OLTP on a server-grade ARM: power, throughput and latency comparison

Although scaling out of low-power cores is an alternative to power-hungry Intel Xeon processors for reducing the power overheads, they have proven inadequate for complex, non-parallelizable workloads. On the other hand, by the introduction of the 64-bit ARMv8 architecture, traditionally low power ARM processors have become powerful enough to run computationally intensive server-class applications. In this study, we compare a high-performance Intel x86 processor with a commercial implementation of the ARM Cortex-A57. We measure the power used, throughput delivered and latency quantified when running OLTP workloads. Our results show that the ARM processor consumes 3 to 15 times less power than the x86, while penalizing OLTP throughput by a much lower factor (1.7 to 3). As a result, the significant power savings deliver up to 9 times higher energy efficiency. The x86's heavily optimized power-hungry micro-architectural structures contribute to throughput only marginally. As a result, the x86 wastes power when utilization is low, while lightweight ARM processor consumes only as much power as it is utilized, achieving energy proportionality. On the other hand, ARM's quantified latency can be up to 11x higher than x86 towards to the tail of latency distribution, making x86 more suitable for certain type of service-level agreements.