...and if it doesn't support something you want to monitor/log, the API is documented and there are examples, so you can roll your own agents (or PMDAs as they are known), create your own visualisations, etc. Disclaimer: I was a PCP developer in a previous life.

The developers are pretty helpful.
Try posting your question on the PCP mailing list or IRC channel.
Details on the "Developers" page at http://oss.sgi.com/projects/pcp/

Disclaimer: I was a PCP developer in a previous life. ;)