@defined in schedtimes.stp

[Joachim Worringen]

Greetings,

I want to use schedtimes.stp 
(http://sourceware.org/systemtap/examples/process/schedtimes.stp) and it 
fails on my CentOS 5.5 box:

[root@x8dth-1 systemtap]# stap schedtimes.stp
parse error: unknown statistic operator @defined
	saw: identifier '@defined' at schedtimes.stp:58:13
      source:         if (@defined($rq) && (get_iowait($rq) - 
io_wait_count[previous_pid]) > 0)
                          ^
parse error: unknown statistic operator @defined
	saw: identifier '@defined' at schedtimes.stp:76:9
      source:     if (@defined($rq))
                      ^
2 parse error(s).
Pass 1: parse failed.  Try again with another '--vp 1' option.

'@defined()' is part of the systemtap language, AFAICT: 
http://sourceware.org/systemtap/langref/Language_elements.html#SECTION00078200000000000000

What am I missing?

This is what is installed:
[root@x8dth-1 tapset]# rpm -qa | grep systemtap
systemtap-sdt-devel-1.1-3.el5_5.2
systemtap-1.1-3.el5_5.2
systemtap-runtime-1.1-3.el5_5.2
systemtap-sdt-devel-1.1-3.el5_5.2

And this is the kernel:
[root@x8dth-1 tapset]# uname -rp
2.6.18-194.17.1.el5 x86_64


  thanks, Joachim