Lecture%205%20Approaches%20to%20Concurrency:%20The%20Multiprocessor

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Lecture 5Approaches to Concurrency The
Multiprocessor
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Outline

• Some basics
• Granularity
• Amdahls Law
• Metrics (speedup, efficiency, redundancy)
• Multi-core (one thread spans an engine, multiple
  engines)
• Tightly coupled vs. Loosely coupled
• Interconnect
• Cache Coherency
• Memory Consistency
• Examples
• Early cm, HEP, cosmic cube
• Recent cell, power, niagara, larrabee
• Tomorrow ACMP

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Outline

• Some basics
• Granularity
• Amdahls Law
• Metrics (speedup, efficiency, redundancy)
• Multi-core (one thread spans an engine, multiple
  engines)
• Tightly coupled vs. Loosely coupled
• Interconnect
• Cache Coherency
• Memory Consistency
• Examples
• Early cm, HEP, cosmic cube
• Recent cell, power, niagara, larrabee
• Tomorrow ACMP

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Granularity of Concurrency

• Intra-instruction (Pipelining)
• Parallel instructions (SIMD, VLIW)
• Tight-coupled MP
• Loosely-coupled MP

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Metrics

• Speed-up
• Efficiency
• Utilization
• Redundancy

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Outline

• Some basics
• Granularity
• Amdahls Law
• Metrics (speedup, efficiency, redundancy)
• Multi-core (one thread spans an engine, multiple
  engines)
• Tightly coupled vs. Loosely coupled
• Interconnect
• Cache Coherency
• Memory Consistency
• Examples
• Early cm, HEP, cosmic cube
• Recent cell, power, niagara, larrabee
• Tomorrow ACMP

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Tightly-coupled vs Loosely-coupled

• Tightly coupled (i.e., Multiprocessor)
• Shared memory
• Each processor capable of doing work on its own
• Easier for the software
• Hardware has to worry about cache coherency,
• memory contention
• Loosely-coupled (i.e., Multicomputer Network)
• Message passing
• Easier for the hardware
• Programmers job is tougher

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• Interconnection networks
• Cost
• Latency
• Contention
• Cache Cohererency
• Snoopy
• Directory
• Memory Consistency
• Sequential Consistency and Mutual Exclusion

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Outline

• Some basics
• Granularity
• Amdahls Law
• Metrics (speedup, efficiency, redundancy)
• Multi-core (one thread spans an engine, multiple
  engines)
• Tightly coupled vs. Loosely coupled
• Interconnect
• Cache Coherency
• Memory Consistency
• Examples
• Early cm, HEP, cosmic cube
• Recent cell, power, niagara, larrabee
• Tomorrow ACMP

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