Browse Prior Art Database

Status Save/ Restore/ Modify of a Unit of Work

IP.com Disclosure Number: IPCOM000048441D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Hitch, LC: AUTHOR

Abstract

External timer interrupts are used to signal the saving and restoring o the status of a unit of work during the operation of a data processing system which may have plural central processors. This allows one processor to be executing more than one unit of work concurrently. When an interrupt occurs, the status of the current unit of work which is executing on the processor is saved in the control blocks which represent the unit of work. The interrupt is then serviced, and a unit of work is dispatched. The dispatched unit of work may or may not be the one which was executing at the time of the interrupt.

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Status Save/ Restore/ Modify of a Unit of Work

External timer interrupts are used to signal the saving and restoring o the status of a unit of work during the operation of a data processing system which may have plural central processors. This allows one processor to be executing more than one unit of work concurrently. When an interrupt occurs, the status of the current unit of work which is executing on the processor is saved in the control blocks which represent the unit of work. The interrupt is then serviced, and a unit of work is dispatched. The dispatched unit of work may or may not be the one which was executing at the time of the interrupt.

Status save/ restore/ modify services allow a unit of work to signal the saving and restoring of its own status. The unit of work may request that its status be saved. restored, or modified. It may request the saving of its current status and then process other work that it has. At a later time it may request that the previously saved status be restored. It may then process the work which it previously was not able to continue processing. Also, while the status is saved, some of the saved status may be changed.

The status which is saved for the unit of work is restricted to processor execution and dispatching status, e.g., general and floating point registers, program status word (PSW), recovery environment processor timing values, and processor affinity information. Hence, no attempt is made to save all status related to the unit of work, but only that status which is required for its processor execution and dispatching is saved. The status of the unit of work is saved in a status save area which is maintained by the unit of work. The status may then be restored and/or modified as requested by the unit of work.

When a unit of work wishes to save its current status, it may call the save service to do so. It must pass to the service the address of a status save area in which the status is to be stored. The status save area is marked as containing valid status. When the status has been saved in the save area, control is r...