256-KB associativity-reconfigurable cache with 7T/14T SRAM for aggressive DVS down to 0.57 V

This paper presents a dependable cache memory for which associativity can be reconfigured dynamically. The proposed associativity-reconfigurable cache consists of pairs of cache ways. Each pair has two modes: the normal mode and the dependable mode. The proposed cache can dynamically enhance its reliability in the dependable mode, thereby trading off its performance. The reliability of the proposed cache can be scaled by reconfiguring its associativity. Moreover, the configuration can be chosen based upon current operating conditions. Our chip measurement results show that the proposed dependable cache possesses the scalable characteristic of reliability. Moreover, it can decrease the minimum operating voltage by 115 mV. The cycle accurate simulation shows that designing the L1, L2 caches using the proposed scheme results in 4.93% IPC loss on average. Area estimation results show that the proposed cache adds area overhead of 1.91% and 5.57% in 32-KB and 256-KB caches, respectively.