• Title/Summary/Keyword: CPU bandwidth

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Dynamic Allocation Method of CPU Bandwidth for Hard Real-Time Task and Multimedia Task Based on MPEG Video Stream (경성 실시간 태스크와 MPEG 비디오 스트림 기반 멀티미디어 태스크를 위한 CPU 대역폭의 동적 할당 기법)

  • Kim, Jin-Hwan
    • Journal of Korea Multimedia Society
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    • v.7 no.7
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    • pp.886-895
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    • 2004
  • In this paper, we propose the dynamic allocation scheme of the CPU bandwidth to efficiently integrate and schedule these tasks in the same system, where multimedia tasks and hard real-time tasks can coexist simultaneously. Hard real-time tasks are guaranteed based on worst case execution times, whereas multimedia tasks modeled as soft real-time tasks are served based on mean parameters. This paper describes a server-based allocation scheme for assigning the CPU resource to two types of tasks. Especially for MPEG video streams, we show how to dynamically control the fraction of the CPU bandwidth allocated to each multimedia task. The primary purpose of the proposed method is to minimize the mean tardiness of multimedia tasks while satisfying the timing constraints of hard real-time tasks present in the system. We showed through simulations that the tardiness experienced by multimedia tasks under the proposed allocation scheme is much smaller than that experienced by using other scheme.

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Analysis of Delay-Bandwidth Normalization Characteristic in Decay Usage Algorithm of UNIX (UNIX의 Decay Usage 알고리즘에서의 지연시간-사용량 정규화 특성 분석)

  • Park, Kyeong-Ho;Hwang, Ho-Young;Lee, Chang-Gun;Min, Sang-Lyul
    • Journal of KIISE:Computer Systems and Theory
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    • v.34 no.10
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    • pp.511-520
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    • 2007
  • Decay usage scheduling algorithm gives preference to processes that have consumed little CPU in the recent past. It has been widely-used in time-sharing systems such as UNIX, where CPU-intensive processes and interactive processes are mixed. However, there has been no sound understanding about the mixed effects of decay usage parameters on the service performance. This paper empirically analyzes their effects in terms of the resulting service bandwidth and delay Based on such empirical analysis, we derive the clear meaning of each parameter. Such analysis and understanding provides a basis of controlling decay usage parameters for desirable service provision as required by applications.

Event Routing Scheme to Improve I/O Latency of SMP VM (SMP 가상 머신의 I/O 지연 시간 감소를 위한 이벤트 라우팅 기법)

  • Shin, Jungsub;Kim, Hagyoung
    • 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.

Performance Evaluation of Interconnection Network in Microservers (마이크로서버의 내부 연결망 성능평가)

  • Oh, Myeong-Hoon
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.21 no.6
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    • pp.91-97
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    • 2021
  • A microserver is a type of a computing server, in which two or more CPU nodes are implemented on a separate computing board, and a plurality of computing boards are integrated on a main board. In building a cluster system, the microserver has advantages in several points such as energy efficiency, area occupied, and ease of management compared to the existing method of mounting legacy servers in multiple racks. In addition, since the microserver uses a fast interconnection network between CPU nodes, performance improvement for data transfers is expected. The proposed microserver can mount a total of 16 computing boards with 4 CPU nodes on the main board, and uses Serial-RapidIO (SRIO) as an interconnection network. In order to analyze the performance of the proposed microserver in terms of the interconnection network which is a core performance issue of the microserver, we compare and quantify the performance of commercial microservers. As a result of the test, it showed up to about 7 times higher bandwidth improvement when transmitting data using the interconnection network. In addition, with CloudSuite benchmark programs used in actual cloud computing, maximum 60% reduction in execution time was obtained compared to commercial microservers with similar CPU performance specification.

PID algorithm-based Adaptive Bandwidth Control(ABC) System with Incoming Traffic in Home Gateway (홈 게이트웨이에서의 입력 트래픽에 관한 적응적 대역폭 제어 시스템)

  • Choi Dong-Hee;Kim Seong-Hoon;Park Hong-Seong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.5B
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    • pp.442-448
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    • 2006
  • This paper considers a home gateway(HG) that processes VOD services and controls home appliances. This paper proposes a PID algorithm-based adaptive bandwidth control method used in the HG, which guarantees QoS of incoming traffic such as VOD and real-time control data via control of outgoing traffic and have little effects on the CPU computation time. The proposed method is validated via implementation of real test environment.

A Fair Traffic Shaper Design Using a Efficient Polling Scheme in ATM Networks (ATM 망에서 효과적인 폴링 방법을 사용한 트패픽 정형화기의 설계)

  • 김형욱;최승원조태경최명렬
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.111-114
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    • 1998
  • 본 논문에서는 CPU의 역할을 최대한으로 줄이고, 고속으로 트패픽을 정형화 하는 효율적인 정형화기를 설계하였다. 기존에 제시되었던 대부분의 정형화 알고리즘들은 큐를 가지고 CPU에 의해 소프트웨어적으로 트래픽 정형화를 수행하게 된다. 본 논문에서는 주로 하드웨어적으로 정형화 작업을 수행하여 CPU의 부하를 줄여 고속으로 정형화를 수행할 수 있도록 BOP(Bandwidth Oriented Priority) Markovian 정형화기와 Circular 정형화기를 설계하고 시뮬레이션을 수행하였다.

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Scalable scheduling techniques for distributed real-time multimedia database systems (분산 실시간 멀티미디어 데이터베이스 시스템을 위한 신축성있는 스케줄링 기법)

  • Kim, Jin-Hwan
    • The KIPS Transactions:PartA
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    • v.9A no.1
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    • pp.9-18
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    • 2002
  • In this paper, we propose scalable scheduling techniques based on EDF to efficiently integrate hard real-time and multimedia soft real-time tasks in the distributed real-time multimedia database system. Hard tasks are guarangteed based on worst case execution times, whereas multimedia soft tasks are served based on mean execution times. This paper describes a served-based scheme for partitioning the CPU bandwidth among different task classes that coexist in the same system. To handle the problem of class overloads characterized by varying number of tasks and varying task arrival rates, thus scheme shows how to adjust the fraction of the CPU bandwidth assigned to each class. This scheme fixes the maximum time that each hard task can execute in the period of the server, whereas it can dynamically change the bandwidth reserved to each multimedia task. The proposed method is capable of minimizing the mean tardiness of multimedia tasks, without jeopardizing the schedulability of the hard tasks. The performance of this scheduling method is compared with that of similar mechanisms through simulation experiments.

Priority-based Group Task Scheduling Policy for a Multiplayer Real-time Game Server (다중사용자용 실시간 게임 서버를 위한 우선순위 기반 그룹 태스크 스케쥴링 정책)

  • Kim, Jin-Hwan
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.4
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    • pp.57-64
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    • 2012
  • Multiplayer, real-time games are a kind of soft real-time systems because a game server has to respond to requests from many clients within specified time constraints. Client events have different timeliness and consistency requirements according to their nature in the game world. These requirements lead to different priorities on CPU processing. Events can be divided into different groups, depending on their consistency degree and priority. To handle these events with different priority and meet their timing constraints, we propose a priority-based group task scheduling policy in this paper. The number of clients or events requested by each client may be increased temporarily. In the presence of transient overloading, the game server needs to allocate more CPU bandwidth to serve an event with the higher priority level preferentially. The proposed scheduling policy is capable of enhancing real-time performance of the entire system by maximizing the number of events with higher priority completed successfully within their deadlines. The performance of this policy is evaluated through extensive simulation experiments.

CUDA based Lossless Asynchronous Compression of Ultra High Definition Game Scenes using DPCM-GR (DPCM-GR 방식을 이용한 CUDA 기반 초고해상도 게임 영상 무손실 비동기 압축)

  • Kim, Youngsik
    • Journal of Korea Game Society
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    • v.14 no.6
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    • pp.59-68
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    • 2014
  • Memory bandwidth requirements of UHD (Ultra High Definition $4096{\times}2160$) game scenes have been much more increasing. This paper presents a lossless DPCM-GR based compression algorithm using CUDA for solving the memory bandwidth problem without sacrificing image quality, which is modified from DDPCM-GR [4] to support bit parallel pipelining. The memory bandwidth efficiency increases because of using the shared memory of CUDA. Various asynchronous transfer configurations which can overlap the kernel execution and data transfer between host and CUDA are implemented with the page-locked host memory. Experimental results show that the maximum 31.3 speedup is obtained according to CPU time. The maximum 30.3% decreases in the computation time among various configurations.

A Prioritized Task Scheduling Method in Multimedia Systems for MPEG-2 Decoding (MPEG-2 디코딩을 위한 멀티미디어 시스템에서 우선순위에 의한 태스크 스케쥴링 기법)

  • Kim Jinhwan
    • The KIPS Transactions:PartB
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    • v.12B no.2 s.98
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    • pp.173-180
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    • 2005
  • In this paper, we propose an efficient real-time scheduling method of multimedia tasks for decoding frames of MPEG-2 video streams. In our task model, each frame is decoded by a separate multimedia task. The decoding task for each frame is assigned to the priority according to the precedence and importance of frames in a video stream. We use a priority-based scheduling policy in order to effectively allocate the CPU bandwidth to multimedia tasks for MPEG-2 decoding. We show how to dynamically control the fraction of the CPU bandwidth allocated to each multimedia task according to the priority. The primary purpose of our scheduling method is to enhance the real-time performance of the multimedia system by minimizing the number of decoding tasks that have missed their deadlines while reducing the decoding times of these multimedia tasks. The performance of this scheduling method is compared with that of similar mechanisms through simulation experiments.