Chapter12 - Chapter 12: Distributed Shared Memory Ajay...

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Chapter 12: Distributed Shared Memory Ajay Kshemkalyani and Mukesh Singhal Distributed Computing: Principles, Algorithms, and Systems Cambridge University Press Distributed Shared Memory CUP 2008 1 / 48
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Distributed Computing: Principles, Algorithms, and Systems Distributed Shared Memory Abstractions communicate with Read/Write ops in shared virtual space No Send and Receive primitives to be used by application I Under covers, Send and Receive used by DSM manager Locking is too restrictive; need concurrent access With replica management, problem of consistency arises! = weaker consistency models (weaker than von Neumann) reqd Memory Shared Virtual Memory Memory Memory Memory manager manager manager CPU CPU CPU Memory Memory process Shared Virtual Memory Memory Memory Memory manager manager manager Distributed shared memory invocation response invocation response invocation response process process Distributed Shared Memory CUP 2008 2 / 48
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Distributed Computing: Principles, Algorithms, and Systems Distributed Shared Memory Abstractions communicate with Read/Write ops in shared virtual space No Send and Receive primitives to be used by application I Under covers, Send and Receive used by DSM manager Locking is too restrictive; need concurrent access With replica management, problem of consistency arises! = weaker consistency models (weaker than von Neumann) reqd Memory Shared Virtual Memory Memory Memory Memory manager manager manager CPU CPU CPU Memory Memory process Shared Virtual Memory Memory Memory Memory manager manager manager Distributed shared memory invocation response invocation response invocation response process process Distributed Shared Memory CUP 2008 2 / 48
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Distributed Computing: Principles, Algorithms, and Systems Advantages/Disadvantages of DSM Advantages: Shields programmer from Send/Receive primitives Single address space; simplifies passing-by-reference and passing complex data structures Exploit locality-of-reference when a block is moved DSM uses simpler software interfaces, and cheaper off-the-shelf hardware. Hence cheaper than dedicated multiprocessor systems No memory access bottleneck, as no single bus Large virtual memory space DSM programs portable as they use common DSM programming interface Disadvantages: Programmers need to understand consistency models, to write correct programs DSM implementations use async message-passing, and hence cannot be more efficient than msg-passing implementations By yielding control to DSM manager software, programmers cannot use their own msg-passing solutions. Distributed Shared Memory CUP 2008 3 / 48
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Distributed Computing: Principles, Algorithms, and Systems Advantages/Disadvantages of DSM Advantages: Shields programmer from Send/Receive primitives Single address space; simplifies passing-by-reference and passing complex data structures Exploit locality-of-reference when a block is moved DSM uses simpler software interfaces, and cheaper off-the-shelf hardware. Hence cheaper than dedicated multiprocessor systems
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Chapter12 - Chapter 12: Distributed Shared Memory Ajay...

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