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，称为时间片或时间片的小时间单位为每个作业提供 CPU。 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)和循环(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. |