Efficient Checkpointing of Live Virtual Machines

Egger, Bernhard,Cho, Younghyun,Jo, Changyeon,Park, Eunbyun,Lee, Jaejin IEEE 2016 IEEE Transactions on Computers Vol. No.

<P>The ability to save the state of a running virtual machine (VM) for later restoration is an important tool for home, server, and virtual desktop cloud (VDC) environments in order to achieve optimal and balanced hardware utilization. With guest memory sizes of four to eight gigabytes being the norm the time-and space-overhead of storing VM checkpoints still prevents an effective use of the technique. This work presents a method for fast and space-efficient checkpointing of VMs. Based on the observation that operating systems cache disk blocks in memory, the proposed technique transparently intercepts I/O operations and maintains an up-to-date mapping of memory pages and disk blocks containing identical data. At a checkpoint, those memory pages are excluded from the checkpoint image leading to a significant reduction of both the time and space required to take a checkpoint of a running VM. The broad applicability and good performance of the proposed method is demonstrated by an extensive set of experiments. We have implemented the technique for para-virtualized (PV), PVHVM, and fully-virtualized (HVM) guests in the Xen hypervisor. In comparison with an unmodified Xen hypervisor, experiments with Linux and Windows guests, on average, achieve a 86, 76, 53, and 47 percent reduction in the stored data and a 73, 62, 47, and 38 percent shorter time required to take a checkpoint for PV, PVHVM, HVM Linux, and HVM Windows guests, respectively.</P>

A novel approach for analyzing the nuclear supply chain cyber-attack surface

Eggers, Shannon Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.3

The nuclear supply chain attack surface is a large, complex network of interconnected stakeholders and activities. The global economy has widened and deepened the supply chain, resulting in larger numbers of geographically dispersed locations and increased difficulty ensuring the authenticity and security of critical digital assets. Although the nuclear industry has made significant strides in securing facilities from cyber-attacks, the supply chain remains vulnerable. This paper discusses supply chain threats and vulnerabilities that are often overlooked in nuclear cyber supply chain risk analysis. A novel supply chain cyber-attack surface diagram is provided to assist with enumeration of risks and to examine the complex issues surrounding the requirements for securing hardware, firmware, software, and system information throughout the entire supply chain lifecycle. This supply chain cyber-attack surface diagram provides a dashboard that security practitioners and researchers can use to identify gaps in current cyber supply chain practices and develop new risk-informed, cyber supply chain tools and processes.

International Outsourcing in a Two-Sector Heckscher-Ohlin Model

Egger, Hartmut 세종대학교 국제경제연구소 2002 Journal of Economic Integration Vol.17 No.4

This paper analyzes the distributional effects of international outsourcing in a two sector Heckscher-Ohlin type model if both sectors get economical access to cost-saving international outsourcing. Thereby, it is shown that if both sectors are engaged in international outsourcing in equilibrium, the cost-saving effects of outsourcing as well as the factor contents of the outsourced fragments are relevant for the factor price effects. Concerning the Pareto-criterion the main finding is that a Pareto-improving factor orice impact of international outsourcing cannot be excluded from a theoretical point of view.

Efficiently Restoring Virtual Machines

Egger, Bernhard,Gustafsson, Erik,Jo, Changyeon,Son, Jeongseok Springer-Verlag 2015 International journal of parallel programming Vol.43 No.3

Scratchpad Memory Management Techniques for Code in Embedded Systems without an MMU

Egger, Bernhard,Kim, Seungkyun,Jang, Choonki,Lee, Jaejin,Min, Sang Lyul,Shin, Heonshik IEEE 2010 IEEE Transactions on Computers Vol.59 No.8

<P>We propose a code scratchpad memory (SPM) management technique with demand paging for embedded systems that have no memory management unit. Based on profiling information, a postpass optimizer analyzes and optimizes application binaries in a fully automated process. It classifies the code of the application including libraries into three classes based on a mixed integer linear programming formulation: External code is executed directly from the external memory. Pinned code is loaded into the SPM when the application starts and stays in the SPM. Paged code is loaded into/unloaded from the SPM on demand. We evaluate the proposed technique by running 14 embedded applications both on a cycle-accurate ARM processor simulator and an ARM1136JF-S core. On the simulator, the reference case, a four-way set-associative cache, is compared to a direct-mapped cache and an SPM of comparable die area. On average, we observe an improvement of 12 percent in runtime performance and a 21 percent reduction in energy consumption. On the ARM11 board, the reference case run on the 16-KB four-way set-associative cache is compared to the demand paging solution on the 16-KB SPM, optionally supported by the cache. The measured results show both a runtime performance improvement and a reduction of the energy consumption by 23 percent, on average.</P>

On the Problem of Endogenous Unobserved Effects in the Estimation of Gravity Models

( Peter Egger ) 세종대학교 경제통합연구소 2004 Journal of Economic Integration Vol.19 No.1

We propose to estimate gravity models by a Hausman and Taylor (1981) 2SLS error components approach. First, this allows to account for the possible correlation of some of the regressors with the unobserved effects, which has been ignored in previous research. Second and in contrast to the Within estimator, one obtains estimates for the time-invariant variables also in a framework with bilateral effects. We show that distance and country size are important sources of correlation. The properly estimated parameter of distance is about twice as high as its biased GLS counterpart and markedly higher than found by others.

International Outsourcing in a Two-Sector Heckscher-Ohlin Model

( Hartmut Egger ) 세종대학교 경제통합연구소 (구 세종대학교 국제경제연구소) 2002 Journal of Economic Integration Vol.17 No.4

This paper analyzes the distributional effects of international outsourcing in a two sector Heckscher-Ohlin type model if both sectors get economical access to cost-saving international outsourcing. Thereby, it is shown that if both sectors are engaged in international outsourcing in equilibrium, the cost-saving effects of outsourcing as well as the factor contents of the outsourced fragments are relevant for the factor price effects. Concerning the Pareto-criterion the main finding is that a Pareto-improving factor price impact of international outsourcing cannot be excluded from a theoretical point of view.

우유의 살균 및 멸균의 목적과 영향

Klaus Eggers 한국유가공협회 1980 牛乳 Vol.1 No.3

우유는 풍부한 영양때문에 인간이나 젖소에 있어서 필수불가결의 완전식품으로 인정 받고 있다. 그러나 미생물인 세균이 번식하는데도 가장 좋은 영양을 지니고 있으므로 우유는 생산자로부터 가공업자를 거쳐 소비자에 이르기까지 세균의 번식을 최대한 억제시킬 수 있도록 취급되어야 한다.

An Application-Specific and Adaptive Power Management Technique for Portable Systems

이강웅(Bernhard Egger),이재진(Jaejin Lee),신현식(Heonshik Shin) 한국정보과학회 2007 정보과학회논문지 : 시스템 및 이론 Vol.34 No.7·8

본 논문은 dynamic voltage scaling (DVS)를 지원하는 휴대장치를 대상으로 하여 응용프로그램 특성에 따라 실행 중에 전력관리 기법이 다르게 적용되는 적응형 전력관리 기법에 대하여 소개한다. 본 논문의 전력관리 기법은 멀티태스킹 시스템에서 실행되는 soft real-time 프로그램의 memory subsystem 과 프로세서의 실행 시간(run time) 및 유휴 시간(idle time)을 고려하여 프로그램 실행 중에 최적의 DVS가 적용될 수 있도록 하여 전력을 관리한다. 세부적인 전력 및 실행시간 프로파일 정보를 이용할 수 있도록 adaptive power manager(APM)를 개발하여 운영체제에 연동시켰고, Post-pass 최적화기는 APM을 위한 적응형 API를 프로그램의 실행이미지에 삽입하여 실행 중 DVS가 적용되는 코드영역을 표시한다. APM은 프로그램 실행 중에 cache miss 수 등을 측정하는 CPU의 performance counter들을 관찰한다. Performance counter들의 값을 바탕으로 CPU와 memory 중심의 코드 영역을 구분하여 프로세서의 유휴 시간에 대한 분석을 수행하고, 표시된 코드영역들에 대한 최적정 전압과 동작 클락을 결정하여 시스템에 반영한다. 제안하는 기법의 효과를 보이기 위하여 Intel의 XScale 프로세서 상에서 동작하는 Windows CE에 본 기법을 구현하였고, 실험을 통하여 본 논문에서 제시하는 기법이 영상이나 음성 데이타를 해독하는 프로그램과 같이 정기적으로 비슷한 일을 수행하는 프로그램에서 효과적임을 알 수 있었다. 실험 결과 본 기법으로 유휴시간에 프로세서를 저전력모드로 바꾸는 기존의 고전적인 전력 관리 기법보다 전체 시스템 전력 소모를 9% 더 절약할 수 있었다. In this paper, we introduce an application-specific and adaptive power management technique for portable systems that support dynamic voltage scaling (DVS). We exploit both the idle time of multitasking systems running soft real-time tasks as well as memory- or CPU-bound code regions. Detailed power and execution time profiles guide an adaptive power manager (APM) that is linked to the operating system. A post-pass optimizer marks candidate regions for DVS by inserting calls to the APM. At runtime, the APM monitors the CPU’s performance counters to dynamically determine the affinity of the each marked region. For each region, the APM computes the optimal voltage and frequency setting in terms of energy consumption and switches the CPU to that setting during the execution of the region. Idle time is exploited by monitoring system idle time and switching to the energy-wise most economical setting without prolonging execution. We show that our method is most effective for periodic workloads such as video or audio decoding. We have implemented our method in a multitasking operating system (Microsoft Windows CE) running on an Intel XScale-processor. We achieved up to 9% of total system power savings over the standard power management policy that puts the CPU in a low power mode during idle periods.

High-Strength Reinforcing Steel Bars: Low Cycle Fatigue Behavior Using RGB Methodology

Jorge E. Egger,Fabian R. Rojas,Leonardo M. Massone 한국콘크리트학회 2021 International Journal of Concrete Structures and M Vol.15 No.5

Low cycle fatigue life of high-strength reinforcing steel bars (ASTM A706 Grade 80), using photogrammetry by RGB methodology is evaluated. Fatigue tests are performed on specimens under constant axial displacement with total strain amplitudes ranging from 0.01 to 0.05. The experimental observations indicate that buckling of high-strength reinforcing bars results in a damaging degradation of their fatigue life performance as the slenderness ratio increases, including an early rebar failure as the total strain amplitude increases since it achieves the plastic range faster. In addition to this, the results show that the ratio of the ultimate tensile strength to yield strength satisfies the minimum of 1.25 specified in ASTM A706 for reinforcement. On the other hand, the RGB methodology indicates that the axial strains measured by photogrammetry provide more accurate data since the registered results by the traditional experimental setup do not detect second-order effects, such as slippage or lengthening of the specimens within the clamps. Moreover, the RGB filter is faster than digital image correlation (DIC) because the RGB methodology requires a fewer computational cost than DIC algorithms. The RGB methodology allows to reduce the total strain amplitude up to 45% compared to the results obtained by the traditional setup. Finally, models relating total strain amplitude with half-cycles to failure and total strain amplitude with total energy dissipated for multiple slenderness ratios (L/d of 5, 10, and 15) are obtained.