• Disk-scheduling algo should be a separate OS module –allowing it to be replaced with a different algorithm if necessary. • Either SSTF or LOOK is a reasonable default algo g 21 How is the disk formatted? • After manufacturing disk has no information –Is stack of platters ...
Disk Sceduling Algo Disk Sceduling 沒有最好跟最差 FCFS SSTF SCAN C-SCAN LOOK C-LOOK (一) FCFS 演算法 (first-come, first-serve) 定義:先到達的請求優先服務。 分析 1.容易製作 2.公平,no starvation 3.排班效果不好,即平均 seek time 長 (二) SSTF 演算法 (short-seek time first) 定義:距離...