On Thu, Jun 30, 2022 at 01:04:09PM +0100, Dave Tucker wrote: > This commit adds documentation for the BPF_MAP_TYPE_ARRAY including > kernel version introduced, usage and examples. > It also documents BPF_MAP_TYPE_PERCPU_ARRAY since this is similar. > Use imperative mood instead of descriptive one for patch description. > Signed-off-by: Dave Tucker <dave@xxxxxxxxxxxxx> > --- > Documentation/bpf/map_array.rst | 183 ++++++++++++++++++++++++++++++++ > 1 file changed, 183 insertions(+) > create mode 100644 Documentation/bpf/map_array.rst > > diff --git a/Documentation/bpf/map_array.rst b/Documentation/bpf/map_array.rst > new file mode 100644 > index 000000000000..eadc714591d2 > --- /dev/null > +++ b/Documentation/bpf/map_array.rst > @@ -0,0 +1,183 @@ > +.. SPDX-License-Identifier: GPL-2.0-only > +.. Copyright (C) 2021 Red Hat, Inc. > + > +================================================ > +BPF_MAP_TYPE_ARRAY and BPF_MAP_TYPE_PERCPU_ARRAY > +================================================ > + > +.. note:: ``BPF_MAP_TYPE_ARRAY`` was introduced in Kernel version 3.19 and > + ``BPF_MAP_TYPE_PERCPU_ARRAY`` in version 4.6 > + nit: s/Kernel/kernel/ > +Since Kernel 5.4, memory mapping may be enabled for ``BPF_MAP_TYPE_ARRAY`` by > +setting the flag ``BPF_F_MMAPABLE``. The map definition is page-aligned and > +starts on the first page. Sufficient page-sized and page-aligned blocks of > +memory are allocated to store all array values, starting on the second page, > +which in some cases will result in over-allocation of memory. The benefit of > +using this is increased performance and ease of use since userspace programs > +would not be required to use helper functions to access and mutate data. > + same nit above > +Examples > +======== > + > +Please see the `tools/testing/selftests/bpf`_ directory for functional examples. > +This sample code simply demonstrates the API. Shouldn't the examples in this doc be put somewhere else in the tree? Or where do they come from? > + > +.. section links > +.. _tools/testing/selftests/bpf: > + https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf I think the link isn't needed, since kernel developers will simply look at their own tree instead. Thanks. -- An old man doll... just what I always wanted! - Clara
