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📜  先来先服务 (FCFS) 和循环 (RR) 调度算法之间的区别

📅  最后修改于: 2021-09-15 01:36:20             🧑  作者: Mango

先到先得的调度算法
先来先服务(FCFS)是最简单的非抢占式调度算法。在先来先服务 (FCFS) 中,进程按照它们到达的顺序分配给 CPU。队列数据结构用于实现FCFS调度算法。当 CPU 空闲时,位于就绪队列头部的进程被分配给 CPU。然后从队列中删除正在运行的进程。当一个新进程进入就绪队列时,它被放到就绪队列的尾部。

循环调度算法
Round Robin (RR) 调度算法是为分时系统设计的。该算法是抢占式调度算法。在循环调度算法中,一个小的时间单位称为时间量或时间片,CPU 为其提供给每个作业。 CPU 被分配给每个作业,持续时间等于循环顺序的时间量。这个时间片、时间片或时间间隔一般在10到100毫秒的数量级。循环调度算法中的就绪队列被视为循环队列。

先来先服务(FCFS)和轮循(RR)调度算法的区别如下:

S.No. First Come First Served (FCFS) Round Robin(RR)
1. First Come First Served (FCFS) is the non-preemptive scheduling algorithm. Round Robin(RR) is the preemptive scheduling algorithm.
2. FCFS has the minimal overhead. While RR has small overhead as it is necessary to record the time elapsed and then switch the process which causes an overhead.
3. First Come First Served Scheduling Algorithm provides high response time for the processes. In Round Robin Scheduling Algorithm, for the short processes there is very low response time.
3. FCFS is inconvenient to use in the time sharing system. It is mainly designed for the time sharing system and hence convenient to use.
5. Average waiting time is generally not minimal in First Come First Served Scheduling Algorithm.  In Round Robin Scheduling Algorithm average waiting time is minimal. 
6. The process is simply processed in the order of their arrival in FCFS. It is similar like FCFS in processing but uses time quantum.