EM 12c Agent footprint on physical host versus VMs
This topic you might find interesting.
The EM 12c Agent footprint is similar when running on physical hosts or VMs. VMs are considered just another host. Since we run agents on each VM, that may increase the physical host footprint, but not by much.
The agent's runtime comprises the fixed cost of loading its binary-text and heap (which can be found by running the size Unix command on emagent executable) plus the variable cost of managing the targets. The variable cost depends on the number of targets and the number of metrics, etc. The number of targets, the number of metrics being collected per target and the frequecy of the metric check all contribute to the variable costs. The more targets, the more metric and the more frequent the metric check, the more cost.