Commit 44bf4611 authored by Alex Tran's avatar Alex Tran Committed by Andrii Nakryiko
Browse files

docs: bpf: map_array: Specify BPF_MAP_TYPE_PERCPU_ARRAY value size limit 



Specify value size limit for BPF_MAP_TYPE_PERCPU_ARRAY which
is PCPU_MIN_UNIT_SIZE (32 kb). In percpu allocator (mm: percpu),
any request with a size greater than PCPU_MIN_UNIT_SIZE is rejected.

Signed-off-by: default avatarAlex Tran <alex.t.tran@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20251115063531.2302903-1-alex.t.tran@gmail.com
parent 590699d8

Documentation/bpf/map_array.rst

+3 −2
Original line number Diff line number Diff line
@@ -15,8 +15,9 @@ of constant size. The size of the array is defined in ``max_entries`` at 
creation time. All array elements are pre-allocated and zero initialized when

created. ``BPF_MAP_TYPE_PERCPU_ARRAY`` uses a different memory region for each

CPU whereas ``BPF_MAP_TYPE_ARRAY`` uses the same memory region. The value

stored can be of any size, however, all array elements are aligned to 8

bytes.

stored can be of any size for ``BPF_MAP_TYPE_ARRAY`` and not more than

``PCPU_MIN_UNIT_SIZE`` (32 kB) for ``BPF_MAP_TYPE_PERCPU_ARRAY``. All

array elements are aligned to 8 bytes.



Since kernel 5.5, memory mapping may be enabled for ``BPF_MAP_TYPE_ARRAY`` by

setting the flag ``BPF_F_MMAPABLE``. The map definition is page-aligned and