A Dynamic Time-Sharing Priority Queue

Adiri, I.

doi:10.1145/321662.321675

Cited by 9 publications

(4 citation statements)

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“…If p~ > 1 the whole system is saturated; and if there exists an integer n such that p~ < 1 < p~+~, then the first n levels are unsaturated, and all service requirements which can be satisfied in these levels are satisfied in a finite time. As Adiri [1] notes, this gradual saturation is one of the advantages of the FB scheduling discipline, as well as of the model presented here, over other scheduling disciplines of queueing systems. In the sequel it will be assumed that the system is in steady state and p~ < 1.…”

Section: Notation and Preliminary Resultsmentioning

confidence: 73%

“…Essentially the same phenomena occur as in Figure 5, but their scope is much more limited. The range of flow times has been decreased, the 1 I 1 I I I I I I I I I I I 2 3 4 5 6 7 8 9 i0 ii 12 …”

Section: In Their Notation E(t) = E(s) + Xe(s2)/2(1 -Xe( S) )mentioning

confidence: 99%

“…After joining the system, a user is serviced in the same way as in the FB system discussed earlier. This system was studied by Shemer [14], Kleinrock [9], Coffman and Kleinrock [6], and Adiri [1]. The CTSS time-sharing system used a variation of such a scheduling discipline (Scherr [12]), with initial queues and prioritms being assigned according to the program's sizes.…”

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confidence: 99%

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A Generalized Multi-Entrance Time-Sharing Priority Queue

Babad

1975

J. ACM

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A generalized multi-entrance and multipriority M/G/1 time-sharing system is dealt with. The system maintains many separate queues, each identified by two integers, the prmnty level and the entry level The arrival process of users is a homogenous Polsson process, while service requirements are identically distributed and have a finite second moment Upon arrival a user joins one of the levels, through the entry queue of this level In the (n, k)-th queue, where n is the priority level and k is the entry level, a user m eligible to a (finite or lnfimte) quantum of service. If the service requirements of the user are satmfied during the quantum, the user departs, and otherwise he is transferred to the end of the (n ~ 1, k)-th queue for addltmnal service When a quantum of service is completed, the highest priority nonempty level is chosen to be served next, within thin level the queues are scanned according to the prmmty of their entry level, and the user at the head of the highest prmnty nonempty queue is chosen to be served In such a priority dlsclphne, preferred users always get an improved service though the serwce of all users is degraded m proportion to their service requirements Expected flow times and expected number of waiting users are demved and then specialized to the head-of-the-hne M/G/1 prmrlty dlsciphne (in whmh quanta have infinite length and serwce is uninterrupted) and to the FB, time-sharing system. Finally, the generahzed multientrance and multipriomty time-sharing dlsclphne is (numermally) compared with several other time-sharing systems.KEY WORDS AND PHRASES. time-sharing, multi-entrance prmrity queue CR CATEGORIES' 4 32, 4 35 IntroductwnSeveral models of time-sharing computer systems have been described and analyzed in recent years. In these models jobs with short service requirements receive enhanced service at the expense of degraded service for longer requirements; the various models differ in the degree of enhancement they provide. In the simplest time-sharing system (Figure 1), known as a round-robin system, a newly arriving user joins the end of a single queue. This queue is served by a single service facility according to an FIFO discipline. The maximum interval of service time which is given to any user is of limited length, and is called a quantum; if the user's request is fulfilled during this quantum he leaves the system. Otherwise, he joins the end of the queue, behind any recycled users and newly arriving users since the most recent moment at which he entered the queue. Such a system was studied by Kleinrock [8], Adiri and Avi-Itzhak [3], Adiri [2]', and others (see McKinney [11] for additional references).The scheduling discipline of a round-robin system ignores the amount of service, measured in number of service quanta, already given to users already present in the sys-

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Section: Notation and Preliminary Resultsmentioning

confidence: 73%

Section: In Their Notation E(t) = E(s) + Xe(s2)/2(1 -Xe( S) )mentioning

confidence: 99%

mentioning

confidence: 99%

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A Generalized Multi-Entrance Time-Sharing Priority Queue

Babad

1975

J. ACM

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“…Schrage [2] has also investigated this system with different quantum sizes for the various levels. Adiri [3] and Coffman and Kleinrock [1] have studied a modification of the multiple-level system wherein the level at which a program enters the system is determined by an externally-assigned priority. Adiri also allows different quantum sizes for the various levels.…”

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confidence: 99%

Analysis of a multi-level time-sharing model

Heacox¹,

Purdom²

1974

BIT

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Abstract.The multi-level time sharing algorithm is studied. Each new job joins the bottom level queue. After each quantum of service it goes to the next higher level until it has completed service. The server always selects the lob at the head of the lowest level nonempty queue. A constant overhead is incurred for each qua~atum of service. Mean waiting time and mean system delay cost are better than those of the round robin model. Description of Model.The multiple-level (ML) system consists of a (possibly infinite) number of levels, each with its own queue. A program entering the system joins the queue at the lowest level and awaits its turn for service. If it does not finish during its allotted quantum service, it is fed back to the queue at the next higher level. At the end of a quantum service, the next program served will be the one at the head of the lowest-level non-empty queue. In the case of a finite number of levels, a program requiring service at the highest level receives a quantum at a time (with associated swap) without feedback to the end of the queue.The multiple-level model has been studied by Coffman and Kleinrock [1] for single-quantum allocation and zero overhead, with a constant quantum size at all levels. Schrage [2] has also investigated this system with different quantum sizes for the various levels. Adiri [3] and Coffman and Kleinrock [1] have studied a modification of the multiple-level system wherein the level at which a program enters the system is determined by an externally-assigned priority. Adiri also allows different quantum sizes for the various levels.Time is continuous, so that a program leaves the system as soon as its service requirement is completed. We assume a constant quantum size, q, and a constant, non-negative swap time, s. The swap is assumed to occur at the beginning of a quantum service.

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Performance evaluation studies for time-sharing computer systems

Jaiswal

1982

Performance Evaluation

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A Dynamic Time-Sharing Priority Queue

Cited by 9 publications

References 8 publications

A Generalized Multi-Entrance Time-Sharing Priority Queue

A Generalized Multi-Entrance Time-Sharing Priority Queue

Analysis of a multi-level time-sharing model

Performance evaluation studies for time-sharing computer systems

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