Factors Affecting CPU Performance

Factors Affecting CPU Performance

1. Materials

   • Different processors are made from different materials.
     • The materials used are of different qualities, which can affect the reliability, speed and performance of the processor.

2. Clock Speed

   • The clock is a crytal that vibrates, generating pulses that control the different components.
     • E.g. 800 MHz is 800 million pulses per second, so 800 million instructions executed per second.
   • The faster the clock speed, the more fetch-decode-execute cycles the CPU can perform every second.

3. Word Size

   • This is the number of bits the CPU can work with on one clock cycle
     • Generally the word size of modern computers is 32bit or 64bit, which is faster than in the past.
   • Depending on the word size, the data bus may not be able to hold an integer greater than a certain value.

4. Cores

   • A core is an independent processor with its own cache.
   • More cores allows the CPU to be working on different parts of the same program at the same time. Meaning if there are 2 cores, the CPU effectively does double the amount of instructions per second.

5. Cache

   • Similar to RAM, but it is faster to read and write to.
     • However, cache is more expensive than RAM.
   • Frequently used data is stored in the cache.
     • Therefore, speeds up performance as data that is used frequently is stored within the CPU and doesn't need to be accessed from memory.
   • There is multiple levels of cache:
     • LEVEL 1 - Extremely fast but very small ( 2-64KB)
       • LEVEL 2 - Fairly fast, larger (256KB, 2MB)
         • LEVEL 3 - Less common but some CPUs have it