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bpf: hashtab memory usage
htab_map_mem_usage() is introduced to calculate hashmap memory usage. In this helper, some small memory allocations are ignore, as their size is quite small compared with the total size. The inner_map_meta in hash_of_map is also ignored. The result for hashtab as follows, - before this change 1: hash name count_map flags 0x1 <<<< no prealloc, fully set key 16B value 24B max_entries 1048576 memlock 41943040B 2: hash name count_map flags 0x1 <<<< no prealloc, none set key 16B value 24B max_entries 1048576 memlock 41943040B 3: hash name count_map flags 0x0 <<<< prealloc key 16B value 24B max_entries 1048576 memlock 41943040B The memlock is always a fixed size whatever it is preallocated or not, and whatever the count of allocated elements is. - after this change 1: hash name count_map flags 0x1 <<<< non prealloc, fully set key 16B value 24B max_entries 1048576 memlock 117441536B 2: hash name count_map flags 0x1 <<<< non prealloc, non set key 16B value 24B max_entries 1048576 memlock 16778240B 3: hash name count_map flags 0x0 <<<< prealloc key 16B value 24B max_entries 1048576 memlock 109056000B The memlock now is hashtab actually allocated. The result for percpu hash map as follows, - before this change 4: percpu_hash name count_map flags 0x0 <<<< prealloc key 16B value 24B max_entries 1048576 memlock 822083584B 5: percpu_hash name count_map flags 0x1 <<<< no prealloc key 16B value 24B max_entries 1048576 memlock 822083584B - after this change 4: percpu_hash name count_map flags 0x0 key 16B value 24B max_entries 1048576 memlock 897582080B 5: percpu_hash name count_map flags 0x1 key 16B value 24B max_entries 1048576 memlock 922748736B At worst, the difference can be 10x, for example, - before this change 6: hash name count_map flags 0x0 key 4B value 4B max_entries 1048576 memlock 8388608B - after this change 6: hash name count_map flags 0x0 key 4B value 4B max_entries 1048576 memlock 83889408B Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Acked-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20230305124615.12358-4-laoar.shao@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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1 changed files with 43 additions and 0 deletions
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@ -2190,6 +2190,44 @@ static int bpf_for_each_hash_elem(struct bpf_map *map, bpf_callback_t callback_f
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return num_elems;
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}
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static u64 htab_map_mem_usage(const struct bpf_map *map)
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{
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struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
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u32 value_size = round_up(htab->map.value_size, 8);
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bool prealloc = htab_is_prealloc(htab);
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bool percpu = htab_is_percpu(htab);
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bool lru = htab_is_lru(htab);
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u64 num_entries;
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u64 usage = sizeof(struct bpf_htab);
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usage += sizeof(struct bucket) * htab->n_buckets;
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usage += sizeof(int) * num_possible_cpus() * HASHTAB_MAP_LOCK_COUNT;
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if (prealloc) {
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num_entries = map->max_entries;
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if (htab_has_extra_elems(htab))
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num_entries += num_possible_cpus();
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usage += htab->elem_size * num_entries;
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if (percpu)
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usage += value_size * num_possible_cpus() * num_entries;
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else if (!lru)
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usage += sizeof(struct htab_elem *) * num_possible_cpus();
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} else {
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#define LLIST_NODE_SZ sizeof(struct llist_node)
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num_entries = htab->use_percpu_counter ?
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percpu_counter_sum(&htab->pcount) :
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atomic_read(&htab->count);
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usage += (htab->elem_size + LLIST_NODE_SZ) * num_entries;
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if (percpu) {
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usage += (LLIST_NODE_SZ + sizeof(void *)) * num_entries;
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usage += value_size * num_possible_cpus() * num_entries;
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}
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}
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return usage;
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}
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BTF_ID_LIST_SINGLE(htab_map_btf_ids, struct, bpf_htab)
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const struct bpf_map_ops htab_map_ops = {
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.map_meta_equal = bpf_map_meta_equal,
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@ -2206,6 +2244,7 @@ const struct bpf_map_ops htab_map_ops = {
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.map_seq_show_elem = htab_map_seq_show_elem,
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.map_set_for_each_callback_args = map_set_for_each_callback_args,
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.map_for_each_callback = bpf_for_each_hash_elem,
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.map_mem_usage = htab_map_mem_usage,
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BATCH_OPS(htab),
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.map_btf_id = &htab_map_btf_ids[0],
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.iter_seq_info = &iter_seq_info,
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@ -2227,6 +2266,7 @@ const struct bpf_map_ops htab_lru_map_ops = {
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.map_seq_show_elem = htab_map_seq_show_elem,
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.map_set_for_each_callback_args = map_set_for_each_callback_args,
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.map_for_each_callback = bpf_for_each_hash_elem,
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.map_mem_usage = htab_map_mem_usage,
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BATCH_OPS(htab_lru),
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.map_btf_id = &htab_map_btf_ids[0],
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.iter_seq_info = &iter_seq_info,
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@ -2378,6 +2418,7 @@ const struct bpf_map_ops htab_percpu_map_ops = {
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.map_seq_show_elem = htab_percpu_map_seq_show_elem,
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.map_set_for_each_callback_args = map_set_for_each_callback_args,
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.map_for_each_callback = bpf_for_each_hash_elem,
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.map_mem_usage = htab_map_mem_usage,
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BATCH_OPS(htab_percpu),
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.map_btf_id = &htab_map_btf_ids[0],
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.iter_seq_info = &iter_seq_info,
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@ -2397,6 +2438,7 @@ const struct bpf_map_ops htab_lru_percpu_map_ops = {
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.map_seq_show_elem = htab_percpu_map_seq_show_elem,
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.map_set_for_each_callback_args = map_set_for_each_callback_args,
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.map_for_each_callback = bpf_for_each_hash_elem,
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.map_mem_usage = htab_map_mem_usage,
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BATCH_OPS(htab_lru_percpu),
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.map_btf_id = &htab_map_btf_ids[0],
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.iter_seq_info = &iter_seq_info,
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@ -2534,6 +2576,7 @@ const struct bpf_map_ops htab_of_maps_map_ops = {
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.map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
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.map_gen_lookup = htab_of_map_gen_lookup,
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.map_check_btf = map_check_no_btf,
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.map_mem_usage = htab_map_mem_usage,
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BATCH_OPS(htab),
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.map_btf_id = &htab_map_btf_ids[0],
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};
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