Timing analysis for preemptive multitasking real-time systems with caches

Tan, Yanliang; Mooney, Vincent J.

doi:10.1145/1210268.1210275

Cited by 61 publications

(35 citation statements)

References 27 publications

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“…The integration of CRPD in the schedulability analysis of tasks has been addressed for FPPS with a focus on the pre-empting tasks (Busquets-Mataix et al 1996;Tomiyama and Dutt 2000), the pre-empted tasks (Lee et al 1998), and by considering both the pre-empting and pre-empted tasks (Staschulat et al 2005;Tan and Mooney 2007;Altmeyer et al 2012). Figure 1 gives an overview of the various approaches and their relation.…”

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

confidence: 99%

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

confidence: 99%

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

et al. 2017

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“…The crudest approach to CRPD analysis is to assume that every preemption causes a complete flush of the entire cache; a safe but often imprecise assumption. Successively more precise estimates have been achieved by researchers [Busquets-Mataix et al 1996;Lee et al 1998;Staschulat et al 2005;Tan and Mooney 2007;Altmeyer and Maiza 2010;Altmeyer et al 2011;2012]. Estimates are generated by examining which cache blocks are definitely reused by lower-priority tasks (useful cache blocks) and which cache blocks are accessed by higher-priority tasks (evicted cache blocks).…”

Section: Real-time Systems Sharing the Cachementioning

confidence: 99%

“…Subsequent analyses introduced UCB sets to the analysis [Tan and Mooney 2007;Altmeyer and Maiza 2010], which can be used in different ways (e.g. ECB-Union, UCB-Union) to produce a more accurate CRPD estimate [Altmeyer et al 2011].…”

Section: Reducing Crpd By Better Analysismentioning

confidence: 99%

Explicit reservation of cache memory in a predictable, preemptive multitasking real-time system

Whitham

Audsley

Davis

2014

ACM Trans. Embed. Comput. Syst.

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We describe and evaluate explicit reservation of cache memory to reduce the cache-related preemption delay (CRPD) observed when tasks share a cache in a preemptive multitasking hard real-time system. We demonstrate the approach using measurements obtained from a hardware prototype, and present schedulability analyses for systems that share a cache by explicit reservation. These analyses form the basis for a series of experiments to further evaluate the approach. We find that explicit reservation is most useful for larger task sets with high utilization. Some task sets cannot be scheduled with a conventional cache, but are schedulable with explicit reservation.

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“…UCB-Union UCB-Union is one definition for γ i,j . Introduced by Tan and Mooney [13], UCB-Union dominates an earlier ECB-only approach described by Busquets et al [12].…”

Section: B Crpd-rtamentioning

confidence: 99%

“…CRPD may be determined by considering which cache blocks are reused by preempted tasks and evicted by preempting tasks. Recent work has established a number of approaches for this [11], [12], [13], [14], [15], [16], [17]. Figure 1 shows how SRPD and CRPD are compared in this paper.…”

Section: Introduction Scratchpad Memory (Spm) Is a Form Of Local Mmentioning

confidence: 99%

Investigation of Scratchpad Memory for Preemptive Multitasking

Whitham

Davis

Audsley

et al. 2012

2012 IEEE 33rd Real-Time Systems Symposium

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Abstract-We present a multitasking scratchpad memory reuse scheme (MSRS) for the dynamic partitioning of scratchpad memory between tasks in a preemptive multitasking system. We specify a means to compute the worst-case response time (WCRT) and schedulability of task sets executed using MSRS. Our scratchpad-related preemption delay (SRPD) is an analog of cache-related preemption delay (CRPD), proposed in previous work as a way to compute the worst-case cost imposed upon a preempted task by preemption in a multitasking system. Unlike CRPD, however, SRPD is independent of the number of tasks and the local memory size.We compare SRPD with CRPD by experiment and determine that neither dominates the other, i.e. either may be better for certain task sets. However, MSRS leads to improved schedulability versus cache when contention for local memory space is high, either because the local memory size is small, or because the task set is large, provided that the cost of loading blocks from external memory to scratchpad is similar to the cost of loading blocks into cache.

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Timing analysis for preemptive multitasking real-time systems with caches

Cited by 61 publications

References 27 publications

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

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

Explicit reservation of cache memory in a predictable, preemptive multitasking real-time system

Investigation of Scratchpad Memory for Preemptive Multitasking

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