Re: [PATCH 2/3] perf ftrace: Add ftrace.tracer config option

[Taeung Song]

Hi, Arnaldo :)

On 01/27/2017 03:58 AM, Arnaldo Carvalho de Melo wrote:
> Em Thu, Jan 26, 2017 at 06:35:38PM +0900, Taeung Song escreveu:
> > Currently perf ftrace command will select 'function_graph' or 'function'.
> > So add ftrace.tracer config option to select tracer
> >
> >     # cat ~/.perfconfig
> >     [ftrace]
> >         tracer = function
> >
> >     # perf ftrace usleep 123456 | head -10
> >       <...>-14450 [002] d... 10089.284231: finish_task_switch <-__schedule
> >       <...>-14450 [002] .... 10089.284232: finish_wait <-pipe_wait
> >       <...>-14450 [002] .... 10089.284232: mutex_lock <-pipe_wait
> >       <...>-14450 [002] .... 10089.284232: _cond_resched <-mutex_lock
> >       <...>-14450 [002] .... 10089.284233: generic_pipe_buf_confirm <-pipe_read
> >
> > Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> > Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> > Signed-off-by: Taeung Song <treeze.taeung@xxxxxxxxx>
> > ---
> >  tools/perf/builtin-ftrace.c | 20 ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> >
> > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> > index 414444d..8df5416 100644
> > --- a/tools/perf/builtin-ftrace.c
> > +++ b/tools/perf/builtin-ftrace.c
> > @@ -17,6 +17,7 @@
> >  #include "evlist.h"
> >  #include "target.h"
> >  #include "thread_map.h"
> > +#include "util/config.h"
> >
> >
> >  #define DEFAULT_TRACER  "function_graph"
> > @@ -198,6 +199,23 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
> >  	return done ? 0 : -1;
> >  }
> >
> > +static int perf_ftrace_config(const char *var, const char *value, void *cb)
> > +{
> > +	struct perf_ftrace *ftrace = cb;
> > +
> > +	if (!strcmp(var, "ftrace.tracer")) {
> > +		if (!strcmp(value, "function_graph"))
> > +			ftrace->tracer = DEFAULT_TRACER;
> > +		else if (!strcmp(value, "function"))
> > +			ftrace->tracer = "function";
> > +		else
> > +			return -1;
>
> Please warn the user for invalid values and either just say that it is
> ignoring that setting or return -1 to make perf_config() return that,
> then make cmd_ftrace() check the return of perf_config() and bail out if
> you're not ignoring the config value.
>
> I think its better to do a: "pr_err()" in that "return -1" branch and
> make 'perf ftrace' fail, so that the user can fix its config before
> proceeding.

I understood it!
I'll modify this patch and resend it. :)

Thanks,
Taeung