Accelerating Asynchronous Programs through Event Sneak Peek

摘要

Asynchronous or event-driven programming is now being used to develop a wide range of systems, including mobile and Web 2.0 applications, Internet-of-Things, and even distributed servers. We observe that these programs perform poorly on conventional processor architectures that are heavily optimized for the characteristics of synchronous programs. Execution characteristics of asynchronous programs significantly differ from synchronous programs as they interleave short events from varied tasks in a fine-grained manner. This paper proposes the Event Sneak Peek (ESP) architecture to mitigate microarchitectural bottlenecks in asynchronous programs. ESP exploits the fact that events are posted to an event queue before they get executed. By exposing this event queue to the processor, ESP gains knowledge of the future events. Instead of stalling on long latency cache misses, ESP jumps ahead to pre-execute future events and gathers useful information that later help initiate accurate instruction and data prefetches and correct branch mispredictions. We demonstrate that ESP improves the performance of popular asynchronous Web 2.0 applications including Amazon, Google maps, and Facebook, by an average of 16%.