Consider a disk queue with requests for 1/O to blocks on cylinders 82,170,43,140,24,16,190 The head is initially at cylinder number 50. The cylinders are numbered from 0 to 199. Calculate the total number of head movements needed to satisfy these requests for the following disk scheduling algorithms 1. FCFS 2. SSTF 3. SCAN(moving towards larger cylinder numbers on its servicing pass) 4. C-SCAN 5 C-LOOK

Consider a disk queue with requests for 1/O to blocks on cylinders 82,170,43,140,24,16,190 The head is initially at cylinder number 50. The cylinders are numbered from 0 to 199. Calculate the total number of head movements needed to satisfy these requests for the following disk scheduling algorithms 1. FCFS 2. SSTF 3. SCAN(moving towards larger cylinder numbers on its servicing pass) 4. C-SCAN 5 C-LOOK

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Suppose we have a system with 50 active processes, P0, P1, ..., P49, some user processes, and some kernel processes. For simplicity, we are not concerned with threads in this question. Ready processes are scheduled to Run by some scheduler. The scheduling algorithm does not matter here. Suppose process P13 makes a disk_read() operating system call. Assume that completion of disk transfer is signaled by an interrupt from the disk controller. Trace as accurately as you can what happens in the CPU (not the disk) until process P13 has received its requested information from the disk. Hints: The question is about interrupt handlingI am looking for a trace of what processes run, why, and what they do.I am not looking for instruction-level explanations.I am not looking for a discussion of disk access, operation, or transfer.
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Suppose we have a system with 50 active processes, P0, P1, ..., P49, some user processes, and some kernel processes. For simplicity, we are not concerned with threads in this question. Ready processes are scheduled to Run by some scheduler. The scheduling algorithm does not matter here. Suppose process P13 makes a disk_read() operating system call. Assume that the completion of disk transfer is signalled by an interrupt from the disk controller. Trace as accurately as you can what happens in the CPU (not the disk) until process P13 has received its requested information from the disk. Hints: The question is about interrupt handling I am looking for a trace of what processes run, why, and what they do. I am not looking for instruction-level explanations. I am not looking for a discussion of disk access, operation, or transfer.
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