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The question whether preemptive algorithms are better than nonpreemptive ones for scheduling a set of real-time tasks has been debated for a long time in the research community. In fact, especially under fixed priority systems, each approach has advantages and disadvantages, and no one dominates the other when both predictability and efficiency have to be(More)
Building safety-critical real-time systems out of inexpensive, non-real-time, COTS components is challenging. Although COTS components generally offer high performance, they can occasionally incur significant timing delays. To prevent this, we propose controlling the operating point of each shared resource (like the cache, memory, and interconnection buses)(More)
Shared resource access interference, particularly memory and system bus, is a big challenge in designing predictable real-time systems because its worst case behavior can significantly differ. In this paper, we propose a software based memory throttling mechanism to explicitly control the memory interference. We developed analytic solutions to compute(More)
Memory bandwidth in modern multi-core platforms is highly variable for many reasons and is a big challenge in designing real-time systems as applications are increasingly becoming more memory intensive. In this work, we proposed, designed, and implemented an efficient memory bandwidth reservation system, that we call MemGuard. MemGuard distinguishes memory(More)
Limited preemption scheduling has been introduced as a viable alternative to non-preemptive and fullypreemptive scheduling when reduced blocking times need to coexist with an acceptable context switch overhead. To achieve this goal, preemptions are allowed only at selected points of the code of each task, decreasing the preemption overhead and simplifying(More)
The question whether preemptive systems are better than non-preemptive systems has been debated for a long time, but only partial answers have been provided in the real-time literature and still some issues remain open. In fact, each approach has advantages and disadvantages, and no one dominates the other when both predictability and efficiency have to be(More)
Preemptive schedulers have been widely adopted in single processor real-time systems to avoid the blocking associated with the non-preemptive execution of lower priority tasks and achieve a high processor utilization. However, under fixed priority assignments, there are cases in which limiting preemptions can improve schedulability with respect to a fully(More)
Schedulability analysis of real-time systems requires the knowledge of the worst-case execution time (WCET) of each computational activity. A precise estimation of such a task parameter is quite difficult to achieve, because execution times depend on many factors, including the task structure, the system architecture details, operating system features and(More)
In the design of hard real-time systems, the feasibility of the task set is one of the primary concerns. However, in embedded systems with scarce resources, optimizing resource usage is equally important. In particular, the RAM is highly expensive in terms of chip space, and it heavily impacts the cost of the final product. In this paper, we address the(More)
CCR4, a poly(A) deadenylase of the exonuclease III family, is a component of the multiprotein CCR4-NOT complex of Saccharomyces cerevisiae that is involved in mRNA degradation. CCR4, unlike all other exonuclease III family members, contains a leucine-rich repeat (LRR) motif through which it makes contact to CAF1 and other factors. The LRR residues important(More)