International Business Machines Corporation

William R Cohen

Peter Grimm Sutton

Robert A Blackburn

A method and system are disclosed for efficiently managing task memory in a multi-tasking data processing system having a processor for processing multiple tasks, task memory associated with each task, main system memory and multiple data records stored within direct access storage. A data record is copied from direct access storage into a buffer in main system memory in response to an access of that data record by a particular task. A buffer within that task's virtual memory is then mapped to the data record and a write protect bit is associated with the task memory buffer. Thereafter, any attempt to store data into the buffer will temporarily halt processing of the task until a copy of the data record is written to a second buffer. Task processing is then resumed, after modifying the task's page table to reference the second buffer, and the task is then permitted to store data within the second buffer. In this manner, a second buffer copy of the data record is only created in response to an attempted modification of the data record, thereby minimizing the processor and memory assets required to manage data records in a multi-tasking data processing system.

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Danbury, CT, United States of America

William R Cohen