DPDK  16.07.2
rte_cuckoo_hash_x86.h
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33 
34 /* rte_cuckoo_hash_x86.h
35  * This file holds all x86 specific Cuckoo Hash functions
36  */
37 
38 /* Only tries to insert at one bucket (@prim_bkt) without trying to push
39  * buckets around
40  */
41 static inline unsigned
42 rte_hash_cuckoo_insert_mw_tm(struct rte_hash_bucket *prim_bkt,
43  hash_sig_t sig, hash_sig_t alt_hash, uint32_t new_idx)
44 {
45  unsigned i, status;
46  unsigned try = 0;
47 
48  while (try < RTE_HASH_TSX_MAX_RETRY) {
49  status = rte_xbegin();
50  if (likely(status == RTE_XBEGIN_STARTED)) {
51  /* Insert new entry if there is room in the primary
52  * bucket.
53  */
54  for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
55  /* Check if slot is available */
56  if (likely(prim_bkt->signatures[i].sig ==
57  NULL_SIGNATURE)) {
58  prim_bkt->signatures[i].current = sig;
59  prim_bkt->signatures[i].alt = alt_hash;
60  prim_bkt->key_idx[i] = new_idx;
61  break;
62  }
63  }
64  rte_xend();
65 
66  if (i != RTE_HASH_BUCKET_ENTRIES)
67  return 0;
68 
69  break; /* break off try loop if transaction commits */
70  } else {
71  /* If we abort we give up this cuckoo path. */
72  try++;
73  rte_pause();
74  }
75  }
76 
77  return -1;
78 }
79 
80 /* Shift buckets along provided cuckoo_path (@leaf and @leaf_slot) and fill
81  * the path head with new entry (sig, alt_hash, new_idx)
82  */
83 static inline int
84 rte_hash_cuckoo_move_insert_mw_tm(const struct rte_hash *h,
85  struct queue_node *leaf, uint32_t leaf_slot,
86  hash_sig_t sig, hash_sig_t alt_hash, uint32_t new_idx)
87 {
88  unsigned try = 0;
89  unsigned status;
90  uint32_t prev_alt_bkt_idx;
91 
92  struct queue_node *prev_node, *curr_node = leaf;
93  struct rte_hash_bucket *prev_bkt, *curr_bkt = leaf->bkt;
94  uint32_t prev_slot, curr_slot = leaf_slot;
95 
96  while (try < RTE_HASH_TSX_MAX_RETRY) {
97  status = rte_xbegin();
98  if (likely(status == RTE_XBEGIN_STARTED)) {
99  while (likely(curr_node->prev != NULL)) {
100  prev_node = curr_node->prev;
101  prev_bkt = prev_node->bkt;
102  prev_slot = curr_node->prev_slot;
103 
104  prev_alt_bkt_idx
105  = prev_bkt->signatures[prev_slot].alt
106  & h->bucket_bitmask;
107 
108  if (unlikely(&h->buckets[prev_alt_bkt_idx]
109  != curr_bkt)) {
110  rte_xabort(RTE_XABORT_CUCKOO_PATH_INVALIDED);
111  }
112 
113  /* Need to swap current/alt sig to allow later
114  * Cuckoo insert to move elements back to its
115  * primary bucket if available
116  */
117  curr_bkt->signatures[curr_slot].alt =
118  prev_bkt->signatures[prev_slot].current;
119  curr_bkt->signatures[curr_slot].current =
120  prev_bkt->signatures[prev_slot].alt;
121  curr_bkt->key_idx[curr_slot]
122  = prev_bkt->key_idx[prev_slot];
123 
124  curr_slot = prev_slot;
125  curr_node = prev_node;
126  curr_bkt = curr_node->bkt;
127  }
128 
129  curr_bkt->signatures[curr_slot].current = sig;
130  curr_bkt->signatures[curr_slot].alt = alt_hash;
131  curr_bkt->key_idx[curr_slot] = new_idx;
132 
133  rte_xend();
134 
135  return 0;
136  }
137 
138  /* If we abort we give up this cuckoo path, since most likely it's
139  * no longer valid as TSX detected data conflict
140  */
141  try++;
142  rte_pause();
143  }
144 
145  return -1;
146 }
147 
148 /*
149  * Make space for new key, using bfs Cuckoo Search and Multi-Writer safe
150  * Cuckoo
151  */
152 static inline int
153 rte_hash_cuckoo_make_space_mw_tm(const struct rte_hash *h,
154  struct rte_hash_bucket *bkt,
155  hash_sig_t sig, hash_sig_t alt_hash,
156  uint32_t new_idx)
157 {
158  unsigned i;
159  struct queue_node queue[RTE_HASH_BFS_QUEUE_MAX_LEN];
160  struct queue_node *tail, *head;
161  struct rte_hash_bucket *curr_bkt, *alt_bkt;
162 
163  tail = queue;
164  head = queue + 1;
165  tail->bkt = bkt;
166  tail->prev = NULL;
167  tail->prev_slot = -1;
168 
169  /* Cuckoo bfs Search */
170  while (likely(tail != head && head <
171  queue + RTE_HASH_BFS_QUEUE_MAX_LEN -
172  RTE_HASH_BUCKET_ENTRIES)) {
173  curr_bkt = tail->bkt;
174  for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
175  if (curr_bkt->signatures[i].sig == NULL_SIGNATURE) {
176  if (likely(rte_hash_cuckoo_move_insert_mw_tm(h,
177  tail, i, sig,
178  alt_hash, new_idx) == 0))
179  return 0;
180  }
181 
182  /* Enqueue new node and keep prev node info */
183  alt_bkt = &(h->buckets[curr_bkt->signatures[i].alt
184  & h->bucket_bitmask]);
185  head->bkt = alt_bkt;
186  head->prev = tail;
187  head->prev_slot = i;
188  head++;
189  }
190  tail++;
191  }
192 
193  return -ENOSPC;
194 }
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