Cross-ISA Execution Migration of Unikernels: Build Toolchain, Memory Alignment, and VM State Transfer Techniques
Mehrab, A K M Fazla
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The data centers are composed of resource-rich expensive server machines. A server, overloadeded with workloads, offloads some jobs to other servers; otherwise, its throughput becomes low. On the other hand, low-end embedded computers are low-power, and cheap OS-capable devices. We propose a system to use these embedded devices besides the servers and migrate some jobs from the server to the boards to increase the throughput when overloaded. The datacenters usually run workloads inside virtual machines (VM), but these embedded boards are not capable of running full-fledged VMs. In this thesis, we propose to use lightweight VMs, called unikernel, which can run on these low-end embedded devices. Another problem is that the most efficient versions of these boards have different instruction set architectures than the servers have. The ISA-difference between the servers and the embedded boards and the migration of the entire unikernel between them makes the migration a non-trivial problem. This thesis proposes a way to provide the unikernels with migration capabilities so that it becomes possible to offload workloads from the server to the embedded boards. This thesis describes a toolchain development process for building migratable unikernel for the native applications. This thesis also describes the alignment of the memory components between unikernels for different ISAs, so that the memory referencing remains valid and consistent after migration. Moreover, this thesis represents an efficient VM state transfer method so that the workloads experience higher execution time and minimum downtime due to the migration.
General Audience Abstract
Cloud computing providers run data centers which are composed of thousands of server machines. Servers are robust, scalable, and thus capable of executing many jobs efficiently. At the same time, they are expensive to purchase and maintain. However, these servers may become overloaded by the jobs and take more time to finish their execution. In this situation, we propose a system which runs low-cost, low-power single-board computers in the data centers to help the servers, in considered scenarios, reduce execution time by transferring jobs from the server to the boards. Cloud providers run services inside virtual machines (VM) which provides isolation from other services. As these boards are not capable of running traditional VMs due to the low resources, we run lightweight VMs, called unikernel, in them. So if the servers are overloaded, some jobs running inside unikernels are offloaded to the boards. Later when the server gets some of its resources freed, these jobs are migrated back to the server. This back and forth migration system development for a unikernel is composed of several modules. This thesis discuss detail design and implementation of a few of these modules such as unikernel build environment implementation, and unikernel's execution state transfer during the migration.
- Masters Theses