On Mon, Feb 27, 2023 at 7:21 AM Yafang Shao <laoar.shao@xxxxxxxxx> wrote:
>
> A new helper ringbuf_map_mem_usage() is introduced to calculate ringbuf
> memory usage.
>
> The result as follows,
> - before
> 15: ringbuf name count_map flags 0x0
> key 0B value 0B max_entries 65536 memlock 0B
>
> - after
> 15: ringbuf name count_map flags 0x0
> key 0B value 0B max_entries 65536 memlock 78424B
>
> Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
> ---
> kernel/bpf/ringbuf.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
> index 80f4b4d..2bbf6e2 100644
> --- a/kernel/bpf/ringbuf.c
> +++ b/kernel/bpf/ringbuf.c
> @@ -336,6 +336,23 @@ static __poll_t ringbuf_map_poll_user(struct bpf_map *map, struct file *filp,
> return 0;
> }
>
> +static u64 ringbuf_map_mem_usage(const struct bpf_map *map)
> +{
> + struct bpf_ringbuf_map *rb_map;
> + struct bpf_ringbuf *rb;
> + int nr_data_pages;
> + int nr_meta_pages;
> + u64 usage = sizeof(struct bpf_ringbuf_map);
> +
> + rb_map = container_of(map, struct bpf_ringbuf_map, map);
> + rb = rb_map->rb;
nit: rb_map seems unnecessary, I'd just go straight to rb
rb = container_of(map, struct bpf_ringbuf_map, map)->rb;
> + usage += (u64)rb->nr_pages << PAGE_SHIFT;
> + nr_meta_pages = RINGBUF_PGOFF + RINGBUF_POS_PAGES;
it would be cleaner to extract this into a constant
RINGBUF_NR_META_PAGES and use it in ringbuf_map_mem_usage and
bpf_ringbuf_area_alloc to keep them in sync
But other than that, looks good:
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> + nr_data_pages = map->max_entries >> PAGE_SHIFT;
> + usage += (nr_meta_pages + 2 * nr_data_pages) * sizeof(struct page *);
> + return usage;
> +}
> +
> BTF_ID_LIST_SINGLE(ringbuf_map_btf_ids, struct, bpf_ringbuf_map)
> const struct bpf_map_ops ringbuf_map_ops = {
> .map_meta_equal = bpf_map_meta_equal,
> @@ -347,6 +364,7 @@ static __poll_t ringbuf_map_poll_user(struct bpf_map *map, struct file *filp,
> .map_update_elem = ringbuf_map_update_elem,
> .map_delete_elem = ringbuf_map_delete_elem,
> .map_get_next_key = ringbuf_map_get_next_key,
> + .map_mem_usage = ringbuf_map_mem_usage,
> .map_btf_id = &ringbuf_map_btf_ids[0],
> };
>
> @@ -361,6 +379,7 @@ static __poll_t ringbuf_map_poll_user(struct bpf_map *map, struct file *filp,
> .map_update_elem = ringbuf_map_update_elem,
> .map_delete_elem = ringbuf_map_delete_elem,
> .map_get_next_key = ringbuf_map_get_next_key,
> + .map_mem_usage = ringbuf_map_mem_usage,
> .map_btf_id = &user_ringbuf_map_btf_ids[0],
> };
>
> --
> 1.8.3.1
>
