Re: [PATCH 1/3] perf top: Fix freeze on --call-graph flat/folded

Jiri Olsa
2015-11-26T14:00:41Z

On Thu, Nov 26, 2015 at 10:52:56PM +0900, Namhyung Kim wrote:
> Hi Jiri,
>
> On Thu, Nov 26, 2015 at 09:38:53AM +0100, Jiri Olsa wrote:
> > On Thu, Nov 26, 2015 at 04:08:18PM +0900, Namhyung Kim wrote:
> > > The callchain rbtree is rebuilt periodically, so it needs to
> > > reinitialize the root everytime. Otherwise it can be stuck in the
> > > rbtree insertion with stale pointers.
> > >
> > > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > > ---
> > > tools/perf/util/callchain.c | 1 +
> > > 1 file changed, 1 insertion(+)
> > >
> > > diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> > > index fc3b1e0d09ee..564377d2bebf 100644
> > > --- a/tools/perf/util/callchain.c
> > > +++ b/tools/perf/util/callchain.c
> > > @@ -290,6 +290,7 @@ static void
> > > sort_chain_flat(struct rb_root *rb_root, struct callchain_root *root,
> > > u64 min_hit, struct callchain_param *param __maybe_unused)
> > > {
> > > + *rb_root = RB_ROOT;
> >
> > it seems ok, but I did not find how this could be called twice?
> >
> > the only sort I can see is done within:
> > __hists__insert_output_entry
> >
> > do we allow resorting of the callchains?
>
> No, but I think it's possible though.
>
> It's called from perf top's display thread.

ah right.. top ;-) ok

isn't there analogical issue with the other sorts?
graph_abs, graph_rel... I dont see that code doing this

thanks,
jirka

>
> display_thread()
> -> while (!done)
> -> perf_top__print_sym_table()
> -> hists__output_resort()
> -> __hists__insert_output_entry()
>
> Thanks,
> Namhyung