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Rendezvous (Plan 9)
Rendezvous is a data synchronization mechanism in Plan 9 from Bell Labs. It is a system call that allows two processes to exchange a single datum while synchronizing. The rendezvous call takes a ''tag'' and a ''value'' as its arguments. The tag is typically an address in memory shared by both processes. Calling rendezvous causes a process to sleep until a second rendezvous call with a matching tag occurs. Then, the values are exchanged and both processes are awakened. More complex synchronization mechanisms can be created from this primitive operation. See also mutual exclusion. See also * Synchronous rendezvous * Communicating sequential processes External links Process Sleep and Wakeup on a Shared-memory Multiprocessorby Rob Pike, Dave Presotto, Ken Thompson and Gerard Holzmann Gerard J. Holzmann (born 1951) is a Dutch-American computer scientist and researcher at Bell Labs and NASA, best known as the developer of the SPIN model checker. Biography Holzmann was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Synchronization
Data synchronization is the process of establishing consistency between source and target data stores, and the continuous harmonization of the data over time. It is fundamental to a wide variety of applications, including file synchronization and mobile device synchronization. Data synchronization can also be useful in encryption for synchronizing public key servers. File-based solutions There are tools available for file synchronization, version control ( CVS, Subversion, etc.), distributed filesystems (Coda, etc.), and mirroring ( rsync, etc.), in that all these attempt to keep sets of files synchronized. However, only version control and file synchronization tools can deal with modifications to more than one copy of the files. * File synchronization is commonly used for home backups on external hard drives or updating for transport on USB flash drives. The automatic process prevents copying already identical files, thus can save considerable time relative to a manual copy, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plan 9 From Bell Labs
Plan 9 from Bell Labs is a distributed operating system which originated from the Computing Science Research Center (CSRC) at Bell Labs in the mid-1980s and built on UNIX concepts first developed there in the late 1960s. Since 2000, Plan 9 has been free and open-source. The final official release was in early 2015. Under Plan 9, UNIX's ''everything is a file'' metaphor is extended via a pervasive network-centric filesystem, and the cursor-addressed, terminal-based I/O at the heart of UNIX-like operating systems is replaced by a windowing system and graphical user interface without cursor addressing, although rc, the Plan 9 shell, is text-based. The name ''Plan 9 from Bell Labs'' is a reference to the Ed Wood 1957 cult science fiction Z-movie ''Plan 9 from Outer Space''. The system continues to be used and developed by operating system researchers and hobbyists. History Plan 9 from Bell Labs was originally developed, starting in the late 1980s, by members of the Computin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
System Call
In computing, a system call (commonly abbreviated to syscall) is the programmatic way in which a computer program requests a service from the operating system on which it is executed. This may include hardware-related services (for example, accessing a hard disk drive or accessing the device's camera), creation and execution of new processes, and communication with integral kernel services such as process scheduling. System calls provide an essential interface between a process and the operating system. In most systems, system calls can only be made from userspace processes, while in some systems, OS/360 and successors for example, privileged system code also issues system calls. Privileges The architecture of most modern processors, with the exception of some embedded systems, involves a security model. For example, the '' rings'' model specifies multiple privilege levels under which software may be executed: a program is usually limited to its own address space so that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Process (computing)
In computing, a process is the instance of a computer program that is being executed by one or many threads. There are many different process models, some of which are light weight, but almost all processes (even entire virtual machines) are rooted in an operating system (OS) process which comprises the program code, assigned system resources, physical and logical access permissions, and data structures to initiate, control and coordinate execution activity. Depending on the OS, a process may be made up of multiple threads of execution that execute instructions concurrently. While a computer program is a passive collection of instructions typically stored in a file on disk, a process is the execution of those instructions after being loaded from the disk into memory. Several processes may be associated with the same program; for example, opening up several instances of the same program often results in more than one process being executed. Multitasking is a method to allow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutual Exclusion
In computer science, mutual exclusion is a property of concurrency control, which is instituted for the purpose of preventing race conditions. It is the requirement that one thread of execution never enters a critical section while a concurrent thread of execution is already accessing said critical section, which refers to an interval of time during which a thread of execution accesses a shared resource or shared memory. The shared resource is a data object, which two or more concurrent threads are trying to modify (where two concurrent read operations are permitted but, no two concurrent write operations or one read and one write are permitted, since it leads to data inconsistency). Mutual exclusion algorithm ensures that if a process is already performing write operation on a data object ritical sectionno other process/thread is allowed to access/modify the same object until the first process has finished writing upon the data object ritical sectionand released the object f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchronous Rendezvous
In parallel computing, a barrier is a type of synchronization method. A barrier for a group of threads or processes in the source code means any thread/process must stop at this point and cannot proceed until all other threads/processes reach this barrier. Many collective routines and directive-based parallel languages impose implicit barriers. For example, a parallel ''do'' loop in Fortran with OpenMP will not be allowed to continue on any thread until the last iteration is completed. This is in case the program relies on the result of the loop immediately after its completion. In message passing, any global communication (such as reduction or scatter) may imply a barrier. In concurrent computing, a barrier may be in a ''raised'' or ''lowered state''. The term latch is sometimes used to refer to a barrier that starts in the raised state and cannot be re-raised once it is in the lowered state. The term count-down latch is sometimes used to refer to a latch that is automatically lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communicating Sequential Processes
In computer science, communicating sequential processes (CSP) is a formal language for describing patterns of interaction in concurrent systems. It is a member of the family of mathematical theories of concurrency known as process algebras, or process calculi, based on message passing via channels. CSP was highly influential in the design of the occam programming language and also influenced the design of programming languages such as Limbo, RaftLib, Erlang, Go, Crystal, and Clojure's core.async. CSP was first described in a 1978 article by Tony Hoare, but has since evolved substantially. CSP has been practically applied in industry as a tool for specifying and verifying the concurrent aspects of a variety of different systems, such as the T9000 Transputer, as well as a secure ecommerce system. The theory of CSP itself is also still the subject of active research, including work to increase its range of practical applicability (e.g., increasing the scale of the systems tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rob Pike
Robert "Rob" Pike (born 1956) is a Canadian programmer and author. He is best known for his work on the Go (programming language), Go programming language and at Bell Labs, where he was a member of the Unix team and was involved in the creation of the Plan 9 from Bell Labs and Inferno (operating system), Inferno operating systems, as well as the Limbo programming language. He also co-developed the Blit (computer terminal), Blit graphical terminal for Unix; before that he wrote the first window system for Unix in 1981. Pike is the sole inventor named in US patent 4,555,775. Over the years Pike has written many text editors; Sam (text editor), sam and Acme (text editor), acme are the most well known and are still in active use and development. Pike, with Brian Kernighan, is the co-author of ''The Practice of Programming'' and ''The Unix Programming Environment (book), The Unix Programming Environment''. With Ken Thompson he is the co-creator of UTF-8. Pike also developed lesser sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dave Presotto
Dave may refer to: Film, television, and theater * ''Dave'' (film), a 1993 film starring Kevin Kline and Sigourney Weaver * ''Dave'' (musical), a 2018 stage musical adaptation of the film * Dave (TV channel), a digital television channel in the United Kingdom and Ireland * ''Dave'' (TV series), a 2020 American comedy series * "Dave" (Lost), an episode of ''Lost'' * ''Meet Dave'', a 2008 film starring Eddie Murphy People * Dave (given name), a list of people and fictional characters * Dave (surname), a common Gujarati surname * Dave (artist) (born 1969), Swiss artist * Dave (rapper) (born 1998), English rapper from London * Dave (singer) (born 1944), Dutch-born French singer Software * Dave (company), a digital banking service * DAvE (Infineon), a C-language software development tool * Thursby DAVE, a Windows file and printer sharing for Macs Other uses * Dave (Belgium), a town in Belgium * DAVE (CP-7), a 1U CubeSat * "Dave", a 1984 song by the Boomtown Rats from ''In the Lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ken Thompson (computer Programmer)
Kenneth Lane Thompson (born February 4, 1943) is an American pioneer of computer science. Thompson worked at Bell Labs for most of his career where he designed and implemented the original Unix operating system. He also invented the B programming language, the direct predecessor to the C programming language, and was one of the creators and early developers of the Plan 9 operating system. Since 2006, Thompson has worked at Google, where he co-developed the Go programming language. Other notable contributions included his work on regular expressions and early computer text editors QED and ed, the definition of the UTF-8 encoding, and his work on computer chess that included the creation of endgame tablebases and the chess machine Belle. He won the Turing Award in 1983 with his long-term colleague Dennis Ritchie. Early life and education Thompson was born in New Orleans, Louisiana. When asked how he learned to program, Thompson stated, "I was always fascinated with logic an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gerard Holzmann
Gerard J. Holzmann (born 1951) is a Dutch-American computer scientist and researcher at Bell Labs and NASA, best known as the developer of the SPIN model checker. Biography Holzmann was born in Amsterdam, Netherlands and received an Engineer's degree in electrical engineering from the Delft University of Technology in 1976. He subsequently also received his PhD degree from Delft University in 1979 under W.L. van der Poel and J.L. de Kroes with a thesis entitled ''Coordination problems in multiprocessing systems''. After receiving a Fulbright Scholarship he was a post-graduate student at the University of Southern California for another year, where he worked with Per Brinch Hansen. In 1980 he started at Bell Labs in Murray Hill for a year. Back in the Netherlands he was assistant professor at the Delft University of Technology for two years.Holzmann, Gerard J. "The Pandora System: an interactive system for the design of data communication protocols." ''Computer Networks'' (1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parallel Computing
Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different forms of parallel computing: bit-level, instruction-level, data, and task parallelism. Parallelism has long been employed in high-performance computing, but has gained broader interest due to the physical constraints preventing frequency scaling.S.V. Adve ''et al.'' (November 2008)"Parallel Computing Research at Illinois: The UPCRC Agenda" (PDF). Parallel@Illinois, University of Illinois at Urbana-Champaign. "The main techniques for these performance benefits—increased clock frequency and smarter but increasingly complex architectures—are now hitting the so-called power wall. The computer industry has accepted that future performance increases must largely come from increasing the number of processors (or cores) on a die, rather tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
