B. Srinivasan, S. Pather, R. Hill, F. Ansari, and D. Niehaus, "A firm real-time system implementation using commercial off-the-shelf hardware and free software," presented at the 4th IEEE Real Time Technology and Applications Symp. (RTAS), Denver, CO, June 1998.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Route 1.76 0.80 2.00 Diagonal Route 1.32 1.50 2.29 Circular Route 1.22 1.51 2.22 Table 1 The best tracking errors of the target in different routes. 4.2. CPU Resource Allocation We have implemented a Real Time Scheduling Service (RTSS) in C , on top of the KU Real Time system (KURT) [5] that adds real time functionality to Linux. First, the RTSS provides an interface between the agents and the system timers, allowing agents to: 1) query the operating system about the current time; 2) ask the RTSS to notify them after the passage of certain length of time; and (3) ask the RTSS ....

Srinivasan, B., Pather, S., Hill, R., Ansari, F., and Niehaus, D. 1998. A Firm Real-Time System Implementation Using Commercial Off-The Shelf Hardware and Free Software, in: Proceedings of RTAS-98, June, Denver, CO, 112-119.

....40000 60000 80000 100000 120000 140000 Video Inter Frame Times Standard Linux Figure 7. Inter Frame times for standard Linux. Heavy kernel load is run in the background. A different approach for reducing the OS latency is used by other systems, such as RTLinux [5] RTAI [12] and KURT [19], which decrease the latency by running Linux as a background process over a small real time executive. In this case, real time tasks are not Linux processes, but run on the lower level real time executive, and the Linux kernel runs as a non real time task. This solution provides good real time ....

B. Srinivasan, S. Pather, R. Hill, F. Ansari, and D. Niehaus. A firm real-time system implementation using commercial off-the-shelf hardware and free software. In Proceedings of the IEEE Real-Time Technology and Applications Symposium, 1998.

....system. The complete real time schedule is such that the owner s constraints are not violated. Including transfers from, and to, the image server, to support not only instantiation of a VM s state in remote resources, but also checkpointing. 9 We currently target Real time Linux [35] KURT [28], or RTAI [5] We also plan to investigate other techniques, including modulating the priority of virtual machine processes under the regular linux scheduler, using SIGSTOP SIGCONT signal delivery to virtual machine processes to approximate the desired real time schedule, and implementing ....

Balaji Srinivasan, Shyamalan Pather, Robert Hill, Furquan Ansari, and Douglas Niehaus. A firm realtime system implementation using commerical off-the-shelf hardware and free software. In Proceedings of the IEEE Real-time Technology Applications Symposium (RTAS 1998.

....worst case evaluations for real time operating systems (e.g. 23] However, we are unaware of any work that specifically addresses the worst case overhead of using address spaces in real time systems. In this paper, we concentrate on hybrid real time and time sharing operating systems: KURT [21] and Linux RK [18] are real time extensions of the Linux kernel. These systems target real time applications that make use of UNIX system services and that may run in separate address spaces (i.e. they are shared kernel system) Additionally, KURT can also operate as a sharedspace system. As ....

B. Srinivasan, S. Pather, R. Hill, F. Ansari, and D. Niehaus. A firm real-time system implementation using commercial off-the-shelf hardware and free software. In Fourth IEEE Denver, Colorado, June 1998.

....time for the first 100 resolution they are rarely scheduled every microsecond. Rather than interrupt CPU at the fixed rate, the timer chip is programmed to interrupt CPU at the time of the earliest scheduled event. This approach yields good results, and the achieved accuracy is up to 50 s [3]. However, UTIME does a large modification of the kernel, and it can possibly havesomenegative side effects. It is not a part of the official kernel that was verified byhundreds of independent people. Another problem is practical usability: the required patch only installs on the certain kernel ....

B. Srinivasan, A Firm Real-Time System Implementation Using Commercial Off-The-Shelf Hardware and Free Software. Master of Science thesis, University of Kansas, 1998.

....task is preempted in favor of the most eligible realtime task. This improves the maximum latency seen by a real time task from default 100 ms in LINUX to 10 ms. Even better latency bounds with microsecond resolution can be achieved by reprogramming the timer chip for every scheduling decision [25]. However, this entails additional overhead for each timer chip reprogramming operation. 3.4 Disk I O Subsystem Traditional disk subsystems use the SCAN algorithm to schedule disk I O requests. SCAN algorithm sorts requests according to their track positions on the disk and services them in the ....

....ensuring liveness of applications that are not real time. Real time LINUX (RT Linux) 4] provides hard real time support by inserting a real time kernel layer between the LINUX kernel and the hardware interrupts. LINUX kernel is just another real time task having the lowest priority. KURT Linux [25] adds rm real time capabilities to the standard Linux by running the hardware timer as an aperiodic device. 6 Summary In this paper, we presented the design and implementation of an Integrated Real time Resource Scheduler (IRS) IRS provides a framework for integrated allocation and scheduling ....

B. Srinivasan, et. al., \A Firm Real-time System Implementation Using Commercial O-The-Shelf Hardware and Free Software", Proc. of RTAS'98, June 1998.

....is that they impose (soft) realtime constraints, and consequently, require predictable performance guarantees from the underlying operating system. Several resource management techniques have been developed for predictable allocation of processor bandwidth to meet the needs of such applications [2, 3, 10, 16]. Proportionate fair schedulers are one such class of scheduling algorithms [5] A proportionate fair (P fair) scheduler allows an application to request x i time units every y i time quanta and guarantees that over any T quanta, T 0, a continuously running application will receive between b x ....

B. Srinivasan, S. Pather, R. Hill, F. Ansari, and D. Niehaus. A Firm Real-Time System Implementation using Commercial Off-the-Shelf Hardware and Free Software. In Proceedings of the IEEE Real-Time Technology and Applications Symposium, June 1998.

....switch developed by Sanchez [21] The ABR switch runs in firm real time mode under KU Real Time control (KURT) and switches ATM cells at an accurate proportion of the line rate. KURT is an extension to the Linux operating system that provides firm real time support using explicit scheduling [24]. Some of the salient features of the software switch are the following : ffl Performs switching at an explicitly scheduled accurate proportional rate in firm real time mode. 24 ffl Supports UNI signaling [26] and uses real signaling code: Q.Port signaler [16] This is the same signaling ....

Srinivasan, B., A Firm Real-Time System Implementation using Commercial Off-The-Shelf Hardware and Free Software. M.S Thesis, University of Kansas, February 1998.

....POSIX SS will be given in the next chapter. 10 CHAPTER 3 DESIGN 3.1 Design Choice 3.1. 1 RTLinux There are several real time Linux operating systems that have been published, including Realtime Linux (RTLinux) Real Time and Embedded (RED) Linux[17] Kansas University Real Time (KURT) Linux[15] and Open Real Time Linux (ORiS Linux) 21] From these, we chose Real Time Linux (RTLinux) as our implementation platform for several reasons. The scheduler in RTLinux is quite simple and modular. It is easy to replace the scheduler with any other desired one[4] since the code associated with the ....

B. Srinivasan, et al, "A Firm Real-Time System Implementation Using Commercial Off-the Shelf Hardware and Free Software", Proceedings of IEEE Real-Time Technology and Application Symposium, 1998.

....a real time FIFO queue so that realtime tasks can run on RT Linux without any Linux interference. The approach is similar to some real time subsystem products for Windows NT (such as RTX ) that intercept realtime requests from real time tasks and devices. Another real time Linux project is KURT [7] which uses different kernel modes to control the scheduling of system resources for real time processes. When the kernel is in the normal mode, no real time support is given and it runs like the normal Linux kernel. When it is in the focused realtime mode, only real time processes are ....

B. Srinivasan et al. A firm real-time system implementation using commercial off-the shelf hardware and free software. In Proc. IEEE Real-Time Technology and Application Symposium, pages 112--119, June 1998.

....of single module scheduler real time tasks can run on RT Linux without any Linux interference. The approach is similar to some real time subsystem products for Windows NT (such as RTX) that intercept real time requests from real time tasks and devices. Another real time Linux project is KURT [20] which uses different kernel modes to control the scheduling of system resources for real time processes. When the kernel is in the normal mode, no real time support is given and it runs like the normal Linux kernel. When it is in the focused realtime mode, only real time processes are ....

B. Srinivasan et al. A firm real-time system implementation using commercial off-the shelf hardware and free software. In Proc. IEEE Real-Time Technology and Application Symposium, pp. 112--119, June 1998.

....modest predictability requirements of coexisting, independently developed soft real time applications. For example, Eclipse [2] extends FreeBSD, Rialto NT [6] and HLS [10] extend Windows 2000, and there are at least five publicly available systems providing soft real time scheduling in Linux [4, 9, 14, 17, 18]. There are several obstacles to widespread use of these systems. First, application developers are unlikely to support scheduling abstractions that (at first) are present on only a small number of machines. Second, these di#erent schedulers provide di#erent scheduling abstractions, making it ....

B. Srinivasan, S. Pather, R. Hill, F. Ansari, and D. Niehaus. A Firm Real-Time System Implementation Using Commercial O#-The-Shelf Hardware and Free Software. In Proc. of the 4th IEEE Real-Time Technology and Applications Symposium, Denver, CO, June 1998.

....clock interrupts, the advanced programmable interrupt controller (APIC) another device found on all modern PCs is left unused and a device driver could be written that uses the APIC to provide precise interrupts. This has been done for other general purpose operating systems such as Linux [80]. 10.5 Solving Problems Using Hierarchical Scheduling Previous sections in this chapter argued that HLS is feasible. This section demonstrates the usefulness of HLS by presenting quantitative data about the performance of application threads being scheduled using HLS. In each of the two examples ....

Balaji Srinivasan, Shyamalan Pather, Robert Hill, Furquan Ansari, and Douglas Niehaus. A Firm Real-Time System Implementation Using Commercial Off-The-Shelf Hardware and Free Software. In Proc. of the 4th IEEE Real-Time Technology and Applications Symposium, Denver, CO, June 1998.

.... and stride scheduling [141] and proportionalshare allocation for time shared systems [131] Proportional share scheduling has also been used to schedule system services [62] Other notable real time kernel extensions include the SMART scheduler in Solaris [95] a real time scheduler for Linux [125], and the concept of resource centric kernels [101] Recently, resource containers have been proposed as an operating system extension 153 motivated by server side processing needs [19] Resource containers allow fine grained control of resource management in monolithic kernels. Different thread ....

B. Srinivasan, S. Pather, F. Ansari, and D. Niehaus, "A firm real-time system implementation using commercial off-the-shelf hardware and free software," in Real-time Technology and Applications Symposium, pp. 112--120, Denver, Colorado, June 1998.

....real systems, thus avoiding the over simplification suffered by some other simulation techniques. 2. Implementation We use KU Real Time (KURT) a firm real time system based on Linux with several modifications including increased temporal resolution (UTIME) to control our distributed computation [7, 13, 14]. With temporal resolution increased to the microsecond level, KURT added simple real time scheduling services and is capable of satisfying the firm real time performance constraints of many applications, including our proportional time simulations. The approach described here implements a firm ....

B. Srinivasan. A Firm Real-Time System Implementation using Commercial Off-The-Shelf Hardware and Free Software. Master's thesis, Department of Electrical Engineering and Computer Science, University of Kansas, February 1998.

....is a practical choice for dedicated systems not working under heavy loads. RTLinux does not have real time scheduling for resources other than the CPU. There is no mechanism for integrated resource management and QoS guarantees which are essential under heavy loads. 3.6. 2 KURT Linux KURT Linux [30] adds real time capabilities to the standard Linux operating system by modifying its core functionalities. This is in contrast to RTLinux which leaves the standard Linux kernel untouched but adds a real time layer between standard Linux and the hardware. Another di erence between RTLinux and KURT ....

B. Srinivasan, S. Pather, R. Hill, S. Ansari, D. Niehaus, \A Firm Real-Time System Implementation Using Commercial O-the-shelf hardware and Free Software", In Proceeding of Real-Time Technology and Applications Symposium, Denver, June 1998.

....tasks through admit reject and priority assignment decisions. In particular, it ensures the important property of task isolation, whereby tasks do not infringe on each other. In this paper we present the design and implementation of SRMS within the KURT Linux Operating System [HSPN98, SPH 98, Sri98] KURT Linux supports conventional tasks as well as real time tasks. It provides a mechanism for transitioning from normal Linux scheduling to a mixed scheduling of conventional and real time tasks, and to a focused mode where only real time tasks are scheduled. We overview the technical issues ....

....fatal. Using RMS for scheduling multiple multimedia applications is impractical, as it would result in very poor utilization. Paper Scope and Outline: This paper presents the design for an implementation of Statistical Rate Monotonic Scheduling (SRMS) AB98c] in KURT Linux [HSPN98, SPH 98, Sri98] SRMS allows the scheduling of periodic tasks with highly variable execution times and statistical QoS requirements. It enforces task isolation (a.k.a. the firewall property) so that tasks cannot interfere with each other. SRMS wastes no resource bandwidth on jobs that will miss their deadlines ....

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Balaji Srinivasan. A firm real-time system implementation using commercial off-the-shelf hardware and free software. Master's thesis, Department of Electrical Engineering and Computer Science, University of Kansas, June 1998.

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Srinivasan, B., Pather, S., Hill, R., Ansari, F., and Niehaus, D. A firm real-time system implementation using commercial off-the shelf hardware and free software. In Proc. of the Real-Time Technology and Applications Symposium, (Denver, CO).

....Kernel F10 Allocation granularity trade offs Kernel F11 Resource utilization trade offs Endsystem F12 Safety vs. interference Endsystem F13 Coordination and communication Endsystem F14 Encapsulation limitations Endsystem F15 Priority management Endsystem F16 Dynamic ordering Endsystem F17 Activities spanning endsystems Distributed F18 Multiple suitable resources Distributed spanning endsystems F19 Heterogeneity among operating Distributed systems and endsystems local scheduling F20 Dynamic heterogeneous Distributed applications within an endsystem F21 Competing quality ....

....The distributed scheduling forces described here will act upon systems in which uniformity across the system is essential to ensure predictability. These forces may act upon local endsystems, the entire system globally, and on possibly all points on the continuum between these two endpoints. F17: Activities spanning endsystems. Each endsystem represents the outer limit of resource allocation scope achievable at lower levels of architectural scale. However, activities such as chains of remote method invocations may traverse many such scopes, and require coordination of scope by scope ....

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B. Srinivasan, S. Pather, R. Hill, F. Ansari, and D. Niehaus, "A Firm Real-Time System Implementation Using Commercial OffThe -Shelf Hardware and Free Software," in Proceedings of the 4 IEEE Real-Time Technology and Applications Symposium,(Den- ver, CO), IEEE, June 1998. 19

....real systems, thus avoiding the over simplification suffered by some other simulation techniques. 2. Implementation We use KU Real Time (KURT) a firm real time system based on Linux with several modifications including increased temporal resolution (UTIME) to control our distributed computation [7, 13, 14]. With temporal resolution increased to the microsecond level, KURT added simple real time scheduling services and is capable of satisfying the firm real time performance constraints of many applications, including our proportional time simulations. The approach described here implements a firm ....

B. Srinivasan, R. Hill, S. Pather, and D. Niehaus. A Firm Real-Time System Implementation Using Commercial OffThe -Shelf Hardware and Free Software. In Proceedings of the IEEE Real-Time Technology and Applications Symposium, December 1997.

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B. Srinivasan, S. Pather, R. Hill, F. Ansari, and D. Niehaus, "A firm real-time system implementation using commercial off-the-shelf hardware and free software," presented at the 4th IEEE Real Time Technology and Applications Symp. (RTAS), Denver, CO, June 1998.

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Srinivasan, B., Pather, S., Hill, R., Ansari, F. and Niehaus, D., "A firm real-time system implementation using commercial off-the-shelf hardware and free software," In Fourth IEEE Denver, Colorado, June 1998.

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B. Srinivasan, S. P. Robert, H. F. Ansari, and D. Niehaus, "A firm real-time system implementation using commercial o#-the-shelf hardware and free software," 4th IEEE Symposium on Real-time Technology and Applications,, pp. 112--119, June 1998.

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B. Srinivasan, "A Firm Real-Time System Implementation Using Commercial O#-The-Shelf Hardware and Free Software", Master of Science thesis, University of Kansas, 1998.

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Balaji Srinivasan, Shyamalan Pather, Robert Hill, Furquan Ansari, and Douglas Niehaus. A firm real-time system implementation using commercial off-the-shelf hardware and free software. In Real-time Technology and Applications Symposium, pages 112--119, June 1998.

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