Taehyoung Kim

VMMB: Virtual Machine Memory Balancing for Unmodified Operating Systems

Virtualization technology has been widely adopted in Internet hosting centers and cloud-based computing services, since it reduces the total cost of ownership by sharing hardware resources among virtual machines (VMs). In a virtualized system, a virtual machine monitor (VMM) is responsible for allocating physical resources such as CPU and memory to individual VMs. Whereas CPU and I/O devices can be shared among VMs in a time sharing manner, main memory is not amendable to such multiplexing. Moreover, it is often the primary bottleneck in achieving higher degrees of consolidation. In this paper, we present VMMB (Virtual Machine Memory Balancer), a novel mechanism to dynamically monitor the memory demand and periodically re-balance the memory among the VMs. VMMB accurately measures the memory demand with low overhead and effectively allocates memory based on the memory demand and the QoS requirement of each VM. It is applicable even to guest OS whose source code is not available, since VMMB does not require modifying guest kernel. We implemented our mechanism on Linux and experimented on synthetic and realistic workloads. Our experiments show that VMMB can improve performance of VMs that suffers from insufficient memory allocation by up to 3.6 times with low performance overhead (below 1%) for monitoring memory demand.

NHVM: Design and Implementation of Linux Server Virtual Machine Using Hybrid Virtualization Technology

The virtualization technology has been developed rapidly with the growth of the hardware supported virtualization technologies and the appearance of the various services. Many researchers are concentrating on developing the virtualization technologies which are recognized as the most significant core technology of the IT applications such as green IT and cloud computing. The major processor companies have introduced various hardware supported virtualization technologies for overcoming the limitations of the software virtualization technologies. Until now, however, the hardware supported virtualization technologies are used only for supporting the full-virtualization technologies. In this paper, we introduced our efficient server virtual machine, which merged the hardware supported virtualization technologies with conventional para-virtualization technologies. Through our proposed hybrid virtualization technology, we could reduce the complexity and overhead of traditional server virtual machines. And lastly, we evaluated and compared our proposed virtual machine with traditional server virtual machines through the experiments.

NEMOSHELL Demo: Windowing System for Concurrent Applications on Multi-user Interactive Surfaces

Recently, the prevalence of large interactive surfaces renewed interests in windowing systems because of the advantages of enabling concurrent applications. We present the NEMOSHELL windowing system for multi-user interactive surfaces. We developed the system based on the Wayland system, a replacement for the Linux X. NEMOSHELL is designed to support multiple simultaneous applications, legacy input devices, legacy applications, and dynamic user interfaces. Finally, our demonstrations illustrate the potential of our system design.

Design and Implementation of Networking Virtualization for Cluster File Systems

An effective network layer which reduces cluster file system complexity is definitely needed in cluster computing environments where more than thousands of nodes are connected on a variety of different networks. Therefore, widely used cluster file systems such as Lustre, PVFS2, and GlusterFS provide networking virtualization layer. Through networking virtualization layer, each node accesses other nodes using a single interface over a variety of networks. However, previous networking virtualization technologies are complicated and not portable. In this paper, we propose a simple, portable, and socket-like networking virtualization layer that operates on user-mode. We also evaluate our virtualization layer using benchmark tools.

A Cooperative Authentication of IPSec and SEND Mechanisms in IPv6 Environments

The IPv6 network protects the IP layer by using the IPSec protocol and the SEND mechanism. However each host should be authenticated repeatedly when the two mechanisms are used at the same time. In this paper, we propose a cooperation scheme to share the authentication information between the SEND mechanism and the IPSec protocol. By sharing the authentication data of the host with the SEND mechanism, IPSec protocol expects the cost reduction for establishing a secure communication channel. We also evaluate the performance of the proposed mechanism by implementing the cooperation scheme.

Hardware assisted dynamic memory balancing in virtual machines

Virtualization technology can reduce the total cost of ownership by sharing resources with respect to the resource demand of each guest. Therefore, an efficient resource sharing mechanism is important for a virtual machine monitor (VMM). We introduce a hardware assisted dynamic memory balancing mechanism that balances memory among guests. Our proposed scheme estimates memory demand for each guest and periodically re-balances memory allocation based on this estimation. In order to estimate working set size (WSS), we use least recently used (LRU) histogram as a prediction model. Construction of LRU histogram is performed in a guest transparent way by using hardware memory management unit (MMU) virtualization support. Our experiments show that the proposed scheme accurately estimates the WSS with low overhead. They also show that it substantially improves performance over static memory allocation.

Software-based single-node multi-GPU systems for multiple display environments

In this paper, we suggest a novel multi-GPU scheme that can provide flexible interconnections between multi-GPUs and displays with no additional hardware by implementing new software features, while avoiding system overhead. Our proposed scheme offers the complete concept of windowing system and GPU driver for single-node multi-GPU system on multiple display environments.

Design and implementation of page sharing scheme between guests in virtualization environments

According to the development of virtualization technology and enhancement of hardware performance, there will be more and more guests on a host in virtualization environments. These guests use many common files and each file should be duplicated on each guest filesystem and memory. In order to eliminate these duplications of resources, many corporations and laboratories proposed several resource sharing schemes. However, there are some problems such as overhead and complexity. In this paper, in order to reduce such duplications, we propose a page sharing scheme optimized for executable files and libraries using shadow paging. Also, we validate our scheme with some evaluation results that show improvements in memory utilization and performance, through the implementation of the proposed scheme and experiments.

Remote-Launch: Borrowing Secure TCB for Constructing Trustworthy Computing Platform

Commodity operating systems have become extremely large to provide a lot of services, and then their vulnerability has been targeted by malicious attack. In order to increase security in operating system, there have been many attempts to reduce the size of Trust Computing Base (TCB). However, most of the approaches have applicability limitations due to hypervisor vulnerability and additional hardware requirements. To address these limitations, instead of reducing TCB size, we propose a novel approach to enhance the security of the system. We hide secure TCB for sensitive applications, and thus build an isolated secure environment using a well-equipped infrastructure. For evaluation, we implement a prototype, called Remote-Launch, which runs a security-sensitive process on the borrowed secure TCB.

MAS: Malware Analysis System Based on Hardware-Assisted Virtualization Technology

There are many analysis techniques in order to analyze malicious codes. However, recently malicious codes often evade detection using stealthy obfuscation techniques, and attack computing systems. We propose an enhanced dynamic binary instrumentation using hardware-assisted virtualization technology. As a machine-level analyzer, our system can be isolated from almost the whole threats of malware, and provides single step analysis environment. Proposed system also supports rapid system call analysis environment. We implement our malware analysis system (referred as MAS) on the KVM hypervisor with Intel VT-x virtualization support. Our experiments with benchmarks show that the proposed system provides efficient analysis environment with low overhead.