[1.1.1] | 3: CPU Performance Flashcards
List the 4 main factors that impact CPU performance.
• Clock Speed
• Cache Memory
• Multiple Cores
• Pipelining
What is overclocking?
• Increasing the clock speed beyond the manufactured default.
• This generates additional heat which can cause errors or permanent damage.
What can be used to counter the adverse effects of overclocking?
A heatsink or a fan.
What is cache memory?
A small amount of very fast memory built into the CPU that holds frequently & recently used instructions.
• What is the Von Neumann bottleneck?
Instructions are executed faster than new ones are fetched. (Fetching from RAM is slow.)
How do L1 and L3 cache memory differ?
• L1: Smallest, Fastest, Most Expensive
• L3: Largest, Slowest, Cheapest
What is multitasking?
Different cores running different applications / processes simultaneously.
What is parallel processing?
Dividing a task between multiple cores and solving them in parallel.
What is a core?
A distinct processing unit within a CPU.
Why may having 2 cores not mean a processor will work twice as fast?
• Programs must be designed to take advantage of multi core processing.
• Not all programs can be solved in parallel.
• Cores must communicate and take turns with shared resources.
What is pipelining?
• Fetching an instruction while the previous one is decoded and the one before is executed.
• Allows for more operations to occur in the same unit time. (Less idle time.)
What is the main issue with pipelining?
• Sometimes programs branch and jump to out-of-sequence instructions.
• The processor has to predict branching to keep the pipeline full & maximise performance.
• If a mistake is made, the pipeline is flushed, degrading performance.
What other 3 factors impact system performance and how?
• RAM: Allows smoother performance as virtual memory is relied on less. (Virtual memory causes hangs / freezes.)
• GPU: Can process many calculations simultaneously.
• Secondary Storage: Read / Write speed can determine how fast files are loaded / saved.
