Analysis and Optimisation of Hierarchically Scheduled Multiprocessor Embedded Systems

Abstract

We present an approach to the analysis and optimisation of heterogeneous multiprocessor embedded systems.

Timing Analysis of Rate Constrained Traffic for the TTEthernet Communication Protocol

“…1 is a recursive function, with bp j x on both sides of the equality. In order to compute the length bp j x of the busy period bp j x , we use the concepts of ET availability and ET demand [12], which we have adapted from tasks to messages, as follows. The demand for a frame f x on a dataflow link dl j during the busy period bp j x is the maximum amount of transfer time which can be demanded by RC frames arrived at the outgoing queue before f x and by frame f x .…”

Timing analysis of mixed-criticality hard real-time applications implemented on distributed partitioned architectures

“…We have extended WCDOPS+ to take into account the partitions by using the concepts of availability and demand, inspired by the approach presented in [10]. Informally, the availability associated to a task τ ij during a time interval t, denoted as A ij (t), is equal to the processor time that is not used by other partitions during t. The demand for a task τ ij during a time interval t, denoted as H ij (t), is equal to the sum of the processor times required by τ ij and all higher priority tasks mapped to the same processor during t. In more general terms, the demand of a task scheduled in a partition P k is equal to the length of its busy period when there wouldn't be any time partitions considered or when P k would be the only partition on the processor.…”

“…Researchers have addressed systems with mixed time-criticality requirements, showing how TT/ET tasks [10] can be integrated onto the same platform. Researchers have also started to address the integration of mixed safetycriticality tasks onto the same architecture [2,14].…”

“…This analysis assumes that the deadlines are smaller or equal to the periods, that the tasks are independent, and that the start times of partition slices within a major frame are periodic. Pop et al [10] have proposed a schedulability analysis for ET tasks, which extends the schedulability analysis in [9] to consider the influence of the TT tasks on the worst-case response times of the ET tasks. Such an analysis can be extended to consider that the TT tasks are "partitions" which can interfere with the ET tasks.…”

Traffic class assignment for mixed-criticality frames in TTEthernet

“…In our model, HRT messages have hard deadlines, whereas for SRT messages we capture the quality-of-service (QoS) using soft deadlines and "utility functions", which model the relative importance of SRT messages and how the performance of the system degrades if the SRT soft deadlines are missed. Similar to the debate in real-time systems between time-triggered and eventtriggered implementations [8,10], there is no agreement on the appropriate traffic class for the mixed-criticality messages, which depends on the particularities of the applications. Therefore, in this paper, we are interested in the problem of Traffic Class Assignment for mixed-criticality messages in TTEthernet.…”