docs/bpf: Add table to describe LRU properties

Depending on the map type and flags for LRU, different properties are
global or percpu. Add a table to describe these.

Signed-off-by: Joe Stringer <joe@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20230422172054.3355436-1-joe@isovalent.com

diff --git a/Documentation/bpf/map_hash.rst b/Documentation/bpf/map_hash.rst
index 8669426..1314dfc 100644 (file)
--- a/Documentation/bpf/map_hash.rst
+++ b/Documentation/bpf/map_hash.rst
@@ -29,7 +29,16 @@ will automatically evict the least recently used entries when the hash
 table reaches capacity. An LRU hash maintains an internal LRU list that
 is used to select elements for eviction. This internal LRU list is
 shared across CPUs but it is possible to request a per CPU LRU list with
-the ``BPF_F_NO_COMMON_LRU`` flag when calling ``bpf_map_create``.
+the ``BPF_F_NO_COMMON_LRU`` flag when calling ``bpf_map_create``.  The
+following table outlines the properties of LRU maps depending on the a
+map type and the flags used to create the map.
+
+======================== ========================= ================================
+Flag                     ``BPF_MAP_TYPE_LRU_HASH`` ``BPF_MAP_TYPE_LRU_PERCPU_HASH``
+======================== ========================= ================================
+**BPF_F_NO_COMMON_LRU**  Per-CPU LRU, global map   Per-CPU LRU, per-cpu map
+**!BPF_F_NO_COMMON_LRU** Global LRU, global map    Global LRU, per-cpu map
+======================== ========================= ================================
 
 Usage
 =====