Memory management
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Memory management involves controlling computer memory by assigning blocks to programs. It occurs in hardware through components like RAM, in the operating system through allocation of memory blocks, and in applications through allocation and recycling of objects. Virtual memory allows programs to exceed physical memory limits by swapping pages or entire processes to secondary storage. Paging divides memory into fixed pages while segmentation uses variable sized segments.
Memory management
- 1. Group 1 Memory Management IT A004 -Pc Maintenance Hardy ATI 29/11/2013
- 2. Inside Persons who contributed About memory management Physical memory Virtual memory Paging and swapping Storage allocation Segmentation Conclusion
- 3. PersonsWhoContributed… ℗ MAM.Safraz HNDIT/F/E/2013/13 ℗ ALM.Basith HNDIT/F/E/2013/35 ℗ HHIM.Fernando HNDIT/F/E/2013/60 ℗ DD.Manawadu HNDIT/F/E/2013/06 ℗ PMU.Dhananjani HNDIT/F/E/2013/07 ℗ KE.Harshika HNDIT/F/E/2013/28
- 4. Memory management is the process of controlling and coordinating computer memory, assigning portions called blocks to various running programs to optimize overall system performance. Memory management resides in hardware, in the OS (operating system), and in programs and applications. In hardware, memory management involves components that physically store data, such as RAM (random access memory) chips, memory caches, and flash-based SSDs (solid-state drives). In the OS, memory management involves the allocation (and constant reallocation) of specific memory blocks to individual programs as user demands change. At the application level, memory management ensures the availability of adequate memory for the objects and data structures of each running program at all times. Application memory management combines two related tasks, known as allocation and recycling.
- 5. Storage Hierarchy Main Memory • Cache on Chip (internal cache) • External Cache memory • RAM Secondary Storage • Hard Disk Tertiary Storage • CD ROM • Floppy • Tape Access time decreases Capacity decreases Cost increases
- 6. Alternatively referred to as the physical storage or the real storage, physical memory is a term used to describe the total amount of memory installed in the computer. For an example, if the computer has two 64MB memory modules installed, it has a total of 128MB of physical memory. Physical memory
- 7. Virtual Memory Virtual memory is a technique of executing program instructions that may not fit entirely in system memory. This is done by calling instructions as and when the application requires it. Virtual memory is implemented by using secondary storage to augment the main memory. Data is transferred from secondary to main storage as and when necessary and the data modified is written back to the secondary storage according to a predetermined algorithm.
- 8. 1. Paging In this approach, physical memory is divided into fixed-size blocks called frames and the logical memory is divided into the fixed-sized blocks called pages. The size of a page is same as that of frame. The key idea of this method is to place the pages of a process into the available frames of memory, whenever, this process is to be executed. The address mapping is done by Page table.
- 9. Swapping Swapping is the technique of temporarily removing inactive programs from the main memory of a computer system. An inactive program is one that is neither executing nor performing an I/O operation. This may also happen when it is desired to place a higher-priority process in the memory. A lower priority process may be swapped out so that higher- priority process may be loaded and executed.
- 10. Paging Compare Swapping Swapping is when an entire process is swapped out. Paging is normal. Paging refers to making individual pages of memory. Swapping happens when the resource load is heavy and the entire process is written out to disk.
- 12. Segmentation segmentation is another technique for the noncontiguous storage allocation. It is different from paging as it supports users’ view of his program. For a programmer it might be more relevant to divide the logical address space of his program into variable sized segments (with respect to his view of main program, subroutines, data, etc.) than to divide it into fixed size pages. Such variable sized segments, which are a collection of logically related information, are the basis of segmentation technique.