Factors Affecting CPU Performance

Not all Central Processing Units (CPUs) will execute code at the same speed. Some processors will be faster than others depending on the following factors:

Clock speed

The CPU's clock sends a pulse at fixed intervals to trigger the next stage of the fetch, decode, execute (FDE) cycle.
The higher the clock speed, the more pulses are sent per second, so more instructions can be executed in the same amount of time.

Cores

Each core of a CPU is capable of processing instructions independently.
Each core has its own Control Unit (CU), and Arithmetic and Logic Unit (ALU), but the cores share access to cache and main memory.
Multiple cores allows a CPU to process multiple instructions at the same time.

Cache memory

Cache memory is a small amount of very fast memory inside the CPU.
In comparison to the cache, accessing the Random Access Memory (RAM) is a very slow operation.
By storing frequently accessed data and instructions in cache memory we can avoid the process of accessing the RAM.

Pipelining

Pipelining is a feature which allows more processor operations to take place in less time.

Idle processor

Processors typically complete one instruction before moving on to the next.
This means parts of the processor are idle while the instruction is completed.
This is an inefficient process.

Effect of pipelining

Pipelines ensure as much of the processor is in use all at one time and increase efficiency of the computer system.
Pipelining is usually split into two pipelines:
- Instruction Pipeline.
- Arithmetic Pipeline.

Instruction pipeline

The instruction pipeline will pre-fetch the next instruction and data and store it in a register.
As one instruction leaves the current instruction register (CIR), the next one is ready to be loaded and decoded.
At any given point, there are instructions being fetched, decoded and executed.

Arithmetic pipeline

The arithmetic pipeline divides up an arithmetic operation into its individual steps.
Each step is performed overlapping the next step.

1Components of a Computer

1.1Structure & Function of the Processor

1.1.1Structure of the CPU

1.1.2Fetch, Decode, Execute Cycle

1.1.3Factors Affecting CPU Performance

1.1.4CPU Architecture

1.2Types of Processors

1.2.1CISC & RISC

1.2.2Multicore & Parallel Cores

1.3Input, Output & Storage

1.3.1Computer Systems

1.3.2Magnetic Storage

1.3.3Optical Storage

1.3.4Types of Optical Storage

1.3.5Types of Memory

1.3.6Flash Memory

1.3.7Virtual Memory

2Software & Software Development

3Exchanging Data

4Data Types, Data Structures & Algorithms

4.1Data Types

4.1.1Data Types

4.1.2Arrays & Strings

4.1.3Representing Numbers

4.1.4Binary Arithmetic

4.1.5Hexadecimal

4.1.6Converting Binary Numbers

4.1.7Floating Points in Binary

4.1.8Floating Point Arithmetic

4.1.9Bitwise Manipulation

4.1.10Character Sets

4.2Data Structures

4.2.1Arrays, Linked Lists & Queues

4.2.2Graphs, Hash Tables & Stacks

4.2.3Trees

4.3Boolean Algebra

4.3.1Computational Logic

4.3.2Boolean Logic

4.3.3Karnaugh Maps

4.3.4Boolean Identities

4.3.5Flip Flops & Adder Circuits

5Legal, Moral, Cultural & Ethical Issues

5.1Computing Related Legislation

5.1.1Data Protection Act (1998)

5.1.2Computer Misuse Act (1990)

5.1.3Copyright Designs and Patents Act (1988)

5.1.4Regulation of Investigatory Powers Act (2000)

5.2Moral & Ethical Issues

5.2.1Online Activity Tracking

5.2.2Censorship

5.2.3Cultural Issues

5.2.4Environmental Issues

5.2.5Layout, Colour Paradigms & Character Sets

6Elements of Computational Thinking

6.1Thinking Abstractly

6.1.1Abstraction

6.2Thinking Procedurally

6.2.1Decomposition

6.3Thinking Logically

6.3.1Pseudocode & Flow Diagrams

7Problem Solving & Programming

7.1Programming Techniques

7.1.1Programming Fundamentals

7.1.2Modularity

7.2Programming Construction

7.2.1Integrated Development Environments

7.2.2Testing

8Algorithms

8.1Algorithms

8.1.1Interpreting, Correcting & Completing Algorithm

8.1.2Sort Algorithms

8.1.3Insertion & Merge Sort

8.1.4Search Algorithms

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