Low latency is critical for interactive networked appli- cations. But while we know how to scale systems to in- crease capacity, reducing latency — especially the tail of the latency distribution — can be much more difficult. We argue that the use of redundancy in the context of the wide-area Internet is an effective way to convert a small amount of extra capacity into reduced latency. By initiating redundant operations across diverse resources and using the first result which completes, redundancy improves a system’s latency even under exceptional con- ditions. We demonstrate that redundancy can signifi- cantly reduce latency for small but critical tasks, and argue that it is an effective general-purpose strategy even on devices like cell phones where bandwidth is rel- atively constrained.

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