2. Processor Performance Flashcards
What are the 3 factors affecting processor performance?
- Clock speed
- Number of cores
- Amount and type of cache memory
What determines clock speed?
The system clock
What is the system clock?
An electronic device that generates signals, switching between 0 and 1
When do processor activities begin?
On a clock pulse
When do CPU operations start?
As clock changes from 0 to 1
What is the clock speed?
The time taken for 1 clock cycle to complete
What is a core?
An independent processor able to run its own FDE cycle
How much faster can a dual core computer perform compared to a single core computer?
Theoretically, twice as fast
How can the number of cores have no effect on performance?
If the programs are not designed to utilise all the cores on a computer efficiently
What is cache?
Small amount of expensive, very fast memory inside the CPU
Why is cache useful?
Stores instructions that have been fetched so that they can be accessed faster if needed
What happens when the cache fills up?
Unused instructions are replaced with the new instructions
Describe the levels of cache.
L1 Cache: Very fast but small capacity
L2 Cache: Relatively fast, medium capacity
L3 Cache: Slow but much larger capacity
What does the width of the address bus determine?
The maximum possible memory capacity of the system
E.g. An address bus of 8 lines would have a maximum address of 1111 1111 (8 bit binary) or 255, thus having a maximum memory capacity of 256 (including address 0).
