Consider the problem of scheduling a set of sporadic tasks on a multiprocessor system to meet deadlines using a task splitting scheduling algorithm. Task-splitting (also called semi partitioning) scheduling algorithms...
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Consider the problem of scheduling a set of sporadic tasks on a multiprocessor system to meet deadlines using a task splitting scheduling algorithm. Task-splitting (also called semi partitioning) scheduling algorithms assign most tasks to just one processor but a few tasks are assigned to two or more processors, and they are dispatched in a way that ensures that a task never executes on two or more processors simultaneously. A certain type of task-splitting algorithms, called slot-based task-splitting, is of particular interest because of its ability to schedule tasks at high processor utilizations. We present a new schedulability analysis for slot-based task-splitting scheduling algorithms that takes the overhead into account and also a new task assignment algorithm.
In order to enhance OS security, most of people use security patches to fix the vulnerabilities of the OS. However, the security patches may also incur vulnerabilities. these vulnerabilities are generated since most O...
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In order to enhance OS security, most of people use security patches to fix the vulnerabilities of the OS. However, the security patches may also incur vulnerabilities. these vulnerabilities are generated since most OSes has a lot of functionalities and their functionalities are very complex to manage the entire source code manually. Moreover, in order to use the security patch, rebooting the system is required. Some of systems such as enterprise servers and embeddedsystems cannot accept the rebooting. therefore, we propose an external integrity checking system to enhance the OS security. the external integrity checking system and a target OS run on a hyper visor simultaneously, therefore, their operations do not affect each other. In addition, the integrity checking system is generated automatically with invariants. therefore, the possibility of inserting vulnerabilities into the system is as small as possible, and the system can cover a lot of vulnerabilities.
We utilize a multiprocessor server-based approach to schedule a general class of soft real-timesystems with stochastic execution demands, when bounded average-case tardiness is sufficient for schedulability. A key fe...
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We utilize a multiprocessor server-based approach to schedule a general class of soft real-timesystems with stochastic execution demands, when bounded average-case tardiness is sufficient for schedulability. A key feature of the task model considered here is that the stochastic execution-time demands can have arbitrary amounts of dependence within pre-specified time intervals of bounded length. this is an important practical step forward from requiring complete independence of execution times between successive jobs of the same task. Our main result does not require the scheduler to know the execution time of each job in advance, and requires only average-case utilization to be bounded by the number of processors. this constraint is mild compared to constraints on worst-case utilization because in multiprocessor systems, worst-case execution times may be orders of magnitude higher than average-case execution times.
In real-timesystems research, validations are usually performed by executing synthetically generated tasks through programmatic implementations of derived algorithms or theoretical results. For every new result, real...
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In real-timesystems research, validations are usually performed by executing synthetically generated tasks through programmatic implementations of derived algorithms or theoretical results. For every new result, real-time researchers have to develop systems, several times from scratch, for generating task sets as well as implementing their derivations. Another issue arises when the results are submitted for peer review. Reviewers only have access to results in the form of numerical values given in the paper, and have no easy way of validating the results themselves. To solve these two issues, we present a new extensible system for real-time task generation and simulation. Using modern software engineering principles of object and reflection-oriented programming, we show how real-time analysis can be partitioned into sub-systems, where each such subsystem can be implemented as a run-time 'plug-in' which can be independently developed by different research groups. this technique is intended to save real-time researchers the significant amount of time spent in result validation, as well as allow reviewers easy access to the experimental setup of the submitted paper for a more efficient review process.
We consider wireless real-timesystemsthat execute computationally-intensive applications and must transmit packets over the network in a timely manner. Existing methods do not consider the importance (i.e., urgency)...
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We consider wireless real-timesystemsthat execute computationally-intensive applications and must transmit packets over the network in a timely manner. Existing methods do not consider the importance (i.e., urgency) of a packet as perceived by end users in conjunction with energy consumption, real-time task deadlines, and packet deadlines, inadvertently causing packet priority inversion during transmissions and possibly starvation of some streams. We present an online holistic scheduling framework that explicitly considers packet importance to select packets to transmit and guarantee their deadline requirements using both packet and energy-aware job assignment and scheduling. Our framework is applicable to wireless real-timesystems equipped with either a single processor or a multicore system. Based on extensive simulations, we show that our proposed method allows for timely transmissions of the most important packets, which helps to control packet urgency, while saving processor(s) energy.
Current approaches to instruction cache analysis for determining worst-case execution time rely on building a mathematical model of the cache that tracks its contents at all points in the program. this requires perfec...
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Current approaches to instruction cache analysis for determining worst-case execution time rely on building a mathematical model of the cache that tracks its contents at all points in the program. this requires perfect knowledge of the functional behaviour of the cache and may result in extreme complexity and pessimism if many alternative paths through code sections are possible. To overcome these issues, this paper proposes a new hybrid approach in which information obtained from program traces is used to automate the construction of a model of how the cache is used. the resulting model involves the learning of a Bayesian network that predicts which instructions result in cache misses as a function of previously taken paths. the model can then be utilised to predict cache misses for previously unseen inputs and paths. the accuracy of this learned model is assessed against real benchmarks and an established statistical approach to illustrate its benefits.
Current real-timesystems such as robots have multiprocessors and the number of processors tends to be increased. In order to achieve these real-timesystems, global real-time scheduling has been required. Many real-t...
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Current real-timesystems such as robots have multiprocessors and the number of processors tends to be increased. In order to achieve these real-timesystems, global real-time scheduling has been required. Many real-time scheduling algorithms are usually based on Liu and Layland's model. Compared to Liu and Layland's model, the imprecise computation model is one of the techniques to overcome the gap between theory and practice. Semi-fixed-priority scheduling is part-level fixed-priority scheduling in the extended imprecise computation model, which has a second mandatory part to terminate an optional part. Unfortunately, current semi-fixed-priority scheduling is only adapted to uniprocessors. this paper presents a global semi-fixed-priority scheduling algorithm, called Global Rate Monotonic with Wind-up Part (G-RMWP). G-RMWP calculates the optional deadline, the termination time of each optional part, by Response time Analysis for Global Rate Monotonic (G-RM). the schedulability analysis shows that one task set is schedulable by G-RMWP if the task set is schedulable by G-RM. Simulation results show that G-RMWP has higher schedulability than G-RM.
In this paper, water tap usage is examined based on water sound analysis. We focus on detecting "water waste" to make persuasion of water savings effective, where two types of water waste are defined: inter-...
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In this paper, water tap usage is examined based on water sound analysis. We focus on detecting "water waste" to make persuasion of water savings effective, where two types of water waste are defined: inter-activity water waste and intra-activity water waste. Based on a preliminary user survey, four types of basin-related activities are identified that occur with water waste. We apply a spectrum subtraction method for feature selection and propose cascaded classifiers for activity recognition. the result of an evaluation presents that the aggregate accuracies to identify inter-activity water waste and intra-activity one are 100.0 % and 81.1%, respectively.
Multiprocessor systems are increasingly being used in real-timecomputing, and much research has been done on schedulability analysis of these systems. However, current schedulability analyses have only limited suppor...
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Multiprocessor systems are increasingly being used in real-timecomputing, and much research has been done on schedulability analysis of these systems. However, current schedulability analyses have only limited support for job-level parallelism (JLP): jobs are typically restricted to a simple parallel structure, and malleable jobs, where the number of processors assigned to a job is dynamic, is not widely supported. this paper presents a framework for analyzing systems with malleable jobs of an arbitrary parallel structure. A fair intra-job scheduler is assumed, allowing the state of a job to be represented by a scalar and its parallel structure to be modeled as a function. It is demonstrated that jobs executing their worst-case computations do not necessarily constitute a worst-case scenario with respect to schedulability. this implies that exact schedulability analysis will not be sustainable. Upper bounds on interference and demand are developed. this framework is then used to construct a pessimistic, but sustainable schedulability test for systems scheduled with EDF. the EDF test has poor worst-case performance, but does allow schedulability analysis for a class of systems for which no other analysis currently exists. We believe the framework itself could also be used to construct analyses with better performance.
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