Memory Management in Operating Systems

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Questions and Answers

What is the primary function of a Memory Manager?

To manage the main memory (RAM) of the system (correct)

To allocate memory to specific users

To execute system calls

To manage the secondary storage devices

What is the purpose of memory addressing?

To enable the CPU to access memory locations (correct)

To manage memory-mapped devices

To store the kernel image of the OS

To allocate memory to specific users

What is the limitation of a 32-bit CPU in terms of memory addressing?

It can only support up to 1 GB of memory

It can only support up to 8 GB of memory

It can only support up to 4 GB of memory (correct)

It can only support up to 16 GB of memory

What is the purpose of deallocating memory?

To free up memory when it is no longer needed Signup and view all the answers

What is the term for the linear sequence of bytes in a system's RAM?

Linear store Signup and view all the answers

What is stored in CPU registers during process execution?

Memory addresses Signup and view all the answers

What is the purpose of the Memory Manager's validation of memory requests?

To check the validity of each request for memory space Signup and view all the answers

What is the term for the process of swapping pages of memory to and from disk storage?

Page swapping Signup and view all the answers

What is the process image in the context of process memory allocation?

The combined memory footprint of a process Signup and view all the answers

What happens to jumps to labels during the loading of a process image?

They are replaced by real memory addresses Signup and view all the answers

In what direction does the stack grow in a process's address space?

Downwards from the top of the process address space Signup and view all the answers

What is the purpose of the heap area in a process's memory allocation?

To provide memory for the programmer to reserve Signup and view all the answers

What is the main disadvantage of compile-time address binding?

It prevents the OS from moving the program to another memory location Signup and view all the answers

What is the main advantage of load-time address binding?

It provides more efficient use of memory by the OS Signup and view all the answers

What happens to the jump location (start label) during compile-time address binding?

It is turned into a fixed memory address Signup and view all the answers

What type of address binding allows a program to be loaded anywhere in memory?

Load-time address binding Signup and view all the answers

Study Notes

Memory Management

The memory manager manages the main memory (RAM) of the system, ensuring each process gets the memory it needs.
It preserves and protects the space in memory occupied by the OS itself.
It checks the validity of each request for memory space, allocates free areas of memory for valid requests, and deallocates memory when no longer needed.

Memory Addressing

Memory inside a system (RAM) can be viewed as a linear sequence of bytes, also known as the linear store or flat model.
Addresses range from zero up to the number of bytes available, and memory is byte addressable.
Addresses are stored in CPU registers during process execution, limiting the address space by the bit length of the CPU.
A 32-bit CPU can address 4,294,967,296 individual bytes, supporting up to 4 GB of memory.

Process Memory

A program exists on disk as a binary executable file, storing program instructions as a sequence of bytes.
When a program is run, the binary image is loaded into main memory, reserving extra memory for variables and the stack.
The combined memory footprint is the process image, with the instruction pointer set to the first byte of the image.
Jumps are replaced by real memory addresses, pointing to a physical location within the process image.

Stack and Heap

The stack grows downwards from the top of the process address space, while the process instructions start at the bottom of the image.
The memory footprint of a process includes the data area (memory for variables and objects) and the heap (memory available for programmer reservation).

Compile-Time and Load-Time Address Binding

Compile-time address binding turns loops and jump locations into fixed memory addresses during compilation, assuming a program will always occupy the same area of memory.
Load-time address binding turns loops and jump locations into relative addresses during compilation, allowing a program to be loaded anywhere in memory.
Load-time binding offers advantages to the memory manager, allowing processes to be loaded anywhere in memory.

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Description

Learn about the role of a memory manager in operating systems, including managing RAM, allocating memory, and deallocating memory when no longer needed.