Loop instruction caching for energy-efficient embedded multitasking processors

With the exponential increase of power consumption in processor generations, energy dissipation has become one of the most critical constraints in system design. Cache memories are usually the most energy consuming components on the processor chip due to their large die size occupation and frequent access operations. Furthermore, in step with the increased complexity of modern embedded applications, microprocessors are increasingly executing multitasking applications. In multitasking processors, the conventional L1 instruction cache (I-cache) is usually shared by multiple tasks and thereby suffering a highly intensive read/write operations, which can be even more energy-consuming than used in a single-task based system. This paper presents an energy-efficient shared multitasking loop instruction cache (SMLIC), which is designed to address the tasks sharing and context switch issues so that it can be efficiently utilized to reduce the I-cache accesses for energy savings in multitasking processors. Experiments on a set of multitasking applications demonstrate that the proposed SMLIC design scheme can reduce I-cache accesses by 12∼86% and energy consumption in instruction supply by 11∼79% for multitasking system, depending on various frequencies of context switch.