Efficient orchestration of sub-word parallelism in media processors

Communication and multimedia applications with increased data rates and enhanced functionality continuously raise the bar for the computational requirements of future microprocessors. In order to meet these computational demands it is necessary to exploit sub-word parallelism efficiently. We propose to make sub-word data movement a first-class operation in microprocessor architectures by introducing a Sub-word Permutation Unit (SPU)in the execution pipeline. The SPU is evaluated in the context of the MMX media co-processor for the Intel Pentium architectures, but our results can be extended to any processor that supports sub-word parallelism. We find that the SPU all ws us to orchestrate sub-word data placement prior to computation, thus all wing the MMX functional units to concentrate on performing calculations. Furthermore, we introduce a decoupled SPU control mechanism at the basic block level which allows static optimization to eliminate data-movement verhead in tight loops, where most media and signal processing occurs. We demonstrated that anywhere from 4% to 20% improvement can be obtained on key media and signal processing kernels with as little as 1% increase in hardware resources.