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Digital data processor with improved checkpointing and forking

  • US 5,313,647 A
  • Filed: 09/20/1991
  • Issued: 05/17/1994
  • Est. Priority Date: 09/20/1991
  • Status: Expired due to Term
First Claim
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1. A digital data processing apparatus comprising:

  • A. memory means for storing data,B. first process means for executing a first process and for generating in connection therewith at least one request for mapped access to said data,C. fork/checkpoint signalling means for generating one or more new-process signals, each new-process signal delineating a successive process interval,the interval preceding the first new-process signal being referred to as the first interval,D. means for responding to a request for access to a datum generated by the first process during said first interval for providing access to the requested datum as stored in a first set of data stored in said memory means,the first set being referred to as associated with said first interval of the first process,E. first address space management means, coupled to said first process means and to said fork/checkpoint signalling means, for responding at least to an initial request by that process during a current interval subsequent to said first interval for write-type access to a datum, fori) accessing the requested datum as stored in a set associated with a prior interval of the first process, andii) generating a further datum initially identical to that accessed datum;

    F. said first address space management means including means for storing said initially identical datum in a set in said memory means associated with the current interval of the first process, andG. said first address space management means further including means responsive to said initial request by the first process during said current interval for at least write-type access to a datum, as well as to subsequent requests for any of read-type and write-type access to that same datum by that same process during that same interval, for accessing said initially identical datum as stored in the set associated with the current interval of the first process, and otherwise for accessing the requested datum as stored in a set associated with a prior interval of the first process.

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