What are four different types of pipelining ?
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According to the levels of processing, Handler (1977) has proposed the following classification schemefor pipeline processors:
Arithmetic Pipeline :
The arithmetic logic units of acomputercan be segmentized for pipelineoperations in various data formats. Well-known arithmetic pipeline examples are the four-stage pipesused in Star-100, the eight-stage pipes used in the TI-ASC, the up to 14 pipelines stages used in theCray-1, and up to 26 stages per pipe in the Cyber-205.
Instruction Pipelining :
The execution of a stream of instruction can be pipelined by overlapping theexecution of the current instruction with the fetch, decode, and operand fetch of subsequentinstruction. This technique is also known as instruction lookahead. Almost all high-performancecomputers are now equipped with instruction-execution pipelines.
Processor Pipelining :
This refers to the pipeline processing of the same data stream by a cascadeof processors, each of which processes a specific task. The data stream passes the firstprocessorwithresults stored in a memory block which is also accessible by the second processor. The secondprocessor then passes the refined results to the third, and so on. The pipelining of multiple processorsis not yet well aecepted as a common practice.According to pipeline configurations and controlstrategies, Ramamooorthy and Li (1977) haveproposed the following three pipeline classification schemes:
Unifunction Vs. Multifunction Pipelines :
A pipeline unit with a fixed and dedicated function, suchas the floating-point adder is called unifunctional. The Cray-1 has 12 unifunctional pipeline units forvarious scalar, vector, fixed-point, and floating-point operations. A multifunction pipe may performdifferent subsets of stages in the pipeline. The TI-ASC. has four multifunction pipeline processors,each of which is reconfigurable for a variety of arithmetic logic operations at different times.
Static Vs. Dynamic Pipelines:
A static pipeline may assume only one functional configuration at atime. Static pipelines can be either unifunctional or multi-functional. Pipelining is made possible instatic pipes only if instructions of the same type are to be executed continuously. The functionperformed by a static pipeline should not change frequently. Otherwise, its performance may be verylow. A dynamic pipeline processor permits several functional configurations to exist simultaneously. Inthis sense, a dynamic pipeline must be multifunctional. On the other hand, a unifunctional pipe mustbe static. The dynamic configuration needs much more elaborate control and sequencing mechanismsthan those for static pipelines. Most existing computers are equipped with static pipes, eitherunifunctional or multifunctional.
Scalar Vs. Vector Pipelines :
Depending on the instruction or data types, pipeline processors can bealso classified as scalar pipelines and vector pipelines. A scalar pipeline processes a sequence of scalaroperands under the control of DO loop. Instructions in a small DO loop are often prefetched into theinstruction buffer. The required scalar operands for repeated scalar instructions are moved into a datacache in order to continuously supply the pipeline with operands. The IBMSystem
/360 Model 91 istypical example of a machine equipped with scalar pipelines. However, the Model 91 does not have acache.Vector pipelines are specially designed to handle vector instructions over vector operands. Computershaving vector instructions are often called vector processors.
Arithmetic Pipeline :
The arithmetic logic units of acomputercan be segmentized for pipelineoperations in various data formats. Well-known arithmetic pipeline examples are the four-stage pipesused in Star-100, the eight-stage pipes used in the TI-ASC, the up to 14 pipelines stages used in theCray-1, and up to 26 stages per pipe in the Cyber-205.
Instruction Pipelining :
The execution of a stream of instruction can be pipelined by overlapping theexecution of the current instruction with the fetch, decode, and operand fetch of subsequentinstruction. This technique is also known as instruction lookahead. Almost all high-performancecomputers are now equipped with instruction-execution pipelines.
Processor Pipelining :
This refers to the pipeline processing of the same data stream by a cascadeof processors, each of which processes a specific task. The data stream passes the firstprocessorwithresults stored in a memory block which is also accessible by the second processor. The secondprocessor then passes the refined results to the third, and so on. The pipelining of multiple processorsis not yet well aecepted as a common practice.According to pipeline configurations and controlstrategies, Ramamooorthy and Li (1977) haveproposed the following three pipeline classification schemes:
Unifunction Vs. Multifunction Pipelines :
A pipeline unit with a fixed and dedicated function, suchas the floating-point adder is called unifunctional. The Cray-1 has 12 unifunctional pipeline units forvarious scalar, vector, fixed-point, and floating-point operations. A multifunction pipe may performdifferent subsets of stages in the pipeline. The TI-ASC. has four multifunction pipeline processors,each of which is reconfigurable for a variety of arithmetic logic operations at different times.
Static Vs. Dynamic Pipelines:
A static pipeline may assume only one functional configuration at atime. Static pipelines can be either unifunctional or multi-functional. Pipelining is made possible instatic pipes only if instructions of the same type are to be executed continuously. The functionperformed by a static pipeline should not change frequently. Otherwise, its performance may be verylow. A dynamic pipeline processor permits several functional configurations to exist simultaneously. Inthis sense, a dynamic pipeline must be multifunctional. On the other hand, a unifunctional pipe mustbe static. The dynamic configuration needs much more elaborate control and sequencing mechanismsthan those for static pipelines. Most existing computers are equipped with static pipes, eitherunifunctional or multifunctional.
Scalar Vs. Vector Pipelines :
Depending on the instruction or data types, pipeline processors can bealso classified as scalar pipelines and vector pipelines. A scalar pipeline processes a sequence of scalaroperands under the control of DO loop. Instructions in a small DO loop are often prefetched into theinstruction buffer. The required scalar operands for repeated scalar instructions are moved into a datacache in order to continuously supply the pipeline with operands. The IBMSystem
/360 Model 91 istypical example of a machine equipped with scalar pipelines. However, the Model 91 does not have acache.Vector pipelines are specially designed to handle vector instructions over vector operands. Computershaving vector instructions are often called vector processors.
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Pipe lining and its types:
Pipe lining is the process of collecting instruction from the processor through a pipeline. It allows storing and performing instructions in an orderly process. It is also recognized as pipeline processing.
Types of pipelining:
It is divided into two types:
• Instruction pipeline
• Arithmetic pipeline
Arithmetic pipeline are used for floating point operations, multiplication of fixed point numbers.
An instruction pipeline read out instruction from the memory while previous instructions are being implemented in other segments of the pipeline.
Hope it helped......
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