History of Use
Compare-and-Swap (and Compare-and-Swap-Double) has been an integral part of the IBM 370 (and all successor) architectures since 1970. The operating systems which run on these architectures make extensive use of this instruction to facilitate process (i.e., system and user tasks) and processor (i.e., central processors) parallelism while eliminating, to the greatest degree possible, the "disabled spin locks" which had been employed in earlier IBM operating systems. Similarly, the use of Test-and-Set was also eliminated. In these operating systems, new units of work may be instantiated "globally", into the Global Service Priority List, or "locally", into the Local Service Priority List, by the execution of a single Compare-and-Swap instruction. This substantially improved the responsiveness of these operating systems.
In the x86 and Itanium architectures this is the compare and exchange (CMPXCHG) instruction, though here the lock prefix should be there to make it really atomic.
Read more about this topic: Compare-and-swap
Famous quotes containing the words history of and/or history:
“Three million of such stones would be needed before the work was done. Three million stones of an average weight of 5,000 pounds, every stone cut precisely to fit into its destined place in the great pyramid. From the quarries they pulled the stones across the desert to the banks of the Nile. Never in the history of the world had so great a task been performed. Their faith gave them strength, and their joy gave them song.”
—William Faulkner (1897–1962)
“Every member of the family of the future will be a producer of some kind and in some degree. The only one who will have the right of exemption will be the mother ...”
—Ruth C. D. Havens, U.S. suffragist. As quoted in History of Woman Suffrage, vol. 4, ch. 13, by Susan B. Anthony and Ida Husted Harper (1902)