Memory Management Basics
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Questions and Answers

What is the primary goal of memory management?

  • To create new processes as needed
  • To remove fragmentation completely
  • To maximize memory usage and simplify access for programs (correct)
  • To maintain physical addresses only

    • What is meant by 'address space'?

  • The size of memory in the system
  • The number of processes that can run simultaneously
  • All memory locations a program can name (correct)
  • The space allocated for physical memory

    • Which type of partitioning divides memory into fixed-sized segments?

  • Fixed partitioning (correct)
  • Dynamic partitioning
  • Variable partitioning
  • Overlaid partitioning

    • What is external fragmentation?

    <p>Unused spaces between allocated memory blocks</p> Signup and view all the answers

    What is the purpose of translating virtual addresses?

    <p>To map program addresses to physical memory locations</p> Signup and view all the answers

    In the context of memory management, what does 'allocation' refer to?

    <p>The distribution of available memory to processes</p> Signup and view all the answers

    Which of the following describes single tasking with overlay?

    <p>Loading only necessary parts of a program into memory to save space</p> Signup and view all the answers

    What does internal fragmentation refer to?

    <p>Unused memory within allocated partitions</p> Signup and view all the answers

    What is the primary purpose of using overlays in a process?

    <p>To keep only needed instructions and data in memory</p> Signup and view all the answers

    Which of the following is a disadvantage of using overlays?

    <p>A process cannot utilize more memory than is allocated</p> Signup and view all the answers

    In a single-tasking OS environment, what is a key characteristic of overlay management?

    <p>Only one program runs at a time</p> Signup and view all the answers

    How does memory partitioning improve memory management?

    <p>It divides memory into separate sections for allocation</p> Signup and view all the answers

    Which method of memory partitioning divides memory into fixed-sized sections?

    <p>Fixed partitioning</p> Signup and view all the answers

    What is a common reason developers implement overlays in programming?

    <p>To manage memory in cases of limited space</p> Signup and view all the answers

    What happens to the previously used memory space when new instructions are loaded using overlays?

    <p>It is reused for other loaded instructions</p> Signup and view all the answers

    Why is the design of the overlay structure considered complex?

    <p>It involves careful management of memory and loading sequences</p> Signup and view all the answers

    What is the primary responsibility of a memory manager?

    <p>To keep track of memory usage and facilitate de-allocation.</p> Signup and view all the answers

    What is a logical address in terms of memory management?

    <p>An address generated by the CPU during program execution.</p> Signup and view all the answers

    Which registers define the logical address space in a computer system?

    <p>Base and Limit Registers.</p> Signup and view all the answers

    In the context of address binding, what happens during loading?

    <p>A program is loaded into physical memory from secondary storage.</p> Signup and view all the answers

    What does swapping in memory management achieve?

    <p>It frees up memory for other processes by moving processes to secondary storage.</p> Signup and view all the answers

    How does the overlay technique in memory management work?

    <p>It loads only essential program parts into memory when needed.</p> Signup and view all the answers

    What is the purpose of address binding during the execution time?

    <p>To execute instructions using physical addresses in memory.</p> Signup and view all the answers

    Which best describes physical addresses in memory management?

    <p>They are the actual locations in memory that the hardware recognizes.</p> Signup and view all the answers

    What does variable partitioning allow in terms of memory allocation?

    <p>Dividing memory based on process requirements</p> Signup and view all the answers

    In fixed memory partitioning, what is a key characteristic of each partition?

    <p>It may contain exactly one process</p> Signup and view all the answers

    What can be a result of memory partitioning techniques?

    <p>Internal fragmentation</p> Signup and view all the answers

    What does the best fit memory allocation strategy aim to do?

    <p>Allocate the smallest available space for the process</p> Signup and view all the answers

    How does fixed partitioning affect the degree of multiprogramming?

    <p>It limits multiprogramming to the number of existing partitions</p> Signup and view all the answers

    What happens when a process in a fixed partition system terminates?

    <p>The partition becomes free for another process</p> Signup and view all the answers

    Which algorithm specifically allocates memory by selecting the first suitable space available?

    <p>First fit</p> Signup and view all the answers

    What is the main difference between internal and external fragmentation?

    <p>Internal fragmentation occurs within allocated memory blocks</p> Signup and view all the answers

    What is external fragmentation?

    <p>Small free spaces that cannot be used for new allocations.</p> Signup and view all the answers

    What causes internal fragmentation?

    <p>Using fixed partitioning that allocates more memory than needed.</p> Signup and view all the answers

    Which memory partitioning technique leads to external fragmentation?

    <p>Variable partitioning.</p> Signup and view all the answers

    What is the result of compaction in memory management?

    <p>It shuffles all free memory spaces together to form a large block.</p> Signup and view all the answers

    When does fragmentation typically occur?

    <p>When memory spaces are frequently used for allocation and deallocation.</p> Signup and view all the answers

    What type of fragmentation results from fixed memory allocation leading to wasted space?

    <p>Internal fragmentation.</p> Signup and view all the answers

    Which of the following best describes the effect of fragmentation on memory management?

    <p>It can cause allocation failures even when total free memory is sufficient.</p> Signup and view all the answers

    What is the main disadvantage of external fragmentation?

    <p>It prevents the system from using sufficient total memory due to non-contiguous free spaces.</p> Signup and view all the answers

    Study Notes

    Memory Management

    • The organization of programs and data within memory.
    • Memory Management aims to simplify space allocation for programs and maximize memory usage.
    • Key responsibilities include tracking memory usage, allocating/de-allocating memory, and ensuring efficient sharing among multiple processes.

    Address Space Basics

    • Defines all memory locations a program can access.
    • Virtual address refers to addresses within the process's address space.
    • Physical address corresponds to the actual memory location.
    • Translation involves mapping virtual addresses to physical addresses.

    Single Tasking with Overlay

    • Implemented in a single-tasking OS environment.
    • Enables running larger programs by loading necessary components (overlays) into memory as required.

    Memory Partitioning

    • Dividing the memory space into separate sections, improving efficiency in allocating space to processes.
    • Two types: Fixed Partitioning and Variable Partitioning

    Fixed Partitioning

    • Divides memory into fixed-sized partitions.
    • Each partition can hold only one process at a time.
    • The degree of multi-programming is limited to the number of partitions available.
    • When a partition becomes free, a process is selected from the input queue and loaded.

    Variable Partitioning

    • Divides memory based on process requirements.
    • Processes can be loaded into any available space.
    • Three allocation methods are: First Fit, Best Fit, and Worst Fit.
    • First Fit: Allocates the first space available to fit the process.
    • Best Fit: Allocates the smallest space that will fit the process.
    • Worst Fit: Allocates the largest space available.

    Fragmentation

    • Occurs when memory spaces are used in a way that leaves small unused pieces of memory.
    • Two Types: Internal Fragmentation and External Fragmentation

    Internal Fragmentation

    • Wasted space within allocated memory blocks.
    • Occurs when extra memory space is allocated to a process, but not used.
    • Common in fixed partitioning, as the unused space cannot be allocated elsewhere.

    External Fragmentation

    • Small free spaces that cannot be used for new allocations, as they are not contiguous.
    • More common in variable partitioning.

    Resolving External Fragmentation

    • Compaction is often used to resolve external fragmentation.
    • It shuffles all free memory spaces together to form a large, usable block.

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    Related Documents

    OS_Lecture4_VU_Final.pptx

    Description

    This quiz explores fundamental concepts of memory management, including organization, address space, and memory partitioning. Understand how programs utilize memory efficiently and the importance of virtual vs physical addresses. Test your knowledge on single-tasking systems and overlay techniques.

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