Load testing Moodle with JMeter
Being the original load testing tool for servers, introduced in 1998(!), JMeter  has always been the number one load testing resp. performance measuring tool for Moodle. Around its release 2.5, Moodle developers made the testing process vastly simpler by adding many scripts. The topic of this page is the usage of the two scripts Make test course  and Make JMeter test plan  and JMeter running on a client machine.
Warning: Do not run these scripts nor JMeter targeting a production system! They generate a large amounts of artificial data and load the server to its limit and beyond, making it to bloat and/or become non-responsive. Don't even run them on a separate Moodle instance in the production server: their effect on the DBMS is undocumented.
JMeter installed on your client computer
JMeter is a Java application so it can run on Windows, Mac, or Linux. It can be run on the command line or on its graphical client on your desktop. First check if Java is installed in your client computer by opening a console and entering 'java -version'. If it doesn't return a version, first install Java on your client. The instructions vary with the operating system.
To install JMeter go to the JMeter page, download the zip and unzip it to the directory of your choice.
A test plan
You can make a test plan from the JMeter client in DIY style. We do not describe that path here, assuming you know JMeter. This page describes how to make a test plan with the scripts built in to Moodle and run it.
Make test course
Make JMeter test plan
Running the test plan on JMeter
To run JMeter open the /bin subdirectory and use either jmeter.bat on Windows or ./jmeter on Linux. This will open the JMeter GUI.
First step is to go to File -> Open and select the testplan.jmx file you downloaded above. This will open a tree on the left hand side of JMeter. Open the Warm-up site -> Default site request and enter the protocol (http or https) and Server name or IP. Then go to CSV Users Data and locate your users.csv file under Filename. Repeat this for Moodle Test.
Right mouse click on the Test Plan, then Add -> Listener. Choose Aggregate Report so you can follow the run as it happens. Save the changes in your test plan and run it.