| Cache as an important component in the computer system is used to relieve great access speed difference between the processor and main memory,but with the rapid development of processor technology and semiconductor manufacturing process,traditional Cache technology that based on the SRAM is limited by the factors such as the storage unit area and static power.STT-MRAM as a new type of nonvolatile memory,not only has the characteristics of high integration,low static power consumption,but also its writing and reading speed,storage density and write endurance are superior to other nonvolatile storage technology,thus it is the most promising alternative for SRAM to use for caching technology.The parallel hybrid cache architecture based on STT-MRAM and SRAM,fully combines the advantages of STT-MRAM’s large storage density and low static power consumption and the advantages of SRAM’s fast speed of reading and writing.In order to maximize reduce the write operation of STT-MRAM cache,we optimization design the migration strategy as follows:(1)Immediate transfer.Firstly,allocating all write-miss data blocks to SRAM and readmiss data blocks to STT-MRAM.Then,a read-hit on SRAM partition would make the data block transfer to the STT-MRAM partition,and a write-hit on STT-MRAM would make it transfer to the SRAM partition.(2)Delayed transfer.Immediate transfer sometimes causes a lot of migrations,in order to improve this,we design delayed transfer strategy,only a continuous reading or a continuous writing can cause a transfer.(3)Adaptive migration.According to the previous access model of a cache block to predictive the block’s access trend,then dynamic modify the transfer strategy.Making all write intensive cache block transfer to SRAM,but when the SRAM partition has enough space,we need not to transfer read intensive block to STT-MRAM.In addition,evicting a dead data block from SRAM is prior to transferring it to STT-MRAM.We carry out the simulation experiment of the parallel hybrid cache architecture on GEM5,and take a contrast test on the delayed transfer and the adaptive migration.Results show that the parallel hybrid cache architecture greatly reduces the energy consumption compared with pure SRAM cache,and the performance of the proposed adaptive migration strategy has certain improved compared to delayed transfer strategy. |
