[PATCH bpf-next v4 04/18] bpf: arraymap memory usage

Yafang Shao
2023-03-05T12:46:32Z

Introduce array_map_mem_usage() to calculate arraymap memory usage. In
this helper, some small memory allocations are ignored, like the
allocation of struct bpf_array_aux in prog_array. The inner_map_meta in
array_of_map is also ignored.

The result as follows,

- before
11: array name count_map flags 0x0
key 4B value 4B max_entries 65536 memlock 524288B
12: percpu_array name count_map flags 0x0
key 4B value 4B max_entries 65536 memlock 8912896B
13: perf_event_array name count_map flags 0x0
key 4B value 4B max_entries 65536 memlock 524288B
14: prog_array name count_map flags 0x0
key 4B value 4B max_entries 65536 memlock 524288B
15: cgroup_array name count_map flags 0x0
key 4B value 4B max_entries 65536 memlock 524288B

- after
11: array name count_map flags 0x0
key 4B value 4B max_entries 65536 memlock 524608B
12: percpu_array name count_map flags 0x0
key 4B value 4B max_entries 65536 memlock 17301824B
13: perf_event_array name count_map flags 0x0
key 4B value 4B max_entries 65536 memlock 524608B
14: prog_array name count_map flags 0x0
key 4B value 4B max_entries 65536 memlock 524608B
15: cgroup_array name count_map flags 0x0
key 4B value 4B max_entries 65536 memlock 524608B

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
kernel/bpf/arraymap.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 4847069..1588c79 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -721,6 +721,28 @@ static int bpf_for_each_array_elem(struct bpf_map *map, bpf_callback_t callback_
return num_elems;
}

+static u64 array_map_mem_usage(const struct bpf_map *map)
+{
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+ bool percpu = map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
+ u32 elem_size = array->elem_size;
+ u64 entries = map->max_entries;
+ u64 usage = sizeof(*array);
+
+ if (percpu) {
+ usage += entries * sizeof(void *);
+ usage += entries * elem_size * num_possible_cpus();
+ } else {
+ if (map->map_flags & BPF_F_MMAPABLE) {
+ usage = PAGE_ALIGN(usage);
+ usage += PAGE_ALIGN(entries * elem_size);
+ } else {
+ usage += entries * elem_size;
+ }
+ }
+ return usage;
+}
+
BTF_ID_LIST_SINGLE(array_map_btf_ids, struct, bpf_array)
const struct bpf_map_ops array_map_ops = {
.map_meta_equal = array_map_meta_equal,
@@ -742,6 +764,7 @@ static int bpf_for_each_array_elem(struct bpf_map *map, bpf_callback_t callback_
.map_update_batch = generic_map_update_batch,
.map_set_for_each_callback_args = map_set_for_each_callback_args,
.map_for_each_callback = bpf_for_each_array_elem,
+ .map_mem_usage = array_map_mem_usage,
.map_btf_id = &array_map_btf_ids[0],
.iter_seq_info = &iter_seq_info,
};
@@ -762,6 +785,7 @@ static int bpf_for_each_array_elem(struct bpf_map *map, bpf_callback_t callback_
.map_update_batch = generic_map_update_batch,
.map_set_for_each_callback_args = map_set_for_each_callback_args,
.map_for_each_callback = bpf_for_each_array_elem,
+ .map_mem_usage = array_map_mem_usage,
.map_btf_id = &array_map_btf_ids[0],
.iter_seq_info = &iter_seq_info,
};
@@ -1156,6 +1180,7 @@ static void prog_array_map_free(struct bpf_map *map)
.map_fd_sys_lookup_elem = prog_fd_array_sys_lookup_elem,
.map_release_uref = prog_array_map_clear,
.map_seq_show_elem = prog_array_map_seq_show_elem,
+ .map_mem_usage = array_map_mem_usage,
.map_btf_id = &array_map_btf_ids[0],
};

@@ -1257,6 +1282,7 @@ static void perf_event_fd_array_map_free(struct bpf_map *map)
.map_fd_put_ptr = perf_event_fd_array_put_ptr,
.map_release = perf_event_fd_array_release,
.map_check_btf = map_check_no_btf,
+ .map_mem_usage = array_map_mem_usage,
.map_btf_id = &array_map_btf_ids[0],
};

@@ -1291,6 +1317,7 @@ static void cgroup_fd_array_free(struct bpf_map *map)
.map_fd_get_ptr = cgroup_fd_array_get_ptr,
.map_fd_put_ptr = cgroup_fd_array_put_ptr,
.map_check_btf = map_check_no_btf,
+ .map_mem_usage = array_map_mem_usage,
.map_btf_id = &array_map_btf_ids[0],
};
#endif
@@ -1379,5 +1406,6 @@ static int array_of_map_gen_lookup(struct bpf_map *map,
.map_lookup_batch = generic_map_lookup_batch,
.map_update_batch = generic_map_update_batch,
.map_check_btf = map_check_no_btf,
+ .map_mem_usage = array_map_mem_usage,
.map_btf_id = &array_map_btf_ids[0],
};
--
1.8.3.1