• Journal of KIISE
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• v.44 no.10
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• pp.1005-1018
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• 2017

Recently, virtualization has become an essential component of cloud computing due to its various strengths, including maximizing server resource utilization, easy-to-maintain software, and enhanced data protection. However, since virtualization allows sharing physical resources among the VMs, the system performance can be deteriorated due to device contentions. In this paper, we first investigate the I/O overhead based on the number of VMs on the same server platform and analyze the block I/O process of the KVM hypervisor. We also propose an in-memory block cache mechanism, called QBic, to overcome I/O virtualization latency. QBic is capable of monitoring the block I/O process of the hypervisor and stores the data with a high access frequency in the cache. As a result, QBic provides a fast response for VMs and reduces the I/O contention to physical devices. Finally, we present a performance measurement of QBic to verify its effectiveness.

• Journal of KIISE
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• v.42 no.11
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• pp.1322-1331
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• 2015

According to the hypervisor scheduler, the vCPU (virtual CPU) operates under two states: the running state and the stop state. When the vCPU is in the stop state, incoming events are delayed until that vCPU's state changes to the running state. The latency in handling such events that are sent to the vCPU is regarded as the I/O latency. Since a SMP (symmetric multiprocessing) VM (virtual machine) incorporates multiple vCPUs, the event latency on a SMP VM can vary according to specific vCPU that receives the event. In this paper, we propose a new scheme named event routing that sends events according to the operation state of each vCPU to reduce the event latency on an SMP VM. We implemented the proposed event routing scheme in Xen ARM hypervisor and confirmed the reduction of I/O latency from measuring the network RTT (round trip time) and the TCP bandwidth under a variety of testing conditions. The network RTT decreases by up to 94% and the TCP bandwidth increases up to 35% when compare to native Xen ARM.

• The Journal of Korean Institute of Next Generation Computing
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• v.15 no.3
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• pp.31-39
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• 2019

Virtualization technology is one of the technologies that have been attracting attention as cloud computing spreads recently. When a system is constructed using virtualization technology, mutiple operation systems can be operated in a single host operating system, thereby facilitating efficient management of computing resources. As more and more operating systems are running on the hypervisor, it is important to measure the overall performance of the virtualization system and this is becoming an important technology. In this paper, we analyze the main functions of the existing profiling tools to measure the performance of the virtualization system, and measure and classify the profiling coverage that the monitoring tools can perform for events that may occur in the virtualization system. In addition, we have studied a framework that enables performance measurement by loading appropriate profiling tools into the guest system when performance measurement is required for the virtualization system according to the information received from the remote system performing the monitoring.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.9
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• pp.315-320
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• 2015

In cloud computing, server virtualization supports one or more virtual machines loaded on multiple operating systems on a single physical host server. Migration of a VM is moving the VM running on a source host to another physical machine called target host. A VM live migration is essential to support task performance optimization, energy efficiency and energy saving, fault tolerance and load balancing. In this paper, we propose open source based adaptive VM live migration technique. For this, we design VM monitoring module to decide VM live migration and open source based full-virtualization hypervisor.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.33-41
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• 2015

With rapid rise of virtualization technology from diverse types of cloud computing service, security problems such as data safety and reliability are the issues at stake. Since damage in virtualization layer of cloud service can cause damage on all host (user) tasks, Hypervisor that provides an environment for multiple virtual operating systems can be a target of attackers. This paper propose a security structure for protecting Hypervisor from hacking and malware infection.

• Journal of Internet of Things and Convergence
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• v.6 no.3
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• pp.31-37
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• 2020

The cloud computing industry is regarded as a key element of the ICT industry and an important industry that will be a watershed for the future development of ICT industry. Korea has established the 1st~2nd cloud computing development basic plan to induce the growth of the cloud industry. However, the domestic information security guide provides technical vulnerability analysis criteria for Unix and Windows servers, DBMS, network equipment, and security equipment, but fails to provide vulnerability analysis criteria for hypervisors that are key elements of cloud computing. Organizations that have deployed cloud systems will be able to assist in vulnerability analysis using the criteria presented in this paper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.8
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• pp.1827-1834
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• 2013

The existing PC-based desktop environment is being changed to a server-based virtual desktop environment due to various advantages such as security, mobility, and upgrade cost reduction. In this paper, a virtual computing lab service system which is applicable to the existing computer lab is designed and implemented using both an open source-based cloud computing platform and hypervisor. In addition, a node power scheduler is proposed in order to reduce power consumption in a server farm. The experimental results show that the power scheduler reduces power consumption considerably over the server farm without the power scheduler.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2056-2063
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• 2015

Recently, as the service scale of cloud service is expanded, an anxiety due to concerns on new vulnerabilities and security related incidents and accidents are also increasing. This paper proposes a certification scheme for multiple session management of security sessions which are generated after the user authentication. The proposed session multiplexing scheme enables the independent management of security sessions in the level of virtualization (hypervisor) within the service provider. As a result of performance analysis, providing a strong safety due to session multiplexing and mutual authentication, and the superiority of performance was proven by comparing it with the existing mutual authentication encryption algorithms.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.541-542
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• 2017

In this paper, we intend to develop an integrated management solution that can be easily operated by integrating complex and various cloud environments. This has the advantage that users and administrators can conveniently solve problems by collecting and analyzing fixed log data and unstructured log data based on big data and realizing integrated monitoring in real time. Hypervisor log pattern analysis technology will be able to manage existing complex and various cloud environment more efficiently.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.6
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• pp.467-478
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• 2020

Hypervisor virtualize hardware resources to utilize them more effectively. At the same time, hypervisor's characteristics of time and space partitioning improves reliability of flight software by reducing a complexity of the flight software. Korea Aerospace Research Institute chooses one of hypervisors for space, XtratuM, and examine its applicability to the flight software. XtratuM has strong points in performance improvement with high reliability. However, it does not support SMP. Therefore, it has limitation in using it with high performance applications including satellite altitude orbit control systems. This paper proposes RTEMS XM-SMP to support SMP with RTEMS, one of real time operating systems for space. Several components are added as hypercalls, and initialization processes are modified to use several processors with inter processors communication routines. In addition, all components related to processors are updated including context switch and interrupts. The effectiveness of the developed RTEMS XM-SMP is demonstrated with a GR740 board by executing SMP benchmark functions. Performance improvements are reviewed to check the effectiveness of SMP operations.