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Parralel Computing Turorial |
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Written by Hemanshu Patel
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Sunday, 23 December 2007 |
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Page 8 of 18
Parallel Computer Memory ArchitecturesHybrid Distributed-Shared Memory
* Summarizing a few of the key characteristics of shared and distributed memory machines:
Comparison of Shared and Distributed Memory Architectures
Architecture CC-UMA CC-NUMA Distributed
Examples SMPs
Sun Vexx
DEC/Compaq
SGI Challenge
IBM POWER3 SGI Origin
Sequent
HP Exemplar
DEC/Compaq
IBM POWER4 (MCM) Cray T3E
Maspar
IBM SP2
Communications MPI
Threads
OpenMP
shmem MPI
Threads
OpenMP
shmem MPI
Scalability to 10s of processors to 100s of processors to 1000s of processors
Draw Backs Memory-CPU bandwidth Memory-CPU bandwidth
Non-uniform access times System administration
Programming is hard to develop and maintain
Software Availability many 1000s ISVs many 1000s ISVs 100s ISVs
* The largest and fastest computers in the world today employ both shared and distributed memory architectures.
Hybrid memory architecture
* The shared memory component is usually a cache coherent SMP machine. Processors on a given SMP can address that machine's memory as global.
* The distributed memory component is the networking of multiple SMPs. SMPs know only about their own memory - not the memory on another SMP. Therefore, network communications are required to move data from one SMP to another.
* Current trends seem to indicate that this type of memory architecture will continue to prevail and increase at the high end of computing for the foreseeable future.
* Advantages and Disadvantages: whatever is common to both shared and distributed memory architectures.
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Last Updated ( Sunday, 23 December 2007 )
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Technology 