一种新的磁盘调度策略：D（0．2，S，d）

On the Simulation of a Scheduling Strategy for Disks

提出了一种新的调度策略Ｄ（０．２，Ｓ，ｄ）．其基本思想是根据请求访问磁盘的申请在磁盘瞬时不均匀分布情况下而进行有选择优先服务的策略，核心是增加磁头向磁盘上申请访问密集处移动倾向的一种调度原则．模拟出各种情形，然后用新旧调度算法调度，比较其调度效果．同时，测定新调度算法中两个调节参数Ｓ和ｄ所处的最佳位置，达到了最佳调度效果：平均等待时间最短和平均响应方差最小．

A new disk scheduling algorithm D(R,S,d)is developed.The basic idea consists in in-creasing the tendency of movement of the head to respond to the higher density of the accessrequest on the disk. By simulations carried out for various cases ,it is shown that the algo-rithm developed is better than any exisling ones in both the niean request waiting time andthe standard variance of the request waiting time,Three parameters for the algorithi i havebeen determined.