Advanced Computer Architecture: Understanding Parallel Computers and Their Design Issues, Assignments of Advanced Computer Architecture

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Advanced Computer Architecture

The Architecture ofParallel Computers

Computer Systems

ApplicationSoftwareOperatingSystemHardwareArchitecture

No ComponentCan be TreatedIn IsolationFrom the Others

Operating System Issues

• Allocating and Managing Resources• Access to Hardware Features
  • Multi-Processing– Multi-Threading
    • I/O Management• Access to Peripherals• Efficiency

Applications Issues

• Compiler/Linker Support• Programmability• OS/Hardware Feature Availability• Compatibility• Parallel Compilers
  • Preprocessor– Precompiler– Parallelizing Compiler

Flynn’s Classification

• Consider Instruction Streams and Data

Streams Separately.

• SISD - Single Instruction, Single Data

Stream

• SIMD - Single Instruction, Multiple Data

Streams

• MIMD - Multiple Instruction, Multiple Data

Streams.

• MISD - (rare) Multiple Instruction, Single

Data Stream

SISD

• Conventional Computers.• Pipelined Systems• Multiple-Functional Unit Systems• Pipelined Vector Processors• Includes most computers encountered in

everyday life

MIMD

• Multiple Processors cooperate on a single

task

• Each Processor runs a different program• Each Processor operates on different data• Many Commercial Examples Exist

MISD

• A Single Data Stream passes through

multiple processors

• Different operations are triggered on

different processors

• Systolic Arrays• Wave-Front Arrays

Performance Issues

• Clock Rate / Cycle Time =

τ

• Cycles Per Instruction (Average) = CPI• Instruction Count = I

c

• Time, T = I

c^

×

CPI

×

τ

• p = Processor Cycles, m = Memory Cycles,

k = Memory/Processor cycle ratio

• T = I

c^

×

(p + m

×

k)

×

τ

Performance Issues II

• Ic & p affected by processor design and

compiler technology.

• m affected mainly by compiler technology

τ

affected by processor design

• k affected by memory hierarchy structure

and design

Parallelizing Code

• Implicitly
  • Write Sequential Algorithms– Use a Parallelizing Compiler– Rely on compiler to find parallelism
    • Explicitly
      • Design Parallel Algorithms– Write in a Parallel Language– Rely on Human to find Parallelism

Multi-Processors

• Multi-Processors generally share memory,

while multi-computers do not.– Uniform memory model– Non-Uniform Memory Model– Cache-Only

• MIMD Machines

Vector Computers

• Independent Vector Hardware• May be an attached processor• Has both scalar and vector instructions• Vector instructions operate in highly

pipelined mode

• Can be Memory-to-Memory or Register-to-

Register

SIMD Computers

• One Control Processor• Several Processing Elements• All Processing Elements execute the same

instruction at the same time

• Interconnection network between PEs

determines memory access and PEinteraction