Date: Tue, 14 Oct 2014 15:56:31 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: Jean Pihet <jean.pihet@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>, Arnaldo Carvalho de Melo <acme@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Fu Wei <fu.wei@linaro.org>, Robert Richter <rric@kernel.org>,
        David Ahern <dsahern@gmail.com>, Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH 1/1] rasd: Use perf_evlist__open() instead of open coded
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On Mon, Oct 13, 2014 at 09:29:57AM +0200, Jean Pihet wrote:
> Hi Arnaldo, Borislav,
> 
> On 10 October 2014 22:44, Borislav Petkov <bp@alien8.de> wrote:
> > On Fri, Oct 10, 2014 at 05:41:58PM -0300, Arnaldo Carvalho de Melo wrote:
> >> Right, stoopid me, no need for some specific tracepoint, just to see
> >> that whatever tp it is, it will show up in "rasd"'s event loop. Ok, I'll
> >> try that later.
> >>
> >> Next stuff I probably will do is to move the bare minimum used by rasd
> >> to tools/lib/api/perf/, i.e. there will be:
> >>
> >> tools/lib/api/perf/evsel.c
> >> tools/perf/util/evsel.c
> >>
> >> Both will share the perf_evsel__ namespace (which I thought at some
> >> point to make just: evsel__<METHOD_NAME>, wdyt?).
> Makes perfectly sense
> 
> >>
> >> That way we just make public the bare minimum that already proved to be
> >> useful outside tools/perf/ and over time we move stuff from
> >> tools/perf/util/evsel.c (and from other tools in or out perf's repo)
> >> into the lib.
> That is great!
> 
> About rasd usage, there are some details at
> https://wiki.linaro.org/LEG/Engineering/Kernel/perfAndRAS#rasd_implementation.

heya,
sorry for late reply.. I was on vacation last week..

I read the rasd sources and realized we could poke this
from another angle..  AFAIU the work the rasd does is following:
   - reads config file and opens configured tracepoints
   - reads samples comming from those tracepoints and displays/writes
     this data to the console/file
   - is there more?

If I'm not missing anything, this is quite usefull/common usage
pattern which would deserve new perf command.

I can see the analogy with ftrace debugfs interface
  - choose/enable tracepoints
  - cat .../tracing/trace-pipe

and there could be '-d' for the command to act as daemon.

thoughts? ;-)

jirka
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