Addressing mode driven low power data caches for embedded processors

Abstract

The size and speed of first-level caches and SRAMs of embedded processors continue to increase in response to demands for higher performance. In power-sensitive devices like PDAs and cellular handsets, decreasing power consumption while increasing performance is desirable. Contemporary caches typically exploit locality in memory access patterns but do not exploit locality information encoded in addressing modes used to access memory. We present two schemes that use locality information inherent in memory addressing modes to reduce power consumption of cache or SRAM nearest to the processor. The level-0 data buffer scheme introduces a set of data buffers controlled by the addressing mode to eliminate over a third of all reads to the next level of memory (cache or SRAM). These buffers can also reduce load-use penalty in processors with long load pipelines. The address register tag-buffer scheme exploits the addressing mode to reduce tag array look-up in set associative first-level caches.