Memori Management

·         Memory management is the act of managing computer memory. In its simpler forms, this involves providing ways to allocate portions of memory to programs at their request, and freeing it for reuse when no longer needed. The management of main memory is critical to the computer system.

·          Virtual Memory systems separate the memory addresses used by a process from actual physical addresses, allowing separation of processes and increasing the effectively available amount of RAM using disk swapping. The quality of the virtual memory manager can have a big impact on overall system performance.

·          Garbage collection is the automated allocation and deallocation of computer memory resources for a program. This is generally implemented at the programming language level and is in opposition to manual memory, the explicit allocation and deallocation of computer memory resources. Region-based memory management is an efficient variant of explicit memory management that can deallocate large groups of objects simultaneously.

ELADORATE ON VIRTUAL MEMORY IMPLEMENTATION

·         virtual memory is a memory management technique developed for multitasking kernels.

·         This technique virtualizes a computer architectyre’s various hardware memory divice (such as ram modules and disk storage drives), allowing a program to be designed as though:-

1.    There is only one hardware memory device and this “virtual” device like a RAM module.

2.    The program has, by default, sole access to this virtual RAM module as the basis for a contiguous working memory.

3.    When the kernel detects a page fault it will generally adjust the virtual memory range of the program which triggered it, granting it access to the memory requested.

4.    This gives the kernel discretionary power over where a particular application's memory is stored, or even whether or not it has actually been allocated yet.

PAGING

·         Paging is one of the memory managment schemes by which a computer can store can and retrieve data from secandary storage for use in main memory.

·         In the paging memory-management scheme, the operating system retrieves data from secondary storage in same-size blocks called pages.

·         The main advantage of paging is that it allows the physical address space of a process to be noncontiguous.

·         Systems had to fit whole programs into storage contiguously, which caused various storage and fragmentation problems.

·         Paging is an important part of virtual memory implementation in most contemporary general-purpose operating systems, allowing them to use disk storage for data that does not fit into physicalrandom-access memory (RAM).

SEGMENTATION

·         Segmentation refers to the process of partitioning a digital image into multiple segments (sets of pixels, also known as superpixels). The goal of segmentation is to simplify and/or change the representation of an image into something that is more meaningful and easier to analyze.

·         Mage segmentation is typically used to locate objects and boundaries (lines, curves, etc.) in images.

·         More precisely, image segmentation is the process of assigning a label to every pixel in an image such that with the same label share certain visual characteristics.

·         In most systema in which a segment doesn’t have a page table associated with it, the address of the first location in the segment is an addres in main memory; in those systems, on paging is done.

·         In the Intel 80386 and later, that address can either be an address in main memory, if paging is not enabled, or an address in a paged “linear” address space, if paging is enabled.