Reining in Long Tails in Warehouse-Scale Computers with Quick Voltage boosting using Adrenaline 6

ABSTRACT: Reducing the long tail of the query latency distribution in modern warehouse scale computers is critical for improving performance and quality of service (QoS) of workloads such as Web search and Memcached. Traditional turbo boost increases a processor's voltage and frequency during a coarse-grained sliding window, boosting all queries that are processed during that window. However, the inability of such a technique to pinpoint tail queries for boosting limits its tail reduction benefit. In this work, we propose Adrenaline, an approach to leverage finer-granularity (tens of nanoseconds) voltage boosting to effectively rein in the tail latency with query-level precision. Two key insights underlie this work. First, emerging finer granularity voltage/frequency boosting is an enabling mechanism for intelligent allocation of the power budget to precisely boost only the queries that contribute to the tail latency; second , per-query characteristics can be used to design indicators for proactively pinpointing these queries, triggering boosting accordingly. Based on these insights, Adrenaline effectively pinpoints and boosts queries that are likely to increase the tail distribution and can reap more benefit from the voltage/frequency boost. By evaluating inder various work-load configurations, we demonstrate the effectiveness of our methodology. We achieve up to a 2.50x tail latency improvement for memcached and up to a 3.03x for Web Search over coarse-grained dynamic voltage and frequency scaling (DVFS) given boosting power budget. When optimizing for energy reduction, adrenaline achieves up to a1.81x improvement for Memcached and up to a 1.99x for web search over coarse-grained DVFS. By using the carefully chosen thresholds, Adrenaline further improves the taillatency reduction to 4.82x over coarse-grained DVFS. 56

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