Address Mapping Methods On Double Data Rate SDRAM

As the development of the performance and frequency of the processor,the memory access has become a bottleneck problem.And the quality of memory control unit plays an essential role in deciding the performance of the processor.The address mapping in memory control unit mainly works to map the system address into memory cell in DDR,which is the key factor that affects the performance of memory control unit.The address mapping is an important approach to improve the performance of memory.The appropriate mapping helps to promote the locality,memory and the productivity of CPU,in order to meets the goal of promoting the performance of control unit.Applied to the main trend theory memory DRAM,the methods that solve the row-conflict using address mapping theory are researched in this thesis.The deficiency of three current main trend DDR3 mapping methods are analyzed,which improve are also provided.The advantages of DDR3,such as XOR,address segmentation,and so on,are integrated with the new DDR4 memory feature,Bankgroup.A new address mapping method about DDR4 is mentioned.The new method is applied to double XOR algorithm of Bankgroup and Bank address to map continuous requests into a new address level.Due to the parallelism principle,the two continuous requests can operate at the same time.Based on open page mode,it is reduced that accessing data and charging activation instructions,and the frequency of charging by the mapping pattern.The conclusion is that row-conflicts rate is dropped by 5%-10% using double XOR algorithm,meanwhile it promotes the performance of memory and reduces the power lose.While analyzing and quantifying the data,the main functions of memory control unit,DDR3 and DDR4 are simulated by Ramulator.By running SPEC CPU 2006 test file,and building different address mapping,the variation of the system performance is analyzed according to four basic parameters,IPC,row-hit,row-miss and row-conflict.By running Ramulator,row-hit is increased by 3%-5%,row-miss decreased by 2%-4%,row-conflict decreased by 6%-10%.IPC is an essential factor to measure CPU performance.The new DDR4 address mapping is accomplished by application to double XOR algorithm,whose IPC is increased by 1%-10%.For a number of data access operation environment,its IPC is increased by 4%-5%.According to the analysis above,it is concluded that the modification of address mapping promotes IPC,thus DRAM performance,CPU even the performance of computer system are promoted.