I have a dedicated machine that runs RHEL ES 4 with two mains tasks: MySQL database (as a service) and a java application that works with that database as its single client. When I launch my java application, 'top' shows that the overall CPU utilization on the machine rises to > 95%, and indeed the java application which is cpu bound is doing what it should. But top does NOT show the processes that consume the CPU. All the processes it lists have very little cpu utilization figures.

When I invoke the ps command, it claims as well that my java application and mysql are not busy (%cpu < 5). I know for a fact this is not true. If I close the java application - the overall CPU on the machine immediately goes does (<5%).

Why does top and ps both claim that the java application and the database are idle? a real mystery to me.

How many % eaten up by iowait ? (see this in 'top' detailed output for cpu or with 'iostat').

It turned out there was a bug in the kernel I was using (RHEL 2.6.9-5). I upgraded the kernel to 2.6.9-34 and now is works fine.

Thanks anyway,
Saar