Dynamic Voltage and Frequency Scaling in Multimedia Servers

In this paper, we experimentally investigate the scope and usefulness of Dynamic Voltage and Frequency Scaling (DVFS) in multimedia servers. For our experiment, we considered four scaling policies, two heterogeneous servers, and two different application scenarios. In the first scenario, we used an IO-Intensive multimedia downloading application while in the second scenario we used a predominately CPU-Intensive application, namely, a video transcoder. We will show that while the advantage of DVFS for IO-Intensive applications is apparent, it is not so for CPU-Intensive applications. The advantage in IO-Intensive applications depends on the selection of frequencies in the machine and the way the CPU speed scales. We observed that the choice of a particular DFVS technique became more consequential when the machine had a wide selection of operation frequencies while a gradual change in the operation frequency was more energy efficient. For CPU-Intensive applications, the use of DVFS was counter productive and the overhead of scaling was not negligible.