Parallelism

Presentation about parallelism.Type of parallelism.

1. Welcome to our presentation
Parallelism

2. Parallelism
Goals of Parallelism
Exploitation of Concurrency
Types of Parallelism
Md. Monirul Awal (161-15-7501)
Md. Raseduzzaman(161-15-7495)

3. Parallelism
Executing two or more operations at the same time is known as Parallelism.

4. Goals of Parallelism
The purpose of parallel processing is to speedup the computer processing
capability or in words, it increases the computational speed.
Increases throughput, i.e. amount of processing that can be accomplished
during a given interval of time.
Improves the performance of the computer for a given clock speed.
Two or more ALUs in CPU can work concurrently to increase throughput.
The system may have two or more processors operating concurrently.

5. Exploitation of Concurrency
Techniques of Concurrency:
Overlap: execution of multiple operations by heterogeneous functional units.
Parallelism : execution of multiple operations by homogenous functional units.
Throughput Enhancement:
Internal Micro-operations: performed inside the hardware functional units
such as the processor, memory, I/O etc.
Transfer of information: between different functional hardware units for
Instruction fetch, operand fetch, I/O operation etc.

6. Types of Parallelism:
1.Instruction Level Parallelism (ILP)
2.Processor Level Parallelism

7. 1. Instruction Level Parallelism (ILP)
Instruction-level parallelism (ILP) is a measure of
how many operations in a computer program can
be performed "in-parallel" at the same time.

8. ILP TECHNIQUES
An instruction pipelineis a technique used in the design of modern
microprocessors, microcontrollers and CPUs to increase their instruction
throughput (the number of instructions that can be executed in a unit of time).
For example, the RISC pipeline is broken
into five stages with a set of flip flops
betweeneach stage as follow:

9. ILP TECHNIQUES
A superscalarCPU architecture implements ILP inside a single processor
which allows faster CPU throughput at the same clock rate
Simple superscalar pipeline. By fetching
and dispatching two instructions at a time,
a maximum of two instructions per cycle
can be completed.

10. 2. Processor Level Parallelism
Instruction-level parallelism (pipelining and superscalar operation) rarely win more than
a factor of five or ten in processor speed.
To get gains of 50, 100, or more, the only way is to design computers with multiple CPUS
We will consider three alternative architectures:
–Array Computers
–Multi-processors

11. Array Computer
An array processor consists of a large number of identical processors that perform the same
sequence of instructions on different sets of data.
A vector processor is efficient at executing a sequence of operations on pairs of Data elements;
all of the addition in a single, heavily-pipelined adder.

12. Multi-processor
The processing elements in an array processor are not independent CPUS,
since there is only one control unit.
The first parallel system with multiple full-blown CPUs is the multiprocessor.
This is a system with more than one CPU sharing a common memory coordinated in software.
The simplest one is to have a single bus with multiple CPUs and one memory all plugged into it.