[1] : The Free On-line Dictionary of Computing (27 SEP 03)

shared memory
     
        1. memory in a parallel computer, usually ram, which can
        be accessed by more than one processor, usually via a shared
        bus or network.
     
        it usually takes longer for a processor to access shared
        memory than to access its own private memory because of
        contention for the processor-to-memory connections and because
        of other overheads associated with ensuring synchronised
        access.  computers using shared memory usually have some kind
        of local cache on each processor to reduce the number of
        accesses to shared memory.  this requires a cache
        consistency protocol to ensure that one processor's cached
        copy of a shared memory location is invalidated when another
        processor writes to that location.
     
        the alternative to shared memory is message passing where
        all memory is private to some particular processor and
        processors communicate by sending messages down special
        links.  this is usually slower than shared memory but it
        avoids the problems of contention for memory and can be
        implemented more cheaply.
     
        2. memory which can be access by more than one process in a
        multitasking operating system with memory protection.
        some unix variants, e.g. sunos provide this kind of shared
        memory.
     
        unix manual pages: shmop2, shmctl2, shmget2.
     
        1994-10-20
     
     
see also:
parallel computer ram bus cache cache consistency protocol 
message passing multitasking operating system unix sunos 
unix manual pages 

Shared Memory >> S Words
Shared Memory, definition of term: Shared Memory
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Shared >> S Words
Shared, definition of term: Shared
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Memory >> M Words
Memory, definition of term: Memory
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Memory Loss >> M Words
Memory Loss, definition of term: Memory Loss
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Memory Manageme >> M Words
Memory Manageme, definition of term: Memory Manageme
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Memory Protecti >> M Words
Memory Protecti, definition of term: Memory Protecti
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Memory Device >> M Words
Memory Device, definition of term: Memory Device
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Memory Farts >> M Words
Memory Farts, definition of term: Memory Farts
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Edo Memory >> E Words
Edo Memory, definition of term: Edo Memory
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Virtual Memory >> V Words
Virtual Memory, definition of term: Virtual Memory
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