Re: [PATCH 00/14] perf clang: Support compiling BPF script use builtin clang

[Wangnan (F)]

On 2016/9/24 23:16, Alexei Starovoitov wrote:
> On Fri, Sep 23, 2016 at 12:49:47PM +0000, Wang Nan wrote:
> > This patch set is the first step to implement features I announced
> > in LinuxCon NA 2016. See page 31 of:
> >
> >   http://events.linuxfoundation.org/sites/events/files/slides/Performance%20Monitoring%20and%20Analysis%20Using%20perf%20and%20BPF_1.pdf
> >
> > This patch set links LLVM and Clang libraries to perf, so perf
> > is able to compile BPF script to BPF object on the fly.
> Nice!
> So single perf binary won't have llvm external dependency anymore
> or both ways will be maintained?
> The command line stays the same?

Yes. This patch set doesn't change interface. It compiles BPF script
with builtin clang, and if it fail, fall back to external clang.

> If I understand the patches correctly, this set is establishing
> the basic functionality and more complex features coming?

Yes. Following steps are:

 1. Ease of use improvement: automatically include BPF functions
    declaration and macros.

 2. Perf's hook: compile part of BPF script into native code, run
    them in perf when something happen. Create a channel, coordinate
    BPF and native code use bpf-output event.

 3. Define a new language to support common profiling task. I'm not
    very clear what the new language should be. It may looks like lua,
    perf converts it to C then to LLVM IR with builtin clang.

Thank you.