The major functions of operating systems:
- Process Management: scheduling processes, creating and deleting user and system processes, suspending and resuming processes, providing mechanisms for process synchronization and communication
- Memory Management: keeps track of memory currently used and by whom, decides which process and data to move from memory, allocates memory space as needed
- Storage Management: creating and deleting files and directories, mapping and backing up files
Illustrate the hierarchy of subsystems, components, or subcomponents of operating systems:
- Kernal: core of the OS, allows the applications to interact with the hardware
- Memory
Management: manages the system’s memory to ensure all applications get the
memory needed to execute instructions efficiently and optimize performance
- Process
Management: handles the creation, scheduling, and termination of processes,
helps ensure CPU efficiency
- File
System: manages file organization and retrieval, allows for easier file
management by users and applications
- Device
Management: manages hardware components
- User Interface: allows users to interact with
the system, controls instructions for hardware and software
D Describe process, process state, and process control block.
- · Process:
A program in execution
- · Process
State: New, Ready, Running, Waiting, Terminated
- · Process
Control Block (PCB): Represents each process in the operating system. Can include process state, program counter,
registers, and lists of open files.
Compare
single- and multi-threaded motivations and models.
- · Single-Threaded:
o
Motivation benefits are simplicity and
predictability.
o Models contain one thread and one CPU core, which requires tasks to be handled sequentially. Most effective on simple applications.
- · Multi-Threaded:
o Motivation
benefits are responsiveness, resource sharing, economy, and scalability
o Models
contain multiple threads and CPU cores for multiple function types. Tasks can run concurrently. More effective with complex applications.
Describe
the critical-section problem and explain a software solution that resolves the
problem.
The critical-section problem occurs when processes or threads must access the same shared resources simultaneously. The solution needs to ensure that when the resources are accessed, there is no deterioration in abilities and functions while the processes run. The simplest software resolution is the Mutex Lock. It ensures that only one process or thread can access the critical section at a time. The lock will be released when the thread has finished using the critical section, allowing other threads to engage.
Objectives and functions of memory
management in operating systems:
- · Resource
Allocation: Memory Allocations allow memory to be divided into partitions that
contain one process. When a process is completed, the partition is freed to
maximize efficiency.
- · Memory
Protection: Prevents unauthorized access to data to ensure no interference with
memory processes.
- · Memory
Organization: Optimizes the use of all memory available by managing the memory
hierarchy.
- · Swapping
and Paging: Swapping is a process moving from the main memory to a secondary
store. Processes must be idle to be swapped. Paging divides memory into pages
and page tables to manage where data is stored.
Compare and contrast the physical and
virtual address space:
- · Physical
Address:
o
Definition: Refers to physical memory
(RAM) in the hardware.
o
Mapping: Direct mapping to hardware
addresses.
o
Size Limitations: Limited to memory size
of the RAM.
o
Protection: Processes are isolated by
hardware mechanisms.
o
Performance: Fast access without needing
address translation.
o Efficiency: Physical Address mapping can cause inefficient memory usage.
- · Virtual
Address:
o
Definition: Created by the OS to provide
the illusion of a contiguous memory space.
o
Mapping: Mapped to physical memory using Memory
Management Unit (MMU).
o
Size Limitations: Determined by the CPU
architecture.
o
Protection: Provides protection by ensuring
each process has it’s own virtual address.
o Performance: Addresses need to be translated from virtual to physical.
Objectives and Functions of File Systems
Management and Supported Operations:
- · Storage
Management: Allocates sufficient space to store files, deallocates files to
free up space.
- · Directory/Organizational
Management: Creates a file system of directories and subdirectories in a
hierarchal structure.
- · File
Operations: Creates, modifies, and deletes files.
- · Security:
Manages access, secures data through encryption.
- · Data
Integrity and Reliability: Backs up data to prevent loss, supports recovery in
cases of unexpected loss.
Directory Structures
- · Single
Level: All files stored in a single directory, no subdirectories or file
sharing.
- · Two-Level:
Separates the file system for users and their files; files are stored in subdirectories,
prohibits sharing of files and directories.
- · Tree-Structured:
Each directory contains files and subdirectories, prohibits the sharing of
files and directories.
- · Acyclic-Graph:
Each directory contains files and subdirectories, shares subdirectories and
files.
- · General Graph: Similar to acyclic-graph but allows cycles within the directory structure.
Input and Output Devices
- · Hardware
Input: keyboard, mouse, microphone, camera
- · Hardware
Output: monitor, printer, speakers, headset
- · Software:
the device drivers facilitating communication between hardware and computer systems. Software translates the commands from the O/S
to the hardware.
Goals and principles of domain- and language-based protection:
- · Goals:
o
Least Privilege: Users and programs have
minimum access needed to perform their duties.
o
Failure Containment: Ensures failures
don’t affect other domains through isolation.
- · Principles:
o
Domain Structure: Established set of
access rights for a user, process, or procedure.
o
Dynamic Domain Switching: Allows switching
of domains for changes in access management.
o
Access Rights: Each domain has a defined
set of operations.
Access
Matrix for Specific Resource Protection:
· The
Access Matrix determines the permissions each subject (domain) has over each
object (file).
Security
for Program, System, and Network Protection:
- · Risks:
o
Malware
o
Denial of Service attacks
o
Unauthorized access
- · Protection:
o
Access Control, such as passwords, to
control user access.
o
Encryption to protect data.
o
Firewalls that prevent unauthorized access.
o
Regular Updates to ensure the latest
security measures are being utilized.
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