Web Search Using Small Cores: Quantifying the Price of Efficiency
The commoditization of hardware, data center economies of scale, and Internet-scale workload growth all demand greater power efficiency to sustain scalability. Traditional enterprise workloads, which are typically memory and I/O bound, have been well served by chip multiprocessors comprising of small, power-efficient cores. While small cores deliver performance-per-Watt efficiency for such data center workloads, small cores impact application quality-of-service robustness, flexibility, and reliability for emerging Internet-scale applications, which increasingly invoke computationally intensive kernels.
These challenges constitute the price of efficiency, which we quantify for an industry-strength, production-quality, next-generation online web search engine. Specifically, we evaluate search on server- and mobile-class architectures using Xeon and Atom processors, quantifying search efficiency at the microarchitecture- and system-level. Our findings prompt us toward re-thinking small core designs for a new breed of data center workloads in order to continue reaping the benefits of small-core power efficiency.