| 1 | /* |
| 2 | * rculfhash-mm-mmap.c |
| 3 | * |
| 4 | * mmap/reservation based memory management for Lock-Free RCU Hash Table |
| 5 | * |
| 6 | * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com> |
| 7 | * |
| 8 | * This library is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU Lesser General Public |
| 10 | * License as published by the Free Software Foundation; either |
| 11 | * version 2.1 of the License, or (at your option) any later version. |
| 12 | * |
| 13 | * This library is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * Lesser General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Lesser General Public |
| 19 | * License along with this library; if not, write to the Free Software |
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 21 | */ |
| 22 | |
| 23 | #include <unistd.h> |
| 24 | #include <sys/mman.h> |
| 25 | #include "rculfhash-internal.h" |
| 26 | |
| 27 | /* reserve inaccessible memory space without allocation any memory */ |
| 28 | static void *memory_map(size_t length) |
| 29 | { |
| 30 | void *ret = mmap(NULL, length, PROT_NONE, |
| 31 | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
| 32 | |
| 33 | assert(ret != MAP_FAILED); |
| 34 | return ret; |
| 35 | } |
| 36 | |
| 37 | static void memory_unmap(void *ptr, size_t length) |
| 38 | { |
| 39 | int ret __attribute__((unused)); |
| 40 | |
| 41 | ret = munmap(ptr, length); |
| 42 | |
| 43 | assert(ret == 0); |
| 44 | } |
| 45 | |
| 46 | static void memory_populate(void *ptr, size_t length) |
| 47 | { |
| 48 | void *ret __attribute__((unused)); |
| 49 | |
| 50 | ret = mmap(ptr, length, PROT_READ | PROT_WRITE, |
| 51 | MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
| 52 | |
| 53 | assert(ret == ptr); |
| 54 | } |
| 55 | |
| 56 | /* |
| 57 | * Discard garbage memory and avoid system save it when try to swap it out. |
| 58 | * Make it still reserved, inaccessible. |
| 59 | */ |
| 60 | static void memory_discard(void *ptr, size_t length) |
| 61 | { |
| 62 | void *ret __attribute__((unused)); |
| 63 | |
| 64 | ret = mmap(ptr, length, PROT_NONE, |
| 65 | MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
| 66 | |
| 67 | assert(ret == ptr); |
| 68 | } |
| 69 | |
| 70 | static |
| 71 | void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order) |
| 72 | { |
| 73 | if (order == 0) { |
| 74 | if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) { |
| 75 | /* small table */ |
| 76 | ht->tbl_mmap = calloc(ht->max_nr_buckets, |
| 77 | sizeof(*ht->tbl_mmap)); |
| 78 | assert(ht->tbl_mmap); |
| 79 | return; |
| 80 | } |
| 81 | /* large table */ |
| 82 | ht->tbl_mmap = memory_map(ht->max_nr_buckets |
| 83 | * sizeof(*ht->tbl_mmap)); |
| 84 | memory_populate(ht->tbl_mmap, |
| 85 | ht->min_nr_alloc_buckets * sizeof(*ht->tbl_mmap)); |
| 86 | } else if (order > ht->min_alloc_buckets_order) { |
| 87 | /* large table */ |
| 88 | unsigned long len = 1UL << (order - 1); |
| 89 | |
| 90 | assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets); |
| 91 | memory_populate(ht->tbl_mmap + len, |
| 92 | len * sizeof(*ht->tbl_mmap)); |
| 93 | } |
| 94 | /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */ |
| 95 | } |
| 96 | |
| 97 | /* |
| 98 | * cds_lfht_free_bucket_table() should be called with decreasing order. |
| 99 | * When cds_lfht_free_bucket_table(0) is called, it means the whole |
| 100 | * lfht is destroyed. |
| 101 | */ |
| 102 | static |
| 103 | void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order) |
| 104 | { |
| 105 | if (order == 0) { |
| 106 | if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) { |
| 107 | /* small table */ |
| 108 | poison_free(ht->tbl_mmap); |
| 109 | return; |
| 110 | } |
| 111 | /* large table */ |
| 112 | memory_unmap(ht->tbl_mmap, |
| 113 | ht->max_nr_buckets * sizeof(*ht->tbl_mmap)); |
| 114 | } else if (order > ht->min_alloc_buckets_order) { |
| 115 | /* large table */ |
| 116 | unsigned long len = 1UL << (order - 1); |
| 117 | |
| 118 | assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets); |
| 119 | memory_discard(ht->tbl_mmap + len, len * sizeof(*ht->tbl_mmap)); |
| 120 | } |
| 121 | /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */ |
| 122 | } |
| 123 | |
| 124 | static |
| 125 | struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index) |
| 126 | { |
| 127 | return &ht->tbl_mmap[index]; |
| 128 | } |
| 129 | |
| 130 | static |
| 131 | struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets, |
| 132 | unsigned long max_nr_buckets) |
| 133 | { |
| 134 | unsigned long page_bucket_size; |
| 135 | |
| 136 | page_bucket_size = getpagesize() / sizeof(struct cds_lfht_node); |
| 137 | if (max_nr_buckets <= page_bucket_size) { |
| 138 | /* small table */ |
| 139 | min_nr_alloc_buckets = max_nr_buckets; |
| 140 | } else { |
| 141 | /* large table */ |
| 142 | min_nr_alloc_buckets = max(min_nr_alloc_buckets, |
| 143 | page_bucket_size); |
| 144 | } |
| 145 | |
| 146 | return __default_alloc_cds_lfht( |
| 147 | &cds_lfht_mm_mmap, sizeof(struct cds_lfht), |
| 148 | min_nr_alloc_buckets, max_nr_buckets); |
| 149 | } |
| 150 | |
| 151 | const struct cds_lfht_mm_type cds_lfht_mm_mmap = { |
| 152 | .alloc_cds_lfht = alloc_cds_lfht, |
| 153 | .alloc_bucket_table = cds_lfht_alloc_bucket_table, |
| 154 | .free_bucket_table = cds_lfht_free_bucket_table, |
| 155 | .bucket_at = bucket_at, |
| 156 | }; |