The Performance Monitor in VoltDB Studio displays data that is gathered from the @Statistics system procedure. So you can view that live to get a sense of the throughput, and also look at the execution times for the stored procedure to see if they are performing well. If you want to export that data, you could derive it from calling @Statistics directly, but it will require some summarization probably in a spreadsheet.
Here is the reference for the @Statistics procedure:
Another way to measure performance is from a client, like our example applications. If you want to write your own client to test a certain workload against your own schema, that is not too difficult. I would recommend starting with one of our other example applications as a template, and replacing the schema, stored procedures, and client-side data generation and procedure calls. The simplest one I would use as a template is this one:
But you might look through the other available examples to see if one is closer to your use case.
Is there a particular use case you're trying to test?