Introduction of Memory Management
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This document provides an introduction to memory management techniques in operating systems. It discusses the differences between logical and physical addresses, the role of the memory management unit (MMU) in mapping logical to physical addresses, and memory allocation schemes including static contiguous allocation with equal or unequal partitions, dynamic contiguous allocation, and non-contiguous allocation using paging and segmentation. It also covers dynamic relocation, hardware support via relocation and limit registers, swapping, and fragmentation. The goal of memory management is to efficiently allocate and deallocate memory to running processes.
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Introduction of Memory Management
- 1. Vadodara Institute of Engineering Active Learning Assignment Sub :- Operating Systems ( 2140702 ) Topic:- Introduction of Memory Management Presented by:- Kashyap Patel 15CE046 Krishna Patel 15CE047 Maitree Patel 15CE048 Computer Engineering - 1
- 2. CONTENT • Physical and Logical address • Dynamic relocation • Memory Management Unit • Memory allocation • Swapping
- 3. LOGICAL AND PHYSICAL ADDRESS • Logical address: It is the address of the program that is generated by a CPU. • Physical address : It is the address generated by the memory management unit(MMU). • Logical and physical address are same at compile time and load time. • They differ in execution time address binding scheme.
- 5. MEMORY MANAGEMENT UNIT • It’s a hardware device that maps logical address to physical address . • In the MMU value the re-location register is added to every address generated by a program at a time the address is then send to memory. • The program deals with logical address.
- 6. HARDWARE SUPPORT FOR RELOCATION AND LIMIT REGISTER CPU < + MEMORY LIMIT REGISTER TRAP ADDRESSING ERRORS RELOCATION REGISTER yeslogical
- 7. • There are multiple partition for multiple processes ,the relocation and limit register are use to protect processes from one another, both the register are part of process context. • Relocation register contains smallest value of physical address. • The limit register contains range of logical address. • Logical address < Limit register
- 8. SWAPPING • The swapping of program from main memory to secondary memory that is back up storage and from secondary to main is called swapping in and swapping out respectively. • This phenomena of process switching its memory is called as swapping.
- 9. MEMORY ALLOCATION • Memory allocation Contiguous Non-contiguous 1 Static 1 Paging 2 Dynamic 2 Segmentation
- 10. • There are mainly two types of memory management. 1 Contiguous 2 Non-contiguous 1 CONTIGUOUS • That divided into two parts, Static : static that is having fix partition in main memory which are their from the system generation time. Dynamic: it’s without partition and the process gets loaded dynamicaly into the memory and find space for itself.
- 11. Static memory allocation: Equal size partition: The main memory is divided into fix equal size partition . For exam, if 1 partition is of 2mb then the all the other partition would be the same size. Main Memory 2mb 2mb 2mb 2mb
- 12. Unequal size partition : Here all the partition of main memory are of different sizes. Main Memory 2mb 4mb 3mb 1mb
- 13. Dynamic memory allocation : The main memory is not having fix partition , so the whole main memory is continuous form. The process dynamically get loaded into the main memory at run time. for eg , suppose there are 5 P1=50mb P2=20mb P3=15mb P4=10mb P5=15mb MM=100mb
- 15. FRAGMENTATION • The extra space that remain in the main memory after all the processes have loaded is called as hole or fragment. • There are 2 type : 1.Internal fragmentation: Internal takes place in static memory allocation. 2.External fragmentation : there is a enough memory space to load a new process but as it is not in a continuous manner the process cant be loaded into main memory.
- 16. CONCLUSION • Memory management is a complex field of computer science and there are many techniques being developed to make it more efficient. MMU allocate memory to process when needed and deallocate when processes are done.