All performance testing tools that I know of are bad at collecting system metrics from Unix-like system (AIX, Solaris, Linux, BSD etc). If you are lucky you might (might!) be able to collect CPU utilisation and maybe one or two memory utilisation counters.
Generally you have to create a shell script to run perfstat (or similar) then, when your load test is over, you process the output file and import it into your analysis tool.
Yesterday I learnt that you can write whatever data you want to an SNMP MIB so, if your performance test tool is able to gather metrics from SNMP, it follows that you can write your performance stats to the SNMP MIB and cut out the painful process of processing and importing for each test.
A little extra research shows that some operating system versions already have MIB objects with performance counters for metrics like CPU and memory use, although collection of these may have to be enabled. The OpenSTA performance testing tool website even has an article on “Monitoring CPU usage with OpenSTA via SNMP“.
This is a useful technique to add to any performance tester’s repertoire.