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Read-copy-update
In computer science, read-copy-update (RCU) is a synchronization mechanism that avoids the use of lock primitives while multiple threads concurrently read and update elements that are linked through pointers and that belong to shared data structures (e.g., linked lists, trees, hash tables). Whenever a thread is inserting or deleting elements of data structures in shared memory, all readers are guaranteed to see and traverse either the older or the new structure, therefore avoiding inconsistencies (e.g., dereferencing null pointers). It is used when performance of reads is crucial and is an example of space–time tradeoff, enabling fast operations at the cost of more space. This makes all readers proceed as if there were no synchronization involved, hence they will be fast, but also making updates more difficult. Name and overview The name comes from the way that RCU is used to update a linked structure in place. A thread wishing to do this uses the following steps: * create a new ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU operating system, which was written to be a free (libre) replacement for Unix. Linux is provided under the GNU General Public License version 2 only, but it contains files under other compatible licenses. Since the late 1990s, it has been included as part of a large number of operating system distributions, many of which are commonly also called Linux. Linux is deployed on a wide variety of computing systems, such as embedded devices, mobile devices (including its use in the Android operating system), personal computers, servers, mainframes, and supercomputers. It can be tailored for specific architectures and for several usage scenarios using a family of simple commands (that is, without the need of manually editing its source code ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-blocking Algorithm
In computer science, an algorithm is called non-blocking if failure or suspension of any thread cannot cause failure or suspension of another thread; for some operations, these algorithms provide a useful alternative to traditional blocking implementations. A non-blocking algorithm is lock-free if there is guaranteed system-wide progress, and wait-free if there is also guaranteed per-thread progress. "Non-blocking" was used as a synonym for "lock-free" in the literature until the introduction of obstruction-freedom in 2003. The word "non-blocking" was traditionally used to describe telecommunications networks that could route a connection through a set of relays "without having to re-arrange existing calls" (see Clos network). Also, if the telephone exchange "is not defective, it can always make the connection" (see nonblocking minimal spanning switch). Motivation The traditional approach to multi-threaded programming is to use locks to synchronize access to shared resourc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Transaction
In database systems, atomicity (; from grc, ἄτομος, átomos, undividable) is one of the ACID (''Atomicity, Consistency, Isolation, Durability'') transaction properties. An atomic transaction is an ''indivisible'' and ''irreducible'' series of database operations such that either ''all'' occurs, or ''nothing'' occurs. A guarantee of atomicity prevents updates to the database occurring only partially, which can cause greater problems than rejecting the whole series outright. As a consequence, the transaction cannot be observed to be in progress by another database client. At one moment in time, it has not yet happened, and at the next it has already occurred in whole (or nothing happened if the transaction was cancelled in progress). An example of an atomic transaction is a monetary transfer from bank account A to account B. It consists of two operations, withdrawing the money from account A and saving it to account B. Performing these operations in an atomic transaction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dragonfly BSD
DragonFly BSD is a free and open-source Unix-like operating system forked from FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and FreeBSD developer between 1994 and 2003, began working on DragonFly BSD in June 2003 and announced it on the FreeBSD mailing lists on 16 July 2003. Dillon started DragonFly in the belief that the techniques adopted for threading and symmetric multiprocessing in FreeBSD 5 would lead to poor performance and maintenance problems. He sought to correct these anticipated problems within the FreeBSD project. Due to conflicts with other FreeBSD developers over the implementation of his ideas, his ability to directly change the codebase was eventually revoked. Despite this, the DragonFly BSD and FreeBSD projects still work together, sharing bug fixes, driver updates, and other improvements. Intended as the logical continuation of the FreeBSD 4.x series, DragonFly has diverged significantly from FreeBSD, implementing lig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Weekly News
LWN.net is a computing webzine with an emphasis on free software and software for Linux and other Unix-like operating systems. It consists of a weekly issue, separate stories which are published most days, and threaded discussion attached to every story. Most news published daily are short summaries of articles published elsewhere, and are free to all viewers. Original articles are usually published weekly on Thursdays and are available only to subscribers for two weeks, after which they become free as well. LWN.net is part of Eklektix, Inc. LWN caters to a more technical audience than other Linux/free software publications. It is often praised for its in-depth coverage of Linux kernel internals and Linux kernel mailing list (LKML) discussions. The acronym "LWN" originally stood for ''Linux Weekly News''; that name is no longer used because the site no longer covers exclusively Linux-related topics, and it has daily as well as weekly content. History Founded by Jonathan Corb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory Barrier
In computing, a memory barrier, also known as a membar, memory fence or fence instruction, is a type of barrier instruction that causes a central processing unit (CPU) or compiler to enforce an ordering constraint on memory operations issued before and after the barrier instruction. This typically means that operations issued prior to the barrier are guaranteed to be performed before operations issued after the barrier. Memory barriers are necessary because most modern CPUs employ performance optimizations that can result in out-of-order execution. This reordering of memory operations (loads and stores) normally goes unnoticed within a single thread of execution, but can cause unpredictable behavior in concurrent programs and device drivers unless carefully controlled. The exact nature of an ordering constraint is hardware dependent and defined by the architecture's memory ordering model. Some architectures provide multiple barriers for enforcing different ordering constraint ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Application Programming Interface
An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build or use such a connection or interface is called an ''API specification''. A computer system that meets this standard is said to ''implement'' or ''expose'' an API. The term API may refer either to the specification or to the implementation. In contrast to a user interface, which connects a computer to a person, an application programming interface connects computers or pieces of software to each other. It is not intended to be used directly by a person (the end user) other than a computer programmer who is incorporating it into the software. An API is often made up of different parts which act as tools or services that are available to the programmer. A program or a programmer that uses one of these parts is said to ''call'' that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lawsuit
- A lawsuit is a proceeding by a party or parties against another in the civil court of law. The archaic term "suit in law" is found in only a small number of laws still in effect today. The term "lawsuit" is used in reference to a civil action brought by a plaintiff (a party who claims to have incurred loss as a result of a defendant's actions) requests a legal remedy or equitable remedy from a court. The defendant is required to respond to the plaintiff's complaint. If the plaintiff is successful, judgment is in the plaintiff's favor, and a variety of court orders may be issued to enforce a right, award damages, or impose a temporary or permanent injunction to prevent an act or compel an act. A declaratory judgment may be issued to prevent future legal disputes. A lawsuit may involve dispute resolution of private law issues between individuals, business entities or non-profit organizations. A lawsuit may also enable the state to be treated as if it were a private party ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sequent Computer Systems
Sequent Computer Systems was a computer company that designed and manufactured multiprocessing computer systems. They were among the pioneers in high-performance symmetric multiprocessing (SMP) open systems, innovating in both hardware (e.g., cache management and interrupt handling) and software (e.g., read-copy-update). Through a partnership with Oracle Corporation, Sequent became a dominant high-end UNIX platform in the late 1980s and early 1990s. Later they introduced a next-generation high-end platform for UNIX and Windows NT based on a non-uniform memory access architecture, NUMA-Q. As hardware prices fell in the late 1990s, and Intel shifted their server focus to the Itanium processor family, Sequent joined the Project Monterey effort in October 1998. which aimed to move a standard Unix to several new platforms. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Patent
A software patent is a patent on a piece of software, such as a computer program, libraries, user interface, or algorithm. Background A patent is a set of exclusionary rights granted by a state to a patent holder for a limited period of time, usually 20 years. These rights are granted to patent applicants in exchange for their disclosure of the inventions. Once a patent is granted in a given country, no person may make, use, sell or import/export the claimed invention in that country without the permission of the patent holder. Permission, where granted, is typically in the form of a license which conditions are set by the patent owner: it may be free or in return for a royalty payment or lump sum fee. Patents are territorial in nature. To obtain a patent, inventors must file patent applications in each and every country in which they want a patent. For example, separate applications must be filed in Japan, China, the United States and India if the applicant wishes to obtain pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Patent And Trademark Office
The United States Patent and Trademark Office (USPTO) is an agency in the U.S. Department of Commerce that serves as the national patent office and trademark registration authority for the United States. The USPTO's headquarters are in Alexandria, Virginia, after a 2005 move from the Crystal City area of neighboring Arlington, Virginia. The USPTO is "unique among federal agencies because it operates solely on fees collected by its users, and not on taxpayer dollars". Its "operating structure is like a business in that it receives requests for services—applications for patents and trademark registrations—and charges fees projected to cover the cost of performing the services tprovide . The Office is headed by the Under Secretary of Commerce for Intellectual Property and Director of the United States Patent and Trademark Office, a position last held by Andrei Iancu until he left office on January 20, 2021. Commissioner of Patents Drew Hirshfeld is performing the funct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
