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Method to control paging subsystem processing in virtual memory data processing system during execution of critical code sections

  • US RE36,462 E
  • Filed: 10/04/1996
  • Issued: 12/21/1999
  • Est. Priority Date: 01/16/1986
  • Status: Expired due to Term
First Claim
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1. In a virtual memory data processing system having a real memory containing a plurality of addresable locations each of which has a different physical address and each of which is capable of storing a page of data, said system further including a plurality of pageable data structures, each of which includes a plurality of entries, each entry containing an address field and a related status field to indicate the current status of a page of data stored at said location having the physical address contained in said related address field of said entry, said status field being updatable by said system to reflect said current status of said related page whenever the status of said related page of data is changed, a method to serialize a plurality of different type system events which operate to change the status of a page of data, and to update said status field of said corresponding entry of said pageable data structure to reflect said change in order to insure the integrity of said data structures, said method comprising the steps of;

  • (1) coding a first section of code that is executed in response to a first page fault to permit an interrupt for a second page fault and to request an I/O paging operation, said first section of code including a critical section,(2) executing said first section of code to completion prior to a section of code having a lower priority being executed by restarting said first section of code at its critical section after said second page fault is serviced in order to service said first page fault,(3) coding a second section of code that is executed in response to the completion of an I/O operation initiated in response to a page fault,(4) enqueueing on a list an indication of said completion of each said I/O operation, and(5) executing said second section of code after said first section completes executing.

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