Nonvolatile MRAM memory used in all levels of cache

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Magnetoresistive random access memory MRAM It's a new type of memory , Its advantages include fast reading speed, high integration and non-volatile . At present, a lot of research is mainly devoted to the research of MRAM Used in computer storage system . At the same time, nonvolatile MRAM Memory is also used at all levels of cache .
 
MRAM replace SRAM do L2 Cache
First compare the same area of MRAM and SRAM. Directly use the same area of MRAM Replace SRAM do L2 Caching can reduce the error rate . But the write latency is long . When the write operation strength is high , The advantage of reduced error rate will be offset by long delay, resulting in performance degradation . Although this direct substitution can greatly reduce the leakage power consumption , But when write intensive , Significant increase in dynamic power consumption , Make the effect of reducing energy consumption worse . If you directly use the same area of MRAM replace sram , When write operations are intensive , Its disadvantages such as long write delay and high energy consumption will offset its advantages .
 
MRAM As L3 Cache
L2 Too much capacity increases access latency, so it is not applicable . Add a level to the storage system L3 The feasibility of caching . The researchers calculated a 128MB,4-banks,16-way,256-byte block The cache area is only 161mm2, Suitable for stacking on current processors . The time model shows that the delay is only 15.82ns, Much less than the average memory access time . In different situations IPC The speed has increased 0.03% To 108%. Yes L2 The high cache error rate is greatly improved . And this improvement only needs to be added 0.4W Power consumption of .
 
 MRAM Used as main memory
Research has shown that stacking on a chip DRAM The feasibility of memory . And DRAM Compared with MRAM There is no need to refresh periodically . But it's still DRAM The highest degree of integration . Current stack DRAM To improve the performance of 19%( For integers ） and 40%( For floating-point numbers ). We have reason to believe that stacking MRAM Technology will perform better because of its shorter latency .
 
although MRAM The low power consumption makes it possible to realize multi-layer stacking without worrying about the temperature , But the delay will increase , And too many stacking layers will lead to a decrease in yield . So the current MRAM The technology is not mature enough to be applied to main memory ( Because it's not big enough ) , But it can be used in embedded devices with special requirements for low power consumption .