Analysis of the Power Consumption of a Multimedia Server under Different DVFS Policies

Dynamic voltage and frequency scaling (DVFS) has been a useful power management strategy in embedded systems, mobile devices, and wireless sensor networks. Recently, it has also been proposed for servers and data centers in conjunction with service consolidation and optimal resource-pool sizing. In this paper, we experimentally investigate the scope and usefulness of DVFS in a server environment. We set up a multimedia server which will be used in two different scenarios. In the first scenario, the server will host requests to download video files of known and available formats. In the second scenario, videos of unavailable formats can be accepted; in which case the server employs a trans coder to convert between AVI, MPEG and SLV formats before the videos are downloaded. The workload we generate has a uniform arrival rate and an exponentially distributed video size. We use four dynamic scaling policies which are widely used with existing mainstream Linux operating systems. Our observation is that while the gain of DVFS is clear in the first scenario (in which a predominantly IO-bound application is used), its use in the second scenario is rather counterproductive.