A Cache-aware program transformation technique suitable for embedded systems

In embedded systems caches are very precious for keeping low the memory bandwidth and to allow employing slow and narrow off-chip devices. Conversely, the power and die size resources consumed by the cache force the embedded system designers to use small and simple cache memories. This kind of caches can experience poor performance because of their not flexible placement policy. In this scenario, a big fraction of the misses can originate from the mismatch between the cache behavior and the memory accesses' locality features (conflict misses). In this paper we analyze the conflict miss phenomenon and define a cache utilization measure. Then we propose an object level Cache Aware allocation Technique (CAT) to transform the application to fit the cache structure, minimize the number of conflict misses and maximize cache exploitation. The solution transforms the program layout using the standard functionalities of a linker. The CAT approach allowed the considered applications to deliver the same performance on two times and sometimes four times smaller caches. Moreover the CAT improved programs on direct-mapped caches outperformed the original versions on set-associative caches. In this way, the results highlight that our approach can help embedded system designers to meet the system requirements with smaller and simpler cache memories. (C) 2002 Elsevier Science B.V. All rights reserved.