Compagnie Honeywell Bull

Patrick Dufond

Benjamin S Franklin

John J Bradley

Jacques Michel Bienvenu

Henri Verdier

Claude Carre

Philippe-Hubert deRivet

Duc L Tuong

Jean-Claude Marcel Cassonnet

Jean-Louis Bogaert

Philippe-Hubert De Rivet

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.

Apparatus and method for transferring information units between

An information structure, or semaphore, serves as a signalling mechanism in process synchronization to connect a process and a non-simultaneously occurring event or resource. The semaphore is a data structure which stores representations of processes awaiting particular events or alternatively stores representations of events awaiting processes. Semaphore data structures are developed in two storage areas. First and second groups of process links are stored in the first storage area to establish, respectively, a first queue of processes ready to operate and a second queue, associated with the semaphore structure, of processes awaiting occurrences of a first particular event prior to being ready to operate. In the second storage area are stored first and second groups of message links to establish respectively a first queue, associated with a semaphore structure, representing second particular events and a second queue of unused links. A signal is generated in response to operation of a first process to denote the occurrence of a first event. In response to the signal, the first event is associated with a process represented by a process link in the second queue of process links when the first event is the first particular event. When no queue has a process link identifying a process awaiting the occurrence of the first event, a representation of the first event occurrence is stored in a message link of the second queue of message links to be transferred to the first queue of message links. Process and event occurrence representations are thus transferred among the process and event queues during synchronization that takes place between the processes and events.

Apparatus and method for providing synchronization between processes and

A system and method for computer process dispatching in a multiprogramming/multiprocessing environment is disclosed. Each process in the multiprogramming/multiprocessing computer system may be in one of four states at any given time as follows: 1. Running -- the process is in control of the computer system and is directing the operation of the central processing unit (CPU); 2. ready -- the process is ready to run as soon as it is given control of the CPU; 3. waiting -- the process is waiting for an external event to occur so it can either resume running or enter the ready state; 4. Suspended -- the process has been temporarily stopped (from a source external to the process). The dispatcher is a firmware/hardware structure that controls the first three states of the process--i.e. running, ready and waiting states.

Process management structures and hardware/firmware control

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Paris, France

Patrick Dufond