DoubleDecker: a cooperative disk caching framework for derivative clouds

Derivative clouds, light weight application containers provisioned in virtual machines, are becoming viable and cost-effective options for infrastructure and software-based services. Ubiquitous dynamic memory management techniques in virtualized systems are centralized at the hypervisor and are ineffective in nested derivative cloud setups. In this paper, we highlight the challenges in management of memory resources in derivative cloud systems. Hypervisor caching, an enabler of centralized disk cache management, provides flexible memory or non-volatile memory management at the hypervisor to improve the resource usage efficiency and performance of applications. Existing hypervisor caching solutions have limited effectiveness in nested setups due to their nesting agnostic design, centralized management model and lack of holistic view of memory management. We propose DoubleDecker, a decentralized disk caching framework, realized through guest OS and hypervisor cooperation, with support for efficient memory management in derivative clouds. The DoubleDecker hypervisor caching framework, an integral part of our proposed solution, provides interfaces for differentiated cache partitioning and management in nested setups and is equipped to handle both memory and SSD based caching stores. We demonstrate the flexibility of DoubleDecker to handle dynamic and changing memory provisioning requirements and its capability to simultaneously provision memory across multiple levels. Such multi-level configurations cannot be explored by centralized designs and are a key feature of DoubleDecker. Our experimentation with DoubleDecker demonstrates that application performance can be consistently improved due to the flexible policy framework for disk caching. With our setup, we report an average performance improvement of 4x and a maximum of 11x.