Questions and Answers
What is an operating system?
A program that acts as an intermediary between a user of a computer and the computer hardware.
What are the components of a computer system? (Select all that apply)
Which of the following are goals of an operating system? (Select all that apply)
What is the basic unit of computer storage?
Signup and view all the answers
What does 'multiprogramming' mean?
Signup and view all the answers
A kilobyte is equal to 1,024 bytes.
Signup and view all the answers
The CPU and I/O devices can execute __________.
Signup and view all the answers
Which of the following is NOT a type of storage discussed?
Signup and view all the answers
What is direct memory access (DMA)?
Signup and view all the answers
What is the role of interrupts in operating systems?
Signup and view all the answers
What resources does a process need to accomplish its task?
Signup and view all the answers
A single-threaded process has one program counter.
Signup and view all the answers
What are the activities of process management in an operating system? (Select all that apply)
Signup and view all the answers
What does memory management determine?
Signup and view all the answers
File-system management is part of storage management.
Signup and view all the answers
What is tertiary storage?
Signup and view all the answers
What are the responsibilities of the I/O subsystem? (Select all that apply)
Signup and view all the answers
______ refers to the control of access of processes or users to resources defined by the OS.
Signup and view all the answers
Which of the following is a user goal for an operating system? (Select all that apply)
Signup and view all the answers
What is the purpose of a system program?
Signup and view all the answers
What are common methods of operating system structure? (Select all that apply)
Signup and view all the answers
What is modularity in operating systems?
Signup and view all the answers
Which operating system is partly based on the Mach microkernel?
Signup and view all the answers
What is a benefit of using a microkernel?
Signup and view all the answers
Microkernel communication takes place through shared memory.
Signup and view all the answers
What is a loadable kernel module?
Signup and view all the answers
Which of the following is NOT a characteristic of hybrid operating systems?
Signup and view all the answers
What programming environment is used in Apple's iOS for app development?
Signup and view all the answers
Android is developed by the Open Handset Alliance and is open source.
Signup and view all the answers
What does DTrace in Solaris allow?
Signup and view all the answers
What is the purpose of the SYSGEN program in operating system generation?
Signup and view all the answers
What initializes the execution of an operating system when power is turned on?
Signup and view all the answers
What does the bootstrap loader do?
Signup and view all the answers
Study Notes
Introduction to Operating Systems
- Operating System (OS) serves as an intermediary between users and computer hardware.
- Goals of an OS: execute user programs, enhance user convenience, and optimize hardware utilization.
Computer System Components
- Four key components: hardware (CPU, memory, I/O), OS, application programs (e.g., word processors, databases), and users (people or machines).
- OS controls and coordinates hardware among applications and users.
User Perspectives on OS
- User requirements: convenience, ease of use, and performance over resource utilization.
- Different environments: shared systems (mainframes), dedicated workstations, and resource-constrained devices (handhelds).
OS Functions
- OS acts as an allocator of resources, managing demands and ensuring fair usage.
- It controls program execution to prevent errors and improper uses.
- Definitions of OS vary; generally, it comprises the kernel and accompanying system and application programs.
System Startup
- Bootstrapping initializes all system aspects, loading the OS kernel from firmware stored in ROM/EPROM.
Computer Organization and Operation
- Modern systems have multiple CPUs and device controllers connected via a bus, enabling concurrent operations.
- Device controllers manage data flow between I/O devices and main memory.
Interrupts
- Interrupts transfer control to the OS and require saving the CPU's state.
- Types of interrupts: hardware interrupts and software-generated traps (e.g., program errors).
- OS is driven by interrupts, responding to various device and user requests.
I/O Operations and Structure
- Control returns to the user program only upon I/O completion unless otherwise specified.
- Device-status tables track each I/O device status.
Storage Structures
- Main memory is volatile and provides direct access to the CPU, whereas secondary storage (e.g., hard disks) offers larger, non-volatile capacity.
- Storage hierarchy organized by speed, cost, and volatility with caching as a vital mechanism for performance.
Direct Memory Access (DMA)
- Enables high-speed data transfers directly between devices and memory, minimizing CPU intervention and reducing interrupts.
Computer-System Architecture
- Predominantly single processor systems, with increasing adoption of multiprocessor and multi-core systems for better performance and reliability.
- Two multiprocessor types: asymmetric (dedicated tasks) and symmetric (shared tasks).
Clustering Systems
- Multiple interconnected systems provide high availability and fault tolerance.
- Types include asymmetric clustering (hot-standby) and symmetric clustering (active monitoring).
OS Structure and Operations
- Multiprogramming increases CPU usage by organizing jobs, while timesharing enables multiple user interactions.
- Dual-mode operation protects the OS from user processes.
- CPU timer counters prevent resource hogging by interrupting processes after a designated time.
Process Management
- A process is an executing program requiring system resources: CPU, memory, I/O.
- Multi-threading allows concurrent execution within a single process, enhancing efficiency.
Memory Management
- Essential for program execution; it ensures that necessary instructions and data reside in memory during runtime.### Memory Management
- Manages memory allocation and tracks usage to optimize CPU performance and user experience.
- Activities include tracking memory usage, deciding data movement in and out of memory, and allocating/deallocating memory.
Storage Management
- Provides a logical abstraction of physical storage, presenting files instead of raw data.
- Controlled by device drivers with varying access speeds, capacities, and methods (sequential/random).
File-System Management
- Files organized into directories with access control for security.
- OS tasks include creating/deleting files, mapping storage, and backing up data.
Mass-Storage Management
- Disks store data not fitting in main memory or requiring long-term retention.
- Key activities: managing free space, storage allocation, and disk scheduling.
- Tertiary storage includes optical media and magnetic tapes, requiring management despite slower speeds.
Data Migration
- Critical in multitasking environments to ensure the most recent data is accessed.
- In multiprocessor systems, cache coherence is essential to keep data synchronized across CPUs.
- Distributed environments complicate data consistency with multiple copies of information.
I/O Subsystem
- Hides hardware complexities from users; manages data transfer and device operations.
- Responsible for buffering, caching, and spooling to optimize input/output processes.
Protection and Security
- Protection mechanisms control access to resources by processes/users.
- Security focuses on defense against various attacks (e.g., denial-of-service, malware).
- User identification through unique IDs and group IDs that regulate access permissions.
Kernel Data Structures
- Utilizes standard programming structures like linked lists and binary search trees for efficiency.
UNIX Example
- A multitasking OS using
fork()to create processes andexec()to load programs. - Processes exit with a status code indicating success (0) or error (non-zero).
System Programs
- Facilitate program development and execution through several functions: file manipulation, status information, programming support, and communication mechanisms.
Operating System Design and Implementation
- Aimed at balancing user goals (convenience, reliability) and system goals (flexibility, maintenance).
- Separation of policy (what to do) from mechanism (how to do it) enhances adaptability.
Implementation Variations
- Early OSes developed in assembly; modern implementations primarily in C/C++.
- Mix of languages enhances portability but can affect performance.
Operating System Structures
- General-purpose OS may follow various structures: simple (MS-DOS), complex (UNIX), layered, or microkernel (Mach).
- Layered systems allow modular development, while microkernels enhance reliability and security but may introduce overhead.
Modules
- Modern OSes use loadable kernel modules for flexibility and dynamic functionality.
- Interfaces facilitate communication among separate components.
Hybrid Systems
- Combine features from multiple architectures for optimized performance and security.
- Examples include Linux/Solaris (monolithic, modular) and Mac OS X (layered, microkernel hybrid).
Mobile Operating Systems
- iOS, structured on Mac OS X, incorporates touch interfaces and cloud services.
- Android, based on a modified Linux kernel, provides power management and a Java-based development environment.
Operating-System Debugging
- Involves identifying and resolving software bugs with log files and memory dumps.
- Performance tuning executed via trace listings and profiling to analyze and enhance efficiency.### Performance Tuning
- Performance improvement involves removing bottlenecks within an operating system (OS).
- The OS should provide tools for measuring and displaying system behavior.
- Examples of such tools include the “top” program on Unix-based systems and Task Manager on Windows.
DTrace
- DTrace is a powerful tool available on Solaris, FreeBSD, and Mac OS X for live instrumentation on production systems.
- Probes within DTrace activate when specific code is executed, capturing state data for analysis.
- An example use case is tracking the
XEventsQueuedsystem call as it transitions from the libc library to the kernel and back.
DTrace Applications (Cont.)
- DTrace can record the duration (in nanoseconds) that each process with UserID 101 spends in a running state on the CPU.
Operating System Generation
- Operating systems are created to function across a variety of machine types, requiring specific configurations for individual hardware setups.
- The SYSGEN program collects hardware configuration data to build a tailored, system-specific kernel that can be more efficient than one-size-fits-all kernels.
System Boot
- System execution begins at a defined memory location upon power initialization, with firmware ROM containing the initial boot code.
- A bootstrap loader, often stored in ROM or EEPROM, is essential for loading the OS into memory and initiating it.
- Booting can be a two-step process where a boot block, loaded by ROM code, finds and loads the bootstrap loader from disk.
- GRUB is a common bootstrap loader that provides options for selecting kernels from various disks and versions, facilitating multi-boot environments.
- Once the kernel is loaded, the operating system becomes operational.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the fundamental concepts of Operating Systems as introduced in Unit I of the 21CSC202J course. Topics include computer-system organization, operating-system structure, process management, and open-source operating systems. Test your understanding of how operating systems function and their various components.
