Direct Memory Access

• Direct memory access (DMA) is a feature of computer systems and allows certain hardware subsystems to access main system memory independently of the central processing unit (CPU).
  • Without DMA, when the CPU is using programmed input/output
  • Each data item transfer is initiated by an instruction in the program, involving the CPU for every transaction.
  • In contrast, in direct memory access (DMA) operations, the CPU is uninvolved in the data transfer.
  • Many hardware systems use DMA, including disk drive controllers, graphics cards, network cards and sound cards.
  • DMA can also be used for “memory to memory” copying or moving of data within memory.

Reference

• wikipedia on direct memory access
• UMA and NUMA