DPDK  17.05.2
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->key_idx[i] == EMPTY_SLOT)) {
57  prim_bkt->sig_current[i] = sig;
58  prim_bkt->sig_alt[i] = alt_hash;
59  prim_bkt->key_idx[i] = new_idx;
60  break;
61  }
62  }
63  rte_xend();
64 
65  if (i != RTE_HASH_BUCKET_ENTRIES)
66  return 0;
67 
68  break; /* break off try loop if transaction commits */
69  } else {
70  /* If we abort we give up this cuckoo path. */
71  try++;
72  rte_pause();
73  }
74  }
75 
76  return -1;
77 }
78 
79 /* Shift buckets along provided cuckoo_path (@leaf and @leaf_slot) and fill
80  * the path head with new entry (sig, alt_hash, new_idx)
81  */
82 static inline int
83 rte_hash_cuckoo_move_insert_mw_tm(const struct rte_hash *h,
84  struct queue_node *leaf, uint32_t leaf_slot,
85  hash_sig_t sig, hash_sig_t alt_hash, uint32_t new_idx)
86 {
87  unsigned try = 0;
88  unsigned status;
89  uint32_t prev_alt_bkt_idx;
90 
91  struct queue_node *prev_node, *curr_node = leaf;
92  struct rte_hash_bucket *prev_bkt, *curr_bkt = leaf->bkt;
93  uint32_t prev_slot, curr_slot = leaf_slot;
94 
95  while (try < RTE_HASH_TSX_MAX_RETRY) {
96  status = rte_xbegin();
97  if (likely(status == RTE_XBEGIN_STARTED)) {
98  while (likely(curr_node->prev != NULL)) {
99  prev_node = curr_node->prev;
100  prev_bkt = prev_node->bkt;
101  prev_slot = curr_node->prev_slot;
102 
103  prev_alt_bkt_idx
104  = prev_bkt->sig_alt[prev_slot]
105  & h->bucket_bitmask;
106 
107  if (unlikely(&h->buckets[prev_alt_bkt_idx]
108  != curr_bkt)) {
109  rte_xabort(RTE_XABORT_CUCKOO_PATH_INVALIDED);
110  }
111 
112  /* Need to swap current/alt sig to allow later
113  * Cuckoo insert to move elements back to its
114  * primary bucket if available
115  */
116  curr_bkt->sig_alt[curr_slot] =
117  prev_bkt->sig_current[prev_slot];
118  curr_bkt->sig_current[curr_slot] =
119  prev_bkt->sig_alt[prev_slot];
120  curr_bkt->key_idx[curr_slot]
121  = prev_bkt->key_idx[prev_slot];
122 
123  curr_slot = prev_slot;
124  curr_node = prev_node;
125  curr_bkt = curr_node->bkt;
126  }
127 
128  curr_bkt->sig_current[curr_slot] = sig;
129  curr_bkt->sig_alt[curr_slot] = alt_hash;
130  curr_bkt->key_idx[curr_slot] = new_idx;
131 
132  rte_xend();
133 
134  return 0;
135  }
136 
137  /* If we abort we give up this cuckoo path, since most likely it's
138  * no longer valid as TSX detected data conflict
139  */
140  try++;
141  rte_pause();
142  }
143 
144  return -1;
145 }
146 
147 /*
148  * Make space for new key, using bfs Cuckoo Search and Multi-Writer safe
149  * Cuckoo
150  */
151 static inline int
152 rte_hash_cuckoo_make_space_mw_tm(const struct rte_hash *h,
153  struct rte_hash_bucket *bkt,
154  hash_sig_t sig, hash_sig_t alt_hash,
155  uint32_t new_idx)
156 {
157  unsigned i;
158  struct queue_node queue[RTE_HASH_BFS_QUEUE_MAX_LEN];
159  struct queue_node *tail, *head;
160  struct rte_hash_bucket *curr_bkt, *alt_bkt;
161 
162  tail = queue;
163  head = queue + 1;
164  tail->bkt = bkt;
165  tail->prev = NULL;
166  tail->prev_slot = -1;
167 
168  /* Cuckoo bfs Search */
169  while (likely(tail != head && head <
170  queue + RTE_HASH_BFS_QUEUE_MAX_LEN -
171  RTE_HASH_BUCKET_ENTRIES)) {
172  curr_bkt = tail->bkt;
173  for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
174  if (curr_bkt->key_idx[i] == EMPTY_SLOT) {
175  if (likely(rte_hash_cuckoo_move_insert_mw_tm(h,
176  tail, i, sig,
177  alt_hash, new_idx) == 0))
178  return 0;
179  }
180 
181  /* Enqueue new node and keep prev node info */
182  alt_bkt = &(h->buckets[curr_bkt->sig_alt[i]
183  & h->bucket_bitmask]);
184  head->bkt = alt_bkt;
185  head->prev = tail;
186  head->prev_slot = i;
187  head++;
188  }
189  tail++;
190  }
191 
192  return -ENOSPC;
193 }
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