Serverless computing along with Function-as-a-Service (FaaS) is forming a new computing paradigm that is anticipated to found the next generation of cloud systems. The popularity of this paradigm is due to offering a highly transparent infrastructure that enables user applications to scale in the granularity of their functions. Since these often small and single-purpose functions are managed on shared computing resources behind the scene, a great potential for computational reuse and approximate computing emerges that if unleashed, can remarkably improve the efficiency of serverless cloud systems -- both from the user's QoS and system's (energy consumption and incurred cost) perspectives. Accordingly, the goal of this survey study is to, first, unfold the internal mechanics of serverless computing and, second, explore the scope for efficiency within this paradigm via studying function reuse and approximation approaches and discussing the pros and cons of each one. Next, we outline potential future research directions within this paradigm that can either unlock new use cases or make the paradigm more efficient.

翻译：无服务器计算与函数即服务（Function-as-a-Service, FaaS）共同构成了一种新型计算范式，预计将奠定下一代云系统的基础。该范式的流行归因于其提供了高度透明的基础设施，使用户应用能够以函数为粒度进行扩展。由于这些通常规模较小且功能单一的函数在后台共享计算资源上被管理，因此产生了计算复用和近似计算的巨大潜力——若加以释放，便能显著提升无服务器云系统的效率，既包括用户的服务质量（QoS）视角，也包括系统的能耗与成本视角。据此，本综述研究的目标是：首先，揭示无服务器计算的内部机制；其次，通过研究函数复用与近似方法并讨论各自的优缺点，探索该范式下的效率提升空间。最后，我们概述了该范式中潜在的未来研究方向，这些方向要么能解锁新的应用场景，要么能使该范式更加高效。