H CS - System performance (revision)

Computer Systems -
System performance

​Increasing processor cores

The average home PC now has a processor with multiple cores (between 2-8). This is effectively two (or more) processor dies integrated into one processor.

How this affects performance - Increasing the number of processor cores allows multiple instructions to be executed at the same time.

​Increasing cache memory

Cache is a small amount of memory which is a part of the CPU. it is placed closer to the CPU than RAM. It is used to temporarily hold instructions and data that the CPU is likely to reuse.

How this affects performance - Increasing the cache memory reduces the number of fetches/accesses from slower main memory. The more cache memory there is, the more instructions can be held closer to the CPU.

​Increasing clock speed

A system's clock speed indicates how fast the CPU can run. This corresponds with how many instruction cycles the CPU can deal with in a second.

How this affects performance - Increasing the clock speed allows the processor to execute more instructions per second.

​Increasing data bus width

The data bus is a set of parallel wires or connectors that transports data between the processor and main memory.

How this affects performance - Increasing the width of the data bus allows for an increase in the number of bits/data transferred in a single operation. This reduces the number of fetch operations required.

Dropdown

Increasing the ​

Select answer

allows the processor to execute more instructions per second.

Dropdown

Increasing the ​

Select answer

allows multiple instructions to be executed at the same time..

Dropdown

Increasing the ​

Select answer

reduces the number of fetches/accesses from slower main memory.

Dropdown

Increasing the width of the

Select answer

​ allows for more bits of data to be transferred in a single fetch-execute cycle.

Match

Match the following

• Increased processor cores

• Increased width of data bus

• Increased clock speed

• Increased cache memory

+ instructions processed simultaneously

+ data transferred in a cycle

+ instructions processed per second

• - required access to slow main memory

• + instructions processed simultaneously

• + data transferred in a cycle

• + instructions processed per second

• • - required access to slow main memory

Open Ended

State one factor that can improve the performance of the fetch-execute cycle and explain why it improves performance. (2 marks)