Performance Testing - Software Testing: Testing Across the Entire Software Development Life Cycle - page 131

the late 1970s, large mainframe computers had the capacity for delivering subsecond
response times over a wide range of software activities for a large number of users.
Computer center managers opted to “tune” these mainframes to a 4-5 seconds (in-
tentionally slowed down) response time. Users became accustomed to the 4-5 sec-
onds response time as the norm and certainly satisfactory with respect to the Rule
of 8. Then, as new software was added to the mainframe, there was reserve capacity
that the computer center managers could “tune” back in so that the response time
never slowed down beyond the 4-5 seconds range. The users came to expect that
adding software to the mainframe's workload would not slow down the response
time as they had experienced in the 1960s and early 1970s. The computer center
managers found a way to manage performance expectations of their users without
giving the users the absolute best performance that the technology could provide.
The emergence of Internet applications has caused great consternation among
end users. Internet application response times often range in the 10 seconds-3 min
range with little hope for improvement using the current technology. Knowing that
the Rule of 8 is still alive and well, the tester must team with the developer in setting
realistic end-user expectations about performance capabilities and limitations of a
new Internet system.

9.2.1 Documenting the Performance Workload
Requirements

The outcome of this workload analysis for a purchasing application might be the
following groups of transactions and their performance requirements. Notice that
the performance requirement is stated as a maximum response time (no slower than)
rather than an average response time.

Draft 1 Performance workload plan

Response time
requirement Transaction group

Menu navigation
Log on/Log off
Product detail display
Purchase steps
Catalog search
Credit card payment
Product ship

Max 3 seconds
Max 3 seconds
Max 4 seconds
Max 7 seconds
Max 10 seconds
Max 30 seconds
Max 24 hours

9.2.2 Documenting the Performance Workload Peaks

The performance tester's second workload challenge is to determine peak usage
of each group of transactions and the timeframes in which the peak usage occurs.