von Neumann bottleneck
The von Neumann bottleneck is a limitation on throughput caused by the standard personal computer architecture. The term is named for John von Neumann, who developed the theory behind the architecture of modern computers. Earlier computers were fed programs and data for processing while they were running.
In 1945, von Neumann proposed a computer design that was based on the concept of the stored program computer, in which program instructions and data are held in memory. Known as the von Neumann architecture -- or sometimes the Princeton architecture -- this model became the standard used for many of the computers to follow and continues to be used for a large number of today's systems.
In the von Neumann architecture, a computer's main components include the central processing unit (CPU), the memory unit, and the input and output devices. The CPU contains the control unit, arithmetic logic unit and registers. The processor and memory are separate components, with data moving between them via the system bus. The memory unit, often referred to as main memory or primary memory, stores both the program instructions and data.
The system bus is used to transfer all data between the components that make up the von Neumann architecture, creating what has become an increasing bottleneck as workloads have changed and data sets have grown larger. Over the years, computer components have evolved to try to meet the needs of these changing workloads. For example, processor speeds are significantly faster, and memory supports greater densities, making it possible to store more data in less space.
