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

Namhyung Kim
2015-11-26T13:53:30Z

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.

display_thread()
-> while (!done)
-> perf_top__print_sym_table()
-> hists__output_resort()
-> __hists__insert_output_entry()

Thanks,
Namhyung