Re: [PATCH 1/1] rasd: Use perf_evlist__open() instead of open coded

Jiri Olsa
2014-10-14T13:56:58Z

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