/* * Copyright (c) 2015 Cisco and/or its affiliates. * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /** @cond DOCUMENTATION_IS_IN_BIHASH_DOC_H */ static inline void *BV (alloc_aligned) (BVT (clib_bihash) * h, uword nbytes) { uword rv; /* Round to an even number of cache lines */ nbytes += CLIB_CACHE_LINE_BYTES - 1; nbytes &= ~(CLIB_CACHE_LINE_BYTES - 1); rv = h->alloc_arena_next; h->alloc_arena_next += nbytes; if (rv >= (h->alloc_arena + h->alloc_arena_size)) os_out_of_memory (); return (void *) rv; } void BV (clib_bihash_init) (BVT (clib_bihash) * h, char *name, u32 nbuckets, uword memory_size) { uword bucket_size; nbuckets = 1 << (max_log2 (nbuckets)); h->name = (u8 *) name; h->nbuckets = nbuckets; h->log2_nbuckets = max_log2 (nbuckets); h->cache_hits = 0; h->cache_misses = 0; /* * Make sure the requested size is rational. The max table * size without playing the alignment card is 64 Gbytes. * If someone starts complaining that's not enough, we can shift * the offset by CLIB_LOG2_CACHE_LINE_BYTES... */ ASSERT (memory_size < (1ULL << BIHASH_BUCKET_OFFSET_BITS)); h->alloc_arena = (uword) clib_mem_vm_alloc (memory_size); h->alloc_arena_next = h->alloc_arena; h->alloc_arena_size = memory_size; bucket_size = nbuckets * sizeof (h->buckets[0]); h->buckets = BV (alloc_aligned) (h, bucket_size); h->alloc_lock = BV (alloc_aligned) (h, CLIB_CACHE_LINE_BYTES); h->alloc_lock[0] = 0; h->fmt_fn = NULL; } void BV (clib_bihash_set_kvp_format_fn) (BVT (clib_bihash) * h, format_function_t * fmt_fn) { h->fmt_fn = fmt_fn; } void BV (clib_bihash_free) (BVT (clib_bihash) * h) { vec_free (h->working_copies); vec_free (h->freelists); clib_mem_vm_free ((void *) (h->alloc_arena), h->alloc_arena_size); memset (h, 0, sizeof (*h)); } static BVT (clib_bihash_value) * BV (value_alloc) (BVT (clib_bihash) * h, u32 log2_pages) { BVT (clib_bihash_value) * rv = 0; ASSERT (h->alloc_lock[0]); if (log2_pages >= vec_len (h->freelists) || h->freelists[log2_pages] == 0) { vec_validate_init_empty (h->freelists, log2_pages, 0); rv = BV (alloc_aligned) (h, (sizeof (*rv) * (1 << log2_pages))); goto initialize; } rv = h->freelists[log2_pages]; h->freelists[log2_pages] = rv->next_free; initialize: ASSERT (rv); /* * Latest gcc complains that the length arg is zero * if we replace (1<<log2_pages) with vec_len(rv). * No clue. */ memset (rv, 0xff, sizeof (*rv) * (1 << log2_pages)); return rv; } static void BV (value_free) (BVT (clib_bihash) * h, BVT (clib_bihash_value) * v, u32 log2_pages) { ASSERT (h->alloc_lock[0]); ASSERT (vec_len (h->freelists) > log2_pages); if (CLIB_DEBUG > 0) memset (v, 0xFE, sizeof (*v) * (1 << log2_pages)); v->next_free = h->freelists[log2_pages]; h->freelists[log2_pages] = v; } static inline void BV (make_working_copy) (BVT (clib_bihash) * h, BVT (clib_bihash_bucket) * b) { BVT (clib_bihash_value) * v; BVT (clib_bihash_bucket) working_bucket __attribute__ ((aligned (8))); BVT (clib_bihash_value) * working_copy; u32 thread_index = os_get_thread_index (); int log2_working_copy_length; ASSERT (h->alloc_lock[0]); if (thread_index >= vec_len (h->working_copies)) { vec_validate (h->working_copies, thread_index); vec_validate_init_empty (h->working_copy_lengths, thread_index, ~0); } /* * working_copies are per-cpu so that near-simultaneous * updates from multiple threads will not result in sporadic, spurious * lookup failures. */ working_copy = h->working_copies[thread_index]; log2_working_copy_length = h->working_copy_lengths[thread_index]; h->saved_bucket.as_u64 = b->as_u64; if (b->log2_pages > log2_working_copy_length) { /* * It's not worth the bookkeeping to free working copies * if (working_copy) * clib_mem_free (working_copy); */ working_copy = BV (alloc_aligned) (h, sizeof (working_copy[0]) * (1 << b->log2_pages)); h->working_copy_lengths[thread_index] = b->log2_pages; h->working_copies[thread_index] = working_copy; } v = BV (clib_bihash_get_value) (h, b->offset); clib_memcpy (working_copy, v, sizeof (*v) * (1 << b->log2_pages)); working_bucket.as_u64 = b->as_u64; working_bucket.offset = BV (clib_bihash_get_offset) (h, working_copy); CLIB_MEMORY_BARRIER (); b->as_u64 = working_bucket.as_u64; h->working_copies[thread_index] = working_copy; } static BVT (clib_bihash_value) * BV (split_and_rehash) (BVT (clib_bihash) * h, BVT (clib_bihash_value) * old_values, u32 old_log2_pages, u32 new_log2_pages) { BVT (clib_bihash_value) * new_values, *new_v; int i, j, length_in_kvs; ASSERT (h->alloc_lock[0]); new_values = BV (value_alloc) (h, new_log2_pages); length_in_kvs = (1 << old_log2_pages) * BIHASH_KVP_PER_PAGE; for (i = 0; i < length_in_kvs; i++) { u64 new_hash; /* Entry not in use? Forget it */ if (BV (clib_bihash_is_free) (&(old_values->kvp[i]))) continue; /* rehash the item onto its new home-page */ new_hash = BV (clib_bihash_hash) (&(old_values->kvp[i])); new_hash >>= h->log2_nbuckets; new_hash &= (1 << new_log2_pages) - 1; new_v = &new_values[new_hash]; /* Across the new home-page */ for (j = 0; j < BIHASH_KVP_PER_PAGE; j++) { /* Empty slot */ if (BV (clib_bihash_is_free) (&(new_v->kvp[j]))) { clib_memcpy (&(new_v->kvp[j]), &(old_values->kvp[i]), sizeof (new_v->kvp[j])); goto doublebreak; } } /* Crap. Tell caller to try again */ BV (value_free) (h, new_values, new_log2_pages); return 0; doublebreak:; } return new_values; } static BVT (clib_bihash_value) * BV (split_and_rehash_linear) (BVT (clib_bihash) * h, BVT (clib_bihash_value) * old_values, u32 old_log2_pages, u32 new_log2_pages) { BVT (clib_bihash_value) * new_values; int i, j, new_length, old_length; ASSERT (h->alloc_lock[0]); new_values = BV (value_alloc) (h, new_log2_pages); new_length = (1 << new_log2_pages) * BIHASH_KVP_PER_PAGE; old_length = (1 << old_log2_pages) * BIHASH_KVP_PER_PAGE; j = 0; /* Across the old value array */ for (i = 0; i < old_length; i++) { /* Find a free slot in the new linear scan bucket */ for (; j < new_length; j++) { /* Old value not in use? Forget it. */ if (BV (clib_bihash_is_free) (&(old_values->kvp[i]))) goto doublebreak; /* New value should never be in use */ if (BV (clib_bihash_is_free) (&(new_values->kvp[j]))) { /* Copy the old value and move along */ clib_memcpy (&(new_values->kvp[j]), &(old_values->kvp[i]), sizeof (new_values->kvp[j])); j++; goto doublebreak; } } /* This should never happen... */ clib_warning ("BUG: linear rehash failed!"); BV (value_free) (h, new_values, new_log2_pages); return 0; doublebreak:; } return new_values; } int BV (clib_bihash_add_del) (BVT (clib_bihash) * h, BVT (clib_bihash_kv) * add_v, int is_add) { u32 bucket_index; BVT (clib_bihash_bucket) * b, tmp_b; BVT (clib_bihash_value) * v, *new_v, *save_new_v, *working_copy; int i, limit; u64 hash, new_hash; u32 new_log2_pages, old_log2_pages; u32 thread_index = os_get_thread_index (); int mark_bucket_linear; int resplit_once; hash = BV (clib_bihash_hash) (add_v); bucket_index = hash & (h->nbuckets - 1); b = &h->buckets[bucket_index]; hash >>= h->log2_nbuckets; BV (clib_bihash_lock_bucket) (b); /* First elt in the bucket? */ if (BV (clib_bihash_bucket_is_empty) (b)) { if (is_add == 0) { BV (clib_bihash_unlock_bucket) (b); return (-1); } BV (clib_bihash_alloc_lock) (h); v = BV (value_alloc) (h, 0); BV (clib_bihash_alloc_unlock) (h); *v->kvp = *add_v; tmp_b.as_u64 = 0; /* clears bucket lock */ tmp_b.offset = BV (clib_bihash_get_offset) (h, v); tmp_b.refcnt = 1; CLIB_MEMORY_BARRIER (); b->as_u64 = tmp_b.as_u64; BV (clib_bihash_unlock_bucket) (b); return (0); } /* WARNING: we're still looking at the live copy... */ limit = BIHASH_KVP_PER_PAGE; v = BV (clib_bihash_get_value) (h, b->offset); v += (b->linear_search == 0) ? hash & ((1 << b->log2_pages) - 1) : 0; if (b->linear_search) limit <<= b->log2_pages; if (is_add) { /* * Because reader threads are looking at live data, * we have to be extra careful. Readers do NOT hold the * bucket lock. We need to be SLOWER than a search, past the * point where readers CHECK the bucket lock. */ /* * For obvious (in hindsight) reasons, see if we're supposed to * replace an existing key, then look for an empty slot. */ for (i = 0; i < limit; i++) { if (!memcmp (&(v->kvp[i]), &add_v->key, sizeof (add_v->key))) { CLIB_MEMORY_BARRIER (); /* Add a delay */ clib_memcpy (&(v->kvp[i]), add_v, sizeof (*add_v)); BV (clib_bihash_unlock_bucket) (b); return (0); } } /* * Look for an empty slot. If found, use it */ for (i = 0; i < limit; i++) { if (BV (clib_bihash_is_free) (&(v->kvp[i]))) { /* * Copy the value first, so that if a reader manages * to match the new key, the value will be right... */ clib_memcpy (&(v->kvp[i].value), &add_v->value, sizeof (add_v->value)); CLIB_MEMORY_BARRIER (); /* Make sure the value has settled */ clib_memcpy (&(v->kvp[i]), &add_v->key, sizeof (add_v->key)); b->refcnt++; BV (clib_bihash_unlock_bucket) (b); return (0); } } /* Out of space in this bucket, split the bucket... */ } else /* delete case */ { for (i = 0; i < limit; i++) { /* Found the key? Kill it... */ if (!memcmp (&(v->kvp[i]), &add_v->key, sizeof (add_v->key))) { memset (&(v->kvp[i]), 0xff, sizeof (*(add_v))); /* Is the bucket empty? */ if (PREDICT_TRUE (b->refcnt > 1)) { b->refcnt--; BV (clib_bihash_unlock_bucket) (b); return (0); } else /* yes, free it */ { /* Save old bucket value, need log2_pages to free it */ tmp_b.as_u64 = b->as_u64; CLIB_MEMORY_BARRIER (); /* Kill and unlock the bucket */ b->as_u64 = 0; /* And free the backing storage */ BV (clib_bihash_alloc_lock) (h); /* Note: v currently points into the middle of the bucket */ v = BV (clib_bihash_get_value) (h, tmp_b.offset); BV (value_free) (h, v, tmp_b.log2_pages); BV (clib_bihash_alloc_unlock) (h); return (0); } } } /* Not found... */ BV (clib_bihash_unlock_bucket) (b); return (-3); } /* Move readers to a (locked) temp copy of the bucket */ BV (clib_bihash_alloc_lock) (h); BV (make_working_copy) (h, b); v = BV (clib_bihash_get_value) (h, h->saved_bucket.offset); old_log2_pages = h->saved_bucket.log2_pages; new_log2_pages = old_log2_pages + 1; mark_bucket_linear = 0; working_copy = h->working_copies[thread_index]; resplit_once = 0; new_v = BV (split_and_rehash) (h, working_copy, old_log2_pages, new_log2_pages); if (new_v == 0) { try_resplit: resplit_once = 1; new_log2_pages++; /* Try re-splitting. If that fails, fall back to linear search */ new_v = BV (split_and_rehash) (h, working_copy, old_log2_pages, new_log2_pages); if (new_v == 0) { mark_linear: new_log2_pages--; /* pinned collisions, use linear search */ new_v = BV (split_and_rehash_linear) (h, working_copy, old_log2_pages, new_log2_pages); mark_bucket_linear = 1; } } /* Try to add the new entry */ save_new_v = new_v; new_hash = BV (clib_bihash_hash) (add_v); limit = BIHASH_KVP_PER_PAGE; if (mark_bucket_linear) limit <<= new_log2_pages; new_hash >>= h->log2_nbuckets; new_hash &= (1 << new_log2_pages) - 1; new_v += mark_bucket_linear ? 0 : new_hash; for (i = 0; i < limit; i++) { if (BV (clib_bihash_is_free) (&(new_v->kvp[i]))) { clib_memcpy (&(new_v->kvp[i]), add_v, sizeof (*add_v)); goto expand_ok; } } /* Crap. Try again */ BV (value_free) (h, save_new_v, new_log2_pages); /* * If we've already doubled the size of the bucket once, * fall back to linear search now. */ if (resplit_once) goto mark_linear; else goto try_resplit; expand_ok: tmp_b.log2_pages = new_log2_pages; tmp_b.offset = BV (clib_bihash_get_offset) (h, save_new_v); tmp_b.linear_search = mark_bucket_linear; tmp_b.refcnt = h->saved_bucket.refcnt + 1; tmp_b.lock = 0; CLIB_MEMORY_BARRIER (); b->as_u64 = tmp_b.as_u64; BV (clib_bihash_alloc_unlock) (h); return (0); } int BV (clib_bihash_search) (BVT (clib_bihash) * h, BVT (clib_bihash_kv) * search_key, BVT (clib_bihash_kv) * valuep) { u64 hash; u32 bucket_index; BVT (clib_bihash_value) * v; BVT (clib_bihash_bucket) * b; int i, limit; ASSERT (valuep); hash = BV (clib_bihash_hash) (search_key); bucket_index = hash & (h->nbuckets - 1); b = &h->buckets[bucket_index]; if (BV (clib_bihash_bucket_is_empty) (b)) return -1; if (PREDICT_FALSE (b->lock)) { volatile BVT (clib_bihash_bucket) * bv = b; while (bv->lock) CLIB_PAUSE (); } hash >>= h->log2_nbuckets; v = BV (clib_bihash_get_value) (h, b->offset); limit = BIHASH_KVP_PER_PAGE; v += (b->linear_search == 0) ? hash & ((1 << b->log2_pages) - 1) : 0; if (PREDICT_FALSE (b->linear_search)) limit <<= b->log2_pages; for (i = 0; i < limit; i++) { if (BV (clib_bihash_key_compare) (v->kvp[i].key, search_key->key)) { *valuep = v->kvp[i]; return 0; } } return -1; } u8 *BV (format_bihash) (u8 * s, va_list * args) { BVT (clib_bihash) * h = va_arg (*args, BVT (clib_bihash) *); int verbose = va_arg (*args, int); BVT (clib_bihash_bucket) * b; BVT (clib_bihash_value) * v; int i, j, k; u64 active_elements = 0; u64 active_buckets = 0; u64 linear_buckets = 0; u64 used_bytes; s = format (s, "Hash table %s\n", h->name ? h->name : (u8 *) "(unnamed)"); for (i = 0; i < h->nbuckets; i++) { b = &h->buckets[i]; if (BV (clib_bihash_bucket_is_empty) (b)) { if (verbose > 1) s = format (s, "[%d]: empty\n", i); continue; } active_buckets++; if (b->linear_search) linear_buckets++; if (verbose) { s = format (s, "[%d]: heap offset %d, len %d, linear %d\n", i, b->offset, (1 << b->log2_pages), b->linear_search); } v = BV (clib_bihash_get_value) (h, b->offset); for (j = 0; j < (1 << b->log2_pages); j++) { for (k = 0; k < BIHASH_KVP_PER_PAGE; k++) { if (BV (clib_bihash_is_free) (&v->kvp[k])) { if (verbose > 1) s = format (s, " %d: empty\n", j * BIHASH_KVP_PER_PAGE + k); continue; } if (verbose) { if (h->fmt_fn) { s = format (s, " %d: %U\n", j * BIHASH_KVP_PER_PAGE + k, h->fmt_fn, &(v->kvp[k])); } else { s = format (s, " %d: %U\n", j * BIHASH_KVP_PER_PAGE + k, BV (format_bihash_kvp), &(v->kvp[k])); } } active_elements++; } v++; } } s = format (s, " %lld active elements %lld active buckets\n", active_elements, active_buckets); s = format (s, " %d free lists\n", vec_len (h->freelists)); for (i = 0; i < vec_len (h->freelists); i++) { u32 nfree = 0; BVT (clib_bihash_value) * free_elt; free_elt = h->freelists[i]; while (free_elt) { nfree++; free_elt = free_elt->next_free; } s = format (s, " [len %d] %u free elts\n", 1 << i, nfree); } s = format (s, " %lld linear search buckets\n", linear_buckets); s = format (s, " %lld cache hits, %lld cache misses\n", h->cache_hits, h->cache_misses); used_bytes = h->alloc_arena_next - h->alloc_arena; s = format (s, " arena: base %llx, next %llx\n" " used %lld b (%lld Mbytes) of %lld b (%lld Mbytes)\n", h->alloc_arena, h->alloc_arena_next, used_bytes, used_bytes >> 20, h->alloc_arena_size, h->alloc_arena_size >> 20); return s; } void BV (clib_bihash_foreach_key_value_pair) (BVT (clib_bihash) * h, void *callback, void *arg) { int i, j, k; BVT (clib_bihash_bucket) * b; BVT (clib_bihash_value) * v; void (*fp) (BVT (clib_bihash_kv) *, void *) = callback; for (i = 0; i < h->nbuckets; i++) { b = &h->buckets[i]; if (BV (clib_bihash_bucket_is_empty) (b)) continue; v = BV (clib_bihash_get_value) (h, b->offset); for (j = 0; j < (1 << b->log2_pages); j++) { for (k = 0; k < BIHASH_KVP_PER_PAGE; k++) { if (BV (clib_bihash_is_free) (&v->kvp[k])) continue; (*fp) (&v->kvp[k], arg); } v++; } } } /** @endcond */ /* * fd.io coding-style-patch-verification: ON * * Local Variables: * eval: (c-set-style "gnu") * End: */