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Prefetch
Prefetching is a technique used in computing to improve performance by retrieving data or instructions before they are needed. By predicting what a program will request in the future, the system can load information in advance to reduced wait times . Prefetching is used in various areas of computing, including CPU architectures and operating systems. It can be implemented in both hardware and software, and it relies on detecting access patterns that suggest what data is likely to be needed soon. Overview Prefetching works by predicting which memory addresses or resources will be accessing and load them into faster access storage, like caches. Prefetching may be used: * Hardware-level, such as CPU memory controllers * Software-level, strategies in compilers, operating systems, logic in web browsers or file systems Hardware Processors (CPU's) often include prefetching that attempts to reduce cache misses by loading data into cache before it is requested by the running prog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cache Prefetching
Cache prefetching is a technique used by computer processors to boost execution performance by fetching instructions or data from their original storage in slower memory to a faster local memory before it is actually needed (hence the term 'prefetch'). Most modern computer processors have fast and local CPU cache, cache memory in which prefetched data is held until it is required. The source for the prefetch operation is usually Computer data storage#Primary storage, main memory. Because of their design, accessing cache memories is typically much faster than accessing main memory, so prefetching data and then accessing it from caches is usually many orders of magnitude faster than accessing it directly from main memory. Prefetching can be done with non-blocking cache control instructions. Data vs. instruction cache prefetching Cache prefetching can either fetch data or instructions into cache. * Data prefetching fetches data before it is needed. Because data access patterns show ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Link Prefetching
Link prefetching allows web browsers to pre-load resources. This speeds up both the loading and rendering of web pages. Prefetching was first introduced in HTML5. Prefetching is accomplished through hints in web pages. These hints are used by the browser to prefetch links. Resources which can be prefetched include: JavaScript, CSS, image, audio, video, and web fonts. DNS names and TCP connections can also be hinted for prefetching. Prefetching in HTML5 There are two W3C standards covering prefetching for HTML5: * Link preload ** Hints to specific URLs. Common hints include JavaScript, CSS, images and web fonts. * Resource hints ** Hints to the browser. Common hints include DNS queries, opening TCP connections, and page pre-rendering. HTML5 methods for prefetch hints: * Standard link prefetch (supported by most browsers): * DNS prefetch (Mozilla Firefox, Google Chrome, and others): * Page pre-rendering (Google Chrome, Internet Explorer and others): * Lazy-load of images (In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Prefetch Input Queue
Fetching the instruction opcodes from program memory well in advance is known as prefetching and it is served by using a prefetch input queue (PIQ). The pre-fetched instructions are stored in a queue. The fetching of opcodes well in advance, prior to their need for execution, increases the overall efficiency of the processor boosting its speed. The processor no longer has to wait for the memory access operations for the subsequent instruction opcode to complete. This architecture was prominently used in the Intel 8086 microprocessor. Introduction Pipelining was brought to the forefront of computing architecture design during the 1960s due to the need for faster and more efficient computing. Pipelining is the broader concept and most modern processors load their instructions some clock cycles before they execute them. This is achieved by pre-loading machine code from memory into a ''prefetch input queue''. This behavior only applies to von Neumann computers (that is, not H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cache (computing)
In computing, a cache ( ) is a hardware or software component that stores data so that future requests for that data can be served faster; the data stored in a cache might be the result of an earlier computation or a copy of data stored elsewhere. A cache hit occurs when the requested data can be found in a cache, while a cache miss occurs when it cannot. Cache hits are served by reading data from the cache, which is faster than recomputing a result or reading from a slower data store; thus, the more requests that can be served from the cache, the faster the system performs. To be cost-effective, caches must be relatively small. Nevertheless, caches are effective in many areas of computing because typical Application software, computer applications access data with a high degree of locality of reference. Such access patterns exhibit temporal locality, where data is requested that has been recently requested, and spatial locality, where data is requested that is stored near dat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Memory Paging
In computer operating systems, memory paging is a memory management scheme that allows the physical memory used by a program to be non-contiguous. This also helps avoid the problem of memory fragmentation and requiring compaction to reduce fragmentation. Paging is often combined with the related technique of allocating and freeing ''page frames'' and storing pages on and retrieving them from secondary storage in order to allow the aggregate size of the address spaces to exceed the physical memory of the system. For historical reasons, this technique is sometimes referred to as ''swapping''. When combined with virtual memory, it is known as ''paged virtual memory''. In this scheme, the operating system retrieves data from secondary storage in blocks of the same size (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. Hardware support is nec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Speculative Execution
Speculative execution is an optimization (computer science), optimization technique where a computer system performs some task that may not be needed. Work is done before it is known whether it is actually needed, so as to prevent a delay that would have to be incurred by doing the work after it is known that it is needed. If it turns out the work was not needed after all, most changes made by the work are reverted and the results are ignored. The objective is to provide more Concurrency (computer science), concurrency if extra Resource (computer science), resources are available. This approach is employed in a variety of areas, including branch predictor, branch prediction in instruction pipeline, pipelined CPU, processors, value prediction for exploiting value locality, prefetching Instruction prefetch, memory and File system, files, and optimistic concurrency control in Relational database management system, database systems. Speculative multithreading is a special case of specu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Instruction Prefetch
Instruction or instructions may refer to: A specific direction or order given to someone to perform a task or carry out a procedure. They provide clear guidance on how to achieve a desired outcome. They can be written or verbal, and they typically include detailed steps or actions to follow. Instructions are crucial for ensuring tasks are completed correctly and efficiently. Computing * Instruction, one operation of a processor within a computer architecture instruction set * Computer program, a collection of instructions Music * Instruction (band), a 2002 rock band from New York City, US * "Instruction" (song), a 2017 song by English DJ Jax Jones * ''Instructions'' (album), a 2001 album by Jermaine Dupri Other uses * Instruction, teaching or education performed by a teacher * Sebayt, a work of the ancient Egyptian didactic literature aiming to teach ethical behaviour * Instruction, the pre-trial phase of an investigation led by a judge in an inquisitorial system of justice * I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cache Pollution
Cache pollution describes situations where an executing computer program loads data into CPU cache unnecessarily, thus causing other useful data to be evicted from the cache into lower levels of the memory hierarchy, degrading performance. For example, in a multi-core processor, one core may replace the blocks fetched by other cores into shared cache, or prefetched blocks may replace demand-fetched blocks from the cache. Example Consider the following illustration: T = T + 1; for i in 0..sizeof(CACHE) C = C + 1; T = T + C izeof(CACHE)-1 (The assumptions here are that the cache is composed of only one level, it is unlocked, the replacement policy is pseudo-LRU, all data is cacheable, the set associativity of the cache is N (where N > 1), and at most one processor register is available to contain program values). Right before the loop starts, T will be fetched from memory into cache, its value updated. However, as the loop executes, because the number of data elem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Bandwidth (computing)
In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth. This definition of ''bandwidth'' is in contrast to the field of signal processing, wireless communications, modem data transmission, digital communications, and electronics, in which ''bandwidth'' is used to refer to the signal bandwidth measured in hertz, meaning the frequency range between lowest and highest attainable frequency while meeting a well-defined impairment level in signal power. The actual bit rate that can be achieved depends not only on the signal bandwidth but also on the noise on the channel. Network capacity The term ''bandwidth'' sometimes defines the net bit rate ''peak bit rate'', ''information rate'', or physical layer ''useful bit rate'', channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Scripting Language
In computing, a script is a relatively short and simple set of instructions that typically automation, automate an otherwise manual process. The act of writing a script is called scripting. A scripting language or script language is a programming language that is used for scripting. Originally, scripting was limited to automating an operating system shell and languages were relatively simple. Today, scripting is more pervasive and some languages include modern features that allow them to be used for Application software, application development as well as scripting. Overview A scripting language can be a general purpose language or a domain-specific language for a particular environment. When embedded in an application, it may be called an extension language. A scripting language is sometimes referred to as very high-level programming language if it operates at a high level of abstraction, or as a control language, particularly for job control languages on mainframes. The te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Font
In metal typesetting, a font is a particular size, weight and style of a ''typeface'', defined as the set of fonts that share an overall design. For instance, the typeface Bauer Bodoni (shown in the figure) includes fonts " Roman" (or "regular"), "" and ""; each of these exists in a variety of sizes. In the digital description of fonts ( computer fonts), the terms "font" and "typeface" are often used interchangeably. For example, when used in computers, each style is stored in a separate digital font file. In both traditional typesetting and computing, the word "font" refers to the delivery mechanism of an instance of the typeface. In traditional typesetting, the font would be made from metal or wood type: to compose a page may require multiple fonts from the typeface or even multiple typefaces. Spelling and etymology The word ''font'' (US) or ''fount'' (traditional UK, CAN; in any case pronounced ) derives from Middle French ''fonte'', meaning "cast iron". The term re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Web Page
A web page (or webpage) is a World Wide Web, Web document that is accessed in a web browser. A website typically consists of many web pages hyperlink, linked together under a common domain name. The term "web page" is therefore a metaphor of paper pages bound together into a book. Navigation Each web page is identified by a distinct URL, Uniform Resource Locator (URL). When the user inputs a URL into their web browser, the browser retrieves the necessary content from a web server and then browser engine, transforms it into an interactive visual representation on the user's screen. If the user point and click, clicks or touchscreen, taps a hyperlink, link, the browser repeats this process to load the new URL, which could be part of the current website or a different one. The browser has web browser#Features, features, such as the address bar, that indicate which page is displayed. Elements A web page is a structured document. The core element is a text file written in the HT ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
