Metrics to be collected during any Performance Tests

Irrespective of the kind of performance test (load test/stress test/volume test/spike test etc), there are certain metrics which needs to be collected from the performance test tool to analyze the system performance.

 

End of the day , we want to know whether the system is able to handle the load meeting the response time level SLA. To achieve that we should identify the following 2 things.

1. Whether my software pipe is able to effectively utilize the available hardware pipe.

2. Whether my hardware pipe is big enough to be used by the software pipe.

 

If the software pipe is not able to utilize the hardware pipe effectively, then no wonder that even if you upgrade the server hardware, there will no improvement in the system performance.

Metrics to be collected
1.As a first step always look for the average & 90th percentile response time of all the transactions. Just neglect if there is other transactions which are inserted by the tool itself. (In case of Load Runner, the tool provides the transaction response time for vuser_init, vuser_end & action transactions depending upon the run time settings).
2.Next look for the load generated from the test tool. Hits/sec is the metric which provides the information on how many requests are fired to the server per second. Look for the average hits/sec & if the test is run using a specific ramp up rate, then measure the hits/sec value during the stress period of the test(when all users where running).
3.Next look for the Throughput, the metric which portrays the load handled by the server. The total transactions passed per second metric helps to identify the how capable is the server to handle the transactions. Also look for throughput in terms of bytes/sec metric which again portrays the server capability to respond to the client requests.
4.Next look for the failures occurred during the test. Observe when the failures have occurred, what is the type of failures (network failure, HTTP 500 errors, HTTP 404 errors, proxy server failures, etc) & is the failures specific for a transaction.
5.Next, look for the basic performance counters of web/application/DB server resources like %CPU, processor queue length, Memory pages/sec, Page faults/sec, % Disk utilization.

These five are the basic performance metrics which are mandatory for any performance tester to analyze the performance of the system. Going forward, in order to isolate the performance bottlenecks, we might end up looking at various performance metrics depending upon type of the performance issue.