Memory Allocation
the process of setting aside sections of memory in a program to be used to store variables, and instances of structures and classes. There are two basic types of memory allocation: Static Memory Allocation and Dynamic Memory Allocation.
Global vs. Local Allocation
To allocate a fixed fraction of the memory to every process, the local algorithm correspond, whereas global algorithm dynamically allocate page frames among the runnable processes.
Techniques to handle Thrashing
a condition or a situation when the system is spending a major portion of its time in servicing the page faults, but the actual processing done is very negligible.
Paging
a method of writing and reading data from a secondary storage(Drive) for use in primary storage(RAM). When a computer runs out of RAM, the operating system (OS) will move pages of memory over to the computer’s hard disk to free up RAM for other processes.
Segmentation
In Operating Systems, Segmentation is a memory management technique in which, the memory is divided into the variable size parts. Each part is known as segment which can be allocated to a process.
Paging VS Segmentation
Paging is a memory management function that presents storage locations to the CPU as additional memory. Segmentation is a virtual process that creates variable-sized address spaces called segments.
Demand Paging
In computer operating systems, demand paging is a method of virtual memory management. In a system that uses demand paging, the operating system copies a disk page into physical memory only if an attempt is made to access it and that page is not already in memory.
top command in Linux
top command is used to show the Linux processes. It provides a dynamic real-time view of the running system. Usually, this command shows the summary information of the system and the list of processes or threads which are currently managed by the Linux Kernel.
Allocating kernel memory
Two strategies for managing free memory that is assigned to kernel processes. Buddy allocation system is an algorithm in which a larger memory block is divided into small parts to satisfy the request. A second strategy for allocating kernel memory is known as slab allocation.
Copy on Write
a resource management technique. One of its main use is in the implementation of the fork system call in which it shares the virtual memory(pages) of the OS.