Cloud is not a silver bullet: a case study of cloud-based mobile browsing

In recent years, there has been growing interest in both industry and academia in augmenting mobile web browsing with support from the cloud [4, 1, 3, 16, 18]). These efforts are motivated by the goals of lowering costs of data transfer, and reducing web latencies and device energy consumption. While these efforts have adopted different approaches to cloud-based browsing, there isn't a systematic understanding of the rich design space due to the proprietary nature of many of the solutions. In this paper, we take a step towards obtaining a better understanding by evaluating an extreme point in the design space that involves cloud support for most browsing functionality including execution of JavaScript (JS), and for compaction of data (e.g., image transcoding and compression). Our study is conducted in the context of Cloud Browser (CB), a popular commercially available browser that embodies this design point. Our results indicate that CB does not provide clear benefits over Direct (a device-based browser) either in energy or download time. For e.g. while CB decreases the download time compared to Direct for 38.87% of pages, it increases it by as much as 29.8s for other pages. Similarly while CB decreases the total energy by up to 20.77J compared to Direct for 52.7% of the pages, it increases it by up to 21.31J for other pages. Interestingly, even though CB does JS execution in the cloud, it increases the CPU and network energy for close to 50% of the pages. Overall our study indicates that cloud-based browsing is not always a win, and there are important trade-offs that must be carefully considered when moving functionality to the cloud.