1.1.2 - CPU Performance

Question 1

Name the three characteristics that affect processor performance

Answer 1

Clock speed, number of cores and cache size

Question 2

What is L1 cache?

Answer 2

Cache that has an extremely fast transfer rate, but is expensive so is usually small in capacity

L1 cache holds the most frequently used instructions and data

Question 3

What is L2 cache?

Answer 3

Cache that has a larger capacity than L1 cache but has slower transfer rates.

L2 cache holds instructions and data that aren’t needed as frequently

Question 4

Explains how different amounts of cache affect the processors performance

Answer 4

The larger the cache size, the less time a processor has to wait for instructions to be fetched.
This is because it is faster to transfer data to and from cache than to and from RAM

This leads to increased processor performance.

Question 5

What is a core in the CPU?

Answer 5

A core is a processing unit in the CPU that can do its own fetch-decode-execute cycle

Question 6

Explain how different numbers of cores affect a processor’s performance

Answer 6

An increased number of cores allows more simultaneous instructions to be processed. This improves the efficiency of the CPU

Question 7

What is the purpose of a clock in the CPU?

Answer 7

The clock sends out electrical impulses to keep all the components working in time

Question 8

What is clockspeed?

Answer 8

The speed of the clock. It is the number of fetch-decode-execute cycles that can run per second. Measures in Hertz

Question 9

Explain how an increased clockspeed will affect the processor’s performance

Answer 9

An increased clockspeed is called over clocking. This allows more cycles to be execute and means more instructions can be processed over time.

However, it will damage the CPU quicker than normal long term as it is working harder and heating up more.

Question 10

Why may a computer with more cores not be faster than a computer with less cores

Answer 10

• The lower core computer may have a higher clock speed - more FDE cycles per second
• Not all software supports multicore processing
• Some tasks can’t be split evenly across the cores so only one core may be used for an instruction
• Cache size and amount of RAM can also affect the performance of the system