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Data prefetching based on store information in multi-processor caches

  • US 5,214,766 A
  • Filed: 08/19/1992
  • Issued: 05/25/1993
  • Est. Priority Date: 04/28/1989
  • Status: Expired due to Fees
First Claim
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1. In a multi-processor system comprising a plurality of processors, a shared main storage and a storage control element, each said processors having a local cache memory and a buffer control element, a computer implemented method of data prefetching comprising the steps of:

  • establishing a local history table at each of said processors, each said local history table containing for each line in cache memory a record of one of whether said line was cross-interrogate invalidated without refetching said line from said shared main storage and whether said line was stored into by the processor corresponding to each said local history table since a last fetch of said line;

    setting an entry in said local history table when one ofa) said line is cross-interrogate invalidated from any processor andb) the buffer control element receivesa data store for said line occurs, corresponding to said record in said local history table, and resetting said entry corresponding to said record in said local history table when said processor fetches said line into its cache memory from said shared main storage; and

    examining entries in said local history table for selected lines which have addresses having a predetermined relationship to a particular line to be accessed by the processor corresponding to said local history table, said predetermined relationship indicating an increased likelihood of a respective one of said selected lines being required, and whena) said particular line is not available in said local cache memory andb) said local history table contains at least one entry which is set corresponding to a respective one of at least one selected line having said predetermined relationship to said particular line,fetching said particular line and prefetching only ones of said selected lines having said predetermined relationship to said particular line and also correspond to ones of said entries in said local history table which are set.

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