Operating system support for multimedia systems

1990

Abstract We describe work on system support for multimedia applications currently underway at UCSD. We are focusing on operating system I/O mechanisms and network multicasting algorithms. The project is comprised of two assistant professors (the authors), seven graduate students, and one undergraduate.

1992

Real-time operating system services are required to support multimedia systems that rely heavily of the workstation processor for control of the audio and video processors and movement of audio and video data. Such services are typically not available in existing workstation operating systems. This note comments on the requirements for such services and briefly describes the YARTOS kernel; an operating system kernel that provides real-time communication and computation services.

Proceedings Real-Time Technology and Applications Symposium, 1995

Distributed multimedia applications are typical of a new class of workstation applications that require realtime communication and computation services to be effective. Unfortunately, there remains a wide gap between the development of real-time computing technology in the research community and the deployment of real-time solutions in commercial systems. In this work we explore technology for allowing two operating systems, a general purpose operating system and a predictable real-time kernel, to co-exist on the same hardware. We discuss the problems of multiplexing shared devices and partitioning shared data structures to accommodate two operating systems, and present a CPU executive that allows the IBM Microkernel (a derivative of the Mach microkernel) with an OSF/1 server to co-exist with a simple real-time kernel we have built. We also extend the traditional theory of scheduling periodic tasks on a uniprocessor to accommodate the case where a real-time kernel is allocated only a fraction of the total CPU capacity.

Proceedings of IEEE International Conference on Multimedia Computing and Systems MMCS-94, 1994

Multimedia applications have timing requirements that cannot generally be satisfied using the time-sharing scheduling algorithms of general purpose operating systems. Our approach is to provide the predictability of real-time systems while retaining the flexibility of a timesharing system. We designed a processor capacity reservation mechanism that isolates programs from the timing and execution characteristics of other programs in the same way that a memory protection system isolates them from outside memory accesses. In this paper, we describe a scheduling framework that supports reservation and admission control, and we introduce a novel reserve abstraction, specifically designed for the microkernel architecture, for measuring and controlling processor usage. We have implemented processor capacity reserves in Real-Time Mach, and we describe the performance of our system on several types of applications.

1994

Multimedia applications have timing requirements that cannot generally be satisfied using the time-sharing scheduling algorithms of general purpose operating systems. Our approach is to provide the predictability of real-time systems while retaining the flexibility of a timesharing system. We designed a processor capacity reservation mechanism that isolates programs from the timing and execution characteristics of other programs in the same way that a memory protection system isolates them from outside memory accesses. In this paper, we describe a scheduling framework that supports reservation and admission control, and we introduce a novel reserve abstraction, specifically designed for the microkernel architecture, for measuring and controlling processor usage. We have implemented processor capacity reserves in Real-Time Mach, and we describe the performance of our system on several types of applications.

1997

Increases in processor speeds and the availability of audio and video devices for personal computers have encouraged the development of interactive multimedia applications for teleconferencing and digital audio/video presentation among others. These applications have stringent timing constraints, and traditional operating systems are not well suited to satisfying such constraints. On the other hand, hard real-time systems that can meet these constraints are typically static and inflexible. This dissertation presents an enforced operating system resource reservation model for the design and implementation of predictable real-time programs. Applications can reserve resources based on their timing constraints, and an enforcement mechanism ensures that they do not overrun their reservations. Thus, reserves isolate real-time applications from the temporal properties of other real-time (and non-real-time) applications just as virtual memory systems isolate applications from memory accesses by other applications. In addition, reserves are first class objects that are separated from control abstractions such as processes or threads. Therefore reserves can be passed between applications, and this model extends naturally to distributed systems. Reserves support the development of hard real-time and soft real-time programs, and programming techniques based on reserves illustrate how to use them effectively. An implementation of processor reserves in Real-Time Mach shows that reserved multimedia applications can achieve predictable real-time performance. vi vii Acknowledgments I would like to express my appreciation to my advisors, Mootaz Elnozahy and Raj Rajkumar, for their guidance, technical expertise, and time which they so generously shared with me during my doctoral studies. Thanks also to M. Satyanarayanan, Hide Tokuda, and Kevin Jeffay for their insights, critical comments, and encouragement. I am especially indebted to Hide Tokuda who was my mentor for several years before I entered the graduate program at CMU. Hide started the Real-Time Mach Project, which provided the research environment for this work, and Raj took over the project in the final years of my thesis work. I am indebted to both of them for their support. I would like to thank Jim Morris for his guidance and assistance. He helped me better understand how to do systems research and served as a role model for me. Thanks go to Roger Dannenberg for the opportunity to work with him and learn from him on several interesting computer music projects (and for the occasional trumpet duet and brass ensemble session). A special thanks to Joan Maddamma who looked out for me in many ways during my years at CMU. From the time I was an undergraduate through my years as a graduate student, Joan has been a very special friend. Many other people who I worked with over the years had a positive influence on me and on the work contained in this dissertation. I would like to thank Stefan Savage and Jim Zelenka for their help with pieces of the implementation of reserves in Real-Time Mach and for being good friends and colleagues. And I would like to thank

This paper describes the general problems in providing system software support for multimedia applications. Wespecifically focus on applications which have digital continuous media (DCM) I/O components, and the type of supportthat must be provided by the network software and operating system. DCM applications have large bandwidth and low delay requirements. We discuss network software support to meetthese requirements, such as resource reservation schemes based on parameterized requests for some level of ...

Future Generation Computer Systems, 2003

An integrated storage platform for open systems should be able to meet the requirements of deterministic applications, multimedia systems, and traditional best-effort applications. It should also provide a scheduling mechanism fitting all those types of applications. In this paper, we propose a two-level hierarchical disk scheduling scheme, named 2-Q, which can guarantee deterministic deadlines, maximize the number of statistic real-time streams processed by the disk system, and minimize the average latency for best-effort requests. The upper level of the scheduling architecture, server level, is divided into three queues: deterministic, statistic, and best-effort requests. Each server may have its own scheduling algorithm. The lower level, disk driver, chooses the ready streams using its own scheduling criteria. We also propose an adaptive admission control algorithm relying on worst and average values of disk server utilization. Only streams satisfying the admission algorithm criteria are accepted for further processing by the disk server. The solution is extended to a parallel disk system by using a third hierarchical level, named meta-scheduler, briefly described in the paper. The performance evaluations demonstrate that our scheduling architecture is adequated for handling stream sets with different deterministic, statistic, or best-effort requirements.

2009

Multimedia is an increasingly important part the mix of applications that users run on personal computers and workstations. The requirements placed on a multimedia operating system are demanding and often conflicting. After studying multimedia characteristics and multimedia system requirements, this paper presents a new operating system for multimedia files and applications and it calls this operating system an Optimal Multimedia Operating System as optimal operating system solution for multimedia applications and files and compare this optimal operating system with three existing operating system: QLinux, Mac osx Leopard, Windows Vista.

2011

Abstract The last decade a trend can be observed towards multi-processor Systems-on-Chip (MPSoC) platforms for satisfying the high computational requirements of modern multimedia applications. The research community has mainly focused on communication issues (eg bus vs. networks-on-chip). Real-time operating systems for MPSoCs however, have gotten very little attention.

Multimedia applications have timing requirements that cannot generally be satisfied using time-sharing scheduling algorithms and system structures. To effectively support these types of programs, operating systems must support processor capacity reservation. A capacity reservation and enforcement mechanism isolates programs from the timing and execution characteristics of other programs in the same way that a memory protection system isolates programs from memory access by other programs. In this paper, we characterize the timing requirements and processor capacity reservation requirements for multimedia applications, we describe a scheduling framework to support reservation and admission control, and we introduce a novel reserve abstraction, specifically designed for the microkernel architecture, for controlling processor usage.

Technology, Management and Applications, 2002

Distributed multimedia applications are characterized by timing constraints and endto-end quality of service (QoS) requirements, and, therefore need efficient management mechanisms to respond to transient changes in the load or the availability of the resources. This chapter presents a real-time distributed multimedia framework, based on the Common Object Request Broker Architecture (CORBA), that provides resource management and Quality of Service (QoS) for CORBA applications. The framework consists of multimedia components and resource management components. The multimedia components produce multimedia streams, and combine multimedia streams generated by individual sources into a single stream to be received by the users. The resource management components provide QoS guarantees during multimedia transmissions based on information obtained from monitoring the usage of the system's resources.

International Journal of Intelligent Systems, 1998

We describe the design and implementation of the RIO (Randomized I/O) multimedia object server which manages a set of parallel disks and supports real-time throughput and statistical delay guarantees. This storage subsystem was implemented as part of a multimedia information server which supports multiple concurrent applications such as video on demand and 3D interactive virtual worlds. We discuss the principal issues and innovations involved in the design and implementation of the RIO storage system, and present experimental performance results measured on a prototype implementation.

International Journal of Parallel, Emergent and Distributed Systems

The emerging real-time hyper-physical system (CPS), such as autonomous vehicle and live interactive media application, requires time deterministic behaviour. This is challenging to achieve by using the traditional general purpose operating system (GPOS). This paper presents a new design of the real-time operating system (OS) scheduling mechanism called 'time deterministic cyclic scheduling' (TDCS) mainly for live multimedia tasks processing. This new scheduler shares a similar philosophy as classic cyclic execution but with flexibility and dynamic configuration. This hybrid design is based on both time-reserved based cyclic execution and priority-based pre-emptive scheduling for mixed criticality applications. The simulation results show that this scheduling scheme can achieve predictable timing behaviour of task delay and jitter under high CPU utilisation. This shows that the proposed scheme is promising for low latency high-performance multimedia censoring tasks that occur in a periodic manner.

2009 IEEE/ACM/IFIP 7th Workshop on Embedded Systems for Real-Time Multimedia, 2009

Multimedia applications are often characterised by implicit temporal constraints but, in many cases, they are not programmed using any specialised real-time API. These "Legacy applications" have no way to communicate their temporal constraints to the OS kernel, and their quality of service (QoS), being necessarily linked to the temporal behaviour, fails to satisfy acceptable standards. In this paper we propose an innovative way for dealing with these applications, based on the combination of an on-line identification mechanism (which extracts from high-level observations such important parameters as the execution rate) and an adaptive scheduler (specialised for legacy applications) that identifies the correct amount of CPU needed by each application.