Integrating Cache-Related Pre-Emption Delays into Analysis of Fixed Priority Scheduling with Pre-Emption Thresholds

Bril, Reinder J.; Altmeyer, Sebastian; Heuvel, Martijn van den; Davis, Robert I.; Behnam, Moris

doi:10.1109/rtss.2014.25

Cited by 20 publications

(12 citation statements)

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“…Initial work in this area is reported in (Rihani et al 2016). (ii) covering processor scheduling policies where analysis of cache-related pre-emption delays already exists, such as fixed-priority scheduling with pre-emption thresholds (Bril et al 2014(Bril et al , 2017, and EDF (Lunniss et al 2013). (iii) covering write-back caches, following recent work in this area Blass et al 2017).…”

Section: Discussionmentioning

confidence: 99%

An extensible framework for multicore response time analysis

et al. 2017

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In this paper, we introduce a multicore response time analysis (MRTA) framework, which decouples response time analysis from a reliance on contextindependent WCET values. Instead, the analysis formulates response times directly The additional material includes: Section 4: analysis for warmed-up caches and dynamic scratchpads (Sects. 4.3 and 4.2). Section 7: extensions to the task model, including RTOS and interrupts, shared software resources, and open systems and incremental verification. Section 8: presentation of a cycle-accurate multicore simulator. Section 9: evaluation of different local memory types (Sect. 9.2), a comparison between predictable and reference architectures (Sect. 9.3), and a verification of the precision of the analysis using results from the simulator (Sect. 9.4). 123Real-Time Syst from the demands placed on different hardware resources. The MRTA framework is extensible to different multicore architectures, with a variety of arbitration policies for the common interconnects, and different types and arrangements of local memory. We instantiate the framework for single level local data and instruction memories (cache or scratchpads), for a variety of memory bus arbitration policies, including: Round-Robin, FIFO, Fixed-Priority, Processor-Priority, and TDMA, and account for DRAM refreshes. The MRTA framework provides a general approach to timing verification for multicore systems that is parametric in the hardware configuration and so can be used at the architectural design stage to compare the guaranteed levels of real-time performance that can be obtained with different hardware configurations. We use the framework in this way to evaluate the performance of multicore systems with a variety of different architectural components and policies. These results are then used to compose a predictable architecture, which is compared against a reference architecture designed for good average-case behaviour. This comparison shows that the predictable architecture has substantially better guaranteed real-time performance, with the precision of the analysis verified using cycle-accurate simulation.

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Section: Discussionmentioning

confidence: 99%

An extensible framework for multicore response time analysis

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“…Compared to Bril et al (2014), this extended version has the following two major contributions. Firstly, it presents a generalized algorithm to improve the layout of tasks in memory (Sect.…”

Section: Extended Versionmentioning

confidence: 99%

“…Section 4 recapitulates analysis for FPTS without CRPD and analysis for FPPS with CRPD. Sections 5-8 present our response-time analysis for FPTS with CRPD [which revisits our analysis in Bril et al (2014)]. The analysis is split into the following sections: Sect.…”

Section: Outlinementioning

confidence: 99%

“…When focussing on the pre-empting tasks, only the ECBs of a task τ j pre-empting another task τ i are used to bound the CRPD of task τ i , as exemplified by the ECB-Only approach (Busquets-Mataix et al 1996). When focussing on the pre-empted tasks, only the UCBs of the tasks pre-empted by task τ j that can affect the response time of task τ i are used to bound the CRPD of task τ i , as exemplified by the UCB-Only approach (Lee et al 1998) and the UCB-Only Multiset approach (Bril et al 2014). Finally, when considering both the pre-empting and pre-empted tasks both the ECBs of the pre-empting tasks as well as the UCBs of the pre-empted tasks are used.…”

Section: Cache-related Pre-emption Delays (Crpds)mentioning

confidence: 99%

“…We observe that Eq. (13) for γ ecb-u i, j (t) in Altmeyer et al (2012) contains the same redundancy or problem as (10) in Bril et al (2014). where the function sort() sorts the values in the multiset M ucb-o i, j (t) in non-increasing order. Hence, the sum of the E j (t) largest sizes in the multiset M ucb-o i, j (t) is taken and multiplied by BRT.…”

Section: Pre-empted Tasksmentioning

confidence: 99%

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Fixed priority scheduling with pre-emption thresholds and cache-related pre-emption delays: integrated analysis and evaluation

et al. 2017

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Commercial off-the-shelf programmable platforms for real-time systems typically contain a cache to bridge the gap between the processor speed and main memory speed. Because cache-related pre-emption delays (CRPD) can have a significant influence on the computation times of tasks, CRPD have been integrated in the response time analysis for fixed-priority pre-emptive scheduling (FPPS). This paper presents CRPD aware response-time analysis of sporadic tasks with arbitrary deadlines for fixed-priority pre-emption threshold scheduling (FPTS), generalizing earlier work. The analysis is complemented by an optimal (pre-emption) threshold assignment algorithm, assuming the priorities of tasks are given. We further improve upon these results by presenting an algorithm that searches for a layout of tasks in memory that makes a task set schedulable. The paper includes an extensive comparative evaluation of the schedulability ratios of FPPS and FPTS, taking CRPD into account. The practical relevance of our work stems from FPTS support in AUTOSAR, a standardized development model for the automotive industry. Keywords Fixed-priority pre-emptive scheduling · Fixed-priority scheduling with pre-emption thresholds · Cache-related pre-emption delay · Response-time analysis B Reinder J. Bril

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On the effectiveness of cache partitioning in hard real-time systems

et al. 2016

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In hard real-time systems, cache partitioning is often suggested as a means of increasing the predictability of caches in pre-emptively scheduled systems: when a task is assigned its own cache partition, inter-task cache eviction is avoided, and timing verification is reduced to the standard worst-case execution time analysis used in nonpre-emptive systems. The downside of cache partitioning is the potential increase in execution times. In this paper, we evaluate cache partitioning for hard real-time systems in terms of overall schedulability. To this end, we examine the sensitivity of (i) task execution times and (ii) pre-emption costs to the size of the cache partition allocated and present a cache partitioning algorithm that is optimal with respect to taskset schedulability. We also devise an alternative algorithm which primarily optimises schedulability but also minimises processor utilization. We evaluate the performance of cache partitioning compared to state-of-the-art pre-emption cost analysis based on benchmark code and on a large number of synthetic tasksets with both fixed priority and EDF scheduling. This allows us to derive general conclusions about the usability of cache partitioning and identify taskset and system parameters that influence the relative effectiveness of cache partitioning. We also examine the improvement in processor -The evaluation now covers both fixed priority and EDF scheduling.-We examined how the schedulability of a group of tasks sharing a partition depends upon partition size. -We present an alternative cache partitioning algorithm which both optimises schedulability and minimises processor utilization. We examine the improvement in processor utilization obtained using this algorithm as compared to the original cache partitioning algorithm, and the tradeoff in terms of increased analysis time.

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Integrating Cache-Related Pre-Emption Delays into Analysis of Fixed Priority Scheduling with Pre-Emption Thresholds

Cited by 20 publications

References 25 publications

An extensible framework for multicore response time analysis

An extensible framework for multicore response time analysis

Fixed priority scheduling with pre-emption thresholds and cache-related pre-emption delays: integrated analysis and evaluation

On the effectiveness of cache partitioning in hard real-time systems

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