ok, i've found an easy solution. In the main report list of the DB in enterprise manager, the last column is INSTANCE CPU (%), that is EXACTLY what i need.

So i 've understood that the TOTAL (100%) is the cluster.... i were doubtfull about TOTAL was each NODE of the cluster.

Now the main question: what tables/views can give me the information of INSTANCE CPU (%) of enterprise manager?

This is the last step for my work!