Documentation/bpf/map_array.rst

1 .. SPDX-License-Identifier: GPL-2.0-only
9    - ``BPF_MAP_TYPE_ARRAY`` was introduced in kernel version 3.19
10    - ``BPF_MAP_TYPE_PERCPU_ARRAY`` was introduced in version 4.6
13 storage. The key type is an unsigned 32-bit integer (4 bytes) and the map is
15 creation time. All array elements are pre-allocated and zero initialized when
22 setting the flag ``BPF_F_MMAPABLE``. The map definition is page-aligned and
23 starts on the first page. Sufficient page-sized and page-aligned blocks of
25 which in some cases will result in over-allocation of memory. The benefit of
26 using this is increased performance and ease of use since userspace programs
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45 ``__sync_fetch_and_add()`` when updating the value in-place.
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64 -------------
66 Values stored in ``BPF_MAP_TYPE_ARRAY`` can be accessed by multiple programs
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134                     __sync_fetch_and_add(value, skb->len);
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