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Futex
In computing, a futex (short for "fast userspace mutex") is a kernel system call that programmers can use to implement basic locking, or as a building block for higher-level locking abstractions such as semaphores and POSIX mutexes or condition variables. A futex consists of a kernel-space ''wait queue'' that is attached to an atomic integer in userspace. Multiple processes or threads operate on the integer entirely in userspace (using atomic operations to avoid interfering with one another), and only resort to the fast but still more expensive system calls to request operations on the wait queue (for example to wake up waiting processes, or to put the current process on the wait queue). A properly programmed futex-based lock will not use system calls except when the lock has contention; since most operations do not require arbitration between processes, this will not happen in most cases. History Hubertus Franke (IBM Thomas J. Watson Research Center), Matthew Kirkwoo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel Mainline
The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the kernel for the GNU operating system (OS) which was created to be a free software, free replacement for Unix. Since the late 1990s, it has been included in many Linux distributions, operating system distributions, many of which are called Linux. One such Linux kernel operating system is Android (operating system), Android which is used in many mobile and embedded devices. Most of the kernel code is written in C (programming language), C as supported by the GNU compiler collection (GCC) which has extensions beyond standard C. The code also contains assembly language, assembly code for architecture-specific logic such as optimizing memory use and task execution. The kernel has a Modular programming, modular design such that modules can be inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C++20
C20 or C-20 may refer to: Science and technology * Carbon-20 (C-20 or 20C), an isotope of carbon * C20, the smallest possible fullerene (a carbon molecule) * C20 (engineering), a mix of concrete that has a compressive strength of 20 newtons per square millimeter * Malignant neoplasm of rectum, a type of colorectal cancer (ICD-10 code: C20) * Caldwell 20 or North America Nebula, an emission nebula in the constellation Cygnus * IEC 60320 C20, a polarised, three pole socket electrical connector * C20 (Capacity, 20 hours), C100 (100 hours), battery capacity Transportation and military * Colt Canada C20 DMR, a Canadian designated marksman rifle * , a 1910 British C-class submarine * Sauber C20, a 2001 racing car * SL C20, a type of rolling stock used in the Stockholm metro * , a cruiser of the Royal Navy * C-20, the proposed in-service designation of the Fokker F-32 * C-20A/B/C/D/E, variants of the Gulfstream III * C-20F/G/H/J, variants of the Gulfstream IV * C20 is a version of the Alli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and software. Computing has scientific, engineering, mathematical, technological, and social aspects. Major computing disciplines include computer engineering, computer science, cybersecurity, data science, information systems, information technology, and software engineering. The term ''computing'' is also synonymous with counting and calculation, calculating. In earlier times, it was used in reference to the action performed by Mechanical computer, mechanical computing machines, and before that, to Computer (occupation), human computers. History The history of computing is longer than the history of computing hardware and includes the history of methods intended for pen and paper (or for chalk and slate) with or without the aid of tables. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ingo Molnár
Ingo Molnár, employed by Red Hat as of May 2013, is a Hungary, Hungarian Linux Hacker culture, hacker. He is known for his contributions to the operating system in terms of Computer security, security and Computer performance, performance. Life and career Molnár studied at Eötvös Loránd University. Work Some of his additions to the Linux Kernel (operating system), kernel include the O(1) scheduler of Linux-2.6.0 and the Completely Fair Scheduler of Linux-2.6.23, the in-kernel TUX web server, TUX HTTP / File Transfer Protocol, FTP Server (computing), server, as well as his work to enhance thread (computing), thread handling. He also wrote a kernel security feature called "Exec Shield", which prevents stack-based buffer overflow exploits in the x86 architecture by disabling the execution (computing), execute permission for the stack. Together with Thomas Gleixner, he worked on the Real-time operating system, real-time preemption (PREEMPT_RT) patch set, which aims to reduce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchronization (computer Science)
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. Motivation The need for synchronization does not arise merely in multi-processor systems but for any kind of concurrent processes; even in single processor systems. Mentioned below are some of the main needs for synchronization: '' Forks and Joins:'' When a job arrives at a fork point, it is split into N sub-jobs which are then serviced by n tasks. After being serviced, each sub-job waits until all other sub-jobs are done processing. Then, they are joined again and leave the system. Thus, parallel programming requires synchronization as all the parallel processes wait for several other processes to occur. '' Producer-Consumer:'' In a producer-consumer relationship, the consumer process is dependent on the producer process until the necessary data has been produced. ''Exclusiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thundering Herd Problem
In computer science, the thundering herd problem occurs when a large number of processes or threads waiting for an event are awakened when that event occurs, but only one process is able to handle the event. When the processes wake up, they will each try to handle the event, but only one will win. All processes will compete for resources, possibly freezing the computer, until the herd is calmed down again. Mitigation The Linux kernel serializes responses for requests to a single file descriptor, so only one thread or process is woken up. For epoll() in version 4.5 of the Linux kernel, the EPOLLEXCLUSIVE flag was added. Thus several epoll sets (different threads or different processes) may wait on the same resource and only one set will be woken up. For certain workloads this flag can give significant processing time reduction. Similarly in Microsoft Windows, Input/output completion port, I/O completion ports can mitigate the thundering herd problem, as they can be configured suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fuchsia (operating System)
Fuchsia is an open-source capability-based operating system developed by Google. In contrast to Google's Linux-based operating systems such as ChromeOS and Android, Fuchsia is based on a custom kernel named Zircon. It publicly debuted as a self-hosted git repository in August 2016 without any official corporate announcement. After years of development, its official product launch was in 2021 on the first-generation Google Nest Hub, replacing its original Linux-based Cast OS. Etymology Fuchsia is named for the color fuchsia, which is a combination of pink and purple. The name is a reference to two operating systems projects within Apple which influenced team members of the Fuchsia project: Taligent (codenamed "Pink") and iOS (codenamed "Purple"). The color-based naming scheme derives from the colors of index cards which Apple employees used to organize their ideas. The name of the color fuchsia is derived from the Fuchsia plant genus, which is derived from the name of botani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Google
Google LLC (, ) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial intelligence (AI). It has been referred to as "the most powerful company in the world" by the BBC and is one of the world's List of most valuable brands, most valuable brands. Google's parent company, Alphabet Inc., is one of the five Big Tech companies alongside Amazon (company), Amazon, Apple Inc., Apple, Meta Platforms, Meta, and Microsoft. Google was founded on September 4, 1998, by American computer scientists Larry Page and Sergey Brin. Together, they own about 14% of its publicly listed shares and control 56% of its stockholder voting power through super-voting stock. The company went public company, public via an initial public offering (IPO) in 2004. In 2015, Google was reorganized as a wholly owned subsidiary of Alphabet Inc. Go ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OpenBSD
OpenBSD is a security-focused operating system, security-focused, free software, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by fork (software development), forking NetBSD 1.0. The OpenBSD project emphasizes software portability, portability, software standard, standardization, software bug, correctness, proactive computer security, security, and integrated cryptography. The OpenBSD project maintains portable versions of many subsystems as package manager, packages for other operating systems. Because of the project's preferred BSD license, which allows binary redistributions without the source code, many components are reused in proprietary and corporate-sponsored software projects. The firewall (computing), firewall code in Apple Inc., Apple's macOS is based on OpenBSD's PF (firewall), PF firewall code, Android (operating system), Android's Bionic (software), Bionic C standard library is based on OpenBSD c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Vulnerabilities And Exposures
The Common Vulnerabilities and Exposures (CVE) system, originally Common Vulnerability Enumeration, provides a reference method for publicly known information security, information-security vulnerability (computing), vulnerabilities and exposures. The United States' Homeland Security Systems Engineering and Development Institute FFRDC, operated by The MITRE Corporation, maintains the system, with funding from the US National Cyber Security Division of the US Department of Homeland Security. The system was officially launched for the public in September 1999. The Security Content Automation Protocol uses CVE, and CVE IDs are listed on MITRE's system as well as the basis for the US National Vulnerability Database. CVE identifiers MITRE Corporation's documentation defines CVE Identifiers (also called "CVE names", "CVE numbers", "CVE-IDs", and "CVEs") as unique, common identifiers for publicly known information-security vulnerabilities in publicly released software packages. Historic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linus Torvalds
Linus Benedict Torvalds ( , ; born 28 December 1969) is a Finnish software engineer who is the creator and lead developer of the Linux kernel. He also created the distributed version control system Git. He was honored, along with Shinya Yamanaka, with the 2012 Millennium Technology Prize by the Technology Academy Finland "in recognition of his creation of a new open source operating system for computers leading to the widely used Linux kernel". He is also the recipient of the 2014 IEEE Computer Society Computer Pioneer Award and the 2018 IEEE Masaru Ibuka Consumer Electronics Award. Life and career Early years Torvalds was born in Helsinki, Finland, on 28 December 1969, the son of journalists Anna and Nils Torvalds, the grandson of statistician Leo Törnqvist and of poet Ole Torvalds, and the great-grandson of journalist and soldier Toivo Karanko. His parents were campus radicals at the University of Helsinki in the 1960s. His family belongs to the Swedish-sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux
Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, packaged as a Linux distribution (distro), which includes the kernel and supporting system software and library (computing), libraries—most of which are provided by third parties—to create a complete operating system, designed as a clone of Unix and released under the copyleft GPL license. List of Linux distributions, Thousands of Linux distributions exist, many based directly or indirectly on other distributions; popular Linux distributions include Debian, Fedora Linux, Linux Mint, Arch Linux, and Ubuntu, while commercial distributions include Red Hat Enterprise Linux, SUSE Linux Enterprise, and ChromeOS. Linux distributions are frequently used in server platforms. Many Linux distributions use the word "Linux" in their name, but the Free ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
