Introducing Service-level Awareness in the Cloud

Resource allocation in clouds is mostly done assuming hard requirements, applications either receive the requested resources or fail. Given the dynamic nature of workloads, guaranteeing on-demand allocations requires large spare capacity. Hence, one cannot have a system that is both reliable and efficient. To solve this issue, we introduce Service Level (SL) awareness in clouds, assuming applications contain some optional code that can be dynamically deactivated as needed. First, we design a model for such applications and synthesize a controller to decide when to execute the optional code and when to skip it. Then, we propose a Resource Manager (RM) that allocates resources to multiple SL aware applications in a fair manner. We theoretically prove properties of the overall system using control and game theory.

To show the practical applicability, we implemented SL aware versions of RUBiS and RUBBoS with less than 170 lines of code. Experiments show that SL awareness may enable a factor 8 improvement in withstanding flash-crowds or failures. SL awareness opens up more flexibility in cloud resource management, which is why we encourage further research by publishing all source code.