Stratus: Clouds with Microarchitectural Resource Management

The emerging next generation of cloud services like Granular and Serverless computing are pushing the boundaries of the current cloud infrastructure. In order to meet the performance objectives, researchers are now leveraging low-level microarchitectural resources in clouds. At the same time these resources are also a major source of security problems that can compromise the confidentiality and integrity of sensitive data in multi-tenant shared cloud infrastructures. The core of the problem is the lack of isolation due to the unsupervised sharing of microarchitectural resources across different performance and security boundaries. In this paper, we introduce Stratus clouds that treat the isolation on microarchitectural elements as the key design principle when allocating cloud resources. This isolation improves both performance and security, but at the cost of reducing resource utilization. Stratus captures this trade-off using a novel abstraction that we call isolation credit, and show how it can help both providers and tenants when allocating microarchitectural resources using Stratus's declarative interface. We conclude by discussing the challenges of realizing Stratus clouds today.