Dynamic Unikernel Construction Framework Based On Memory Page Mapping

Recently,unikernels have emerged as a promising approach to application deployment in cloud environments.A unikernel is a specialized,single address space machine image constructed by using library operating systems.During the construction of a unikernel,the source code and all the dependent components are compiled together to generate a whole image that directly runs on the hypervisor which is difficult to reconfigure/update applications at runtime.If the running unikernel needs to be reconfigured/updated,it needs to modify the configuration files and application source code,then compile,link,test,and deploy the new unikernels in the cloud.These processes are very time-consuming and need to disrupt the cloud service.This offline updating model significantly affects the flexibility and efficiency of using unikernels for cloud service deployment.To solve the above problem,a lightweight framework to reconfigure/update unikernels based on Xen is proposed,which includes a unikernel binary analyzer,parameter updating module,and function updating module.The former is aimed at analyzing the unikernel image file and establishing a mapping relationship with the running unikernel binary code to obtain the configuration parameters and function address information of the unikernel in the running state.The two latter are used for updating the configuration parameters and function modules.The configuration parameter updating module is aimed at locating and mapping the data memory page,computing the configuration parameter memory address,and modifying the value.The function updating module is aimed at loading and mapping the new version of the function library,analyzing,and modifying the function call process.The grant table mechanism provided by Xen is applied to the mapping mechanism of the memory page.By directly locating and modifying the key data in the memory,the speed of online updating is fully improved,and the service running in the unikernel will not be interrupted,which ensures its flexibility and applicability.D-Unikernel,a prototype system,is implemented on the Xen platform based on MiniOS.A series of customized configuration parameters and function libraries were evaluated on Ubuntu 16.04(kernel version 4.15).The experimental results show that D-Unikernel can significantly reduce the time cost of reconfiguring and updating running unikernel by about 26 x compared to the static unikernels while remaining the excellent characteristics of unikernel.