Semaphore queue priority assignment for real-time multiprocessor synchronization

Lortz, V.B.; Shin, Kang G.

doi:10.1109/32.469457

Cited by 18 publications

(8 citation statements)

References 8 publications

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“…We therefore derived recursive equations for both a discrete as well a continuous scheduling model to determine (i) the worst-case start time of a job, see (18) in Lemma 1 and (25) in Lemma 6; (ii) the worst-case start time of the final sub-job, see (19) in Lemma 2 and (27) in Lemma 7; and (iii) the worstcase finalization time of a job, see (20) in Lemma 3 and (29) in Lemma 8. Each of these recursive equations can be solved by an iterative procedure by starting with an appropriate lower bound, similar to, e.g., the recursive equations of the level-i active period in (7) and the worst-case response time under FPDS in (12).…”

Section: Discussionmentioning

confidence: 99%

“…For a maximum blocking time B i , the maximum finalization-time F G i,k (B i ) of job k of τ i is therefore given by the smallest x ∈ R + satisfying (20). Note that similar to (19) the summation term prevents activations of higher priority tasks in the initial interval of length S G i,k,m i (B i ) to be accounted for twice.…”

Section: B Maximum Response Timesmentioning

confidence: 98%

“…Our approach for FPGS is similar to the approach for non-preemptive regions presented by Bertogna et al [14], i.e. we (i) convert the recursive response time equations to an exact schedulability test based on executionrequest curves, (ii) minimize the response time of a task, while respecting so-called blocking tolerances [20] of higher priority tasks, and (iii) compute blocking tolerances of tasks. Our algorithm for FPGS specializes to algorithms for its derivatives, including the algorithm in [14].…”

Section: Improving Schedulabilitymentioning

confidence: 99%

“…Given a θ i,m i , we assign the largest length for C i,m i guaranteeing schedulability of all the earlier considered, higher priority tasks. The length of C i,m i is at most equal to the smallest blocking tolerance of any higher priority task with a priority lower than, or equal to, threshold θ i,m i (line [13][14][15][16][17][18][19][20].…”

Section: Optimization Algorithmsmentioning

confidence: 99%

See 3 more Smart Citations

Generalized Fixed-Priority Scheduling with Limited Preemptions

Bril

Heuvel

Keskin

et al. 2012

2012 24th Euromicro Conference on Real-Time Systems

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Fixed-priority scheduling with deferred preemption (FPDS) and fixed-priority scheduling with preemption thresholds (FPTS) have been proposed in the literature as viable alternatives to fixed-priority preemptive scheduling (FPPS), that reduce memory requirements, reduce the cost of arbitrary preemptions, and may improve the feasibility of a task set even when preemption overheads are neglected.This paper aims at advancing the relative strength of limitedpreemptive schedulers by combining FPDS and FPTS. In particular, we present a refinement of FPDS with preemption thresholds for both jobs and sub-jobs, termed FPGS. We provide an exact schedulability analysis for FPGS, and show how to maximize the feasibility of a set of sporadic tasks under FPGS for given priorities, computation times, periods, and deadlines of tasks. We evaluate the effectiveness of FPGS by comparing the feasibility of task sets under FPGS with other fixed-priority scheduling algorithms by means of a simulation. Our experiments show that FPGS allows an increase of the number of task sets that are schedulable under fixed-priority scheduling.

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Section: Discussionmentioning

confidence: 99%

Section: B Maximum Response Timesmentioning

confidence: 98%

Section: Improving Schedulabilitymentioning

confidence: 99%

Section: Optimization Algorithmsmentioning

confidence: 99%

See 2 more Smart Citations

Generalized Fixed-Priority Scheduling with Limited Preemptions

Bril

Heuvel

Keskin

et al. 2012

2012 24th Euromicro Conference on Real-Time Systems

View full text Add to dashboard Cite

show abstract

“…An alternative approach, used by the Multiprocessor Priority Ceiling Protocol (m-pcp) [40], Multiprocessor Stack Resource Protocol (m-srp) [25], and Flexible Multiprocessor Locking Protocol (fmlp) [20], is to raise tasks holding global locks to nonpreemptible local priority. It was shown in [37] that using the same priorities for local scheduling and service order on global locks could be harmful for overall system schedulability, as compared to service based on tasks' tolerance for blocking, or even FIFO. The m-srp and fmlp adopt FIFO service.…”

Section: Partitioned Dynamic Schedulingmentioning

confidence: 99%

What to Make of Multicore Processors for Reliable Real-Time Systems?

Baker

2010

Reliable Software Technologiey – Ada-Europe 2010

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Now that multicore microprocessors have become a commodity, it is natural to think about employing them in all kinds of computing, including high-reliability embedded real-time systems. Appealing aspects of this development include the ability to process more instructions per second and more instructions per watt. However, not all problems are amenable to parallel decomposition, and for those that are, designing a correct scalable solution can be difficult. If there are deadlines or other hard timing constraints the difficulty becomes much greater.This paper reviews some of what is known about multiprocessor scheduling of task systems with deadlines, including recent advances in the analysis of arbitrary sporadic task systems under fixed-priority and earliest-deadline first scheduling polices. It also examines critically the foundations of these theoretical results, including assumptions about task independence and worst-case execution time estimates, with a view toward their practical applicability.

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A Comparison of the M-PCP, D-PCP, and FMLP on LITMUSRT

Brandenburg

Anderson

2008

Lecture Notes in Computer Science

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Abstract. This paper presents a performance comparison of three multiprocessor real-time locking protocols: the multiprocessor priority ceiling protocol (M-PCP), the distributed priority ceiling protocol (D-PCP), and the flexible multiprocessor locking protocol (FMLP). In the FMLP, blocking is implemented via either suspending or spinning, while in the M-PCP and D-PCP, all blocking is by suspending. The presented comparison was conducted using a UNC-produced Linux extension called LITMUS RT . In this comparison, schedulability experiments were conducted in which runtime overheads as measured on LITMUS RT were used. In these experiments, the spin-based FMLP variant always exhibited the best performance, and the M-PCP and D-PCP almost always exhibited poor performance. These results call into question the practical viability of the M-PCP and D-PCP, which have been the de-facto standard for real-time multiprocessor locking for the last 20 years.

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Semaphore queue priority assignment for real-time multiprocessor synchronization

Cited by 18 publications

References 8 publications

Generalized Fixed-Priority Scheduling with Limited Preemptions

Generalized Fixed-Priority Scheduling with Limited Preemptions

What to Make of Multicore Processors for Reliable Real-Time Systems?

A Comparison of the M-PCP, D-PCP, and FMLP on LITMUSRT

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