Figure 9-30. Shown is the workload diagnostic information. Compared to Figure 9-24, logical IO response time dropped from 0.02119 ms/lio down to a staggering 0.00935 ms/lio. In addition, the overall logical IO workload increased from 69.29 lio/ms to 74.66 lio/ms, representing an 8% increase. So again, performance has improved while the workload has also increased.

Figure 9-31 shows the initial and current (buffer cache increase) response-time curves using logical IO as the workload metric. The variables used to create the response-time curve are four CPU cores (M=4); service times (St) of 0.01507 ms/lio and 0.009326 ms/lio for the initial and increased buffer cache situation, respectively; and their various arrival rates of 69.3 lio/ms and 74.7 lio/ms, as indicated on the graph as points A and B, respectively. Because Oracle now performs less work per logical IO, the service time for logical IO decreased. As shown graphically in Figure 9-31, the performance situation changed from point A to point B, allowing both improved SQL statement elapsed time combined with an increase in workload and a reduction in CPU utilization.

Figure 9-31. Shown is the response-time curve shift as a result of the logical IO service time decrease (improvement). Not only does this increase performance with no workload change (69 lio/ms), but in the current situation (point B), the response time remains improved along with an 8% workload increase (74 lio/ms).