perf top: Fix -z option behavior

The current -z option does almost nothing.  It doesn't zero the existing
samples so that we can see profiles of exited process after last
refresh.  It seems it only affects annotation.

This patch clears existing entries before processing if -z option is
given.  For this original decaying logic also moved before processing.

Reported-by: Stephane Eranian <eranian@google.com>
Tested-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1407831366-28892-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-top.c

@@ -276,11 +276,17 @@ static void perf_top__print_sym_table(struct perf_top *top)
 		return;
 	}
 
+	if (top->zero) {
+		hists__delete_entries(&top->sym_evsel->hists);
+	} else {
+		hists__decay_entries(&top->sym_evsel->hists,
+				     top->hide_user_symbols,
+				     top->hide_kernel_symbols);
+	}
+
 	hists__collapse_resort(&top->sym_evsel->hists, NULL);
 	hists__output_resort(&top->sym_evsel->hists);
-	hists__decay_entries(&top->sym_evsel->hists,
-			     top->hide_user_symbols,
-			     top->hide_kernel_symbols);
+
 	hists__output_recalc_col_len(&top->sym_evsel->hists,
 				     top->print_entries - printed);
 	putchar('\n');
@@ -542,11 +548,16 @@ static void perf_top__sort_new_samples(void *arg)
 	if (t->evlist->selected != NULL)
 		t->sym_evsel = t->evlist->selected;
 
+	if (t->zero) {
+		hists__delete_entries(&t->sym_evsel->hists);
+	} else {
+		hists__decay_entries(&t->sym_evsel->hists,
+				     t->hide_user_symbols,
+				     t->hide_kernel_symbols);
+	}
+
 	hists__collapse_resort(&t->sym_evsel->hists, NULL);
 	hists__output_resort(&t->sym_evsel->hists);
-	hists__decay_entries(&t->sym_evsel->hists,
-			     t->hide_user_symbols,
-			     t->hide_kernel_symbols);
 }
 
 static void *display_thread_tui(void *arg)

tools/perf/util/hist.c

@@ -277,6 +277,28 @@ void hists__decay_entries(struct hists *hists, bool zap_user, bool zap_kernel)
 	}
 }
 
+void hists__delete_entries(struct hists *hists)
+{
+	struct rb_node *next = rb_first(&hists->entries);
+	struct hist_entry *n;
+
+	while (next) {
+		n = rb_entry(next, struct hist_entry, rb_node);
+		next = rb_next(&n->rb_node);
+
+		rb_erase(&n->rb_node, &hists->entries);
+
+		if (sort__need_collapse)
+			rb_erase(&n->rb_node_in, &hists->entries_collapsed);
+
+		--hists->nr_entries;
+		if (!n->filtered)
+			--hists->nr_non_filtered_entries;
+
+		hist_entry__free(n);
+	}
+}
+
 /*
  * histogram, sorted on item, collects periods
  */

tools/perf/util/hist.h

@@ -152,6 +152,7 @@ void hists__output_resort(struct hists *hists);
 void hists__collapse_resort(struct hists *hists, struct ui_progress *prog);
 
 void hists__decay_entries(struct hists *hists, bool zap_user, bool zap_kernel);
+void hists__delete_entries(struct hists *hists);
 void hists__output_recalc_col_len(struct hists *hists, int max_rows);
 
 u64 hists__total_period(struct hists *hists);