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Directory-based Coherence Protocols
In computer engineering, directory-based cache coherence is a type of cache coherence mechanism, where directories are used to manage caches in place of bus snooping. Bus snooping methods scale poorly due to the use of broadcasting. These methods can be used to target both performance and scalability of directory systems. Full bit vector format In the full bit vector format, for each possible cache line in memory, a bit is used to track whether every individual processor has that line stored in its cache. The full bit vector format is the simplest structure to implement, but the least scalable. The SGI Origin 2000 uses a combination of full bit vector and coarse bit vector depending on the number of processors. Each directory entry must have 1 bit stored per processor per cache line, along with bits for tracking the state of the directory. This leads to the total size required being ''(number of processors)×number of cache lines'', having a storage overhead ratio of ''(numb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Engineering
Computer engineering (CE, CoE, or CpE) is a branch of engineering specialized in developing computer hardware and software. It integrates several fields of electrical engineering, electronics engineering and computer science. Computer engineering is referred to as ''electrical and computer engineering'' or '' computer science and engineering'' at some universities. Computer engineers require training in hardware-software integration, software design, and software engineering. It can encompass areas such as electromagnetism, artificial intelligence (AI), robotics, computer networks, computer architecture and operating systems. Computer engineers are involved in many hardware and software aspects of computing, from the design of individual microcontrollers, microprocessors, personal computers, and supercomputers, to circuit design. This field of engineering not only focuses on how computer systems themselves work, but also on how to integrate them into the larger pictur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coarse Bit Vector Format Diagram
Coarse may refer to: *Bosnian Coarse-Haired Hound, developed by 19th century Bosnian hunters as a scent hound. *Coarse (behavior), vulgar behavior *Coarse bubble diffusers, produce 1/4 to 1/2 inch bubbles which rise rapidly from the floor of a wastewater treatment plant or sewage treatment plant tank. *Coarse fishing, an angling method, mostly popular throughout Europe. * Coarse sandpaper, a form of paper where an abrasive material has been fixed to its surface, allowing rapid removal of material by rubbing. *Coarse structure, on a set X is a collection of subsets of the cartesian product X × X with certain. properties which allow the large-scale structure of metric spaces and topological spaces to be defined. Used in the mathematical fields of geometry and topology. *Coarse woody debris (CWD), a term used for the dead trees left standing or fallen, including branches on the ground. *Styrian Coarse Haired Hound, a rough coated, hardy hunting dog used by Austrians and Slovenians to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latency (engineering)
Latency, from a general point of view, is a time delay between the Causality, cause and the effect of some physical change in the system being observed. Lag (video games), Lag, as it is known in Gaming culture, gaming circles, refers to the latency between the input to a simulation and the visual or auditory response, often occurring because of network delay in online games. The original meaning of “latency”, as used widely in psychology, medicine and most other disciplines, derives from “latent”, a word of Latin origin meaning “hidden”. Its different and relatively recent meaning (this topic) of “lateness” or “delay” appears to derive from its superficial similarity to the word “late”, from the old English “laet”. Latency is physically a consequence of the limited velocity at which any Event (relativity), physical interaction can propagate. The magnitude of this velocity is always less than or equal to the speed of light. Therefore, every physical s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linked List
In computer science, a linked list is a linear collection of data elements whose order is not given by their physical placement in memory. Instead, each element points to the next. It is a data structure consisting of a collection of nodes which together represent a sequence. In its most basic form, each node contains data, and a reference (in other words, a ''link'') to the next node in the sequence. This structure allows for efficient insertion or removal of elements from any position in the sequence during iteration. More complex variants add additional links, allowing more efficient insertion or removal of nodes at arbitrary positions. A drawback of linked lists is that data access time is linear in respect to the number of nodes in the list. Because nodes are serially linked, accessing any node requires that the prior node be accessed beforehand (which introduces difficulties in pipelining). Faster access, such as random access, is not feasible. Arrays have better cache ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graph Traversal
In computer science, graph traversal (also known as graph search) refers to the process of visiting (checking and/or updating) each vertex in a graph. Such traversals are classified by the order in which the vertices are visited. Tree traversal is a special case of graph traversal. Redundancy Unlike tree traversal, graph traversal may require that some vertices be visited more than once, since it is not necessarily known before transitioning to a vertex that it has already been explored. As graphs become more dense, this redundancy becomes more prevalent, causing computation time to increase; as graphs become more sparse, the opposite holds true. Thus, it is usually necessary to remember which vertices have already been explored by the algorithm, so that vertices are revisited as infrequently as possible (or in the worst case, to prevent the traversal from continuing indefinitely). This may be accomplished by associating each vertex of the graph with a "color" or "visitation" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cache Invalidation
Cache invalidation is a process in a computer system whereby entries in a cache are replaced or removed. It can be done explicitly, as part of a cache coherence protocol. In such a case, a processor changes a memory location and then invalidates the cached values of that memory location across the rest of the computer system. Explicit invalidation ''Cache invalidation'' can be used to push new content to a client. This method functions as an alternative to other methods of displaying new content to connected clients. ''Invalidation'' is carried out by changing the application data, which in turn marks the information received by the client as out-of-date. After the cache is invalidated, if the client requests the cache, they are delivered a new version. Methods There are three specific methods to invalidate a cache, but not all caching proxies support these methods. Purge Removes content from caching proxy immediately. When the client requests the data again, it is fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pointer (computer Programming)
In computer science, a pointer is an object in many programming languages that stores a memory address. This can be that of another value located in computer memory, or in some cases, that of memory-mapped computer hardware. A pointer ''references'' a location in memory, and obtaining the value stored at that location is known as ''dereferencing'' the pointer. As an analogy, a page number in a book's index could be considered a pointer to the corresponding page; dereferencing such a pointer would be done by flipping to the page with the given page number and reading the text found on that page. The actual format and content of a pointer variable is dependent on the underlying computer architecture. Using pointers significantly improves performance for repetitive operations, like traversing iterable data structures (e.g. strings, lookup tables, control tables, linked lists, and tree structures). In particular, it is often much cheaper in time and space to copy and deref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tree (data Structure)
In computer science, a tree is a widely used abstract data type that represents a hierarchical tree structure with a set of connected nodes. Each node in the tree can be connected to many children (depending on the type of tree), but must be connected to exactly one parent, except for the ''root'' node, which has no parent (i.e., the root node as the top-most node in the tree hierarchy). These constraints mean there are no cycles or "loops" (no node can be its own ancestor), and also that each child can be treated like the root node of its own subtree, making recursion a useful technique for tree traversal. In contrast to linear data structures, many trees cannot be represented by relationships between neighboring nodes (parent and children nodes of a node under consideration, if they exist) in a single straight line (called edge or link between two adjacent nodes). Binary trees are a commonly used type, which constrain the number of children for each parent to at most two. Whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Tree
In computer science, a binary tree is a tree data structure in which each node has at most two children, referred to as the ''left child'' and the ''right child''. That is, it is a ''k''-ary tree with . A recursive definition using set theory is that a binary tree is a triple , where ''L'' and ''R'' are binary trees or the empty set and ''S'' is a singleton (a single–element set) containing the root. From a graph theory perspective, binary trees as defined here are arborescences. A binary tree may thus be also called a bifurcating arborescence, a term which appears in some early programming books before the modern computer science terminology prevailed. It is also possible to interpret a binary tree as an undirected, rather than directed graph, in which case a binary tree is an ordered, rooted tree. Some authors use rooted binary tree instead of ''binary tree'' to emphasize the fact that the tree is rooted, but as defined above, a binary tree is always rooted. In ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bus (computing)
In computer architecture, a bus (historically also called a data highway or databus) is a communication system that transfers Data (computing), data between components inside a computer or between computers. It encompasses both Computer hardware, hardware (e.g., wires, optical fiber) and software, including communication protocols. At its core, a bus is a shared physical pathway, typically composed of wires, traces on a circuit board, or busbars, that allows multiple devices to communicate. To prevent conflicts and ensure orderly data exchange, buses rely on a communication protocol to manage which device can transmit data at a given time. Buses are categorized based on their role, such as system buses (also known as internal buses, internal data buses, or memory buses) connecting the Central processing unit, CPU and Computer memory, memory. Expansion buses, also called peripheral buses, extend the system to connect additional devices, including peripherals. Examples of widely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Node (computer Science)
A node is a basic unit of a data structure, such as a linked list or Tree (data structure), tree data structure. Nodes contain data and also may link to other nodes. Links between nodes are often implemented by Pointer (computer programming), pointers. Nodes and trees Nodes are often arranged into tree structures. A node represents the information contained in a single data structure. These nodes may contain a value or condition, or possibly serve as another independent data structure. Nodes are represented by a single parent node. The highest point on a tree structure is called a root node, which does not have a parent node, but serves as the parent or 'grandparent' of all of the nodes below it in the tree. The height of a node is determined by the total number of edges on the path from that node to the furthest leaf node, and the height of the tree is equal to the height of the root node. Node depth is determined by the distance between that particular node and the root node. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overhead (computing)
Overhead in computer systems consists of shared functions that benefit all users or processes but are not directly attributable to any specific task. It is thus similar to overhead in organizations. Computer system overhead shows up as slower processing, less memory, less storage capacity, less network bandwidth, or bigger latency than would be expected from reading the system specifications. It is a special case of engineering overhead. Overhead can be a deciding factor in software design, with regard to structure, error correction, and feature inclusion. Examples of computing overhead may be found in object-oriented programming (OOP), functional programming, data transfer, data structures, and file systems on data storage devices. Software design Choice of implementation A programmer/software engineer may have a choice of several algorithms, encodings, data types or data structures, each of which have known characteristics. When choosing among them, their respective overhead ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
