General Purpose Operating Systems (GPOSes)

International Conference on Enterprise Information Systems, 2005

The CEDRIC and the IRCAM conduct since 2002 a project entitled "distributed orchestra" which proposes to coordinate on a network the actors of a musical orchestra (musicians, sound engineer, listeners) in order to produce a live concert. At each site (musician), mainly two components are active: the sound engine ( FTS ) and an auto-synchronisation module ( nJam ), two

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.

ARTOSS

Resource Reservation (RR) is a class of real-time schedulers, proposed by the research community for hard and soft real-time systems, which are receiving considerable attention from industry. With this white paper, we would like to trigger a broad discussion between the academic and the industrial world on the use of RR techniques in standard operating systems. After presenting the major reasons for using RR ("why"), we present a set of propositions on "what" and "how" should be provided, which pinpoint the demands on operating systems and the research issues that remain to be addressed.

2008 IEEE International Conference on Emerging Technologies and Factory Automation, 2008

Many applications executed nowadays on Personal Computers are multimedia applications characterised by soft real-time constraints. Even if they could benefit from a specialised OS support for real-time computing, the absence of standardised solutions often hinders this possibility. We propose a mechanism to export the benefits of real-time scheduling to legacy applications, based on the combination of two techniques: 1) a real-time monitor that observes the sequence of events generated by the application to infer its activation period, 2) a feedback mechanism that adapts the scheduling parameters to ensure a timely execution of the application.

1996

Hard Real Time (HRT) kernels have their timely behaviour guaranteed on the cost of a rather restrictive use of the available resources. This makes current HRT scheduling techniques inadequate for use in a multimedia environment where we can make a considerable pro t by a better and more exible use of the resources. We will show that we can improve the exibility and e ciency of multimedia kernels by combining Real Time Transactions with Deadline Inheritance policies under the Earliest Deadline First or the Deadline Monotonic rule. A currently running multimedia experiment shows a scheduling overhead of less than 0.5 percent. We also present the main ingredients for an open and adaptive Quality of Service (QoS) management. In particular a technique for rapid QoS schedulability analyses is o ered. This technique can be applied to Hard Real Time analyses as well 1 .

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. Preliminary experimental results are reported, proving the effectiveness of the proposed idea in providing a widely used multimedia player on Linux with appropriate QoS guarantees, through an appropriate choice of the scheduling parameters. Finally, a detailed road-map is presented with the possible extensions to the approach.

International Computer Music Conference Proceedings, 1998

The Audio Rendering Engine And Library (AREAL) offers a set of tools for developing realtime audio applications for Pentium computers running Windows 95/NT. It consists of a real-time scheduler and a framework for developing sound synthesis classes. AREAL lets composers and sound designers develop applications which address research into audio algorithms, their control in real time, and their correlation with non-audio processes. It emphasizes efficiency and low CPU overhead, coexisting well with other graphics and modeling computation possibly sharing its CPU. We briefly describe AREAL's design goals, architecture, and use.

2009 10th International Symposium on Pervasive Systems, Algorithms, and Networks, 2009

Nowadays, most embedded systems support different kinds of multimedia applications and real-time tasks. The computational requirements of multimedia applications are usually very expensive and embedded systems may not be powerful enough to support multiple multimedia applications. As a result, real-time tasks will miss their deadlines and thus get rejected. To solve this problem, we propose a Dynamic Workload Shaping (DWS) method by extending a Dynamic Buffering Technique to multiple multimedia tasks and integrating two optimization methods. The scheduling method dynamically changes the playout buffer fill level of multimedia applications to periodically free up sufficient processor bandwidth to support other concurrently running real-time applications. The original scheduling method can only guarantee that the playout devices can always read out data items from the playout buffers, but cannot guarantee any QoS. Two algorithms are proposed in this work to optimize and guarantee the quality of multimedia applications. The first algorithm optimizes the multimedia playout device rates, in terms of frames per second, while allowing a real-time task to meet its deadline. The second algorithm optimizes the processor bandwidth allocations, in terms of MHz, given to each of the multimedia tasks, while allowing a real-time task to meet its deadline. We use several examples to illustrate how both algorithms can be applied to real systems.

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.

Proceedings of the sixteenth ACM symposium on Operating systems principles - SOSP '97, 1997

Workstations and personal computers are increasingly being used for applications with real-time characteristics such as speech understanding and synthesis, media computations and I/O, and animation, often concurrently executed with traditional nonreal-time workloads. This paper presents a system that can schedule multiple independent activities so that: