Caching Problem

Hey all,

    I'm trying not to cache a page.  I have the following code:

       $return = split(" ", exec("vmstat"));
       $cpu_top = 100;
       $return = $cpu_top - $return[count($return) -1];

which returns the amount of idle cpu time. The problem is this, every time the page is loaded, it always show the first value when the page was first loaded. I tried adding : header("Cache-Control: no-store, no-cache, must-revalidate"); header("Cache-Control: post-check=0, pre-check=0", false); header("Pragma: no-cache"); all randomly, and together, but nothing seems to work. I can run one of my binaries in a forever loop causing the cpu not ever to be idle, but still nothing. Help? Thanks in advance, Paul