I'm thinking that jitlog.MARK_TRACE_OPT is the only marker I need to keep track of as I'm dumping pycode (overloading execute_frame as vmprof does). When I see a MARK_TRACE_OPT, I just walk backward to find the closest pycode dump. This will give me the actual source code lines that was JITTED. Would this approach work ? Thanks, SHubha