- P is proportional speed up, and
- S is speed up. Also, note that, for a web application the system should include browser render time and networklatency.
When you are using Cache, an application performance depends on a minimum of two of thefollowing factors:
- how many times a cached piece of data is retrieved by the application;
- and the proportion of the response time that is alleviated by caching.
Assume, we have a web application and uncached full page rendering time is 3 seconds. Now, let’scalculate the speed up from a database level cache. In our case:
- Uncached page time : 3 seconds
- Database time : 228 ms. (see figure 3.16)
- Cache retrieval time : 6 ms (see figure 3.17)
- Proportion : 228/3*1000 ∼ 7.6%
The expected system speedup should be:
1/((1-0.076) + 0.076/(228/6)) = 1/(0.924 + 0.002) ∼ 1.07 times overall system speed up.
