Memory Positioning of Real-Time Code for Smaller Worst-Case Execution Times

2011 ◽  
Author(s):  
Amine Marref ◽  
Adam Betts
Keyword(s):  
Real Time ◽  
Time Code ◽  
Worst Case ◽  
Execution Times

scholarly journals Optimisation of scheduled tasks by real-time measurement and correlation

2020 ◽  
pp. 36-43
Author(s):  
Berkay Saydam ◽  
Cem Orhan ◽  
Niyazi Toker ◽  
Mansur Turasan
Keyword(s):  
Real Time ◽  
Functional Safety ◽  
Worst Case ◽  
System Cost ◽  
Simulation Tools ◽  
Real Time Measurement ◽  
Real Hardware ◽  
Execution Times ◽  
Time Critical ◽  
Time Systems

For functional safety, the scheduler should perform all time critical tasks in an order and within predefined deadlines in embedded systems. Scheduling of time critical tasks is determined by estimating their worst-case execution times. To justify the model design of task scheduling, it is required to simulate and visualise the task execution and scheduling maps. This helps to figure out possible problems before deploying the schedule model to real hardware. The simulation tools which are used by companies in an industry perform scheduling simulation and visualisation of all time critical tasks to design and verify the model. All of them lack the capability of comparing simulation results versus real results to achieve the optimised scheduling design. This sometimes leads the overestimated worst-case execution times and increased system cost. The aim of our study is to decrease the system cost with optimisation of scheduled tasks via using the static analysing method.   Keywords: Schedule visualisation, scheduler optimisation, functional safety, real-time systems, scheduler.

scholarly journals PSO based optimization of worst-case execution time for ASIP application

2018 ◽  
Vol 7 (3.3) ◽  
pp. 252
Author(s):  
Mood Venkanna ◽  
Rameshwar Rao ◽  
P Chandra Sekhar
Keyword(s):  
Real Time ◽  
Upper Bounds ◽  
Real Time Systems ◽  
Worst Case ◽  
Reconfigurable Processor ◽  
Worst Case Execution Time ◽  
Execution Times ◽  
Hard Real Time ◽  
Time Systems ◽  
Time Bounds

Industrial requires hard real-time systems for safety and critical applications like automotive, Aeronautics, manufacturing control and train industries. Hard Real-Time Systems’ embedded controllers are with expectation of complete the tasks within a certain time bounds reliably including task scheduling. The estimation of upper bound limits corresponding to the execution times is often termed as the Worst-Case Execution Times (WCETs). It is an essential step in developing and validating the hard real-time systems. Particularly, the upper bounds need to satisfy these constraints related to the execution times. However, it is often not feasible many times to set upper bounds on execution times for programs. In present work, the problem of choosing reconfigurable Custom Instructions (CIs) is accomplished by optimizing the WCET corresponding to an application. This issue is designed using Particle Swarm Optimization (PSO) based program for a path analysis. The work emphasizes on the effectiveness of optimizing the WCET when applied to a reconfigurable processor. It evaluates a compound application of multimedia with a host of reconfigurable CIs corresponding to a number of hardware parameters.  

scholarly journals On the Use of Probabilistic Worst-Case Execution Time Estimation for Parallel Applications in High Performance Systems

Mathematics ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 314 ◽  
Author(s):  
Matteo Fusi ◽  
Fabio Mazzocchetti ◽  
Albert Farres ◽  
Leonidas Kosmidis ◽  
Ramon Canal ◽  
...  
Keyword(s):  
Real Time ◽  
Execution Time ◽  
High Performance ◽  
Effective Means ◽  
Time Estimation ◽  
Value Theory ◽  
Parallel Applications ◽  
Worst Case ◽  
Worst Case Execution Time ◽  
Execution Times

Some high performance computing (HPC) applications exhibit increasing real-time requirements, which call for effective means to predict their high execution times distribution. This is a new challenge for HPC applications but a well-known problem for real-time embedded applications where solutions already exist, although they target low-performance systems running single-threaded applications. In this paper, we show how some performance validation and measurement-based practices for real-time execution time prediction can be leveraged in the context of HPC applications on high-performance platforms, thus enabling reliable means to obtain real-time guarantees for those applications. In particular, the proposed methodology uses coordinately techniques that randomly explore potential timing behavior of the application together with Extreme Value Theory (EVT) to predict rare (and high) execution times to, eventually, derive probabilistic Worst-Case Execution Time (pWCET) curves. We demonstrate the effectiveness of this approach for an acoustic wave inversion application used for geophysical exploration.

Reliability Test based on a Binomial Experiment for Probabilistic Worst-Case Execution Times

2020 ◽  
Author(s):  
Luis Fernando Arcaro ◽  
Karila Palma Silva ◽  
Romulo Silva de Oliveira ◽  
Luis Almeida
Keyword(s):  
Reliability Test ◽  
Worst Case ◽  
Execution Times

scholarly journals Network Calculus-Based Latency for Time-Triggered Traffic under Flexible Window-Overlapping Scheduling (FWOS) in a Time-Sensitive Network (TSN)

2021 ◽  
Vol 11 (9) ◽  
pp. 3896
Author(s):  
Khaled M. Shalghum ◽  
Nor Kamariah Noordin ◽  
Aduwati Sali ◽  
Fazirulhisyam Hashim
Keyword(s):  
Real Time ◽  
Connected Vehicles ◽  
Network Calculus ◽  
Timing Constraints ◽  
Traffic Scheduling ◽  
Worst Case ◽  
Continuous Increase ◽  
Scheduled Traffic ◽  
Support Time ◽  
New Framework

Deterministic latency is an urgent demand to pursue the continuous increase in intelligence in several real-time applications, such as connected vehicles and automation industries. A time-sensitive network (TSN) is a new framework introduced to serve these applications. Several functions are defined in the TSN standard to support time-triggered (TT) requirements, such as IEEE 802.1Qbv and IEEE 802.1Qbu for traffic scheduling and preemption mechanisms, respectively. However, implementing strict timing constraints to support scheduled traffic can miss the needs of unscheduled real-time flows. Accordingly, more relaxed scheduling algorithms are required. In this paper, we introduce the flexible window-overlapping scheduling (FWOS) algorithm that optimizes the overlapping among TT windows by three different metrics: the priority of overlapping, the position of overlapping, and the overlapping ratio (OR). An analytical model for the worst-case end-to-end delay (WCD) is derived using the network calculus (NC) approach considering the relative relationships between window offsets for consecutive nodes and evaluated under a realistic vehicle use case. While guaranteeing latency deadline for TT traffic, the FWOS algorithm defines the maximum allowable OR that maximizes the bandwidth available for unscheduled transmission. Even under a non-overlapping scenario, less pessimistic latency bounds have been obtained using FWOS than the latest related works.

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