Load test with databases. Best practices , tools
Take a snapshot of your production database and at the same time enable the general log. Record 24 hours of a general log on what is a fairly typical day.

Restore the data to clean server.

Write a few lines of your favourite $scripting_language to parse out the general log and split it up into n files where n is at least the number of CPU threads you have in the server. Also, separate SELECTs, INSERTs, UPDATEs, and DELETEs into separate sets of files.

Replay them in parallel, SELECTs only, to prime the caches. Then do it again and time the 2nd run.

Now you have a baseline to measure everything else against. From there on, triple up the number of rows in the table by adding more rows, and replay it again to measure the performance.

No generic benchmark will ever come close to producing as meaningful a benchmark number as this method.