linux-kernel - Re: [PATCH 03/31] perf tools: Enable passing bpf object file to --event

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Message-ID: <20151020151558.GG5119@kernel.org>
Date:	Tue, 20 Oct 2015 12:15:58 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Wang Nan <wangnan0@...wei.com>
Cc:	ast@...mgrid.com, brendan.d.gregg@...il.com,
	a.p.zijlstra@...llo.nl, daniel@...earbox.net, dsahern@...il.com,
	hekuang@...wei.com, jolsa@...nel.org, lizefan@...wei.com,
	masami.hiramatsu.pt@...achi.com, namhyung@...nel.org,
	paulus@...ba.org, linux-kernel@...r.kernel.org, pi3orama@....com,
	xiakaixu@...wei.com
Subject: Re: [PATCH 03/31] perf tools: Enable passing bpf object file to
 --event

Em Tue, Oct 20, 2015 at 12:12:55PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Wed, Oct 14, 2015 at 12:41:14PM +0000, Wang Nan escreveu:
> > By introducing new rules in tools/perf/util/parse-events.[ly], this
> > patch enables 'perf record --event bpf_file.o' to select events by an
> > eBPF object file. It calls parse_events_load_bpf() to load that file,
> > which uses bpf__prepare_load() and finally calls bpf_object__open() for
> > the object files.
> > 
> > After applying this patch, commands like:
> > 
> >  # perf record --event foo.o sleep
> > 
> > become possible.
> 
> So, trying the above command I get almost perfect output:
> 
>   [root@...icio ~]# perf record --event foo.o sleep
>   libbpf: failed to open foo.o: No such file or directory
>   event syntax error: 'foo.o'
>                        \___ BPF object file 'foo.o' is invalid
> 
>   (add -v to see detail)
>   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 ~]# 
> 
> 
> Good thing would be to not have any message from libbpf and the right error
> message from the parser, i.e. the first three lines become these two:
> 
> 
>   event syntax error: 'foo.o'
>                        \___ BPF object file 'foo.o' not found.o
> 
> But that can be fixed up in an upcoming patch, so I am applying this one now in
> my new attempt at processing this patchkit.

Ditto for:

  [acme@...icio linux]$ perf record --event /tmp/build/perf/perf.o sleep
  libbpf: /tmp/build/perf/perf.o is not an eBPF object file
  event syntax error: '/tmp/build/perf/perf.o'
                       \___ BPF object file '/tmp/build/perf/perf.o' is invalid
  
  (add -v to see detail)
  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
  [acme@...icio linux]$

Now trying to find a _valid_ ebpf object file to test with.

- Arnaldo
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