Operating Systems
Lecture 22:
Memory Management (cont)
1
Docsity.com
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Guidelines and tips
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Memory Management Three - Operating Systems - Lecture Slides, Slides of Computer Science
These are the Lecture Slides of Operating Systems which includes File-System Structure, Defining, Logical File, Physical Device, Secondary, System Organized, File Control Block, Structure Consisting, Typical File Control Block etc.Key important points are: Memory Management Three, Mechanisms, Effective Address, Fetch From Instruction, Index Offset, Physical Memory, Section, Logical Address, Physical Address, Memory Unit
Typology: Slides
2012/2013
1 / 21
This page cannot be seen from the preview
Don't miss anything!
Related documents
Partial preview of the text
Download Memory Management Three - Operating Systems - Lecture Slides and more Slides Computer Science in PDF only on Docsity!
Operating Systems
Lecture 22:
Memory Management (cont)
Types of Partitioning
- Fixed Partitioning
- Dynamic Partitioning
- Simple Paging
- Simple Segmentation
Processes and Frames
- A.
- A.
- A.
- A.
- B.
- B.
- B.
- C.
- C.
- C.
- C.
- D.
- D.
- D.
- D.
- D.
Page Table
Paging: Logical Addresses
16-bit addresses 1K page size Bits for offset? Max # of pages per process?
Paging: Logical to Physical
Address Translation
Problem 2
Consider a simple paging system with the following parameters: 2 32 bytes of physical memory; page size of 2 10 bytes; 2^16 pages of logical address space.
- How many bits are in a logical address?
- How many bytes in a frame?
- How many bits in the physical address specify the frame?
- How many entries in the page table?
Problem 3
Suppose the page size in a computing environment is 4 KB. What is the page number and the offset for the following logical addresses:
- 425 (a decimal number)
- 24667 (a decimal number)
- 0x0007C (a hexadecimal number).
QoD Work Time (individual)
Segmentation
- A program can be subdivided into segments
- Segments may vary in length
- There is a maximum segment length
- A segment is a logical unit such as main program, procedures, local/global variables, stack, etc.
- Addressing consist of two parts
- a segment number and
- an offset
- Segmentation is similar to dynamic partitioning
Logical View of Segmentation
1
3
2
4
1 4
2
3
user space physical memory space
Segmentation Architecture
- Logical address consists of a two tuple: <segment-number, offset>,
- Segment table – maps two-dimensional physical addresses; each table entry has: - base – contains the starting physical address where the segments reside in memory - limit – specifies the length of the segment
- Segment-table base register (STBR) points to the segment table’s location in memory
- Segment-table length register (STLR) indicates number of segments used by a program; segment number s is legal if s < STLR