There are a few things to keep in mind about pipelining.
Pipelining is part of the hardware and can’t be turned off. All of the logic for how the processor handles instructions in a pipeline is built into the hardware.
Nothing is free, and this is true for processor pipelines as well. The increase in the complexity of the hardware comes at the cost of the processer running hotter and using more power. This also causes an increase in the cost to manufacture.
The entire goal of pipelining is to get many instructions completed as quickly as possible. Pipelining does nothing to improve the speed of an individual instruction. The power of pipelining shows when there are many instructions that need processing.
The theoretical improvement of a pipeline is proportional to the number of stages in the pipeline. In our overview of pipeline and laundry, we keep our number of steps to just a few for clarity; however, many CPUs have 7, 10, 20, or even more than 30 stages in their pipeline.
Up to 30 stages? But I thought before we were told that there are five stages in the pipeline? The five stages we examined earlier in this lesson can be thought of as general groupings of stages of the pipeline. These stages can be broken down even further into more individual steps.
Take a look at the chart to the right. Take note of the trade-off between power, cost, heat, power, and number of stages.
As a note, this graph is purely for illustration purposes and has NO correlation between any real balance of these elements.