4.4 Analysis

With the results from formula (6) we can give an explanation for the data in Fig. 9. When the available bandwidth is over 3Mbps, the compression time is larger than ($t_s-t_b$). That is why the change of available bandwidth from 4Mbps to 10Mbps does not affect the total execution time, and we see no changes in the total execution time with the increase of competing flow bandwidth.

With the improved model, we can improve our prediction model in the following way. We can still use formula (1) to compute the processing time in uncompression mode. But for the compression mode, we should use formula (6) instead of formula (2). Given the data size and the performance parameters from Compression Module and Network Module, it is not difficult to calculate $t_c$ and $t_s$, while $t_b$ can be measured directly in the application, that is, the execution time that the application sees from socket function send() is actually the socket buffer copying time.