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: <20150731203125.GB16700@kernel.org>
Date:	Fri, 31 Jul 2015 17:31:25 -0300
From:	Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:	"Wangnan (F)" <wangnan0@...wei.com>
Cc:	He Kuang <hekuang@...wei.com>, Li Zefan <lizefan@...wei.com>,
	ast@...mgrid.com, pi3orama@....com, xiakaixu@...wei.com,
	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

Em Fri, Jul 31, 2015 at 12:35:22PM -0300, Arnaldo Carvalho de Melo escreveu:
> But point here is, when I see "enable passing
> bpf object file to --event" I apply the patch and expect to be able to
> go straight away and do:
 
>     perf record -e foo.o sleep 1
 
> And get some informative message as to hey, yes, I managed to do what
> you asked or something is wrong, but I get:
 
>   [root@...icio ~]# perf record --event foo.o sleep
>   event syntax error: 'foo.o'
>                        \___ parser error
>   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 ~]#
 
> So, is it enabled or is it not? Doesn't look like. I.e. I think the best
> thing is to only expose this when it can be used. Till that time, we can

I just tried gdb'ing this with a breakpoint on parse_events_load_bpf(),
but when I run:

  (gdb) b parse_events_load_bpf
  Breakpoint 1 at 0x48b11b: file util/parse-events.c, line 488.
  (gdb) run record -e foo.o sleep 1
  Starting program: /root/bin/perf record -e foo.o sleep 1
  [Thread debugging using libthread_db enabled]
  Using host libthread_db library "/lib64/libthread_db.so.1".
  event syntax error: 'foo.o'
                       \___ parser error
  Run 'perf list' for a list of valid events

Somehow it is not calling what the changeset says it would call when passing
"-e foo.o", investigating...

- Arnaldo
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