perf tools: Release thread resources on PERF_RECORD_EXIT

For long running sessions with many threads with short lifetimes the
amount of memory that the buildid process takes is too much.

Since we don't have hist_entries that may be pointing to them, we can
just release the resources associated with each thread when the exit
(PERF_RECORD_EXIT) event is received.

For normal processing we need to annotate maps with hits, and thus
hist_entries pointing to it and drop the ones that had none. Will be
done in a followup patch.

Cc: David S. Miller <davem@davemloft.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 37cab90..2ddbae3 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -228,6 +228,39 @@
 	self->machine = NULL;
 }
 
+static void maps__delete(struct rb_root *self)
+{
+	struct rb_node *next = rb_first(self);
+
+	while (next) {
+		struct map *pos = rb_entry(next, struct map, rb_node);
+
+		next = rb_next(&pos->rb_node);
+		rb_erase(&pos->rb_node, self);
+		map__delete(pos);
+	}
+}
+
+static void maps__delete_removed(struct list_head *self)
+{
+	struct map *pos, *n;
+
+	list_for_each_entry_safe(pos, n, self, node) {
+		list_del(&pos->node);
+		map__delete(pos);
+	}
+}
+
+void map_groups__exit(struct map_groups *self)
+{
+	int i;
+
+	for (i = 0; i < MAP__NR_TYPES; ++i) {
+		maps__delete(&self->maps[i]);
+		maps__delete_removed(&self->removed_maps[i]);
+	}
+}
+
 void map_groups__flush(struct map_groups *self)
 {
 	int type;