排序方式: 共有30条查询结果,搜索用时 15 毫秒
1.
Peixia Gao Sabine Wittevrongel Joris Walraevens Herwig Bruneel 《Mathematical Methods of Operations Research》2008,67(2):269-284
In this paper, we study the behavior of a discrete-time multiserver buffer system with infinite buffer size. Packets arrive
at the system according to a two-state Markovian arrival process. The service times of the packets are assumed to be constant,
equal to multiple slots. The behavior of the system is analyzed by means of an analytical technique based on probability generating
functions (PGF’s). Explicit expressions are obtained for the PGF’s of the system contents and the packet delay. From these,
the mean values, the variances and the tail distributions of the system contents and the packet delay are calculated. Numerical
examples are given to show the influence of various model parameters on the system behavior. 相似文献
2.
Tom Maertens Joris Walraevens Herwig Bruneel 《European Journal of Operational Research》2007,180(3):1168-1185
In this paper, we introduce and analyze a modified HOL (head-of-the-line) priority scheduling discipline. The modification is incorporated to cope with the so-called starvation problem of regular HOL priority queues. We consider a discrete-time single-server queueing system with two priority queues of infinite capacity and with the introduced priority scheme. We show that the use of probability generating functions is suitable for analyzing the system contents and the packet delay. Some performance measures (such as means and variances) of these stochastic quantities will be derived. Furthermore, approximate expressions of the tail probabilities are obtained from the probability generating functions, by means of the dominant-singularity method. These expressions, together with their characteristics, constitute one of the main contributions of this paper. Finally, the impact and significance of the m-HOL (modified HOL) priority scheduling on these performance measures is illustrated by some numerical examples. 相似文献
3.
In this paper, we analyze a discrete-time preemptive repeat priority queue with resampling. High-priority packets have preemptive
repeat priority, and interrupted low-priority packets are subjected to independent retransmission attempts. Both classes contain
packets with generally distributed transmission times. We show that the use of generating functions is beneficial for analyzing
the system contents and packet delay of both classes. The influence of the priority scheduling on the performance measures
is illustrated by some numerical examples.
This work has been supported by the Interuniversity Attraction Poles Programme–Belgian Science Policy. 相似文献
4.
Priority queueing systems come natural when customers with diversified delay requirements have to wait to get service. The
customers that cannot tolerate but small delays get service priority over customers which are less delay-sensitive. In this
contribution, we analyze a discrete-time two-class preemptive repeat identical priority queue with infinite buffer space and
generally distributed service times. Newly arriving high-priority customers interrupt the on-going service of a low-priority
customer. After all high-priority customers have left the system, the interrupted service of the low-priority customer has
to be repeated completely. By means of a probability generating functions approach, we analyze the system content and the
delay of both types of customers. Performance measures (such as means and variances) are calculated and the impact of the
priority scheduling is discussed by means of some numerical examples. 相似文献
5.
Dieter Claeys Koenraad Laevens Joris Walraevens Herwig Bruneel 《Mathematical Methods of Operations Research》2010,72(1):1-23
Whereas the buffer content of batch-service queueing systems has been studied extensively, the customer delay has only occasionally
been studied. The few papers concerning the customer delay share the common feature that only the moments are calculated explicitly.
In addition, none of these surveys consider models including the combination of batch arrivals and a server operating under
the full-batch service policy (the server waits to initiate service until he can serve at full capacity). In this paper, we
aim for a complete characterisation—i.e., moments and tail probabilities - of the customer delay in a discrete-time queueing
system with batch arrivals and a batch server adopting the full-batch service policy. In addition, we demonstrate that the
distribution of the number of customer arrivals in an arbitrary slot has a significant impact on the moments and the tail
probabilities of the customer delay. 相似文献
6.
Dieter Claeys Joris Walraevens Koenraad Laevens Herwig Bruneel 《4OR: A Quarterly Journal of Operations Research》2010,8(3):255-269
In this paper, we compute the probability generating functions (PGF’s) of the customer delay for two batch-service queueing
models with batch arrivals. In the first model, the available server starts a new service whenever the system is not empty
(without waiting to fill the capacity), while the server waits until he can serve at full capacity in the second model. Moments
can then be obtained from these PGF’s, through which we study and compare both systems. We pay special attention to the influence
of the distribution of the arrival batch sizes. The main observation is that the difference between the two policies depends
highly on this distribution. Another conclusion is that the results are considerably different as compared to Bernoulli (single)
arrivals, which are frequently considered in the literature. This demonstrates the necessity of modeling the arrivals as batches. 相似文献
7.
In this paper, we present an in-depth analytical study of a semi-preemptive priority scheduling discipline. This discipline eliminates the deficits of both the full- and non-preemptive versions. Under the non-preemptive category, in particular, higher-priority customers may have to wait even when the service of a lower-priority customer has just started, while under the full-preemptive discipline, the almost completed service of a lower-priority customer may be interrupted due to the arrival of higher-priority customers, possibly causing a large extra delay. For fixed low-priority service times, the semi-preemptive priority scheduling discipline shows a performance gain of up to 6% compared to the full- and non-preemptive versions. 相似文献
8.
Jasper Vanlerberghe Tom Maertens Joris Walraevens Stijn De Vuyst Herwig Bruneel 《4OR: A Quarterly Journal of Operations Research》2016,14(3):281-308
Numerous scheduling policies are designed to differentiate quality of service for different applications. Service differentiation can in fact be formulated as a generalized resource allocation optimization towards the minimization of some important system characteristics. For complex scheduling policies, however, optimization can be a demanding task, due to the difficult analytical analysis of the system at hand. In this paper, we study the optimization problem in a queueing system with two traffic classes, a work-conserving parameterized scheduling policy, and an objective function that is a convex combination of either linear, convex or concave increasing functions of given performance measures of both classes. In case of linear and concave functions, we show that the optimum is always in an extreme value of the parameter. Furthermore, we prove that this is not necessarily the case for convex functions; in this case, a unique local minimum exists. This information greatly simplifies the optimization problem. We apply the framework to some interesting scheduling policies, such as Generalized Processor Sharing and semi-preemptive priority scheduling. We also show that the well-documented \(c\mu \)-rule is a special case of our framework. 相似文献
9.
Herwig Bruneel Willem Mélange Bart Steyaert Dieter Claeys Joris Walraevens 《European Journal of Operational Research》2012
This paper considers a simple discrete-time queueing model with two types (classes) of customers (types 1 and 2) each having their own dedicated server (servers A and B resp.). New customers enter the system according to a general independent arrival process, i.e., the total numbers of arrivals during consecutive time slots are i.i.d. random variables with arbitrary distribution. Service times are deterministically equal to 1 slot each. The system uses a “global FCFS” service discipline, i.e., all arriving customers are accommodated in one single FCFS queue, regardless of their types. As a consequence of the “global FCFS” rule, customers of one type may be blocked by customers of the other type, in that they may be unable to reach their dedicated server even at times when this server is idle, i.e., the system is basically non-workconserving. One major aim of the paper is to estimate the negative impact of this phenomenon on the queueing performance of the system, in terms of the achievable throughput, the system occupancy, the idle probability of each server and the delay. As it is clear that customers of different types hinder each other more as they tend to arrive in the system more clustered according to class, the degree of “class clustering” in the arrival process is explicitly modeled in the paper and its very direct impact on the performance measures is revealed. The motivation of our work are systems where this kind of blocking is encountered, such as input-queueing network switches or road splits. 相似文献
10.
In this paper, we consider several discrete-time priority queues with priority jumps. In a priority scheduling scheme with
priority jumps, real-time and non-real-time packets arrive in separate queues, i.e., the high- and low-priority queue respectively.
In order to deal with possibly excessive delays however, non-real-time packets in the low-priority queue can in the course
of time jump to the high-priority queue. These packets are then treated in the high-priority queue as if they were real-time
packets. Many criteria can be used to decide when packets of the low-priority queue jump to the high-priority queue. Some
criteria have already been introduced in the literature, and we first overview this literature. Secondly, we propose and analyse
a new priority scheme with priority jumps. Finally, we extensively compare all cited schemes. The schemes all differ in their
jumping mechanism, based on a certain jumping criterion, and thus all have a different performance. We show the pros and cons
of each jumping scheme. 相似文献