Cooperating Process in Operating System
Cooperating processes are those that can affect or are affected by other processes running on the system.
Cooperating processes may share data with each other.
There may be many reasons for the requirement of cooperating processes such as modularity, information sharing, convenience, etc.
Prevent fork bomb by limiting user process in linux
A Fork Bomb is a denial-of-service (DoS) attack against a Linux based system.
It makes use of the fork operation to create infinite processes and is called as Rabbit Virus or wabbit.
The system process continually replicates itself to deplete available system resources, causing resource starvation, slowing or crashing the system.
Race Condition, Critical Section and Semaphore
Race conditions, Critical Sections and Semaphores are an key part of Operating systems.
A race condition is a situation that may occur inside a critical section.
The critical section in a code segment where the shared variables can be accessed.
A semaphore is a signalling mechanism and a thread that is waiting on a semaphore can be signalled by another thread.
Deadlock Characterization
A deadlock happens in operating system when two or more processes need some resource to complete their execution that is held by the other process.
A deadlock occurs if the four Coffman conditions hold true.
But these conditions are not mutually exclusive such as hold and wait, no preemption, and circular wait.
Deadlock Prevention And Avoidance
We can prevent Deadlock by eliminating any of the above four conditions.
For eliminate mutual exclusion, it is not possible to dis-satisfy the mutual exclusion because some resources, such as the tape drive and printer, are inherently non-shareable.
For eliminate no preemption, preempt resources from the process when resources required by other high priority processes.
And deadlock avoidance can be done with Bankers Algorithm.
Difference between Deadlock and Starvation in OS
Deadlock occurs when each process holds a resource and wait for other resource held by any other process.
Starvation is the problem that occurs when high priority processes keep executing and low priority processes get blocked for indefinite time.
Deadlock Detection And Recovery
Deadlock Detection can happen if resources have single instance or if there are multiple instances of resources.
Deadlock Recovery can be done by two method, killing the process or resource preemption.
Fixed (or static) Partitioning in Operating System
In operating systems, Memory Management is the function responsible for allocating and managing computers main memory.
Memory Management function keeps track of the status of each memory location, either allocated or free to ensure effective and efficient use of Primary Memory.
There are two Memory Management Techniques: Contiguous, and Non-Contiguous.
In Contiguous Technique, executing process must be loaded entirely in main-memory.
Contiguous Technique can be divided into: Fixed (or static) partitioning and Variable (or dynamic) partitioning.
Fixed partitioning is the oldest and simplest technique used to put more than one processes in the main memory.
Variable (or dynamic) Partitioning in Operating System
Variable partitioning is a part of Contiguous allocation technique.
It is used to alleviate the problem faced by Fixed Partitioning.
In contrast with fixed partitioning, partitions are not made before the execution or during system configure.
Segmentation in Operating System
A process is divided into Segments.
The chunks that a program is divided into which are not necessarily all of the same sizes are called segments.
Segmentation gives users view of the process which paging does not give.
There are two types of segmentation, virtual memory segmentation and simple segmentation.