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

From: Wangnan (F)
Date: Sun Sep 25 2016 - 21:53:36 EST

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:

This patch set links LLVM and Clang libraries to perf, so perf
is able to compile BPF script to BPF object on the fly.
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.