after timingon,what is the meaning of cycle parameter

You will also find the iRule Editor can do this for you very simply. After turning timing on for you irule by modifying the header...

while EVENT timing on {
   ... your iRule ...
}

Get the platform CPU speed using the command below as this does not appear to be available in the GUI.

config  b platform | grep MHz
... cpu Mhz:2992.540

Now back in the iRule editor, right click on the iRule, select properties then choose the Statistics tab. Enter the cpu value from the command above. Send a few initial requests through to make it compile the first time as the initial compilation uses far more CPU than normal processing. Now reset the stats from that window and refresh to make sure they are all zero again. Remember to do this "initial compile/stats reset" again when you save an updated version of your iRule.

Now send through about 100 requests. Then hit refresh and view your results.

Jarvil