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Mobile — 60
NSL — 19
NSL Project — 2

Unifying DVFS and Offlining in Mobile Multicores

by Wonjun Hwang on 2015-05-04 18:49:20

Date: 2015. 05. 08. (Fri) 10:00 A.M. Locate: EB5. 533 Presenter: Wonjun Hwang Seminar title: Unifying DVFS and Offlining in Mobile Multicores Authors: Aaron Carroll and Gernot Heiser Abstract: Energy efficiency is a primary design criterion of the modern smartphone due to limitations in battery capacity. Multi-core processors are now commonplace in these devices, which adds a new dimension, the number cores used, to energy management. In this paper we investigate how the mechanisms of frequency scaling and core offlining interact, and how to use them to reduce energy consumption. We find surprising differences in the characteristics of latest-generation smartphones, specifically in the importance of static power. This implies that policies that work well on one processor can lead to poor results on another.  We propose a simple policy that integrates core offlining with frequency scaling and implement it ... Continue reading →

372 Views

The Missing Numerator: Toward a Value Measure for Smartphone Apps

by Jemin Lee on 2015-04-08 10:36:23

Date: 2015. 04. 08. (Fri) 10:00 A.M. Locate: EB5. 533 Presenter: Jemin Lee Seminar title: The Missing Numerator: Toward a Value Measure for Smartphone Apps Authors: Anudipa Maiti and Geoffrey Challen Abstract: While great strides have been made in measuring energy consumption, these measures alone are not sufficient to enable effective energy management on battery-constrained mobile devices. What is urgently needed is a way to put energy consumption into context by measuring the value delivered by mobile apps. While difficult to compute, an accurate value measure would enable cross-app comparison, app improvement, energy inefficient app detection, and effective runtime energy allocation and prioritization. Our paper motivates the problem, describes requirements for a value measure, discusses and evaluates several possible inputs to such a measure, and presents results from a preliminary (unsuccessful) attempt to formulate one.  Download: paper   Continue reading →

512 Views

A case for battery charging-aware power management and deferrable task scheduling in smartphones

by Donggeon Han on 2015-04-03 09:56:17

Date: 2015. 04. 03. (Fri) 10:00 A.M. Locate: EB5. 533 Presenter: Donggeon Han Seminar title: A case for battery charging-aware power management and deferrable task scheduling in smartphones Authors: Salma Elmalaki Abstract: Prior battery-aware systems research has focused on discharge power management in order to maximize the usable battery lifetime of a device. In order to achieve the vision of perpetual mobile device operation, we propose that software also needs to carefully consider the process of battery charging. This is because the power consumed by the system when plugged in can influence the rate of battery charging, and hence, the availability of the system to the user. We characterize the charging process of a Nexus 4 smartphone and analyze the charging behaviors of anonymous Nexus 4 users using the Device Analyzer dataset. We find that there is potential for software schedulers to increase ... Continue reading →

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A Virtualized Separation Kernel for Mixed Criticality Systems

by SiHyeong Park on 2015-03-24 20:40:36

Date: 2015. 03. 27. (Fri) 10:00 A.M. Locate: EB5. 533 Presenter: SiHyeong Park Seminar title: A Virtualized Separation Kernel for Mixed Criticality Systems Authors: Ye Li, Richard West, Eric Missimer Abstract: Multi- and many-core processors are becoming increasingly popular in embedded systems. Many of these processors now feature hardware virtualization capabilities, such as the ARM Cortex A15, and x86 processors with Intel VT-x or AMD-V support. Hardware virtualization offers opportunities to partition physical resources, including processor cores, memory and I/O devices amongst guest virtual machines. Mixed criticality systems and services can then coexist on the same platform in separate virtual machines. However, traditional virtual machine systems are too expensive because of the costs of trapping into hypervisors to multiplex and manage machine physical resources on behalf of separate guests. For example, hypervisors are needed to schedule separate VMs on physical ... Continue reading →

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LEON3 DBT 엔진을 이용한 ERC32 기반의 하이퍼바이저 프로토 타입 개발

by Juyeob Kim on 2015-03-20 11:31:35

Date : 2015. 03. 20. (Fri) 10:00 A.M. Locate : EB5. 533 Presenter : Jooyoeb Kim   Seminar title: LEON3 DBT 엔진을 이용한 ERC32 기반의 하이퍼바이저 프로토타입 개발 Authors 최종욱, 천이진 Abstract 가상화 기술은 여러 개의 게스트 운영체제를 동시에 하나의 물리 머신에서 실행 할 수 있는 기술로 오 늘날 컴퓨팅 시스템에 광범위하게 이용되고 있으며 서버급 및 클라우드 컴퓨팅 환경의 핵심기술로 활용된다. 이러한 가상화 기술은 모바일 환경에서도 적극 개발 및 활용 되고 있으며, 위성 분야에서도 프로세서의 성능 향상과 함께 멀티코어로 발전됨에 따라 IMA기술에 대한 연구가 ESA를 주축으로 진행되고 있으며 국내 대학에서도 우주용 전가상화 하이퍼바이저 관련 연구를 수행하고 있다. 본 논문에서는 지난 연구에 이어 LEON3 vCPU의 성능 향상을 위해 인터프리터 방식 대신 Dynamic Binary Translation 기술을 적용한 전가상화 기법의 Bare-Metal 하이퍼바이저 개발 방법에 대해서 기술하며, 개발 된 하이퍼바이저 상에서 LEON3 벤치마킹 프로그램을 통한 성능 비교 분석을 수행한다. Proceeding : 한국항공우주학회 학술논문 발표집 한국항공우주학회 2013년도 추계학술대회, 2013.11, 699-705 (7 pages)   Continue reading →

551 Views

Contextual Experience Sampling of Mobile Application Micro-Usage

by Jinyoung Choi on 2015-03-16 16:06:33

Date : 2015. 03. 20. (Fri) 10:00 A.M. Locate : EB5. 533 Presenter : Jinyoung Choi   Seminar title: Contextual Experience Sampling of Mobile Application Micro-Usage Authors Denzil Ferreira, Jorge Goncalves, Vassilis Kostakos, Louise Barkhuus, Anind Dey Abstract Research suggests smartphone users face “application overload”, but literature lacks an in-depth investigation of how users manage their time on smartphones. In a 3-week study we collected smartphone application usage patterns from 21 participants to study how they manage their time interacting with the device. We identified events we term application micro-usage: brief bursts of interaction with applications. While this practice has been reported before, it has not been investigated in terms of the context in which it occurs (e.g., location, time, trigger and social context). In a 2-week follow-up study with 15 participants, we captured participants’ context while micro-using, with a ... Continue reading →

393 Views

Designing A Microphone Array For Measurement On Wind Noise Of Vehicle In The Wind Tunnel

by Jinse Kwon on 2015-02-23 15:17:38

Date : 2015. 03. 03 (Tue) 01:00 P.M. Locate : EB5. 533 Presenter : Kwon JinSe Seminar title: Designing A Microphone Array For Measurement On Wind Noise Of Vehicle In The Wind Tunnel Authors : JunGoo Kang, Jong-Soo Choi, Myunghan Lee and Byung-ho An Abstract The delay and sum beamforming method of microphone array is widely used in localization of noise source. In this paper, the wind noise generated from a vehicle was measured in the wind tunnel with microphone array and the array pattern was specifically designed for localization of the wind noise. The performance of microphone array was evaluated with both the 3-dB bandwidth of the main-lobe and the level difference between the main-lobe and the maximum side-lobe. While measuring vehicle noise outside the flow stream of wind tunnel, we should know the flow velocity and the propagation path of the sound waves which was refracted according to wind profile as it travels through the airstream. This can cause the ... Continue reading →

426 Views

The Trouble With Multicore

by Wonjun Hwang on 2015-02-09 14:00:52

Date : 2015. 02. 10 (Tue) 01:00 P.M. Locate : EB5. 533 Presenter : Hwang Wonjun Seminar title: The Trouble With Multicore Authors David Patterson University of California, Berkeley Abstract Designers now accept that although transistors will still get smaller and more numerous on each chip, they aren't going to operate faster than they do toady.And if you tried to incorporate all those transistors into one giant microprocessor, you might well end up with a device that couldn't compute any faster than the chip it was replacing, which explains the shift to assembling them into multiple microprocessor cores instead. Proceeding :  Spectrum, IEEE  (Volume:47 ,  Issue: 7 ) Link : http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5491011&tag=1   Continue reading →

374 Views

User interaction-based profiling system for Android application tuning

by Jorge Frisancho on 2015-01-27 04:12:26

Date : 2015. 01. 27 (Tue) 01:00 P.M. Locate : EB5. 533 Presenter : Jorge Frisancho Seminar title: User interaction-based profiling system for Android application tuning Authors: Seokjun Lee, Chanmin Yoon, Hojung Cha Abstract Quality improvement in mobile applications should be based on the consideration of several factors, such as users' diversity in spatio-temporal usage, as well as the device's resource usage, including battery life. Although application tuning should consider this practical issue, it is difficult to ensure the success of this process during the development stage due to the lack of information about application usage. This paper proposes a user interaction-based profiling system to overcome the limitations of development-level application debugging. In our system, the analysis of both device behavior and energy consumption is possible with fine-grained process-level application monitoring. By providing fine-grained information, including user ... Continue reading →

440 Views

Application of NASA CFS on the Development of Korea Moon Explorer Flight Software

by Guest on 2015-01-26 21:34:21

Date : 2015. 2. 10 (Tue) 01:00 P.M. Presenter : 변대철 Authors : 구철회*, 문성태, 이훈희, 한상혁, 주광혁, 심은섭 Seminar title : Application of NASA CFS on the Development of Korea Moon Explorer Flight Software ABSTRACT : Conceptual design and lander demonstrator of Korea Lunar exploration mission has been developing since 2010 by Korea Aerospace Research Institute. Propulsion and attitude control system are planed to test at Goheung Aviation Center at 2012. But it is only the beginning of research when comparing with USA, Europe, Japan and China whose countries have the advanced space technology and experiences, for example for Moon and space exploration. So these results from the prior-executed missions shall be referenced to internal researching and planning for this Moon exploration mission. Especially USA NASA has a lot of cases of space exploration missions, recently NASA launched LRO/LCROSS to Moon at 2009 and Curiosity to Mars at 2012. The stable and cost effective software development ... Continue reading →

384 Views

BatteryExtender: An Adaptive User-Guided Tool for Power Management of Mobile Devices

by Jemin Lee on 2015-01-19 21:46:21

Date : 2015. 01. 20 (Tue) 01:00 P.M. Locate : EB5. 533 Presenter : Jemin Lee   Title: BatteryExtender: An Adaptive User-Guided Tool for Power Management of Mobile Devices Authors     Grace Metri   Department of Computer Science, Wayne State University Abstract The battery life of mobile devices is one of their most important resources. Much of the literature focuses on accurately profiling the power consumption of device components or enabling application developers to develop energy-efficient applications through fine-grained power profiling. However, there is a lack of tools to enable users to extend battery life on demand. What can users do if they need their device to last for a specific duration in order to perform a specific task? To this extent, we developed BatteryExtender, a user-guided power management tool that enables the reconfiguration of the device’s resources based on ... Continue reading →

372 Views

VIT: A Timer Hypercall to Support Real-time of Guest Operating Systems

by Guest on 2015-01-13 12:35:56

Abstract Guest operating systems running over the virtual machines share a variety of resources. Since CPU is allocated in a time division manner it consequently leads them to having the unknown physical time. It is not regarded as a serious problem in the server virtualization fields. However, it becomes critical in embedded systems because it prevents guest OS from executing real time tasks when it does not occupy CPU. In this paper we propose a hypercall to register a timer service to notify the timer request related real time. It enables hypervisor to schedule a virtual machine which has real time tasks to execute, and allows guest OS to take CPU on time to support real time. The following experiment shows its implementation on Xen-Arm and para-virtualized Linux. We also analyze the real time performance with response time of test application and frames per second of Mplayer. Continue reading →

371 Views

powerlet:An active battery interface for smartphones

by Donggeon Han on 2015-01-13 12:34:14

Date : 2015. 01. 13 (Tue) 13:00  Locate : EB5. 533 Presenter : Donggeon Han   Title : Powerlet: An Active Battery Interface for Smartphones Authors Wonwoo Jung, Yohan Chon, Dongwon Kim, Hojung Cha (Department of Computer Science, Yonsei university, Seoul, Korea) Abstract A smartphone battery interface should provide ener-gy-related information efficiently with high accuracy be-cause it is the basis for user actions on battery consumption. Previous studies have mainly focused on battery information per se, but the effectiveness of user interaction with the interface has barely been studied. In this paper, we first discuss the results of a survey on different types of ener-gy-related information and features to investigate what users want in terms of battery consumption for smartphones. We then introduce Powerlet, which is a new battery interface that attempts to actively interact with users to provide battery usage information. We validated the efficiency of ... Continue reading →

379 Views

Common ESL Mistakes in Research Writing

by Jorge Frisancho on 2014-12-24 05:07:18

Title: Common ESL Mistakes in Research Writing By Robert C. Meurant. Date: 2014. 12. 24 (Wed) 10:00 A.M. Locate: EB5. 533 Presenter: Jorge Frisancho   Continue reading →

382 Views

Efficient Memory Virtualization for Cross-ISA System Mode Emulation

by SiHyeong Park on 2014-12-05 14:00:52

Date : 2015. 01. 06 (Tue) 13:00  Locate : EB5. 533 Presenter : Sihyeong Park   Title : Efficient Memory Virtualization for Cross-ISA System Mode Emulation Authors Chao-Jui Chang    Academia Sinica, Taipei, Taiwan Roc Jan-Jan Wu          Academia Sinica, Taipei, Taiwan Roc Wei-Chung Hsu    National Taiwan University, Taipei, Taiwan Roc Pangfeng Liu         National Taiwan University, Taipei, Taiwan Roc Pen-Chung Yew    University of Minnesota at Twin Cities, Minneapolis, USA   Abstract Cross-ISA system-mode emulation has many important applications. For example, Cross-ISA system-mode emulation helps computer architects and OS developers trace and debug kernel execution-flow efficiently by emulating a slower platform (such as ARM) on a more powerful plat-form (such as an x86 machine). Cross-ISA system-mode emulation also enables workload consolidation in data centers with platforms ... Continue reading →

517 Views