Frequently Asked Questions on DMA

What is Direct Memory Access?

Some computer bus architectures incorporate a functionality called Direct Memory Access whereby data can be transferred directly from an attached device like a disk drive to the system’s main memory in the motherboard without necessarily passing through the CPU. Data transfer frees the microprocessor from operations that include data transfer leading to a faster computer work rate....

How Does DMA Work?

By using DMA, usually some specified portion of memory is allocated and earmarked to be utilized for direct memory access. As an illustration, 00765K of memory can be addressed for DMA in Industry’s Standard Architecture bus. In other such buses standards, memory access might be through the full range of addressable locations. With regards to this, peripheral component interconnect has the ability of utilizing a bus master where the CPU gives orders on I/O control to the PCI controller....

DMA vs RDMA

DMA (Direct Memory Access) RDMA (Remote Direct Memory Access) Direct memory access (DMA) enables peripheral device transfers of data to system memory without engaging CPU. By passing the CPU in every data transfer, it improves the data throughput by boosting efficiencies. Unlike RDMA, this advanced technology provides direct memory-to-memory communication and excludes the CPUs of both systems. The host CPU usually starts and monitors all its DMA transfers. The computer then informs the DMA controller on which address to transfer data from, how much data, and where to store it. This eliminates the need for the CPU to be involved in data transfer. Instead, such transfers operate as a result of the interaction between the network adapters. It is commonly employed within connections where it facilitates rapid transfer of information at a pace between system memory and peripheral, for example on networks and in cases of storing devices. Distributed systems typically utilize them, particularly in situations involving high performance computing and networks that demand very low latency and throughput. It communicates within the system and transfers data among the different internal elements of it. RDMA creates point to point channels of data transfer between computers in a distributed network allowing for direct memory-to-memory communication which is suitable for distributed computing and storage architectures. However, there is some latency involved because the CPU must set up the transfer and control the DMA controller. Compared to traditional DMA, RDMA tends to have less latency because the processor is not involved in the data transfers....

Conclusion

Lastly, Direct Memory Access (DMA) acts as a traffic officer for your computer’s data. It relieves the main processor thus making it easier for devices such as hard drives and graphics cards to communicate with the memory of computers. Therefore, data transfer becomes quicker and your computer can perform more tasks at a time without being bogged down. There are several types of DMA and each mode transfers data very intelligently....

Frequently Asked Questions on DMA – FAQs

State advantages of DMA controllers?...