Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
In demand paging, a page is loaded into primary memory only when the process references it. It is the simplest fetch policy implemented in virtual memory.
Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
The fork () system call works by creating a copy of parent's address space for the child process.
Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
Virtual memory is a method of using hard disk space to provide extra memory. It simulates additional main memory.
Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
Most of the architecture support paging and segmentation. All the pages of segment need not be in main memory.
Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
In segmentation, a program's data and instructions are divided into blocks called segments. A segment is a logical entity in a program.
Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
Page tables can consume a significant amount of memory. So page table may consists of upto 1 million entries, one for each page, for a total address capacity of about four billion bytes.
Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
In paging, operating system divides each incoming programs into pages of equal size. The sections of a disk are called block or sectors.
Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
The use of unequal size partitions provides a degree of flexibility to fixed partitioning. In dynamic partitioning, the partitions are of variable length and number.
Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
In a fixed size partitioning of the main memory all partitions are of the same size. The operating system divides main memory into a number of fixed size partition. Each partition holds a single program.
Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
Keeping all processes in memory all the time requires a large amount of main memory. For execution of the process, it must be swapped.
Memory Management - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit III: Memory Management
Memory is used to store information. Secondary storage memory is long term persistent memory that is held in storage device such as disk drive.
Deadlock - Introduction to Operating Systems
Subject and UNIT: Introduction to Operating Systems: Unit II(b): Deadlock
A set of processes is deadlocked if each process in the set is waiting for an event that only another process in the set can cause.