4 Model the Overlap of Local Computation and Network Execution

As mentioned in the previous section, in Fig. 9(b), when the available bandwidth is higher than 3Mbps, the execution time with compression does not change very much. This result does not comply with the prediction formulas (2) - (5), which says that with the decreasing of available bandwidth, transmission time should increase, finally increasing the total execution time. In this section, we show that this abnormal results is due to the overlap between network transmission and local compression on the host. More specifically, if the computation time is big enough, what really matters for the total execution time is the socket buffer copying time, not network transmission time. That is why the network available bandwidth will not affect the application performance.