Design And Implementation Of Self Migration System

Live migration is to migrate a virtual machine from one host to another.Traditional live migration implemented by the Hypervisor,called the Host Migration.And Host Migration has the following shortcomings: The migration strategy is decided by the Hypervisor,which lead to the lack of customization.Host Migration as a hypervisor level process,has threaten to the whole host machine.System resources such as CPU and network occupied by the migration process are difficult to audit,which may lead to unfair resource allocation.The semantic gap problem leads to a decrease in transmission efficiency,and invalid data in the virtual machine is also transmitted through the network.In view of the above problems,this paper proposes a virtual machine self-migration scheme,which implements most of the migration mechanism by the guest virtual machine.The hypervisor only needs to provide few support functions.With virtual machine self-migration,the guest virtual machine can customize different migration strategies,specify memory validity to reduce invalid memory transfer,and the cloud platform simplifies the audit process of the computing resources occupied by the migration,and can also be caused by migration.Security issues are isolated inside the virtual machineVirtual machine self-migration faces a series of technical challenges.First of all,the virtual machine is both the executor of the migration and the object to be migrated.Therefore,on the one hand,its memory data will be modified during the execution process,and on the other hand,it needs to maintain a stable state to facilitate migration.Secondly,the traditional migration The virtual machine is usually required to suspend execution,but in the virtual machine selfmigration,the virtual machine itself cannot be suspended,otherwise the self-migrating program running inside the virtual machine will be suspended.This paper proposes a virtual machine self-migration scheme based on the self-snapshot function.The solution takes full advantage of the Intel processor's VMFUNC to allow the guest virtual machine to directly switch its own extended page table features,create additional memory mapped space for the virtual machine to save the complete memory state,and isolate the virtual machine working memory from the snapshot memory.Therefore,the virtual machine can access the memory state at a certain moment without suspending the operation,and ensure the consistency of the memory data.Specifically,when the client system invokes the snapshot function,it generates a working EPT that is identical to the mapping of the current EPT(Extended Page Table),backs up all client physical pages in a backup mapping manner,and adopts the original EPT.Write-time copy mechanism.During the self-migration process,when the memory data consistency is ensured and the virtual machine is not suspended,when the memory state of the last iteration is copied,the virtual machine can suspend all user processes,save the memory state as a snapshot,and continue to Run the migration program in the work EPT.The state of the virtual machine that is finally restored on the target host is the state in the last iteration of the snapshot of the source virtual machine.The contribution of this article consists of the following:1.Analyze and summarize the four shortcomings of host migration,and propose to use self-migration technology to improve.2.Propose a virtual machine self-migration scheme based on self-snapshot function,which has better flexibility than host migration under the condition that Hypervisor provides little support function,more accurate resource audit,and smaller trusted computing base.TCB and support customization.3.Based on KVM,the self-migration mechanism is implemented,and the performance of self-snapshot and self-migration is tested.Experimental data sheet In a virtual machine with a memory size of 4 GB,the snapshot creation speed is less than 1 millisecond;the performance impact of running a program in a self-snapshot due to a physical page write copy is negligible;the total number of iterations of the migration in the self-migrating system The downtime are close to the host migration under the same conditions,and the first round of iterative page copy volume and total migration time is slightly reduced.