An operating system (OS) is system software that manages computer hardware and software resources, and provides common services for computer programs.
In computing, time-sharing is the concurrent sharing of a computing resource among many tasks or users by giving each task or user a small slice of processing time. This quick switch between tasks or users gives the illusion of simultaneous execution. It enables multi-tasking by a single user or enables multiple-user sessions.
Peter Gabriel Neumann is a computer-science researcher who worked on the Multics operating system in the 1960s. He edits the RISKS Digest columns for ACM Software Engineering Notes and Communications of the ACM. He founded ACM SIGSOFT and is a Fellow of the ACM, IEEE, and AAAS.
Copy-on-write (COW), also called implicit sharing or shadowing, is a resource-management technique used in programming to manage shared data efficiently. Instead of copying data right away when multiple programs use it, the same data is shared between programs until one tries to modify it. If no changes are made, no private copy is created, saving resources. A copy is only made when needed, ensuring each program has its own version when modifications occur. This technique is commonly applied to memory, files, and data structures.
A process control block (PCB), also sometimes called a process descriptor, is a data structure used by a computer operating system to store all the information about a process.
nice is a program found on Unix and Unix-like operating systems such as Linux. It directly maps to a kernel call of the same name. nice is used to invoke a utility or shell script with a particular CPU priority, thus giving the process more or less CPU time than other processes. A niceness of -20 is the lowest niceness, or highest priority. The default niceness for processes is inherited from its parent process and is usually 0.
David A. Bader is a Distinguished Professor and Director of the Institute for Data Science at the New Jersey Institute of Technology. Previously, he served as the Chair of the Georgia Institute of Technology School of Computational Science & Engineering, where he was also a founding professor, and the executive director of High-Performance Computing at the Georgia Tech College of Computing. In 2007, he was named the first director of the Sony Toshiba IBM Center of Competence for the Cell Processor at Georgia Tech.
In computer science, a multilevel feedback queue is a scheduling algorithm. Scheduling algorithms are designed to have some process running at all times to keep the central processing unit (CPU) busy. The multilevel feedback queue extends standard algorithms with the following design requirements:
- Separate processes into multiple ready queues based on their need for the processor.
- Give preference to processes with short CPU bursts.
- Give preference to processes with high I/O bursts.
In the mathematical discipline of graph theory, a feedback vertex set (FVS) of a graph is a set of vertices whose removal leaves a graph without cycles. Equivalently, each FVS contains at least one vertex of any cycle in the graph. The feedback vertex set number of a graph is the size of a smallest feedback vertex set. The minimum feedback vertex set problem is an NP-complete problem; it was among the first problems shown to be NP-complete. It has wide applications in operating systems, database systems, and VLSI chip design.
Working set is a concept in computer science which defines the amount of memory that a process requires in a given time interval.
In computer science, synchronization is the task of coordinating multiple processes to join up or handshake at a certain point, in order to reach an agreement or commit to a certain sequence of action.
The Donald E. Knuth Prize is a prize for outstanding contributions to the foundations of computer science, named after the American computer scientist Donald E. Knuth.
A dirty bit or modified bit is a bit that is associated with a block of computer memory and indicates whether the corresponding block of memory has been modified. The dirty bit is set when the processor writes to (modifies) this memory. The bit indicates that its associated block of memory has been modified and has not been saved to storage yet. When a block of memory is to be replaced, its corresponding dirty bit is checked to see if the block needs to be written back to secondary memory before being replaced or if it can simply be removed. Dirty bits are used by the CPU cache and in the page replacement algorithms of an operating system.
A wait-for graph in computer science is a directed graph used for deadlock detection in operating systems and relational database systems.
Michael Athans was a Greek-American control theorist and a Professor Emeritus in the Department of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology. He was a Fellow of the IEEE (1973) and a Fellow of the AAAS (1977). He was the recipient of numerous awards for his contributions in the field of control theory. A pioneer in the field of control theory, he helped shape modern control theory and spearheaded the field of multivariable control system design and the field of robust control. Athans was a member of the technical staff at Lincoln Laboratory from 1961 to 1964, and a Department of Electrical Engineering and Computer Science faculty member from 1964 to 1998. Upon retirement, Athans moved to Lisbon, Portugal, where he was an Invited Research Professor in the Institute for Systems and Robotics, Instituto Superior Técnico where he received a honoris causa doctorate from the Universidade Técnica de Lisboa in 2011.
In computer science for Operating systems, aging or ageing is a scheduling technique used to avoid starvation. Fixed priority scheduling is a scheduling discipline, in which tasks queued for utilizing a system resource are assigned a priority each. A task with a high priority is allowed to access a specific system resource before a task with a lower priority is allowed to do the same. A disadvantage of this approach is that tasks assigned with a lower priority may be starved when a large number of high priority tasks are queued. Aging is used to gradually increase the priority of a task, based on its waiting time in the ready queue.
Jerry M. Woodall is a professor of electrical and computer engineering at the University of California, Davis who is widely known for his revolutionary work on LEDs and semiconductors. Over the course of his career, he has published close to 400 scientific articles and his work has directly contributed to the development of major technologies that are used around the world, such as TVs, optical fibers, and mobile phones. Woodall currently holds over 80 U.S. patents for a variety of inventions and has received prestigious awards from IBM, NASA, and the U.S. President for his contributions to science, technology, and humanity.
Operating System Concepts by Abraham Silberschatz and James Peterson is a classic textbook on operating systems. It is often called the "dinosaur book", as the first edition of the book had on the cover a number of dinosaurs labeled with various old operating systems. The bigger dinosaurs were labeled with the older big OSs. The ape-like creature was labeled UNIX. The idea was that like dinosaurs, operating systems evolve.
This page is a glossary of Operating systems terminology.
Henry Francis Korth is a professor of Computer Science and Engineering. He is a fellow of the Association for Computing Machinery (ACM) and of the IEEE. He is one of the coauthors of the university textbook Database System Concepts.
