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: <20150803150728.GA3864@kernel.org>
Date:	Mon, 3 Aug 2015 12:07:28 -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 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
  invalid or unsupported event: './foo.o'
  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 ~]#

Way too much verbosity, I think this should be just:

  [root@...icio ~]# perf record -e ./foo.o sleep 1
  perf: Failed to open ./foo.o: No such file or directory

I.e. Avoid messages coming directly from a library, as you don't know
what kind of UI tools using such library will use, it maybe GTK, for
instance, and then sending stuff to stderr or stdout is inappropriate.
 
> I have reproduced the problem. Haven't noticed that because I always use './' name.

Right, right now this is required, it should not be.
 
> Will look into it.

Thanks, I will try checkint the other patches, taking this current
limitation into account, so that I can comment on them.

- Arnaldo
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