Operating System Concepts - Storage Hierarchy and Device Management
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Questions and Answers

Which of the following is NOT a benefit of multiprocessing?

  • Economy of scale
  • Increased reliability through graceful degradation or fault tolerance
  • Reduced reliability due to increased complexity (correct)
  • Increased throughput

    • In a symmetric multiprocessing architecture, which of the following statements is true?

  • Each processor is assigned a specific task
  • Each processor performs all tasks (correct)
  • Processors are assigned tasks based on their computing power
  • Processors are assigned tasks based on their location in the system

    • In a non-uniform memory access (NUMA) system, which of the following is true?

  • Memory access times are always faster than in a uniform memory access system
  • Memory access times are always slower than in a uniform memory access system
  • All memory access times are equal
  • Memory access times vary depending on the memory location relative to the processor (correct)

    • Which of the following statements about clustered systems is NOT true?

    <p>They are designed for low-performance computing applications</p> Signup and view all the answers

    In the context of computing environments, what is a thin client?

    <p>A network computer with minimal software and hardware resources</p> Signup and view all the answers

    Which of the following computing environments is characterized by devices interconnecting via wireless networks?

    <p>Mobile</p> Signup and view all the answers

    What is the purpose of caching in a computer system?

    <p>To copy information into a faster storage system</p> Signup and view all the answers

    In the context of operating systems, what is the purpose of a device driver?

    <p>To manage I/O operations between device controllers and the kernel</p> Signup and view all the answers

    What is the key characteristic of Direct Memory Access (DMA) regarding data transfer?

    <p>Allows devices to transmit data at speeds close to memory speeds</p> Signup and view all the answers

    Which type of interrupt is generated per block in Direct Memory Access (DMA)?

    <p>One hardware interrupt per block</p> Signup and view all the answers

    What is the primary function of a bootstrap program in an operating system?

    <p>To load and initialize the operating system</p> Signup and view all the answers

    What allows CPU to switch jobs frequently in timesharing systems?

    <p>Multiprogramming</p> Signup and view all the answers

    What is the main goal of multitasking in an operating system?

    <p>To create interactive computing environments</p> Signup and view all the answers

    True or False: Dual-mode operation distinguishes between user code and kernel code.

    <p><strong>True</strong></p> Signup and view all the answers

    Which of the following is responsible for ensuring a user process cannot directly transition to kernel mode?

    <p>The hardware enforces a separation between user and kernel mode through privileged instructions</p> Signup and view all the answers

    What is the primary purpose of the timer mechanism described in the text?

    <p>To prevent user processes from executing indefinitely and hogging system resources</p> Signup and view all the answers

    Which of the following statements accurately describes the relationship between a program and a process?

    <p>A process is an instance of a program in execution, representing an active unit of work within the system</p> Signup and view all the answers

    Which of the following actions is typically performed by the operating system when transitioning from user to kernel mode?

    <p>Saving the current state of the user process and loading the kernel context</p> Signup and view all the answers

    In the context of process management, what is the significance of the term 'unit of work'?

    <p>It denotes the logical separation of a program's execution into manageable and schedulable entities</p> Signup and view all the answers

    Which of the following statements accurately describes the role of privileged instructions in the context of user and kernel mode separation?

    <p>Privileged instructions can only be executed in kernel mode, preventing user processes from accessing critical system resources</p> Signup and view all the answers

    What is the primary difference between a traditional laptop and a mobile computing device like a smartphone or tablet?

    <p>Mobile devices have additional hardware features such as GPS and gyroscopes</p> Signup and view all the answers

    In a client-server computing model, which statement accurately describes the role of the server?

    <p>The server provides an interface for clients to request various services</p> Signup and view all the answers

    Which of the following statements accurately describes the peer-to-peer (P2P) model of distributed systems?

    <p>Nodes in a P2P network can act as both clients and servers, without a predefined role</p> Signup and view all the answers

    Which of the following is NOT an example of a peer-to-peer (P2P) application mentioned in the text?

    <p>Dropbox</p> Signup and view all the answers

    What is the relationship between cloud computing and virtualization, as described in the text?

    <p>Virtualization is a prerequisite for enabling cloud computing services</p> Signup and view all the answers

    Which of the following statements accurately describes the concept of cloud computing?

    <p>Cloud computing involves delivering computing resources and applications as a service over a network</p> Signup and view all the answers

    What is the purpose of the I/O subsystem mentioned in the text?

    <p>Managing the memory of I/O devices including buffering and caching</p> Signup and view all the answers

    In a multitasking environment, why must careful consideration be given to ensure the most recent value is used?

    <p>To ensure cache coherency across all CPUs</p> Signup and view all the answers

    What is the main function of mass-storage management in an operating system?

    <p>Storing data that cannot fit in main memory or needs long-term retention</p> Signup and view all the answers

    What does memory management aim to optimize in an operating system?

    <p>Computer response to users</p> Signup and view all the answers

    What is the key activity performed by the operating system regarding file-system management?

    <p>Creating and deleting files and directories</p> Signup and view all the answers

    What is the primary reason for caching data in a computer system?

    <p>To optimize CPU performance</p> Signup and view all the answers

    Which of the following is NOT a responsibility of the operating system in process management activities?

    <p>Optimizing CPU speed</p> Signup and view all the answers

    Why is memory management crucial for optimizing CPU utilization and computer response to users?

    <p>To manage what is in memory based on program needs</p> Signup and view all the answers

    What is the primary function of the mass-storage management provided by the operating system?

    <p>Storing data that cannot fit in main memory or for long-term retention</p> Signup and view all the answers

    In the context of file-system management, what does mapping files onto secondary storage involve?

    <p>Associating files with physical storage locations</p> Signup and view all the answers

    Study Notes

    Mobile Computing

    • Mobile computing has extra features such as GPS, gyroscope, and allows for new types of apps like augmented reality.
    • Mobile devices use IEEE 802.11 wireless or cellular data networks for connectivity.
    • Leaders in mobile operating systems are Apple iOS and Google Android.

    Client-Server Computing

    • Client-server computing is a model of distributed system where dumb terminals are replaced by smart PCs.
    • The compute-server system provides an interface for clients to request services such as database access.
    • The file-server system provides an interface for clients to store and retrieve files.

    Peer-to-Peer (P2P) Computing

    • P2P computing is another model of distributed system where nodes are considered peers.
    • Peers can act as both clients and servers.
    • Each node must join a P2P network and register its service with a central lookup service or broadcast requests for service via a discovery protocol.
    • Examples of P2P systems include Napster, Gnutella, and Voice over IP (VoIP) systems like Skype.

    Cloud Computing

    • Cloud computing delivers computing, storage, and applications as a service across a network.
    • It is a logical extension of virtualization, using virtualization as its base functionality.
    • Cloud computing provides resources such as CPU, memory, I/O, and files as needed.

    Process Management

    • Creating and deleting both user and system processes.
    • Suspending and resuming processes.
    • Providing mechanisms for process synchronization, communication, and deadlock handling.
    • Process management is responsible for reclaiming resources after process termination.

    Memory Management

    • Memory management determines what is in memory and when.
    • It optimizes CPU utilization and computer response to users.
    • Activities include:
      • Keeping track of which parts of memory are currently being used and by whom.
      • Deciding which processes and data to move into and out of memory.
      • Allocating and deallocating memory space as needed.

    File-System Management

    • The OS provides a uniform, logical view of information storage.
    • Files are usually organized into directories.
    • Access control is used to determine who can access what.
    • File-system management activities include:
      • Creating and deleting files and directories.
      • Primitives to manipulate files and directories.
      • Mapping files onto secondary storage.
      • Backing up files onto stable storage media.

    Mass-Storage Management

    • Mass storage is used to store data that does not fit in main memory or data that must be kept for a long period.
    • Proper management is critical.
    • OS activities include:
      • Mounting and unmounting.
      • Free-space management.
      • Storage allocation.
      • Disk scheduling.
      • Partitioning.
      • Protection.

    Caching

    • Caching is an important principle performed at many levels in a computer.
    • Information in use is copied from slower to faster storage temporarily.
    • Faster storage (cache) is checked first to determine if information is there.
    • Cache management is an important design problem.

    I/O Subsystem

    • The I/O subsystem is responsible for hiding hardware device peculiarities from the user.
    • Activities include:
      • Memory management of I/O.
      • Buffering, caching, and spooling.
      • General device-driver interface.
      • Drivers for specific hardware devices.

    Protection and Security

    • Protection is any mechanism for controlling access to resources defined by the OS.
    • Security is the 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, one per user.
    • Group identifier (group ID) allows set of users to be defined and controls managed.

    Virtualization

    • Virtualization allows operating systems to run applications within other OSes.
    • It is a vast and growing industry.
    • Emulation is used when source CPU type is different from target type.

    Multiprocessing

    • Multiprocessing is a system that contains multiple processors.
    • It provides:
      • Increased throughput.
      • Economy of scale.
      • Increased reliability – graceful degradation or fault tolerance.
    • There are two types: asymmetric and symmetric multiprocessing.

    Symmetric Multiprocessing Architecture

    • Each processor performs all tasks.
    • The OS is responsible for scheduling processes across processors.

    Clustered Systems

    • Clustered systems are like multiprocessor systems, but multiple systems working together.
    • They usually share storage via a storage-area network (SAN).
    • They provide:
      • High-availability service that survives failures.
      • Asymmetric clustering has one machine in hot-standby mode.
      • Symmetric clustering has multiple nodes running applications, monitoring each other.

    PC Motherboard

    • A PC motherboard is an example of a computer system.

    Computer System Environments

    • There are several types of computer system environments:
      • Traditional.
      • Mobile.
      • Client-server.
      • Peer-to-peer.
      • Cloud computing.
      • Real-time.
      • Embedded.
      • Computing environments are becoming more interconnected.

    Traditional Computing

    • Traditional computing is characterized by stand-alone general-purpose machines.
    • But, most systems interconnect with others (e.g., the Internet).
    • Portals provide web access to internal systems.
    • Network computers (thin clients) are like Web terminals.
    • Mobile computers interconnect via wireless networks.
    • Networking is becoming ubiquitous – even home systems use firewalls to protect home computers from Internet attacks.

    Mobile Computing

    • Mobile computing is characterized by handheld devices such as smartphones and tablets.
    • Mobile devices interconnect via wireless networks.

    Storage Hierarchy

    • The storage hierarchy is organized by speed, cost, and volatility.
    • Caching is copying information into faster storage system.
    • Device drivers are used to manage I/O.

    Storage-Device Hierarchy

    • The storage-device hierarchy is a hierarchical organization of storage devices.

    How a Modern Computer Works

    • A modern computer works using a von Neumann architecture.
    • The CPU fetches instructions from memory and executes them.

    Direct Memory Access Structure

    • Direct memory access is used for high-speed I/O devices.
    • The device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention.

    Operating-System Operations

    • The bootstrap program is a simple code that initializes the system and loads the kernel.
    • The kernel loads, starts system daemons, and kernel interrupt-driven.
    • Hardware interrupts are generated by devices.
    • Software interrupts are generated by software errors or requests for operating system service.

    Multiprogramming

    • Multiprogramming is a system that organizes jobs (code and data) so that the CPU always has one to execute.
    • When a job has to wait, the OS switches to another job.

    Multitasking

    • Multitasking is a logical extension of batch systems.
    • The CPU switches jobs so frequently that users can interact with each job while it is running.
    • Response time should be less than 1 second.
    • Each user has at least one program executing in memory.
    • CPU scheduling is used to schedule jobs.

    Memory Layout for Multiprogrammed System

    • The memory layout for a multiprogrammed system includes multiple jobs running concurrently.

    Dual-mode Operation

    • Dual-mode operation allows the OS to protect itself and other system components.
    • The mode bit is used to distinguish between user mode and kernel mode.
    • Privileged instructions are only executable in kernel mode.
    • System calls are used to change the mode to kernel mode.

    Timer

    • The timer is used to prevent infinite loops.
    • The timer is set to interrupt the computer after some time period.
    • The OS sets the timer (privileged instruction).
    • When the timer is zero, an interrupt is generated.

    Process Management

    • A process is a program in execution.
    • It is a unit of work within the system.
    • Process management is responsible for creating, deleting, suspending, and resuming processes.
    • It is also responsible for providing mechanisms for process synchronization, communication, and deadlock handling.

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    Description

    Learn about storage hierarchy in operating systems, including caching and device drivers for efficient I/O operations. Understand how main memory acts as a cache for secondary storage and the role of device controllers in managing input/output processes.

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