The Design And Optimization Of ISCSI Storage Controller Based On SoPC

Object-based Storage combines the advantages of block-based interface stotage and file interface storage, it has characters of high performance and sound security. iSCSI(Internet Small Computer System Interface)storage controller which is the port between Object-based storage controller and clients, takes charge of mapping of file to object and resolving the iSCSI protocol. To check the function of this storage controller and probe a good path for the future work on Xilinx platform, this project uses Xilinx ML300 development board to build a prototype of the controller and optimize it.This project adopts the SoPC(System o Programmable Chip) and embedded Linux architecture to realize the iSCSI storage controller. SoPC has the advantages of flexibly design and modification; customizable the function interface between software and hardware to optimize the whole system. Using the board FPGA chip to create the hardware platform. Using Linux Operating System not only benefits the modification, but also easily iSCSI program port. Porting Open Source UNH_iSCSI as the top-level program., realizing the communication between initiator and target as the software model.Due to the processing of TCP layer leads to a high CPU utilization, meanwhile adds much delay. Take part of offload of TCP protocol, taking advantage of hardware core to calculate the checksum in the TCP layer; Using SG-DMA(scatter/gather Direct Memory Access)to accelerate the transfer between network card and memory. SG-DMA model can effectively reduce the times of CPU interrupts, which can avoid frequent context switch. With the Data Realignment Engine(DRE for short), the performance of DMA controller will be significantly improved. And to improve the efficiency of the packet through kernel protocol stack, analyzing the Light-weight IP(LwIP for short ), and achieves some fruit.