Step 1:
Define the Workload(s)

The first step in any analysis of product performance is to answer the fundamental question:

What does the product do?

To elaborate, any computing and communication product accepts inputs, manipulates (processes) those inputs, and generates output. A workload is a unambiguous description of inputs that contains enough detail to enable predicting or measuring the product's performance.

Workloads are best defined by a joint effort of the marketing and architecture/development teams for a new product. In many cases, it may be appropriate to seek input from key customers as well. Using a "real" workload may seem appealing, but this approach has disadvantages. Most importantly, the workload applied to a deployed product can vary widely from day to day or even from minute to minute; therefore it is difficult, if not impossible, to rerun a particular day's workload at a later date to evaluate another product configuration. For this reason performance analysis relies on a synthetic workload. A synthetic workload has similar characteristics to a real world workload, but it is specified and implemented so as to be repeatable.

The role of the performance analyst (whether an employee or a consultant) is to facilitate translating a high-level description of a workload into a sufficiently detailed specification. For example, one of the workloads for a network processor might be described as "Internet Protocol (IP) routing at 10 gigabits/second. After discussion, the specification of the workload might include the following elements:

• OC-192 SONET framing with 7 bytes of HDLC/PPP overhead per packet.
• IP version 4
• 5-tuple classification (source IP address and port, destination IP address and port, protocol type) with 1000 routing rules
• Number of bytes (as opposed to number of packets) is evenly divided (25%) between 40, 64, 512, and 1500 packet lengths, where packet length includes IP headers but not lower level headers.

All of these details would be needed to analyze product performance for this workload.