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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Thu, 28 May 2020 11:34:25 -0700
Message-ID: <CAEf4BzYHFAbOeVbs8Y2j5HjYOavDC+M+HtOst69Qtm2h5A3M=A@mail.gmail.com>
Subject: Re: [RFC PATCH] samples:bpf: introduce task detector
To:     =?UTF-8?B?546L6LSH?= <yun.wang@linux.alibaba.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@chromium.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:BPF (Safe dynamic programs and tools)" 
        <netdev@vger.kernel.org>,
        "open list:BPF (Safe dynamic programs and tools)" 
        <bpf@vger.kernel.org>
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On Thu, May 28, 2020 at 1:14 AM =E7=8E=8B=E8=B4=87 <yun.wang@linux.alibaba.=
com> wrote:
>
> Hi, Andrii
>
> Thanks for your comments :-)
>
> On 2020/5/28 =E4=B8=8B=E5=8D=882:36, Andrii Nakryiko wrote:
> [snip]
> >> ---
> >
> > I haven't looked through implementation thoroughly yet. But I have few
> > general remarks.
> >
> > This looks like a useful and generic tool. I think it will get most
> > attention and be most useful if it will be part of BCC tools. There is
> > already a set of generic tools that use libbpf and CO-RE, see [0]. It
> > feels like this belongs there.
> >
> > Some of the annoying parts (e.g., syscall name translation) is already
> > generalized as part of syscount tool PR (to be hopefully merged soon),
> > so you'll be able to save quite a lot of code with this. There is also
> > a common build infra that takes care of things like vmlinux.h, which
> > would provide definitions for all those xxx_args structs that you had
> > to manually define.
> >
> > With CO-RE, it also will allow to compile this tool once and run it on
> > many different kernels without recompilation. Please do take a look
> > and submit a PR there, it will be a good addition to the toolkit (and
> > will force you write a bit of README explaining use of this tool as
> > well ;).
>
> Aha, I used to think bcc only support python and cpp :-P
>

libbpf-tools don't use BCC at all, they are just co-located with BCC
and BCC tools in the same repository and are lightweight alternatives
to BCC-based tools. But it needs kernel with BTF built-in, which is
the only (temporary) downside.

> I'll try to rework it and submit PR, I'm glad to know that you think
> this tool as a helpful one, we do solved some tough issue with it
> already.
>
> >
> > As for the code itself, I haven't gone through it much, but please
> > convert map definition syntax to BTF-defined one. The one you are
> > using is a legacy one. Thanks!
> >
> >   [0] https://github.com/iovisor/bcc/tree/master/libbpf-tools
>
> Will check the example there :-)
>
> Regards,
> Michael Wang
>
> >
> >>  samples/bpf/Makefile             |   3 +
> >>  samples/bpf/task_detector.h      | 382 ++++++++++++++++++++++++++++++=
+++++++++
> >>  samples/bpf/task_detector_kern.c | 329 ++++++++++++++++++++++++++++++=
+++
> >>  samples/bpf/task_detector_user.c | 314 ++++++++++++++++++++++++++++++=
++
> >>  4 files changed, 1028 insertions(+)
> >>  create mode 100644 samples/bpf/task_detector.h
> >>  create mode 100644 samples/bpf/task_detector_kern.c
> >>  create mode 100644 samples/bpf/task_detector_user.c
> >>
> >
> > [...]
> >