Apparatus and method for transferring information units between processes in a multiprocessing system
US4394725A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 4, 1978 |
| Grant date | Jul 19, 1983 |
| Priority date | — |
| Expiry date | Dec 4, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/52
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method of and apparatus for executing a family of instructions provides synchronization of processes in a multiprocessing system. Representations of processes awaiting data (information units) such as the completion of an asynchronous operation or the availability of a resource are stored in a memory in a first queue and representations of information units available to processes are stored in memory in a second queue. Transfer of information units between processes is controlled by data elements known as "semaphores" stored in the memory. Each semaphore contains a field having a numerical value identifying which of the two different kinds of queues is present. When a P instruction is executed by a process indicating that the process requires data in order to continue operating or a V instruction is executed indicating that an information unit is available for transfer to another process, a semaphore is addresses and its field tested to determine whether processes or information units are available to enable the information transfer between processes to be effected. Once the information transfer is completed, the field of the addressed semaphore is up-dated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.