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Date: Mon, 3 Aug 2015 12:19:05 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: "Wangnan (F)" <wangnan0@huawei.com>
Cc: He Kuang <hekuang@huawei.com>, Li Zefan <lizefan@huawei.com>,
        ast@plumgrid.com, pi3orama@163.com, xiakaixu@huawei.com,
        linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>, David Ahern <dsahern@gmail.com>,
        Namhyung Kim <namhyung@kernel.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
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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@felicio ~]# 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@felicio ~]# 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
  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@felicio ~]#

Now to find a hello.c BPF scriptlet...

- Arnaldo