[PATCH bpf-next v4 07/18] bpf: ringbuf memory usage

Yafang Shao
2023-03-05T12:46:36Z

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@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
---
kernel/bpf/ringbuf.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index 80f4b4d..57b8896 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -19,6 +19,7 @@
(offsetof(struct bpf_ringbuf, consumer_pos) >> PAGE_SHIFT)
/* consumer page and producer page */
#define RINGBUF_POS_PAGES 2
+#define RINGBUF_NR_META_PAGES (RINGBUF_PGOFF + RINGBUF_POS_PAGES)

#define RINGBUF_MAX_RECORD_SZ (UINT_MAX/4)

@@ -96,7 +97,7 @@ static struct bpf_ringbuf *bpf_ringbuf_area_alloc(size_t data_sz, int numa_node)
{
const gfp_t flags = GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL |
__GFP_NOWARN | __GFP_ZERO;
- int nr_meta_pages = RINGBUF_PGOFF + RINGBUF_POS_PAGES;
+ int nr_meta_pages = RINGBUF_NR_META_PAGES;
int nr_data_pages = data_sz >> PAGE_SHIFT;
int nr_pages = nr_meta_pages + nr_data_pages;
struct page **pages, *page;
@@ -336,6 +337,21 @@ 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 *rb;
+ int nr_data_pages;
+ int nr_meta_pages;
+ u64 usage = sizeof(struct bpf_ringbuf_map);
+
+ rb = container_of(map, struct bpf_ringbuf_map, map)->rb;
+ usage += (u64)rb->nr_pages << PAGE_SHIFT;
+ nr_meta_pages = RINGBUF_NR_META_PAGES;
+ 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 +363,7 @@ 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 +378,7 @@ 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