In computer science , read–modify–write is a class of atomic operations (such as test-and-set , fetch-and-add , and compare-and-swap ) that both read a memory location and write a new value into it simultaneously, either with a completely new value or some function of the previous value. These operations prevent race conditions in multi-threaded applications. Typically they are used to implement mutexes or semaphores . These atomic operations are also heavily used in non-blocking synchronization .
3-404: Maurice Herlihy (1991) ranks atomic operations by their consensus numbers, as follows: It is impossible to implement an operation that requires a given consensus number with only operations with a lower consensus number, no matter how many of such operations one uses. Read–modify–write instructions often produce unexpected results when used on I/O devices, as a write operation may not affect
6-503: Is an American computer scientist active in the field of multiprocessor synchronization . Herlihy has contributed to areas including theoretical foundations of wait-free synchronization, linearizable data structures, applications of combinatorial topology to distributed computing , as well as hardware and software transactional memory . He is the An Wang Professor of Computer Science at Brown University , where he has been
9-443: The same internal register that would be accessed in a read operation. This term is also associated with RAID levels that perform actual write operations as atomic read–modify–write sequences. Such RAID levels include RAID 4 , RAID 5 and RAID 6 . This computer science article is a stub . You can help Misplaced Pages by expanding it . Maurice Herlihy Maurice Peter Herlihy (born 4 January 1954)
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