Compagnie Honeywell Bull

Honeywell Information Systems Inc.

Philippe-Hubert deRivet

Benjamin S Franklin

John J Bradley

Jacques Michel Bienvenu

Claude Carre

Henri Verdier

Duc L Tuong

Patrick Dufond

Jean-Louis Bogaert

Duc Luu

A time accounting system for accounting for the time a process spends in a ready state, a wait state, or a running state. The system includes a time-of-day clock coupled to a central processing unit for outputting the time-of-day whenever a process changes state. A memory also coupled to the central processing unit stores the contents of a plurality of addressable process control blocks and each process control block includes first, second, and third storage locations for storing indications of the amount of time an associated process has been in the running, ready, and wait states, respectively. The central processor unit accesses the process control blocks and updates the process times stored therein in accordance with control signals generated by decoding a string of microinstructions stored in a control store memory. The time-of-day clock is accessed each time a process enters one of the running, ready, or wait states and each time the execution of a process is completed. The process control blocks are accessed and updated with the differences in the access times of the time-of-day clock to accumulate in the appropriate storage locations in each process control block the amount of time the associated process was in the running, ready, or wait states.

Process execution time accounting system

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

Apparatus in a data processing system to initialize a semaphore held in a memory field of the data processing system or, alternatively, to restore the semaphore to a previous predetermined state. A count field, or tally field, provided in the semaphore is initialized by a particular instruction. The semaphore can be either a non-message semaphore or a message semaphore. The instruction initializes the semaphore count field of a non message semaphore to zero or a preloaded positive value. For a message semaphore, this instruction initializes the count field to zero. If the message semaphore previously had a positive count, the messages tied to the semaphore are released and the message links holding the messages are transferred to a free message link queue tied to the free link semaphore in the same semaphore descriptor segment. The apparatus includes a retrieving member for reading the content of the semaphore in the memory of the data processing system, a testing member for testing the count field of the semaphore for generating a first signal when the count field represents the number of processes in queue and a second signal when the count field represents the number of times a particular kind of event has occurred, a changing unit responsive to the second signal and controlled by the particular instruction for changing the number inside the count field to a predetermined number and a control member responsive to the first signal and controlled by the particular instruction for controlling the data processing system to cease execution of the particular instruction and to begin to execute a different instruction.

Apparatus and method for semaphore initialization in a multiprocessing

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Paris, France

Philippe-Hubert deRivet