Question about Oracle's interpretation of “host cpu utilization” in v$sysmetric view

Question

I am studying the v$sysmetric view from Oracle and trying to understand what is Oracle's interpretation of "Host CPU Utilization"

It says in the metric_unit as % busy/(idle + busy), but what is busy? Is that the sum of usr + sys time? I tried comparing the query results from v$sysmetric against output from mpstat but it didn't seem to match.