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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 4 of 18
Single Instruction, Single Data (SISD):
* A serial (non-parallel) computer
* Single instruction: only one instruction stream is being acted on by the CPU during any one clock cycle
* Single data: only one data stream is being used as input during any one clock cycle
* Deterministic execution
* This is the oldest and until recently, the most prevalent form of computer
* Examples: most PCs, single CPU workstations and mainframes
SISD
Single Instruction, Multiple Data (SIMD):
* A type of parallel computer
* Single instruction: All processing units execute the same instruction at any given clock cycle
* Multiple data: Each processing unit can operate on a different data element
* This type of machine typically has an instruction dispatcher, a very high-bandwidth internal network, and a very large array of very small-capacity instruction units.
* Best suited for specialized problems characterized by a high degree of regularity,such as image processing.
* Synchronous (lockstep) and deterministic execution
* Two varieties: Processor Arrays and Vector Pipelines
* Examples:
o Processor Arrays: Connection Machine CM-2, Maspar MP-1, MP-2
o Vector Pipelines: IBM 9000, Cray C90, Fujitsu VP, NEC SX-2, Hitachi S820
SIMD
Multiple Instruction, Single Data (MISD):
* A single data stream is fed into multiple processing units.
* Each processing unit operates on the data independently via independent instruction streams.
* Few actual examples of this class of parallel computer have ever existed. One is the experimental Carnegie-Mellon C.mmp computer (1971).
* Some conceivable uses might be:
o multiple frequency filters operating on a single signal stream
o multiple cryptography algorithms attempting to crack a single coded message.
MISD
Multiple Instruction, Multiple Data (MIMD):
* Currently, the most common type of parallel computer. Most modern computers fall into this category.
* Multiple Instruction: every processor may be executing a different instruction stream
* Multiple Data: every processor may be working with a different data stream
* Execution can be synchronous or asynchronous, deterministic or non-deterministic
* Examples: most current supercomputers, networked parallel computer "grids" and multi-processor SMP computers - including some types of PCs.
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Last Updated ( Sunday, 23 December 2007 )
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