1.1.6 - Factors Affecting CPU Performance

What are the 3 factors that affect the speed of a CPU?

Clock speed, Cores and Cache Memory.

What does an increase in Clock speed mean?

• The CPU’s clock sends a pulse at fixed intervals to trigger the next stage of the 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.

What are Cores?

• Each core of a CPU is capable of processing instructions independently

• Each core has its own CU and ALU, but the cores share access to L2/L3 cache and main memory.

• Multiple cores allows a CPU to process multiple instructions at the same time.

What is Cache Memory?

• Cache memory is a small amount of very fast memory inside the CPU.

• In comparison to the cache, accessing the 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.

What is the difference between Cache and Registers?

Cache is for frequently accessed data, registers are for providing immediate access to data needing to be processed by the CPU. Cache memory stores data in a processed form, whereas Registers store data in an unprocessed form. Registers are faster.