ARCHITECTURAL CLASSIFICATIONS

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Architectural

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ARCHITECTURAL CLASSIFICATION

• _{Basic types of architectural classification}

• _{FLYNN’S TAXONOMY OF COMPUTER ARCHITECTURE}

• _{FENG’S CLASSIFICATION} • _{Handler Classification}

Other types of architectural classification

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ARCHITECTURAL CLASSIFICATION

• _{Flynn classification: (1966) is based on multiplicity of instruction}

streams and the data streams in computer systems.

• _{Feng’s classification: (1972) is based on serial versus parallel}

processing.

• _{Handler’s classification: (1977) is determined by the degree of}

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FLYNN’S

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Flynn's taxonomy

• _{Flynn's taxonomy}_{is a classification of}_{computer architectures}_,

proposed by Michael J. Flynn in 1966

• _{is based on multiplicity of instruction streams and the data streams in}

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Flynn's Classical Taxonomy

• _{Flynn's taxonomy distinguishes multi-processor computer architectures}

according to two independent dimensions of Instruction and Data. Each of these dimensions can have only one of two possible states:

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Single Instruction, Single Data

(SISD)

• _{A serial (non-parallel) computer (single uni-core}

processor)

• _{Single instruction:} _{only one instruction stream is}

being acted on by the CPU during any one clock cycle

• _{Single data stream:} _{only one data stream is being}

used as input during any one clock cycle

• _{Deterministic execution (Produces same result on}

every execution)

• _{This is the oldest and until recently, the most}

prevalent form of computer

• _Examples: _{Most PCs, single CPU workstations and}

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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

• Examples:

• Processor Arrays: Connection Machine CM-2, Maspar MP-1, MP-2

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Multiple Instruction, Single Data

(MISD)

• _{A single data stream is fed into multiple}

processing units.

• _{Here many functional units perform}

different operations on the same data

• _{Each processing unit operates on the data}

independently via independent instruction streams.

• _{Few actual examples of this class of}

parallel computer have ever existed.

• _{Example :}_{Multiple cryptography}

algorithms attempting to crack a single coded message.

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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: _{Supercomputers,}

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FLYNN’s Classification

Computer Class Computer Model

SISD PCs, single CPU workstations and mainframes E.g. IBM 701(1); IBM 1620; IBM 7090(1) ; CDC 6600 ;

SIMD ILLIAC-IV, PEPE, BSP, STARAN, MPP, DAP and the Connection Machine (CM-1). MISD C.mmp built by Carnegie-Mellon University.

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FENG’s

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FENG’S CLASSIFICATION

• _{Tse-yun Feng suggested the use of degree of parallelism to classify}

various computer architectures.

• _{It is based on serial versus parallel processing.}

• _{The maximum number of binary digits that can be processed within a}

unit time by a computer system is called the maximum parallelism degree P.

• _{A bit slice is a string of bits one from each of the words at the same}

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FENG’S CLASSIFICATION

Word serial bit serial (WSBS)

• _{One bit of one selected word is processed at a time. This represents}

serial processing and needs maximum processing time.

Word serial bit parallel (WSBP)

• _{is found in most existing computers and has been called as Word Slice}

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FENG’S CLASSIFICATION

Word parallel bit serial (WPBS)

• _{It has been called bit slice processing because m-bit slice is processed}

at a time. Word parallel signifies selection of all words. It can be considered as one bit from all words are processed at a time.

Word parallel bit parallel (WPBP)

• _{It is known as fully parallel processing in which an array on n x m bits}

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Handler’s Classification

• _{In 1977, Wolfgang Handler proposed an elaborate notation for}

expressing the pipelining and parallelism of computers.

• _{It is determined by the degree of parallelism and pipelining in various}

subsystem levels.

Handler's classification addresses the computer at three distinct levels:

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Handler’s Classification

• _{PCU corresponds to a processor or CPU,}

• _{ALU corresponds to a functional unit or a processing element and} • _{BLC corresponds to the logic circuit needed to perform one-bit}

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Handler's classification

• _{Handler's classification uses the following three pairs of integers to}

describe a computer:

Computer = (p * p', a * a', b * b’) Where p = number of PCUs

p'= number of PCUs that can be pipelined a = number of ALUs controlled by each PCU a'= number of ALUs that can be pipelined

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Handler's classification

• The '*' operator is used to indicate that the units are pipelined or macro-pipelined with a stream of data running through all the units. • The '~' symbol is used to indicate a range of values for any one of the parameters.

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Examples

1.

Texas Instrument's Advanced Scientific

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we have: ASC = (1, 4, 64 * 8)

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Examples

3. The CDC 6600 has a single main processor supported by 10 I/O

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Examples

CDC 6600I/O = (10, 1, 12)

The description for the main processor is: CDC 6600main = (1, 1 * 10, 60) The main processor and the I/O processors can be regarded as

forming a macro-pipeline so the '*' operator is used to combine the two structures:

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Classification based on

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Classification based on coupling

between processing elements

Coupling

refers to the way in which PEs cooperate with one another

• _{Loosely coupled}

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Classification based on coupling

between processing elements Coupling

• _{Loosely coupled:} _{the degree of coupling between the PEs is less.}

Example: parallel computer consisting of workstations connected together by local area network such as Ethernet is loosely coupled. In this case each one of the workstations works independently. If they want to cooperate they will exchange message. Thus logically they are autonomous and physically they do not share any memory and communication via I/O channels.

• _{Tightly coupled}_{: a tightly coupled parallel computer, on the other hand}

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Classification based on

mode of accessing

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Classification based on mode of

accessing memory

• _{Uniform memory access parallel computers (UMC}_{): in a shared memory}

computer system all processors share a common global address space. For these systems the time to access a work in memory is constant for all processors. Such a parallel computer is said to have a Uniform Memory Access (UMA).

• _{Non uniform memory access parallel computers:}_{in a distributed shared}