linux-kernel - Re: perf eBPF patch ordering. was: Re: perf test LLVM was: Re: [GIT PULL 00/39] perf tools: filtering events using eBPF programs

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Message-Id: <DC6736CC-5186-4A36-985A-A3F8BA142AA2@163.com>
Date:	Mon, 3 Aug 2015 23:53:05 +0800
From:	pi3orama <pi3orama@....com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	"Wangnan (F)" <wangnan0@...wei.com>, He Kuang <hekuang@...wei.com>,
	Li Zefan <lizefan@...wei.com>,
	"ast@...mgrid.com" <ast@...mgrid.com>,
	"xiakaixu@...wei.com" <xiakaixu@...wei.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
	David Ahern <dsahern@...il.com>,
	Namhyung Kim <namhyung@...nel.org>
Subject: Re: perf eBPF patch ordering.  was: Re: perf test LLVM was: Re: [GIT PULL 00/39] perf tools: filtering events using eBPF programs



发自我的 iPhone

> 在 2015年8月3日，下午11:19，Arnaldo Carvalho de Melo <acme@...nel.org> 写道：
> 
> Em Mon, Aug 03, 2015 at 12:07:28PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Mon, Aug 03, 2015 at 10:37:59AM +0800, Wangnan (F) escreveu:
>>> On 2015/8/1 4:31, Arnaldo Carvalho de Melo wrote:
>>>> Somehow it is not calling what the changeset says it would call when passing
>>>> "-e foo.o", investigating...
>> 
>>> Have you tried
>> 
>>> /root/bin/perf record -e ./foo.o sleep 1
>> 
>>> The key is './'.
>> 
>> Nope, trying it now I get:
>> 
>>  [root@...icio ~]# perf record -e ./foo.o sleep 1
>>  libbpf: failed to open ./foo.o: No such file or directory
>>  bpf: failed to load ./foo.o
> 
> And with a .c suffix:
> 
>  [root@...icio ~]# perf record -e ./foo.c sleep 1
>  clang-3.8: error: no such file or directory: '/root/./foo.c'
>  clang-3.8: error: no input files

What's the content of your foo.c? Could you please have a look?

I considered moving .o enabler down so when you see that patch the filter will be
 workable. However , like the llvm support, doing so will enable a bulk of code by
one patch, that's not good. Moving .c enabler down is easy.

Now I'm working on a BPF testcase. Tomorrow you will see a new test:

# perf test BPF

It enforces test__llvm, and forks a 'perf record' to do the filtering, then checks the
result using perf report -D. The patch of the new test is a mark which indicates the
basic function of BPF filter is done. What do you think about this idea?

Thank you.

>  ERROR:    unable to compile ./foo.c
>  Hint:    Check error message shown above.
>         LLVM 3.7 or newer is required. Which can be found from http://llvm.org
>         You may want to try git trunk:
>             git clone http://llvm.org/git/llvm.git
>                  and
>             git clone http://llvm.org/git/clang.git
> 
>         Or fetch the latest clang/llvm 3.7 from pre-built llvm packages for
>         debian/ubuntu:
>             http://llvm.org/apt
> 
>         If you are using old version of clang, change 'clang-bpf-cmd-template'
>         option in [llvm] section of ~/.perfconfig to:
> 
>           "$CLANG_EXEC $CLANG_OPTIONS $KERNEL_INC_OPTIONS \
>              -working-directory $WORKING_DIR -c $CLANG_SOURCE \
>              -emit-llvm -o - | /path/to/llc -march=bpf -filetype=obj -o -"
>         (Replace /path/to/llc with path to your llc)
> 
>  Hint:    You can also pre-compile it into .o
>  invalid or unsupported event: './foo.c'
>  Run 'perf list' for a list of valid events
> 
>   usage: perf record [<options>] [<command>]
>      or: perf record [<options>] -- <command> [<options>]
> 
>      -e, --event <event>   event selector. use 'perf list' to list available events
>  [root@...icio ~]#
> 
> Now to find a hello.c BPF scriptlet...
> 
> - Arnaldo

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