Data transmission method and a data transmission device for a Scaler-Gather DMA (Direct Memory Access)

Abstract

The invention discloses a SG DMA data transmission method. The method comprises the steps that a first SG DMA data transmission link table and a second SG DMA data transmission link table are createdin an array mode, and a first set of buffer areas and a second set of buffer areas are created; copying the user space data into a first group of buffer areas through a CPU (Central Processing Unit),and writing the address of the linked list I into IO (Input / Output) equipment; When SG DMA data transmission is started, user space data is copied into the second group of buffer areas through the CPU; creating an interrupt processing program, and after the SG DMA transmission is completed, receiving a transmission completion interrupt instruction sent by the SG DMA by the CPU, and writing the address of the linked list II into IO equipment; and circulating in sequence until the user space data is completely written into the IO equipment memory position. The invention also discloses a data transmission device of the SG DMA. The method and the device solve the problem that the CPU and the DMA cannot participate in data transmission at the same time, and the DMA transmission efficiency of the data is improved.

Description

technical field [0001] The present invention relates to the field of computer data transmission, and more specifically, to a Scatter-GatherDMA data transmission method and device. Background technique [0002] DMA (Direct Memory Access), that is, direct memory access, is a mechanism for quickly transferring data. Data transfer can be from IO device to memory, from memory to IO device or from one piece of memory to another. It does not require the participation of the CPU when using it for data transfer. Every computer motherboard has a DMA controller, which is usually programmed by the computer and uses a ROM on the adapter (such as the ROM on the floppy disk drive controller) to store the programs that control the DMA to transfer data. Once the controller is initialized and the data is transferred, the DMA can complete the data transfer independently from the CPU. [0003] The Scatter-gather DMA (SG DMA, scatter-gather DMA) method is a DMA method corresponding to the blo...

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Problems solved by technology

[0006] In view of this, the purpose of the embodiment of the present invention is to propose a data transmission method and device for SG DMA. The method and device create two SG DMA data transmission linked lists and two sets of kernel space buffers to transfer data in SG DMA. At the same time, the CPU copies the user space data into the buffer to realize parallel data transmission from user space to kernel space and from kernel space to IO device space, which solves the problem that CPU and DMA cannot participate in data transmission at the same time, and improves the efficiency of data transmission in DMA

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