void sgen_ensure_free_space (size_t size, int generation);
void sgen_gc_collect (int generation);
-void sgen_perform_collection (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish);
+void sgen_perform_collection (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish, gboolean stw);
int sgen_gc_collection_count (int generation);
/* FIXME: what exactly does this return? */