+/* from resource_utilization.c */
+void TRACE_surf_host_set_utilization (const char *name, smx_action_t smx_action, double value, double now, double delta);
+void TRACE_surf_link_set_utilization (const char *name, smx_action_t smx_action, double value, double now, double delta);
+void __TRACE_surf_resource_utilization_start (smx_action_t action);
+void __TRACE_surf_resource_utilization_event (smx_action_t action, double now, double delta, const char *variable, const char *resource, double value);
+void __TRACE_surf_resource_utilization_end (smx_action_t action);
+void __TRACE_surf_resource_utilization_initialize (void);
+void __TRACE_surf_resource_utilization_finalize (void);