Re: [RFC 0/2] Introduce perf-stat -b for BPF programs

From: Arnaldo Carvalho de Melo
Date: Thu Nov 19 2020 - 09:52:53 EST


Em Wed, Nov 18, 2020 at 08:50:44PM -0800, Song Liu escreveu:
> This set introduces perf-stat -b option to count events for BPF programs.
> This is similar to bpftool-prog-profile. But perf-stat makes it much more
> flexible.
>
> Sending as RFC because I would like comments on some key design choices:
> 1. We are using BPF skeletons here, which is by far the easiest way to
> write and ship BPF programs. However, this requires bpftool, which
> makes building perf slower.
> 2. A Makefile is added to tools/perf/util/bpf_skel/ to build bpftool,
> and BPF skeletons. This keeps main perf Makefiles simple. But we may
> not like it for some reason?

I'll review it in detail, but before that: thanks a lot for working on
this! Looks super cool from a first quick look. :-)

- Arnaldo

> Some known limitations (or work to be done):
> 1. Only counting events for one BPF program at a time.
> 2. Need extra logic in target__validate().


> Song Liu (2):
> perf: support build BPF skeletons with perf
> perf-stat: enable counting events for BPF programs
>
> tools/build/Makefile.feature | 3 +-
> tools/perf/Makefile.config | 8 +
> tools/perf/Makefile.perf | 15 +-
> tools/perf/builtin-stat.c | 59 ++++-
> tools/perf/util/Build | 1 +
> tools/perf/util/bpf_counter.c | 215 ++++++++++++++++++
> tools/perf/util/bpf_counter.h | 71 ++++++
> tools/perf/util/bpf_skel/.gitignore | 3 +
> tools/perf/util/bpf_skel/Makefile | 71 ++++++
> .../util/bpf_skel/bpf_prog_profiler.bpf.c | 96 ++++++++
> tools/perf/util/bpf_skel/dummy.bpf.c | 19 ++
> tools/perf/util/evsel.c | 10 +
> tools/perf/util/evsel.h | 5 +
> tools/perf/util/target.h | 6 +
> 14 files changed, 571 insertions(+), 11 deletions(-)
> create mode 100644 tools/perf/util/bpf_counter.c
> create mode 100644 tools/perf/util/bpf_counter.h
> create mode 100644 tools/perf/util/bpf_skel/.gitignore
> create mode 100644 tools/perf/util/bpf_skel/Makefile
> create mode 100644 tools/perf/util/bpf_skel/bpf_prog_profiler.bpf.c
> create mode 100644 tools/perf/util/bpf_skel/dummy.bpf.c
>
> --
> 2.24.1

--

- Arnaldo