hash)));
-               *sec_hash_matches |= _mm256_movemask_ps((__m256)_mm256_cmpeq_epi32(
+               *sec_hash_matches = _mm256_movemask_ps((__m256)_mm256_cmpeq_epi32(
                                _mm256_load_si256(
                                        (__m256i const *)sec_bkt->sig_current),
                                _mm256_set1_epi32(sec_hash)));
@@ -975,7 +939,7 @@ compare_signatures(unsigned int *prim_hash_matches,
 #ifdef RTE_MACHINE_CPUFLAG_SSE2
        case RTE_HASH_COMPARE_SSE:
                /* Compare the first 4 signatures in the bucket */
-               *prim_hash_matches |= _mm_movemask_ps((__m128)_mm_cmpeq_epi16(
+               *prim_hash_matches = _mm_movemask_ps((__m128)_mm_cmpeq_epi16(
                                _mm_load_si128(
                                        (__m128i const *)prim_bkt->sig_current),
                                _mm_set1_epi32(prim_hash)));
@@ -984,7 +948,7 @@ compare_signatures(unsigned int *prim_hash_matches,
                                        (__m128i const *)&prim_bkt->sig_current[4]),
                                _mm_set1_epi32(prim_hash)))) << 4;
                /* Compare the first 4 signatures in the bucket */
-               *sec_hash_matches |= _mm_movemask_ps((__m128)_mm_cmpeq_epi16(
+               *sec_hash_matches = _mm_movemask_ps((__m128)_mm_cmpeq_epi16(
                                _mm_load_si128(
                                        (__m128i const *)sec_bkt->sig_current),
                                _mm_set1_epi32(sec_hash)));
@@ -1005,244 +969,134 @@ compare_signatures(unsigned int *prim_hash_matches,
 
 }
 
-/*
- * Lookup bulk stage 2:  Search for match hashes in primary/secondary locations
- * and prefetch first key slot
- */
+#define PREFETCH_OFFSET 4
 static inline void
-lookup_stage2(unsigned idx, hash_sig_t prim_hash, hash_sig_t sec_hash,
-               const struct rte_hash_bucket *prim_bkt,
-               const struct rte_hash_bucket *sec_bkt,
-               const struct rte_hash_key **key_slot, int32_t *positions,
-               uint64_t *extra_hits_mask, const void *keys,
-               const struct rte_hash *h)
+__rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys,
+                       int32_t num_keys, int32_t *positions,
+                       uint64_t *hit_mask, void *data[])
 {
-       unsigned int prim_hash_matches, sec_hash_matches, key_idx;
-       unsigned int total_hash_matches;
+       uint64_t hits = 0;
+       int32_t i;
+       uint32_t prim_hash[RTE_HASH_LOOKUP_BULK_MAX];
+       uint32_t sec_hash[RTE_HASH_LOOKUP_BULK_MAX];
+       const struct rte_hash_bucket *primary_bkt[RTE_HASH_LOOKUP_BULK_MAX];
+       const struct rte_hash_bucket *secondary_bkt[RTE_HASH_LOOKUP_BULK_MAX];
+       uint32_t prim_hitmask[RTE_HASH_LOOKUP_BULK_MAX] = {0};
+       uint32_t sec_hitmask[RTE_HASH_LOOKUP_BULK_MAX] = {0};
+
+       /* Prefetch first keys */
+       for (i = 0; i < PREFETCH_OFFSET && i < num_keys; i++)
+               rte_prefetch0(keys[i]);
 
-       prim_hash_matches = 1 << RTE_HASH_BUCKET_ENTRIES;
-       sec_hash_matches = 1 << RTE_HASH_BUCKET_ENTRIES;
+       /*
+        * Prefetch rest of the keys, calculate primary and
+        * secondary bucket and prefetch them
+        */
+       for (i = 0; i < (num_keys - PREFETCH_OFFSET); i++) {
+               rte_prefetch0(keys[i + PREFETCH_OFFSET]);
 
-       compare_signatures(&prim_hash_matches, &sec_hash_matches, prim_bkt,
-                               sec_bkt, prim_hash, sec_hash, h->sig_cmp_fn);
+               prim_hash[i] = rte_hash_hash(h, keys[i]);
+               sec_hash[i] = rte_hash_secondary_hash(prim_hash[i]);
 
-       key_idx = prim_bkt->key_idx[__builtin_ctzl(prim_hash_matches)];
-       if (key_idx == 0)
-               key_idx = sec_bkt->key_idx[__builtin_ctzl(sec_hash_matches)];
+               primary_bkt[i] = &h->buckets[prim_hash[i] & h->bucket_bitmask];
+               secondary_bkt[i] = &h->buckets[sec_hash[i] & h->bucket_bitmask];
 
-       total_hash_matches = (prim_hash_matches |
-                               (sec_hash_matches << (RTE_HASH_BUCKET_ENTRIES + 1)));
-       *key_slot = (const struct rte_hash_key *) ((const char *)keys +
-                                       key_idx * h->key_entry_size);
+               rte_prefetch0(primary_bkt[i]);
+               rte_prefetch0(secondary_bkt[i]);
+       }
 
-       rte_prefetch0(*key_slot);
-       /*
-        * Return index where key is stored,
-        * substracting the first dummy index
-        */
-       positions[idx] = (key_idx - 1);
+       /* Calculate and prefetch rest of the buckets */
+       for (; i < num_keys; i++) {
+               prim_hash[i] = rte_hash_hash(h, keys[i]);
+               sec_hash[i] = rte_hash_secondary_hash(prim_hash[i]);
 
-       *extra_hits_mask |= (uint64_t)(__builtin_popcount(total_hash_matches) > 3) << idx;
+               primary_bkt[i] = &h->buckets[prim_hash[i] & h->bucket_bitmask];
+               secondary_bkt[i] = &h->buckets[sec_hash[i] & h->bucket_bitmask];
 
-}
+               rte_prefetch0(primary_bkt[i]);
+               rte_prefetch0(secondary_bkt[i]);
+       }
 
+       /* Compare signatures and prefetch key slot of first hit */
+       for (i = 0; i < num_keys; i++) {
+               compare_signatures(&prim_hitmask[i], &sec_hitmask[i],
+                               primary_bkt[i], secondary_bkt[i],
+                               prim_hash[i], sec_hash[i], h->sig_cmp_fn);
+
+               if (prim_hitmask[i]) {
+                       uint32_t first_hit = __builtin_ctzl(prim_hitmask[i]);
+                       uint32_t key_idx = primary_bkt[i]->key_idx[first_hit];
+                       const struct rte_hash_key *key_slot =
+                               (const struct rte_hash_key *)(
+                               (const char *)h->key_store +
+                               key_idx * h->key_entry_size);
+                       rte_prefetch0(key_slot);
+                       continue;
+               }
 
-/* Lookup bulk stage 3: Check if key matches, update hit mask and return data */
-static inline void
-lookup_stage3(unsigned idx, const struct rte_hash_key *key_slot, const void * const *keys,
-               const int32_t *positions, void *data[], uint64_t *hits,
-               const struct rte_hash *h)
-{
-       unsigned hit;
-       unsigned key_idx;
+               if (sec_hitmask[i]) {
+                       uint32_t first_hit = __builtin_ctzl(sec_hitmask[i]);
+                       uint32_t key_idx = secondary_bkt[i]->key_idx[first_hit];
+                       const struct rte_hash_key *key_slot =
+                               (const struct rte_hash_key *)(
+                               (const char *)h->key_store +
+                               key_idx * h->key_entry_size);
+                       rte_prefetch0(key_slot);
+               }
+       }
 
-       hit = !rte_hash_cmp_eq(key_slot->key, keys[idx], h);
-       if (data != NULL)
-               data[idx] = key_slot->pdata;
+       /* Compare keys, first hits in primary first */
+       for (i = 0; i < num_keys; i++) {
+               positions[i] = -ENOENT;
+               while (prim_hitmask[i]) {
+                       uint32_t hit_index = __builtin_ctzl(prim_hitmask[i]);
+
+                       uint32_t key_idx = primary_bkt[i]->key_idx[hit_index];
+                       const struct rte_hash_key *key_slot =
+                               (const struct rte_hash_key *)(
+                               (const char *)h->key_store +
+                               key_idx * h->key_entry_size);
+                       /*
+                        * If key index is 0, do not compare key,
+                        * as it is checking the dummy slot
+                        */
+                       if (!!key_idx & !rte_hash_cmp_eq(key_slot->key, keys[i], h)) {
+                               if (data != NULL)
+                                       data[i] = key_slot->pdata;
 
-       key_idx = positions[idx] + 1;
-       /*
-        * If key index is 0, force hit to be 0, in case key to be looked up
-        * is all zero (as in the dummy slot), which would result in a wrong hit
-        */
-       *hits |= (uint64_t)(hit && !!key_idx)  << idx;
-}
+                               hits |= 1ULL << i;
+                               positions[i] = key_idx - 1;
+                               goto next_key;
+                       }
+                       prim_hitmask[i] &= ~(1 << (hit_index));
+               }
 
-static inline void
-__rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys,
-                       uint32_t num_keys, int32_t *positions,
-                       uint64_t *hit_mask, void *data[])
-{
-       uint64_t hits = 0;
-       uint64_t extra_hits_mask = 0;
-       uint64_t lookup_mask, miss_mask;
-       unsigned idx;
-       const void *key_store = h->key_store;
-       int ret;
-       hash_sig_t hash_vals[RTE_HASH_LOOKUP_BULK_MAX];
-
-       unsigned idx00, idx01, idx10, idx11, idx20, idx21, idx30, idx31;
-       const struct rte_hash_bucket *primary_bkt10, *primary_bkt11;
-       const struct rte_hash_bucket *secondary_bkt10, *secondary_bkt11;
-       const struct rte_hash_bucket *primary_bkt20, *primary_bkt21;
-       const struct rte_hash_bucket *secondary_bkt20, *secondary_bkt21;
-       const struct rte_hash_key *k_slot20, *k_slot21, *k_slot30, *k_slot31;
-       hash_sig_t primary_hash10, primary_hash11;
-       hash_sig_t secondary_hash10, secondary_hash11;
-       hash_sig_t primary_hash20, primary_hash21;
-       hash_sig_t secondary_hash20, secondary_hash21;
-
-       lookup_mask = (uint64_t) -1 >> (64 - num_keys);
-       miss_mask = lookup_mask;
-
-       lookup_stage0(&idx00, &lookup_mask, keys);
-       lookup_stage0(&idx01, &lookup_mask, keys);
-
-       idx10 = idx00, idx11 = idx01;
-
-       lookup_stage0(&idx00, &lookup_mask, keys);
-       lookup_stage0(&idx01, &lookup_mask, keys);
-       lookup_stage1(idx10, &primary_hash10, &secondary_hash10,
-                       &primary_bkt10, &secondary_bkt10, hash_vals, keys, h);
-       lookup_stage1(idx11, &primary_hash11, &secondary_hash11,
-                       &primary_bkt11, &secondary_bkt11, hash_vals, keys, h);
-
-       primary_bkt20 = primary_bkt10;
-       primary_bkt21 = primary_bkt11;
-       secondary_bkt20 = secondary_bkt10;
-       secondary_bkt21 = secondary_bkt11;
-       primary_hash20 = primary_hash10;
-       primary_hash21 = primary_hash11;
-       secondary_hash20 = secondary_hash10;
-       secondary_hash21 = secondary_hash11;
-       idx20 = idx10, idx21 = idx11;
-       idx10 = idx00, idx11 = idx01;
-
-       lookup_stage0(&idx00, &lookup_mask, keys);
-       lookup_stage0(&idx01, &lookup_mask, keys);
-       lookup_stage1(idx10, &primary_hash10, &secondary_hash10,
-                       &primary_bkt10, &secondary_bkt10, hash_vals, keys, h);
-       lookup_stage1(idx11, &primary_hash11, &secondary_hash11,
-                       &primary_bkt11, &secondary_bkt11, hash_vals, keys, h);
-       lookup_stage2(idx20, primary_hash20, secondary_hash20, primary_bkt20,
-                       secondary_bkt20, &k_slot20, positions, &extra_hits_mask,
-                       key_store, h);
-       lookup_stage2(idx21, primary_hash21, secondary_hash21, primary_bkt21,
-                       secondary_bkt21, &k_slot21, positions, &extra_hits_mask,
-                       key_store, h);
-
-       while (lookup_mask) {
-               k_slot30 = k_slot20, k_slot31 = k_slot21;
-               idx30 = idx20, idx31 = idx21;
-               primary_bkt20 = primary_bkt10;
-               primary_bkt21 = primary_bkt11;
-               secondary_bkt20 = secondary_bkt10;
-               secondary_bkt21 = secondary_bkt11;
-               primary_hash20 = primary_hash10;
-               primary_hash21 = primary_hash11;
-               secondary_hash20 = secondary_hash10;
-               secondary_hash21 = secondary_hash11;
-               idx20 = idx10, idx21 = idx11;
-               idx10 = idx00, idx11 = idx01;
-
-               lookup_stage0(&idx00, &lookup_mask, keys);
-               lookup_stage0(&idx01, &lookup_mask, keys);
-               lookup_stage1(idx10, &primary_hash10, &secondary_hash10,
-                       &primary_bkt10, &secondary_bkt10, hash_vals, keys, h);
-               lookup_stage1(idx11, &primary_hash11, &secondary_hash11,
-                       &primary_bkt11, &secondary_bkt11, hash_vals, keys, h);
-               lookup_stage2(idx20, primary_hash20, secondary_hash20,
-                       primary_bkt20, secondary_bkt20, &k_slot20, positions,
-                       &extra_hits_mask, key_store, h);
-               lookup_stage2(idx21, primary_hash21, secondary_hash21,
-                       primary_bkt21, secondary_bkt21, &k_slot21, positions,
-                       &extra_hits_mask, key_store, h);
-               lookup_stage3(idx30, k_slot30, keys, positions, data, &hits, h);
-               lookup_stage3(idx31, k_slot31, keys, positions, data, &hits, h);
-       }
+               while (sec_hitmask[i]) {
+                       uint32_t hit_index = __builtin_ctzl(sec_hitmask[i]);
+
+                       uint32_t key_idx = secondary_bkt[i]->key_idx[hit_index];
+                       const struct rte_hash_key *key_slot =
+                               (const struct rte_hash_key *)(
+                               (const char *)h->key_store +
+                               key_idx * h->key_entry_size);
+                       /*
+                        * If key index is 0, do not compare key,
+                        * as it is checking the dummy slot
+                        */
+
+                       if (!!key_idx & !rte_hash_cmp_eq(key_slot->key, keys[i], h)) {
+                               if (data != NULL)
+                                       data[i] = key_slot->pdata;
 
-       k_slot30 = k_slot20, k_slot31 = k_slot21;
-       idx30 = idx20, idx31 = idx21;
-       primary_bkt20 = primary_bkt10;
-       primary_bkt21 = primary_bkt11;
-       secondary_bkt20 = secondary_bkt10;
-       secondary_bkt21 = secondary_bkt11;
-       primary_hash20 = primary_hash10;
-       primary_hash21 = primary_hash11;
-       secondary_hash20 = secondary_hash10;
-       secondary_hash21 = secondary_hash11;
-       idx20 = idx10, idx21 = idx11;
-       idx10 = idx00, idx11 = idx01;
-
-       lookup_stage1(idx10, &primary_hash10, &secondary_hash10,
-               &primary_bkt10, &secondary_bkt10, hash_vals, keys, h);
-       lookup_stage1(idx11, &primary_hash11, &secondary_hash11,
-               &primary_bkt11, &secondary_bkt11, hash_vals, keys, h);
-       lookup_stage2(idx20, primary_hash20, secondary_hash20, primary_bkt20,
-               secondary_bkt20, &k_slot20, positions, &extra_hits_mask,
-               key_store, h);
-       lookup_stage2(idx21, primary_hash21, secondary_hash21, primary_bkt21,
-               secondary_bkt21, &k_slot21, positions, &extra_hits_mask,
-               key_store, h);
-       lookup_stage3(idx30, k_slot30, keys, positions, data, &hits, h);
-       lookup_stage3(idx31, k_slot31, keys, positions, data, &hits, h);
-
-       k_slot30 = k_slot20, k_slot31 = k_slot21;
-       idx30 = idx20, idx31 = idx21;
-       primary_bkt20 = primary_bkt10;
-       primary_bkt21 = primary_bkt11;
-       secondary_bkt20 = secondary_bkt10;
-       secondary_bkt21 = secondary_bkt11;
-       primary_hash20 = primary_hash10;
-       primary_hash21 = primary_hash11;
-       secondary_hash20 = secondary_hash10;
-       secondary_hash21 = secondary_hash11;
-       idx20 = idx10, idx21 = idx11;
-
-       lookup_stage2(idx20, primary_hash20, secondary_hash20, primary_bkt20,
-               secondary_bkt20, &k_slot20, positions, &extra_hits_mask,
-               key_store, h);
-       lookup_stage2(idx21, primary_hash21, secondary_hash21, primary_bkt21,
-               secondary_bkt21, &k_slot21, positions, &extra_hits_mask,
-               key_store, h);
-       lookup_stage3(idx30, k_slot30, keys, positions, data, &hits, h);
-       lookup_stage3(idx31, k_slot31, keys, positions, data, &hits, h);
-
-       k_slot30 = k_slot20, k_slot31 = k_slot21;
-       idx30 = idx20, idx31 = idx21;
-
-       lookup_stage3(idx30, k_slot30, keys, positions, data, &hits, h);
-       lookup_stage3(idx31, k_slot31, keys, positions, data, &hits, h);
-
-       /* ignore any items we have already found */
-       extra_hits_mask &= ~hits;
-
-       if (unlikely(extra_hits_mask)) {
-               /* run a single search for each remaining item */
-               do {
-                       idx = __builtin_ctzl(extra_hits_mask);
-                       if (data != NULL) {
-                               ret = rte_hash_lookup_with_hash_data(h,
-                                               keys[idx], hash_vals[idx], &data[idx]);
-                               if (ret >= 0)
-                                       hits |= 1ULL << idx;
-                       } else {
-                               positions[idx] = rte_hash_lookup_with_hash(h,
-                                                       keys[idx], hash_vals[idx]);
-                               if (positions[idx] >= 0)
-                                       hits |= 1llu << idx;
+                               hits |= 1ULL << i;
+                               positions[i] = key_idx - 1;
+                               goto next_key;
                        }
-                       extra_hits_mask &= ~(1llu << idx);
-               } while (extra_hits_mask);
-       }
+                       sec_hitmask[i] &= ~(1 << (hit_index));
+               }
 
-       miss_mask &= ~hits;
-       if (unlikely(miss_mask)) {
-               do {
-                       idx = __builtin_ctzl(miss_mask);
-                       positions[idx] = -ENOENT;
-                       miss_mask &= ~(1llu << idx);
-               } while (miss_mask);
+next_key:
+               continue;
        }
 
        if (hit_mask != NULL)
index 504661d..c00aafa 100644 (file)
@@ -173,8 +173,7 @@ enum rte_hash_sig_compare_function {
 struct rte_hash_bucket {
        hash_sig_t sig_current[RTE_HASH_BUCKET_ENTRIES];
 
-       /* Includes dummy key index that always contains index 0 */
-       uint32_t key_idx[RTE_HASH_BUCKET_ENTRIES + 1];
+       uint32_t key_idx[RTE_HASH_BUCKET_ENTRIES];
 
        hash_sig_t sig_alt[RTE_HASH_BUCKET_ENTRIES];