Memory Management and Storage Management Quiz

Memory Management

• Determines what is in memory and when
• Optimizes CPU utilization and computer response to users
• Keeps track of which parts of memory are currently being used and by whom
• Decides which processes and data to move into and out of memory
• Allocates and deallocates memory space as needed

Storage Management

• Provides uniform, logical view of information storage
• Abstracts physical properties to logical storage unit - file
• Each medium is controlled by a device (e.g. disk drive, tape drive)
• Files are usually organized into directories
• Access control is implemented to determine who can access what
• OS activities include creating and deleting files and directories, primitives to manipulate files and directories, mapping files onto secondary storage, and backing up files onto stable storage media

Mass-Storage Management

• Disks are used to store data that doesn't fit in main memory or data that must be kept for a long period
• Proper management is central to the speed of computer operation
• OS activities include free-space management, storage allocation, and disk scheduling
• Some storage doesn't need to be fast (e.g. tertiary storage like optical storage, magnetic tape)

Performance of Various Levels of Storage

• Movement between levels of storage hierarchy can be explicit or implicit
• Data migration between levels of storage (e.g. from disk to register) requires careful management to ensure the most recent value is used

I/O Subsystem

• Hides peculiarities of hardware devices from the user
• Responsible for memory management of I/O, including buffering, caching, and spooling
• Provides a general device-driver interface and drivers for specific hardware devices

Protection and Security

• Protection: controlling access to resources defined by the OS
• Security: defense of the system against internal and external attacks
• Systems distinguish among users to determine who can do what
• User identities (user IDs, security IDs) include name and associated number
• User ID is associated with all files and processes of that user to determine access control

Kernel Data Structures

• Similar to standard programming data structures
• Examples include singly linked lists, doubly linked lists, circular linked lists, and binary search trees

Operating System Overview

• What operating systems do: manage computer hardware resources and provide common services to computer programs
• Computer-system organization: CPU, device controllers, and memory connected through a common bus
• Operating-system structure: system programs, application programs, and kernel
• Operating-system operations: process management, memory management, storage management, I/O management, and security
• Computing environments: various types of computing environments, including open-source operating systems