[PATCH bpf-next v4 09/18] bpf: cpumap memory usage

Yafang Shao
2023-03-05T12:46:39Z

A new helper is introduced to calculate cpumap memory usage. The size of
cpu_entries can be dynamically changed when we update or delete a cpumap
element, but this patch doesn't include the memory size of cpu_entry
yet. We can dynamically calculate the memory usage when we alloc or free
a cpu_entry, but it will take extra runtime overhead, so let just put it
aside currently. Note that the size of different cpu_entry may be
different as well.

The result as follows,
- before
48: cpumap name count_map flags 0x4
key 4B value 4B max_entries 64 memlock 4096B

- after
48: cpumap name count_map flags 0x4
key 4B value 4B max_entries 64 memlock 832B

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
kernel/bpf/cpumap.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index d2110c1..871809e 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -673,6 +673,15 @@ static int cpu_map_redirect(struct bpf_map *map, u64 index, u64 flags)
__cpu_map_lookup_elem);
}

+static u64 cpu_map_mem_usage(const struct bpf_map *map)
+{
+ u64 usage = sizeof(struct bpf_cpu_map);
+
+ /* Currently the dynamically allocated elements are not counted */
+ usage += (u64)map->max_entries * sizeof(struct bpf_cpu_map_entry *);
+ return usage;
+}
+
BTF_ID_LIST_SINGLE(cpu_map_btf_ids, struct, bpf_cpu_map)
const struct bpf_map_ops cpu_map_ops = {
.map_meta_equal = bpf_map_meta_equal,
@@ -683,6 +692,7 @@ static int cpu_map_redirect(struct bpf_map *map, u64 index, u64 flags)
.map_lookup_elem = cpu_map_lookup_elem,
.map_get_next_key = cpu_map_get_next_key,
.map_check_btf = map_check_no_btf,
+ .map_mem_usage = cpu_map_mem_usage,
.map_btf_id = &cpu_map_btf_ids[0],
.map_redirect = cpu_map_redirect,
};
--
1.8.3.1