On Wed, Jul 1, 2020 at 7:17 PM Daniel T. Lee <danieltimlee@xxxxxxxxx> wrote:
>
> Previously, in order to set the numa_node attribute at the time of map
> creation using "libbpf", it was necessary to call bpf_create_map_node()
> directly (bpf_load approach), instead of calling bpf_object_load()
> that handles everything on its own, including map creation. And because
> of this problem, this sample had problems with refactoring from bpf_load
> to libbbpf.
>
> However, by commit 1bdb6c9a1c43 ("libbpf: Add a bunch of attribute
> getters/setters for map definitions"), a helper function which allows
> the numa_node attribute to be set in the map prior to calling
> bpf_object_load() has been added.
>
> By using libbpf instead of bpf_load, the inner map definition has
> been explicitly declared with BTF-defined format. And for this reason
> some logic in fixup_map() was not needed and changed or removed.
>
> Signed-off-by: Daniel T. Lee <danieltimlee@xxxxxxxxx>
> ---
> samples/bpf/Makefile | 2 +-
> samples/bpf/map_perf_test_kern.c | 180 +++++++++++++++----------------
> samples/bpf/map_perf_test_user.c | 130 +++++++++++++++-------
> 3 files changed, 181 insertions(+), 131 deletions(-)
>
[...]
> +struct inner_lru {
> + __uint(type, BPF_MAP_TYPE_LRU_HASH);
> + __type(key, u32);
> + __type(value, long);
> + __uint(max_entries, MAX_ENTRIES);
> + __uint(map_flags, BPF_F_NUMA_NODE); /* from _user.c, set numa_node to 0 */
> +} inner_lru_hash_map SEC(".maps");
you can declaratively set numa_node here with __uint(numa_node, 0),
which is actually a default, but for explicitness it's better
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
> + __uint(max_entries, MAX_NR_CPUS);
> + __uint(key_size, sizeof(u32));
> + __array(values, struct inner_lru); /* use inner_lru as inner map */
> +} array_of_lru_hashs SEC(".maps");
> +
[...]
> -static void fixup_map(struct bpf_map_data *map, int idx)
> +static void fixup_map(struct bpf_object *obj)
> {
> + struct bpf_map *map;
> int i;
>
> - if (!strcmp("inner_lru_hash_map", map->name)) {
> - inner_lru_hash_idx = idx;
> - inner_lru_hash_size = map->def.max_entries;
> - }
> + bpf_object__for_each_map(map, obj) {
> + const char *name = bpf_map__name(map);
>
> - if (!strcmp("array_of_lru_hashs", map->name)) {
I'm a bit too lazy right now to figure out exact logic here, but just
wanted to mention that it is possible to statically set inner map
elements for array_of_maps and hash_of_maps. Please check
tools/testing/selftests/bpf/progs/test_btf_map_in_map.c and see if you
can use this feature to simplify this logic a bit.
> - if (inner_lru_hash_idx == -1) {
> - printf("inner_lru_hash_map must be defined before array_of_lru_hashs\n");
> - exit(1);
> + /* Only change the max_entries for the enabled test(s) */
> + for (i = 0; i < NR_TESTS; i++) {
> + if (!strcmp(test_map_names[i], name) &&
> + (check_test_flags(i))) {
> + bpf_map__resize(map, num_map_entries);
> + continue;
> + }
> }
> - map->def.inner_map_idx = inner_lru_hash_idx;
> - array_of_lru_hashs_idx = idx;
> }
>
[...]
