Lecture 5 Approaches to Concurrency: The Multiprocessor
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Transcript of Lecture 5 Approaches to Concurrency: The Multiprocessor
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Lecture 5
Approaches to Concurrency: The Multiprocessor
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Outline
• Some basics– Granularity– Amdahl’s 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
![Page 3: Lecture 5 Approaches to Concurrency: The Multiprocessor](https://reader035.fdocuments.us/reader035/viewer/2022062321/56813c38550346895da5b73e/html5/thumbnails/3.jpg)
Outline
• Some basics– Granularity– Amdahl’s 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– Amdahl’s 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
![Page 8: Lecture 5 Approaches to Concurrency: The Multiprocessor](https://reader035.fdocuments.us/reader035/viewer/2022062321/56813c38550346895da5b73e/html5/thumbnails/8.jpg)
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– Programmer’s 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– Amdahl’s 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
![Page 11: Lecture 5 Approaches to Concurrency: The Multiprocessor](https://reader035.fdocuments.us/reader035/viewer/2022062321/56813c38550346895da5b73e/html5/thumbnails/11.jpg)
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