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bpf: devmap memory usage

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A new helper is introduced to calculate the memory usage of devmap and
devmap_hash. The number of dynamically allocated elements are recored
for devmap_hash already, but not for devmap. To track the memory size of
dynamically allocated elements, this patch also count the numbers for
devmap.

The result as follows,
- before
40: devmap  name count_map  flags 0x80
        key 4B  value 4B  max_entries 65536  memlock 524288B
41: devmap_hash  name count_map  flags 0x80
        key 4B  value 4B  max_entries 65536  memlock 524288B

- after
40: devmap  name count_map  flags 0x80  <<<< no elements
        key 4B  value 4B  max_entries 65536  memlock 524608B
41: devmap_hash  name count_map  flags 0x80 <<<< no elements
        key 4B  value 4B  max_entries 65536  memlock 524608B

Note that the number of buckets is same with max_entries for devmap_hash
in this case.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230305124615.12358-11-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yafang Shao
2023-03-05 12:46:07 +00:00
committed by Alexei Starovoitov
parent 835f1fca95
commit fa5e83df17
1 changed files with 24 additions and 2 deletions
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26
kernel/bpf/devmap.c
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@@ -819,8 +819,10 @@ static int dev_map_delete_elem(struct bpf_map *map, void *key)
return -EINVAL;
old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
if (old_dev)
if (old_dev) {
call_rcu(&old_dev->rcu, __dev_map_entry_free);
atomic_dec((atomic_t *)&dtab->items);
}
return 0;
}
@@ -931,6 +933,8 @@ static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
if (old_dev)
call_rcu(&old_dev->rcu, __dev_map_entry_free);
else
atomic_inc((atomic_t *)&dtab->items);
return 0;
}
@@ -1016,6 +1020,20 @@ static int dev_hash_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
__dev_map_hash_lookup_elem);
}
static u64 dev_map_mem_usage(const struct bpf_map *map)
{
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
u64 usage = sizeof(struct bpf_dtab);
if (map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)
usage += (u64)dtab->n_buckets * sizeof(struct hlist_head);
else
usage += (u64)map->max_entries * sizeof(struct bpf_dtab_netdev *);
usage += atomic_read((atomic_t *)&dtab->items) *
(u64)sizeof(struct bpf_dtab_netdev);
return usage;
}
BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)
const struct bpf_map_ops dev_map_ops = {
.map_meta_equal = bpf_map_meta_equal,
@@ -1026,6 +1044,7 @@ const struct bpf_map_ops dev_map_ops = {
.map_update_elem = dev_map_update_elem,
.map_delete_elem = dev_map_delete_elem,
.map_check_btf = map_check_no_btf,
.map_mem_usage = dev_map_mem_usage,
.map_btf_id = &dev_map_btf_ids[0],
.map_redirect = dev_map_redirect,
};
@@ -1039,6 +1058,7 @@ const struct bpf_map_ops dev_map_hash_ops = {
.map_update_elem = dev_map_hash_update_elem,
.map_delete_elem = dev_map_hash_delete_elem,
.map_check_btf = map_check_no_btf,
.map_mem_usage = dev_map_mem_usage,
.map_btf_id = &dev_map_btf_ids[0],
.map_redirect = dev_hash_map_redirect,
};
@@ -1109,9 +1129,11 @@ static int dev_map_notification(struct notifier_block *notifier,
if (!dev || netdev != dev->dev)
continue;
odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));
if (dev == odev)
if (dev == odev) {
call_rcu(&dev->rcu,
__dev_map_entry_free);
atomic_dec((atomic_t *)&dtab->items);
}
}
}
rcu_read_unlock();