global depth = 0
global max_depth = 0

probe process("fib").function("fib").call {
    depth++
    if (depth > max_depth) {
            max_depth = depth
            %( $# > 0 %? print_ubacktrace_brief(); printf("\n") %)
    }
}

probe process("fib").function("fib").return {
    %( $# == 0 %?
    if (depth == max_depth) {
            print_ubacktrace_brief()
            printf("\n")
    }
    %)
    depth--
}