Cross-ISA Container Migration

Abstract

Containers are a convenient way of encapsulating and isolating applications. They incur less overhead than virtual machines and provide more flexibility and versatility to improve server utilization. Many new cloud applications are being written in the microservices style to take advantage of container technologies. Each component of the application can be encapsulated in a separate container, which enables the use of other features such as auto-scaling. However, legacy applications can also benefit from containers which provide more efficient development and deployment models. In modern data centers, orchestration middle-ware is responsible for container placement, SLA enforcement and resource management. The orchestration software can implement various policies for managing the resources. The orchestration software can take corrective actions when detecting inefficiencies in the data center operation to satisfy the current policy. Power efficiency is becoming one of the most important characteristics taken into account when designing a data center and defining policy for the orchestration middleware [4]. Different server architectures have different power efficiency and energy proportionality characteristics. Recent research has shown that heterogeneous systems have the potential to significantly improve energy efficiency[3, 5]. Our work focuses on the mechanism required by the middle-ware to implement a power optimization policy. We research migration of containerized applications between servers inside a heterogeneous data center, for the purpose of optimizing power efficiency. Migrating a running container between different architectures relies on the compatibility of the application environment on the source and destination servers. Containers are viewed as a set of one or more processes and each process must have the ability to be migrated. A modified compiler is used to build executables in a manner allowing the program migration between different architectures. The source and destination servers must also have a shared file system and comparable networking capabilities. We take advantage of the recently added user-space page fault feature in the Linux kernel [2] to implement post-copy container migration in CRIU [1]. Post-copy migration significantly reduces perceived down-time of the container, and can potentially reduce network traffic as well. We propose creating a cluster of servers with different architectures (i.e., ARM, POWER, and x86) connected with a high-speed, low-latency network. This cluster will run SaaS applications in a containerized environment. The applications will be built using a specialized toolchain that ensures an identical memory layout across all architectures, enabling seamless migration at runtime. The majority of the challenges in cross-ISA migration are related to the toolchain adaptation, and ensuring the compatibility of the runtime environment across various servers in the cluster. The ability to efficiently migrate running containers between servers with different energy proportionality characteristics provides improved power savings during idle periods without compromising SLA commitments.