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Release Consistency
Release consistency is one of the synchronization-based consistency models used in concurrent programming (e.g. in distributed shared memory, distributed transactions etc.). Introduction In modern parallel computing systems, memory consistency must be maintained to avoid undesirable outcomes. Strict consistency models like sequential consistency are intuitively composed but can be quite restrictive in terms of performance as they would disable instruction level parallelism which is widely applied in sequential programming. To achieve better performance, some relaxed models are explored and release consistency is an aggressive relaxing attempt. Release consistency vs. sequential consistency Hardware structure and program-level effort Sequential consistency can be achieved simply by hardware implementation, while release consistency is also based on an observation that most of the parallel programs are properly synchronized. In programming level, synchronization is applied to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Consistency Model
In computer science, a consistency model specifies a contract between the programmer and a system, wherein the system guarantees that if the programmer follows the rules for operations on memory, memory will be consistent and the results of reading, writing, or updating memory will be predictable. Consistency models are used in distributed systems like distributed shared memory systems or distributed data stores (such as filesystems, databases, optimistic replication systems or web caching). Consistency is different from coherence, which occurs in systems that are cached or cache-less, and is consistency of data with respect to all processors. Coherence deals with maintaining a global order in which writes to a single location or single variable are seen by all processors. Consistency deals with the ordering of operations to multiple locations with respect to all processors. High level languages, such as C++ and Java, maintain the consistency contract by translating memory operat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lock (computer Science)
In computer science, a lock or mutex (from mutual exclusion) is a synchronization primitive: a mechanism that enforces limits on access to a resource when there are many threads of execution. A lock is designed to enforce a mutual exclusion concurrency control policy, and with a variety of possible methods there exists multiple unique implementations for different applications. Types Generally, locks are ''advisory locks'', where each thread cooperates by acquiring the lock before accessing the corresponding data. Some systems also implement ''mandatory locks'', where attempting unauthorized access to a locked resource will force an exception in the entity attempting to make the access. The simplest type of lock is a binary semaphore. It provides exclusive access to the locked data. Other schemes also provide shared access for reading data. Other widely implemented access modes are exclusive, intend-to-exclude and intend-to-upgrade. Another way to classify locks is by what hap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weak Consistency
The name weak consistency can be used in two senses. In the first sense, strict and more popular, weak consistency is one of the consistency models used in the domain of concurrent programming (e.g. in distributed shared memory, distributed transactions etc.). A protocol is said to support weak consistency if: #All accesses to synchronization variables are seen by all processes (or nodes, processors) in the same order (sequentially) - these are synchronization operations. Accesses to critical sections are seen sequentially. #All other accesses may be seen in different order on different processes (or nodes, processors). #The set of both read and write operations in between different synchronization operations is the same in each process. Therefore, there can be no access to a synchronization variable if there are pending write operations. And there can not be any new read/write operation started if the system is performing any synchronization operation. In the second, more genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandhya Dwarkadas
Sandhya Dwarkadas is a professor and Chair of the Department of Computer Science at the University of Virginia. She was formerly the Albert Arendt Hopeman Professor of Engineering and Professor and Chair of the Department of Computer Science at the University of Rochester. She is known for her research on shared memory and reconfigurable computing. Education Dwarkadas was educated at the Indian Institute of Technology Madras and Rice University, completing her Ph.D. at Rice in 1993. Her dissertation, ''Synchronization, Coherence, and Consistency for High Performance Shared-Memory Multiprocessing'', was jointly supervised by J. Robert Jump and Bart Sinclair. Recognition Dwarkadas became a fellow of the Institute of Electrical and Electronics Engineers in 2017. She was elected as an ACM Fellow ACM or A.C.M. may refer to: Aviation * AGM-129 ACM, 1990–2012 USAF cruise missile * Air chief marshal * Air combat manoeuvring or dogfighting * Air cycle machine * Arica Airport (Colom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lazy RC
Lazy is the adjective for laziness, a lack of desire to expend effort. It may also refer to: Music Groups and musicians * Lazy (band), a Japanese rock band * Lazy Lester, American blues harmonica player Leslie Johnson (1933–2018) * Lazy Bill Lucas (1918–1982), American blues musician and singer * Doug Lazy, stage name of American hip hop and dance music producer and DJ Gene Douglas Finley * Lazy, an American band featuring former members of the Supreme Beings of Leisure Albums * ''Lazy'' (album), an album by The Hot Monkey Songs * "Lazy" (Deep Purple song), 1972 * "Lazy" (Irving Berlin song), 1924 * "Lazy" (Suede song), 1997 * "Lazy" (X-Press 2 song), 2002 * "Lazy", by Exo-CBX from ''Blooming Days'' * "Lazy", by Love & Rockets from ''Earth, Sun, Moon'' * "Lazy", by Parokya Ni Edgar from ''Gulong Itlog Gulong'' * "Lazy", by The Vaccines and Kylie Minogue for '' A Shaun the Sheep Movie: Farmageddon'', 2019 Places * Lazy (Orlová), a former village now part of the town of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eager RC
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Eager may refer to: *Eager (band) *Eager (horse), (1788 – after 1795), a British Thoroughbred racehorse * ''Eager'' (novel), a children's science-fiction novel written by Helen Fox *Eager (surname) *, an Admirable-class minesweeper built for the United States Navy during World War II See also * *Eagers *Eager beaver (other) * Eagre, another term for a tidal bore *Eger (other) Eger may refer to: Places *Eger, a city in Hungary **Eger (Tisza), tributary of the river Tisza **Eger wine region **Roman Catholic Archdiocese of Eger * Eger (Balaton), river flowing to Lake Balaton, Hungary *''Eger'', German name of Cheb, Czech ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lock Release In RC
Lock(s) may refer to: Common meanings *Lock and key, a mechanical device used to secure items of importance *Lock (water navigation), a device for boats to transit between different levels of water, as in a canal Arts and entertainment * ''Lock'' (film), a 2016 Punjabi film * Lock (''Saga of the Skolian Empire''), a sentient machine in the novels by Catherine Asaro *Lock (waltz), a dance figure * ''Locked'' (miniseries), Indian web miniseries * ''The Lock'' (Constable), an 1824 painting by John Constable * ''The Lock'' (Fragonard) or ''The Bolt'', a 1777 painting by Jean-Honoré Fragonard * ''Locks'' (album), by Garnet Crow, 2008 People *Lock (surname) *Ormer Locklear (1891–1920), American stunt pilot and film actor nicknamed "Lock" * George Locks (1889–1965), English cricketer *Lock Martin (1916–1959), stage name of American actor Joseph Lockard Martin, Jr. Places *Lock, Ohio, an unincorporated community in the United States *Lock, South Australia, a small town in the ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Processor Consistency
Processor Consistency is one of the consistency models used in the domain of concurrent computing (e.g. in distributed shared memory, distributed transactions, etc.). A system exhibits Processor Consistency if the order in which other processors see the writes from any individual processor is the same as the order they were issued. Because of this, Processor Consistency is only applicable to systems with multiple processors. It is weaker than the Causal Consistency model because it does not require writes from ''all'' processors to be seen in the same order, but stronger than the PRAM Consistency model because it requires Cache Coherence. Another difference between Causal Consistency and Processor Consistency is that Processor Consistency removes the requirements for loads to wait for stores to complete, and for Write Atomicity. Processor Consistency is also stronger than Cache Consistency because Processor Consistency requires all writes by a processor to be seen in order, not just ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrent Programming
Concurrent means happening at the same time. Concurrency, concurrent, or concurrence may refer to: Law * Concurrence, in jurisprudence, the need to prove both ''actus reus'' and ''mens rea'' * Concurring opinion (also called a "concurrence"), a legal opinion which supports the conclusion, though not always the reasoning, of the majority. * Concurrent estate, a concept in property law * Concurrent resolution, a legislative measure passed by both chambers of the United States Congress * Concurrent sentences, in criminal law, periods of imprisonment that are served simultaneously Computing * Concurrency (computer science), the property of program, algorithm, or problem decomposition into order-independent or partially-ordered units * Concurrent computing, the overlapping execution of multiple interacting computational tasks * Concurrence (quantum computing), a measure used in quantum information theory * Concurrent Computer Corporation, an American computer systems manufacturer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Critical Section
In concurrent programming, concurrent accesses to shared resources can lead to unexpected or erroneous behavior, so parts of the program where the shared resource is accessed need to be protected in ways that avoid the concurrent access. One way to do so is known as a critical section or critical region. This protected section cannot be entered by more than one process or thread at a time; others are suspended until the first leaves the critical section. Typically, the critical section accesses a shared resource, such as a data structure, a peripheral device, or a network connection, that would not operate correctly in the context of multiple concurrent accesses. Need for critical sections Different codes or processes may consist of the same variable or other resources that need to be read or written but whose results depend on the order in which the actions occur. For example, if a variable is to be read by process A, and process B has to write to the same variable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instruction-level Parallelism
Instruction-level parallelism (ILP) is the parallel or simultaneous execution of a sequence of instructions in a computer program. More specifically ILP refers to the average number of instructions run per step of this parallel execution. Discussion ILP must not be confused with concurrency. In ILP there is a single specific thread of execution of a process. On the other hand, concurrency involves the assignment of multiple threads to a CPU's core in a strict alternation, or in true parallelism if there are enough CPU cores, ideally one core for each runnable thread. There are two approaches to instruction-level parallelism: hardware and software. Hardware level works upon dynamic parallelism, whereas the software level works on static parallelism. Dynamic parallelism means the processor decides at run time which instructions to execute in parallel, whereas static parallelism means the compiler decides which instructions to execute in parallel. The Pentium processor wor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
