netdev - Re: [PATCH v5 bpf-next 0/5] bpf: Introduce minimal support for sleepable progs

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Message-ID: <CAEf4BzYG2drMiUvjgAF5vgdjAo5+N3zL+5TTvCoUUK=Z3ErVwA@mail.gmail.com>
Date:   Mon, 29 Jun 2020 22:14:18 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Daniel Borkmann <daniel@...earbox.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH v5 bpf-next 0/5] bpf: Introduce minimal support for
 sleepable progs

On Mon, Jun 29, 2020 at 9:34 PM Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
>
> From: Alexei Starovoitov <ast@...nel.org>
>
> v4->v5:
> - addressed Andrii's feedback.
>
> v3->v4:
> - fixed synchronize_rcu_tasks_trace() usage and accelerated with synchronize_rcu_mult().
> - removed redundant synchronize_rcu(). Otherwise it won't be clear why
>   synchronize_rcu_tasks_trace() is not needed in free_map callbacks.
> - improved test coverage.
>
> v2->v3:
> - switched to rcu_trace
> - added bpf_copy_from_user
>
> Here is 'perf report' differences:
> sleepable with SRCU:
>    3.86%  bench     [k] __srcu_read_unlock
>    3.22%  bench     [k] __srcu_read_lock
>    0.92%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep
>    0.50%  bench     [k] bpf_trampoline_10297
>    0.26%  bench     [k] __bpf_prog_exit_sleepable
>    0.21%  bench     [k] __bpf_prog_enter_sleepable
>
> sleepable with RCU_TRACE:
>    0.79%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep
>    0.72%  bench     [k] bpf_trampoline_10381
>    0.31%  bench     [k] __bpf_prog_exit_sleepable
>    0.29%  bench     [k] __bpf_prog_enter_sleepable
>
> non-sleepable with RCU:
>    0.88%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry
>    0.84%  bench     [k] bpf_trampoline_10297
>    0.13%  bench     [k] __bpf_prog_enter
>    0.12%  bench     [k] __bpf_prog_exit
>
> Happy to confirm that rcu_trace overhead is negligible.
>
> v1->v2:
> - split fmod_ret fix into separate patch
> - added blacklist
>
> v1:
> This patch set introduces the minimal viable support for sleepable bpf programs.
> In this patch only fentry/fexit/fmod_ret and lsm progs can be sleepable.
> Only array and pre-allocated hash and lru maps allowed.
>
> Alexei Starovoitov (5):
>   bpf: Remove redundant synchronize_rcu.
>   bpf: Introduce sleepable BPF programs
>   bpf: Add bpf_copy_from_user() helper.
>   libbpf: support sleepable progs
>   selftests/bpf: Add sleepable tests
>
>  arch/x86/net/bpf_jit_comp.c                   | 32 +++++----
>  include/linux/bpf.h                           |  4 ++
>  include/uapi/linux/bpf.h                      | 19 +++++-
>  init/Kconfig                                  |  1 +
>  kernel/bpf/arraymap.c                         | 10 +--
>  kernel/bpf/hashtab.c                          | 20 +++---
>  kernel/bpf/helpers.c                          | 22 +++++++
>  kernel/bpf/lpm_trie.c                         |  5 --
>  kernel/bpf/queue_stack_maps.c                 |  7 --
>  kernel/bpf/reuseport_array.c                  |  2 -
>  kernel/bpf/ringbuf.c                          |  7 --
>  kernel/bpf/stackmap.c                         |  3 -
>  kernel/bpf/syscall.c                          | 13 +++-
>  kernel/bpf/trampoline.c                       | 28 +++++++-
>  kernel/bpf/verifier.c                         | 62 ++++++++++++++++-
>  kernel/trace/bpf_trace.c                      |  2 +
>  tools/include/uapi/linux/bpf.h                | 19 +++++-
>  tools/lib/bpf/libbpf.c                        | 25 ++++++-
>  tools/testing/selftests/bpf/bench.c           |  2 +
>  .../selftests/bpf/benchs/bench_trigger.c      | 17 +++++
>  .../selftests/bpf/prog_tests/test_lsm.c       |  9 +++
>  tools/testing/selftests/bpf/progs/lsm.c       | 66 ++++++++++++++++++-
>  .../selftests/bpf/progs/trigger_bench.c       |  7 ++
>  23 files changed, 315 insertions(+), 67 deletions(-)
>
> --
> 2.23.0
>

For the series:

Acked-by: Andrii Nakryiko <andriin@...com>