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Multiprocessor system having distributed shared resources and dynamic global data replication

  • US 5,247,673 A
  • Filed: 11/16/1990
  • Issued: 09/21/1993
  • Est. Priority Date: 12/04/1989
  • Status: Expired due to Term
First Claim
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1. A multiprocessor system which performs the method of dynamically allocating and replicating global data, said system having distributed shared resources and dynamic global data replication comprising a system bus, a plurality of central processing units (CPU) operating under control of a UNIX type operating system, each CPU comprising a processor, a related local memory connected to said processor, a related memory management unit (MMU) connected to said processor for converting virtual addresses received from said processor into addresses having a bit field which identifies said addresses as related to global data used in more CPUs of said plurality and which read replication in the local memory of each CPU in said plurality, or as related to local data used by one only of said CPUs and an interface unit connected to said system bus and enabling information exchange among said CPUs through said system bus, said method comprising the steps of:

  • generating a memory table (GSD) in the local memory of each of said CPUs under control of said operating system for referencing by codes related to virtual page addresses of shared segments, said memory table storing information which, for each virtual page address, defines if the data in said virtual page are global data or local data and in which of said CPUs said global data are used and validity stored in the related local memory;

    at least one CPU of said plurality of CPUs performing a page fault procedure in response to an indication of missing page generated by the related MMU which references said GSD table in the local memory related to said one CPU upon detecting that said missing page is used in another CPU of said plurality of CPUs and stored in the local memory of said another CPU as local data page, for generating signals for requesting all other CPUs to allocate a free physical memory page of the related local memory for storing a global data page and for causing said page missing in said one CPU and stored in the local memory of said another CPU to be replicated in the local memories of all other of said CPUs; and

    ,changing the information stored in said GSD table by said one CPU to indicate that said page requested to be replicated is global upon completion of said page being replicated in the local memories of all other of said CPUs.

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