Pipeline stall

Imagine you are building a tower with blocks. You have different shapes and sizes of blocks that you need to put together in a specific order to create your tower.

However, sometimes you come across a block that doesn't fit quite right or needs to be placed in a certain way before you can continue stacking the other blocks on top. This block is causing a delay, or stall, in building your tower.

Similarly, in a computer's central processing unit (CPU), there are different steps or stages in processing instructions. These instructions come in a specific order and need to go through each stage before the CPU can move on to the next instruction.

However, sometimes an instruction might need additional processing or data before it can move on to the next stage. This causes a pipeline stall, or a delay in processing the rest of the instruction pipeline, much like the block in the tower-building analogy.

Pipeline stalls can occur for various reasons, such as data dependencies between instructions, branch mispredictions, or cache misses. These stalls can affect the performance of a CPU and slow down the processing of instructions.