Spatial locality exploitation for runtime reordering of JPEG2000 wavelet data layouts

Exploitation of spatial locality is essential for memories to increase the access bandwidth and to reduce the access-related latency and energy per word. Spatial locality exploitation of a kernel can be improved by modifying placement of data in memory, but this may be felt not only by the kernel itself, but also in other application components accessing the same data. Thus care is needed to avoid global miss-rate improvements are thwarted by miss-rate increases in other application components. This article examines application-level miss-rate increases due to handling modified Wavelet Transform data layouts by explicitly reordering at runtime, exploiting the execution order freedom within a reordering buffer when the layout of surrounding components is known. For the JPEG2000 application, taking into account the reordering costs still results in 80% net WT miss-rate gains.