1.1.2 CPU performance Flashcards
what is the cache?
A cache is a high-speed memory that sits close to or can be directly on the processor; it is used to store the instructions and data most frequently used.
When running programs, a computer system is constantly swapping data in and out of cache memory and RAM. When an instruction, or set of instructions, is frequently used, it is inefficient for a processor to fetch these from RAM each time. To overcome this, cache memory is used to store the instructions that are likely to be called upon. As with RAM, cache memory is erased when power is removed
how does the number of cores affect processor performance?
Computers with more than one processing unit (core) are called ‘multicore processors’. For example:
Dual-core = two processing units
Quad-core = four processing units
Hexa-core = six processing units
Octo-core = eight processing units
Generally speaking, the more cores a computer has, the more instructions it can execute. As a result, the computer will perform more efficiently than computers with the same type of processor but fewer cores
Does doubling the number of cores make your computer twice as fast?
The benefit of having multiple cores is that they can run a program designed to run instructions in parallel at the same time. Increasing the number of cores will make a computer faster, therefore. Unfortunately, the cores have to communicate with each other and have to take their turn when accessing the cache and RAM; all of which uses up some of the potential speed that adding more cores gives you. So, although doubling the number of cores theoretically doubles the speed, in reality the computer will always run slightly slower than that
what is the clock speed?
The time taken between two sequential rising edges is called a clock cycle or a clock period. The clock speed is measured by the number of clock cycles in one second — 1 clock cycle per second is 1Hz.
Herz Measurement
1 hertz (Hz) 1 clock cycle per second
1 million Hz megahertz (MHz)
1,000 MHz gigahertz (GHz)
what is the cache?
A cache is a high-speed memory that sits close to or can be directly on the processor; it is used to store the instructions and data most frequently used.
When running programs, a computer system is constantly swapping data in and out of cache memory and RAM. When an instruction, or set of instructions, is frequently used, it is inefficient for a processor to fetch these from RAM each time. To overcome this, cache memory is used to store the instructions that are likely to be called upon. As with RAM, cache memory is erased when power is removed.
