I thought most folks do this by using things like the Nix and Win TAs to get process resource consumption in the same way they would for any process running on the host. (A la ps.sh and its Windows equivalent)
You can enable platform instrumentation which will start populating the _introspection index (disabled by default on UF) by following these steps: http://docs.splunk.com/Documentation/Splunk/6.1.4/Troubleshooting/ConfigurePIF
sourcetype=splunkresourceusage should give you some insights into what you're looking for.
I would recommend using the "Splunk Add-on for Unix" app. It has many scripted inputs that can be turned on via the inputs.conf to collect such performance and usage data. (https://splunkbase.splunk.com/app/833/#/overview)
I would also like to note if you are going to use this on many UFs it is recommended that you use a deployment server to mange the app.