Performance & Pipelining

Question 1

factors affecting CPU: clock speed

Answer 1

1) clock speed can be determined by the system clock

2) each CPU operation stars as the clock changes from 0 to 1 or in some other systems from 1 to 0

3) the CPU can not perform faster than the clock speed.

4) the clock speed is defined as the time taken for one clock cycle to complete

Question 2

factors affecting CPU: number of cores

Answer 2

1) a core is an independent processor that can carry out the FDE cycle on its own.

2) this means that if a CPU has multiple cores it will be able to carry more than one FD cycle at any given time.

3) a computer with dual cores, theoretically can finish tasks twice as fast as a single core.

4) not all programs can benefit from multiple cores and this is because they were not designed to do so.

Question 3

factors affecting CPU: amount and type of cache memory

Answer 3

1) cache memory is a small very fast secondary memory inside the CPU.

2) instructions that are fetched from main memory are copied into it for easy access to data.

3) as cache fills up, unused data and instructions are replaced with more recent ones.

Question 4

cache types and properties

Answer 4

1) cache level 1:
- very fast memory cell with small capacity.

2) cache level 2:
- relatively fast memory cell with a medium capacity.

3) cache level 3:
- slower memory cell with a large sized capacity.

Question 5

What is pipelining ?

Answer 5

1) it is the process of carrying multiple instructions concurrently.

2) it holds the data in a buffer in a close proximity to the CPU until it is required.

3) while one instruction can be executed, another can be decoded and another can be fetched.

4) pipelining aims to reduce the amount of CPU which should be kept ideal.

Question 6

types of pipelining

Answer 6

1) instruction pipelining:
- it separate the instruction into fetching, decoding and executing

2) arithmetic pipelining:
- it breaks down the arithmetic operations and overlaps them as
they are performed

Question 7

What happens to the pipeline in the case of branch ?

Answer 7

The pipeline will be flushed

Question 8

How dues pipelining improve CPU performance?

Answer 8

1. Pipelining reduces latency
2. The CPU is not idle while waiting for the next instruction, therefore the speed of execution will increase
3. All part of the processor can be used at any instance of time