Efficiently Handling Process Overruns and Underruns in Real-Time Embedded Systems

2015 ◽  
Author(s):  
Jia Xu
Keyword(s):  
Embedded Systems ◽  
Real Time ◽  
Time Process ◽  
Time System ◽  
Worst Case ◽  
Real Time System ◽  
System Utilization ◽  
System Overhead ◽  
Run Time

Methods for handling process underruns and overruns when scheduling a set of real-time processes increase both system utilization and robustness in the presence of inaccurate estimates of the worst-case computations of real-time processes. In this paper, we present a method that efficiently re-computes latest start times for real time processes during run-time in the event that a real-time process is preempted or has completed (or overrun). The method effectively identifies which process latest start times will be affected by the preemption or completion of a process. Hence the method is able to effectively reduce real-time system overhead by selectively re-computing latest start times for the specific processes whose latest start times are changed by a process preemption or completion, as opposed to indiscriminately re-computing latest start times for all the processes.

Handling Overruns and Underruns of Real-Time Processes With Precedence and Exclusion Relations Using a Pre-Run-Time Schedule

2013 ◽  
Author(s):  
Jia Xu
Keyword(s):  
Real Time ◽  
Computation Time ◽  
Total System ◽  
Time Process ◽  
Time Schedule ◽  
Worst Case ◽  
Processor Time ◽  
The Real ◽  
Actual Computation ◽  
Run Time

Many embedded systems applications have hard timing requirements where real-time processes with precedence and exclusion relations must be completed before specified deadlines. This requires that the worst-case computation times of the real-time processes be estimated with sufficient precision during system design, which sometimes can be difficult in practice. If the actual computation time of a real-time process during run-time exceeds the estimated worst-case computation time, an overrun will occur, which may cause the real-time process to not only miss its own deadline, but also cause a cascade of other real-time processes to also miss their deadline, possibly resulting in total system failure. However, if the actual computation time of a real-time process during run-time is less than the estimated worst-case computation time, an underrun will occur, which may result in under-utilization of system resources. This paper describes a method for handling underruns and overruns when scheduling a set of real-time processes with precedence and exclusion relations using a pre-run-time schedule. The technique effectively tracks and utilizes unused processor time resources to reduce the chances of missing real-time process deadlines, thereby providing the capability to significantly increase both system utilization and system robustness in the presence of inaccurate estimates of the worst-case computation times of real-time processes.

Efficiently Handling Process Overruns and Underruns on Multiprocessors in Real-Time Embedded Systems

2017 ◽  
Author(s):  
Jia Xu
Keyword(s):  
Embedded Systems ◽  
Real Time ◽  
Time Complexity ◽  
Multiprocessor System ◽  
Multiprocessor Systems ◽  
Worst Case ◽  
Real World Applications ◽  
Run Time ◽  
Hard Real Time ◽  
Time Overhead

In hard real-time and embedded multiprocessor system real-world applications, it is very important to strive to minimize the run-time overhead of the scheduler as much as possible, especially in hard real-time and embedded multiprocessor systems with limited processor and system resources. In this paper, we present a method that reduces the worst-case time complexity of the run-time scheduler for re-computing latest start times and for selecting processes for execution on a multiprocessor at run-time to O(n), where n is the number of processes.

Dynamic Partitioned Cache Memory for Real-Time MPSoCs with Mixed Criticality

2016 ◽  
Vol 25 (06) ◽  
pp. 1650062 ◽  
Author(s):  
Gang Chen ◽  
Kai Huang ◽  
Long Cheng ◽  
Biao Hu ◽  
Alois Knoll
Keyword(s):  
Real Time ◽  
Cache Memory ◽  
Time System ◽  
Worst Case ◽  
Real Time System ◽  
Average Performance ◽  
Shared Cache ◽  
Worst Case Execution Time ◽  
The One ◽  
Major Factors

Shared cache interference in multi-core architectures has been recognized as one of major factors that degrade predictability of a mixed-critical real-time system. Due to the unpredictable cache interference, the behavior of shared cache is hard to predict and analyze statically in multi-core architectures executing mixed-critical tasks, which will not only result in difficulty of estimating the worst-case execution time (WCET) but also introduce significant worst-case timing penalties for critical tasks. Therefore, cache management in mixed-critical multi-core systems has become a challenging task. In this paper, we present a dynamic partitioned cache memory for mixed-critical real-time multi-core systems. In this architecture, critical tasks can dynamically allocate and release the cache resourse during the execution interval according to the real-time workload. This dynamic partitioned cache can, on the one hand, provide the predicable cache performance for critical tasks. On the other hand, the released cache can be dynamically used by non-critical tasks to improve their average performance. We demonstrate and prototype our system design on the embedded FPGA platform. Measurements from the prototype clearly demonstrate the benefits of the dynamic partitioned cache for mixed-critical real-time multi-core systems.

A Scalable Approach to Real-Time System Timing Applications

2010 ◽  
pp. 606-644
Author(s):  
Alan Grigg ◽  
Lin Guan
Keyword(s):  
Real Time ◽  
Reference Model ◽  
Timing Analysis ◽  
Target System ◽  
Time System ◽  
Worst Case ◽  
Real Time System ◽  
Resource Requirements ◽  
Time Scheduling ◽  
Execution Model

This chapter describes a real-time system performance analysis approach known as reservation-based analysis (RBA). The scalability of RBA is derived from an abstract (target-independent) representation of system software components, their timing and resource requirements and run-time scheduling policies. The RBA timing analysis framework provides an evolvable modeling solution that can be instigated in early stages of system design, long before the software and hardware components have been developed, and continually refined through successive stages of detailed design, implementation and testing. At each stage of refinement, the abstract model provides a set of best-case and worst-case timing ‘guarantees’ that will be delivered subject to a set of scheduling ‘obligations’ being met by the target system implementation. An abstract scheduling model, known as the rate-based execution model then provides an implementation reference model with which compliance will ensure that the imposed set of timing obligations will be met by the target system.

A Scalable Approach to Real-Time System Timing Analysis

2012 ◽  
pp. 637-668
Author(s):  
Alan Grigg ◽  
Lin Guan
Keyword(s):  
Real Time ◽  
Reference Model ◽  
Timing Analysis ◽  
Target System ◽  
Time System ◽  
Worst Case ◽  
Real Time System ◽  
Resource Requirements ◽  
Time Scheduling ◽  
Execution Model

This chapter describes a real-time system performance analysis approach known as reservation-based analysis (RBA). The scalability of RBA is derived from an abstract (target-independent) representation of system software components, their timing and resource requirements and run-time scheduling policies. The RBA timing analysis framework provides an evolvable modeling solution that can be instigated in early stages of system design, long before the software and hardware components have been developed, and continually refined through successive stages of detailed design, implementation and testing. At each stage of refinement, the abstract model provides a set of best-case and worst-case timing ‘guarantees’ that will be delivered subject to a set of scheduling ‘obligations’ being met by the target system implementation. An abstract scheduling model, known as the rate-based execution model then provides an implementation reference model with which compliance will ensure that the imposed set of timing obligations will be met by the target system.

scholarly journals Run-time middleware to support real-time system scenarios

2015 ◽  
Author(s):  
Kees Goossens ◽  
Martijn Koedam ◽  
Shubhendu Sinha ◽  
Andrew Nelson ◽  
Marc Geilen
Keyword(s):  
Real Time ◽  
Time System ◽  
Real Time System ◽  
Run Time

Real-Time System for Sending Data from Three Clients to One Server with MATLAB

2015 ◽  
Vol 2 (1) ◽  
pp. 35-41
Author(s):  
Rivan Risdaryanto ◽  
Houtman P. Siregar ◽  
Dedy Loebis
Keyword(s):  
Information System ◽  
Real Time ◽  
Time System ◽  
Real Time System ◽  
The Real ◽  
Performance Time ◽  
Data Process ◽  
Effectiveness And Efficiency

The real-time system is now used on many fields, such as telecommunication, military, information system, evenmedical to get information quickly, on time and accurate. Needless to say, a real-time system will always considerthe performance time. In our application, we define the time target/deadline, so that the system should execute thewhole tasks under predefined deadline. However, if the system failed to finish the tasks, it will lead to fatal failure.In other words, if the system cannot be executed on time, it will affect the subsequent tasks. In this paper, wepropose a real-time system for sending data to find effectiveness and efficiency. Sending data process will beconstructed in MATLAB and sending data process has a time target as when data will send.

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