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Bus mastering

Bus mastering definition

Bus mastering is a feature where a device connected to the bus is able to access system memory directly without the continuous involvement of the CPU. It allows devices like network cards, sound cards, or disk controllers to transfer data to and from system memory, thereby offloading these tasks from the CPU.

See also: system bus, data bus

Bus mastering benefits

  • Reduced CPU load. Devices can communicate directly with the system's RAM, resulting in less load on the CPU and better overall device performance.
  • Enhanced multitasking capability. Because the CPU is handling fewer data transfer tasks, the system can manage multiple processes more effectively. This results in smoother operation, especially in systems running several high-demand applications simultaneously.
  • Scalability. As new, faster devices are developed, a bus mastering architecture ensures that these devices can be fully utilized without being bottlenecked by the CPU..
  • Reduced latency. It minimizes delays in data processing, which is essential for applications requiring real-time, such as audio or video processing.

How does bus mastering work?

Many modern devices can already perform bus mastering, but for it to work, a computer motherboard and its chipset must also support bus mastering. In most cases, bus mastering is automatically configured by the operating system and device drivers.

In some architectures, a DMA controller is used to manage DMA operations, which allows devices to access the system memory directly.