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bpf: introduce per-cpu cgroup local storage

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This commit introduced per-cpu cgroup local storage.

Per-cpu cgroup local storage is very similar to simple cgroup storage
(let's call it shared), except all the data is per-cpu.

The main goal of per-cpu variant is to implement super fast
counters (e.g. packet counters), which don't require neither
lookups, neither atomic operations.

>From userspace's point of view, accessing a per-cpu cgroup storage
is similar to other per-cpu map types (e.g. per-cpu hashmaps and
arrays).

Writing to a per-cpu cgroup storage is not atomic, but is performed
by copying longs, so some minimal atomicity is here, exactly
as with other per-cpu maps.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Roman Gushchin 2018-09-28 14:45:43 +00:00 • committed by Daniel Borkmann
parent f294b37ec7
commit b741f16303
8 changed files with 179 additions and 28 deletions
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8
kernel/bpf/helpers.c
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@ -206,10 +206,16 @@ BPF_CALL_2(bpf_get_local_storage, struct bpf_map *, map, u64, flags)
*/
enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
struct bpf_cgroup_storage *storage;
void *ptr;
storage = this_cpu_read(bpf_cgroup_storage[stype]);
return (unsigned long)&READ_ONCE(storage->buf)->data[0];
if (stype == BPF_CGROUP_STORAGE_SHARED)
ptr = &READ_ONCE(storage->buf)->data[0];
else
ptr = this_cpu_ptr(storage->percpu_buf);
return (unsigned long)ptr;
}
const struct bpf_func_proto bpf_get_local_storage_proto = {