To a user, the file is the smallest unit of storage on a computer system. The user performs file operations such as open, close, read, write and modify. They can create or delete files from the system. In this article, you will learn the basics of file and file system. File Concept Computer store information … Read more
Paging allows the physical address space of a process to be non-contiguous. It avoids the external fragmentation and there is no need for compaction. Fragmentation problem affects the backing store (disk) of the main memory where processes are swapped in or out. The compaction is not possible due to the slow access speed of the … Read more
The contiguous memory allocation uses memory partitions to allocate memory. These partitions could be fixed or variable size partitions allocated according to first fit, best fit, or wort fit method. The memory fragmentation is a common problem that affects these partition memory allocation system. Contiguous Memory Contiguous memory allocation is a method of allocating memory … Read more
To run a process, the entire process and its data must be in physical memory. Thus, the size of a process is limited to the size of physical memory. The dynamic loading and linking are run-time operations. Dynamic Loading The dynamic binding is a method to obtain better memory-space utilization. A routine is not loaded … Read more
The memory binding could be static or dynamic. In dynamic binding system, user-generated virtual addresses are mapped to physical addresses. This leads to better memory utilization. The address generated by CPU is called a logical address, and the address seen by the memory unit is called a physical address. The physical address is loaded into … Read more
In a multiprocessing environment, several processes compete for limited resources. A running process goes to waiting state when a resource is not available. The process could not change its state because some other process holds the resources. This is called a deadlock. Normal Conditions The operating system does not provide with deadlock prevention mechanism, the … Read more
The shortest job first (SJF) algorithm is preemptive or non-preemptive. You have learned about the non-preemptive SJF in the previous article. In this article, you will learn about preemptive SJF, also called the shortest remaining time first scheduling algorithm. Preemptive SJF A new process arrives at the ready queue while an old process is executing … Read more
A multilevel queue is suitable when the processes are classified in groups. The multilevel queue scheduling algorithm partition the queue into several separate queues. Each of the processes are permanently assigned to one queue based on some property such as memory requirement, process priority, or process type. Then each queue has its own scheduling algorithm. … Read more
The fork-join is a basic method of expressing concurrency within a computation. This is implemented in the UNIX operating system as system calls. Fork The fork() call creates a new child process which runs concurrently with the parent. The child process is an exact copy of the parent except that it has a new process … Read more
There are certain conditions for concurrency. Here we have listed them for you in this article. Conditions for Concurrency , the read set for , is the set of all variables whose values are referenced in statement during its execution. , the write set for , is the set of all variables whose values are … Read more
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