SIMD processing
Processors that issue a single instruction involving zero, one, or two data items per clock cycle are referred to as scalar processors. Processors capable of issuing multiple instructions per clock cycle, though not explicitly executing vector processing instructions, are called superscalar processors. Some algorithms benefit from explicitly vectorized execution, which means performing the same operation on many data items simultaneously. Processor instructions tailored to such tasks are called single-instruction, multiple-data (SIMD) instructions.
The simultaneously issued instructions in superscalar processors generally perform different tasks on different data, representing a multiple-instruction, multiple-data (MIMD) parallel processing system. Some processing operations, such as the dot product operation used in digital signal processing described in Chapter 6, Specialized Computing Domains, perform the same mathematical operation on an array of values.
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