Netswap: Network-based Swapping for Server-Embedded Board Clusters

Capital equipment costs and energy costs are the major cost drivers in datacenters. Prior works have explored various techniques, like efficient scheduling algorithms and advanced power management techniques, to maximize resource utilization to reduce the capital and energy costs. The project HEXO has explored heterogeneous-Instruction Set Architecture (ISA) server-embedded clusters to minimize the cost. HEXO's key idea is to migrate stateful virtual machines from high-performance x86-based servers to low-power, low-cost ARM-based embedded boards, reducing server's resource congestion and thereby improving throughput and energy efficiency. However, embedded boards generally have significantly lower onboard memory, typically in the range of 100MB to 4GB. Due to this limitation, high memory-demand applications cannot be migrated to embedded devices. This limits the scope of applications that can be used with heterogeneous-ISA server-embedded clusters such as HEXO. This thesis proposes Netswap, a mechanism that utilizes the server's free memory as remote memory for the embedded board. Netswap comprises three main components: the swap-out and swap-in mechanism, a bitmap-based Free Memory Manager, and the Netswap Remote Daemon. Experimental studies using micro- and macro benchmarks reveal that Netswap improves the throughput and energy efficiency of server-embedded clusters by as much as 40% and 20%, respectively, over server-only baselines.