Mach is a kernel developed at Carnegie Mellon University to support operating system research, primarily distributed and parallel computing. Mach is often mentioned as one of the earliest examples of a microkernel. However, not all versions of Mach are microkernels. Mach's derivatives are the basis of the modern operating system kernels in GNU Hurd and Apple's operating systems macOS, iOS, tvOS, and watchOS.
An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs.
Transaction Processing Facility (TPF) is an IBM real-time operating system for mainframe computers descended from the IBM System/360 family, including zSeries and System z9.
In computing, virtual memory is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very large (main) memory."
In computer science, locality of reference, also known as the principle of locality, is the tendency of a processor to access the same set of memory locations repetitively over a short period of time. There are two basic types of reference locality – temporal and spatial locality. Temporal locality refers to the reuse of specific data, and/or resources, within a relatively small time duration. Spatial locality refers to the use of data elements within relatively close storage locations. Sequential locality, a special case of spatial locality, occurs when data elements are arranged and accessed linearly, such as, traversing the elements in a one-dimensional array.
In computer architecture, the memory hierarchy separates computer storage into a hierarchy based on response time. Since response time, complexity, and capacity are related, the levels may also be distinguished by their performance and controlling technologies. Memory hierarchy affects performance in computer architectural design, algorithm predictions, and lower level programming constructs involving locality of reference.
In computing, scheduling is the method by which work is assigned to resources that complete the work. The work may be virtual computation elements such as threads, processes or data flows, which are in turn scheduled onto hardware resources such as processors, network links or expansion cards.
Round-robin (RR) is one of the algorithms employed by process and network schedulers in computing. As the term is generally used, time slices are assigned to each process in equal portions and in circular order, handling all processes without priority. Round-robin scheduling is simple, easy to implement, and starvation-free. Round-robin scheduling can also be applied to other scheduling problems, such as data packet scheduling in computer networks. It is an operating system concept.
In computer operating systems, paging is a memory management scheme by which a computer stores and retrieves data from secondary storage for use in main memory. In this scheme, the operating system retrieves data from secondary storage in same-size blocks called pages. Paging is an important part of virtual memory implementations in modern operating systems, using secondary storage to let programs exceed the size of available physical memory.
Prime95 is the freeware application written by George Woltman that is used by GIMPS, a distributed computing project dedicated to finding new Mersenne prime numbers. More specifically, Prime95 refers to the Windows and macOS versions of the software.
A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost to access data from the main memory. A cache is a smaller, faster memory, closer to a processor core, which stores copies of the data from frequently used main memory locations. Most CPUs have different independent caches, including instruction and data caches, where the data cache is usually organized as a hierarchy of more cache levels.
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 priority, thus giving the process more or less CPU time than other processes. A niceness of -20 is the highest priority and 19 is the lowest priority. The default niceness for processes is inherited from its parent process and is usually 0.
Dreambox is a series of Linux-powered DVB satellite, terrestrial and cable digital television receivers, produced by German multimedia vendor Dream Multimedia.
In computer storage, fragmentation is a phenomenon in which storage space is used inefficiently, reducing capacity or performance and often both. The exact consequences of fragmentation depend on the specific system of storage allocation in use and the particular form of fragmentation. In many cases, fragmentation leads to storage space being "wasted", and in that case the term also refers to the wasted space itself. For other systems the space used to store given data is the same regardless of the degree of fragmentation.
A memory-mapped file is a segment of virtual memory that has been assigned a direct byte-for-byte correlation with some portion of a file or file-like resource. This resource is typically a file that is physically present on disk, but can also be a device, shared memory object, or other resource that the operating system can reference through a file descriptor. Once present, this correlation between the file and the memory space permits applications to treat the mapped portion as if it were primary memory.
A page, memory page, or virtual page is a fixed-length contiguous block of virtual memory, described by a single entry in the page table. It is the smallest unit of data for memory management in a virtual memory operating system. Similarly, a page frame is the smallest fixed-length contiguous block of physical memory into which memory pages are mapped by the operating system.
Entitlement in fair division describes that proportion of the resources or goods to be divided that a player can expect to receive. The idea is based on the normal idea of entitlement. Entitlements can in the main be determined by agreeing on a cooperative game and using its value as the entitlement.
In computing, unique set size (USS) is the portion of main memory (RAM) occupied by a process which is guaranteed to be private to that process. The unshared memory of a process is reported as USS.
Cache hierarchy, or multi-level caches, refers to a memory architecture which uses a hierarchy of memory stores based on varying access speeds to cache data. Highly-requested data is cached in high-speed access memory stores, allowing swifter access by central processing unit (CPU) cores.
