Re: [PATCH] perf report: Provide libtraceevent with a kernel symbol resolver

From: Wang YanQing
Date: Tue Jan 16 2018 - 12:02:58 EST


On Mon, Jan 15, 2018 at 11:06:11AM +0100, Jiri Olsa wrote:
> On Mon, Jan 15, 2018 at 12:47:32PM +0800, Wang YanQing wrote:
> > So that beautifiers wanting to resolve kernel function addresses to
> > names can do its work, and when we use "perf report" for output of
> > "perf kmem record", we will get kernel symbol output.
> >
> > Signed-off-by: Wang YanQing <udknight@xxxxxxxxx>
> > ---
> > tools/perf/builtin-report.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
> > index dd4df9a..7b65100 100644
> > --- a/tools/perf/builtin-report.c
> > +++ b/tools/perf/builtin-report.c
> > @@ -1317,6 +1317,15 @@ int cmd_report(int argc, const char **argv)
> > report.range_num = 1;
> > }
> >
> > + if (session->tevent.pevent &&
> > + pevent_set_function_resolver(session->tevent.pevent,
> > + machine__resolve_kernel_addr,
> > + &session->machines.host) < 0) {
> > + pr_err("%s: failed to set libtraceevent function resolver\n",
> > + __func__);
> > + return -1;
> > + }
>
> why not calling the wrapper trace_event__register_resolver?
The reason is the same as builtin-script doesn't use trace_event__register_resolver,
because we only use report and script to analyze offline perf.data, and there could
be no tracepoints in perf.data.

The wrapper trace_event__register_resolver always initialize tevent.pevent, and calling
pevent_set_function_resolver which isn't necessary when there is no tracepoints in the
perf.data.
>
> jirka
>
> > +
> > sort__setup_elide(stdout);
> >
> > ret = __cmd_report(&report);
> > --
> > 1.8.5.6.2.g3d8a54e.dirty
> >