The Priority Problem and Computer Time Sharing
The Priority Problem and Computer Time Sharing
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优先级问题和计算机时间共享
DOI：
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发表时间：
1966
期刊：
影响因子：
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通讯作者：
M. Greenberger
中科院分区：
文献类型：
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作者：
M. Greenberger
当有限的设施必须分配给竞争性的服务需求时，就会作出优先权决定。从广义上看，即使是熟悉的先到先得的纪律也是一个优先规则。它有利于等待时间最长的用户，并防止过度延迟。其他优先规则，如最短作业-下一个，则主要考虑运营效率。请求的紧迫性仍然是另一个共同考虑因素。由于这些考虑往往相互冲突，优先权规则起着调解作用。使用一个共同的大衣措施可以帮助实现这一调解，从最近的车间模拟结果说明。一个优先级操作的当代利益是调度一个分时计算机之间的并发用户。服务要求在执行之前是未知的。为了保持小请求的响应时间较短，服务间隔被划分，并且以循环方式分别为段提供服务。数学分析精确地指出了在这个过程中隐含的开销和歧视之间的权衡，并允许替代策略进行成本计算。简单的循环程序的扩展建议，分时的目标进行审查，并得出未来的优先级和定价系统的设计的影响。
Priority decisions arise whenever limited facilities must be apportioned among competitive demands for service. Broadly viewed, even the familiar first-come-first-served discipline is a priority rule. It favors the longest-waiting user, and guards against excessive delays. Other priority rules, such as shortest-job-next, are keyed instead to considerations of operating efficiency. Urgency of request is still another common consideration. Since these considerations often conflict, the priority rule serves as mediator. Use of a common coat measure can help effect this mediation, as results from recent job-shop simulations illustrate. A priority operation of contemporary interest is scheduling a time-shared computer among its concurrent users. Service requirements are not known in advance of execution. To keep response times short for small requests, service intervals are partitioned and segments are served separately in round-robin fashion. A mathematical analysis pinpoints the tradeoff between overhead and discrimination implicit in this procedure, and allows alternate strategies to be costed. Extensions of the simple round-robin procedure are suggested, the objectives of time sharing are reviewed, and implications are drawn for the design of future priority and pricing systems.