linux-kernel - [PATCHv2 bpf-next 0/4] bpf: Speed up symbol resolving in kprobe multi link

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Message-Id: <20220418124834.829064-1-jolsa@kernel.org>
Date:   Mon, 18 Apr 2022 14:48:30 +0200
From:   Jiri Olsa <jolsa@...nel.org>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        lkml <linux-kernel@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>
Subject: [PATCHv2 bpf-next 0/4] bpf: Speed up symbol resolving in kprobe multi link

hi,
sending additional fix for symbol resolving in kprobe multi link
requested by Alexei and Andrii [1].

This speeds up bpftrace kprobe attachment, when using pure symbols
(3344 symbols) to attach:

Before:

  # perf stat -r 5 -e cycles ./src/bpftrace -e 'kprobe:x* {  } i:ms:1 { exit(); }'
  ...
  6.5681 +- 0.0225 seconds time elapsed  ( +-  0.34% )

After:

  # perf stat -r 5 -e cycles ./src/bpftrace -e 'kprobe:x* {  } i:ms:1 { exit(); }'
  ...
  0.5661 +- 0.0275 seconds time elapsed  ( +-  4.85% )


v2 changes (first version [2]):
  - removed the 2 seconds check [Alexei]
  - moving/forcing symbols sorting out of kallsyms_lookup_names function [Alexei]
  - skipping one array allocation and copy_from_user [Andrii]
  - several small fixes [Masami,Andrii]
  - build fix [kernel test robot]

thanks,
jirka


[1] https://lore.kernel.org/bpf/CAEf4BzZtQaiUxQ-sm_hH2qKPRaqGHyOfEsW96DxtBHRaKLoL3Q@mail.gmail.com/
[2] https://lore.kernel.org/bpf/20220407125224.310255-1-jolsa@kernel.org/
---
Jiri Olsa (4):
      kallsyms: Add kallsyms_lookup_names function
      fprobe: Resolve symbols with kallsyms_lookup_names
      bpf: Resolve symbols with kallsyms_lookup_names for kprobe multi link
      selftests/bpf: Add attach bench test

 include/linux/kallsyms.h                                   |   6 ++++++
 kernel/kallsyms.c                                          |  70 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 kernel/trace/bpf_trace.c                                   | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------------------------------------------
 kernel/trace/fprobe.c                                      |  32 ++++++++++++--------------------
 tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/kprobe_multi_empty.c     |  12 ++++++++++++
 6 files changed, 302 insertions(+), 67 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/kprobe_multi_empty.c