High-performance and energy-efficient heterogeneous subword parallel instructions

High instruction throughput and energy efficiency are becoming increasingly important design requirements for embedded and mobile computing systems. The paper presents the quantized color pack extension (QCPX) ISA to improve execution performance of multimedia processing applications on programmable superscalar processors while reducing the energy consumption for these applications. QCPX exploits parallelism within the color space representation (YCbCr - luminance-chrominance) in addition to generic subword parallelism exploited by existing multimedia instruction set extensions (e.g., MMX, SSE, MDMX). We evaluate the performance (execution time in cycles) and energy consumption using QCPX on a media benchmark suite that includes vector median filter, scalar median filter, edge detection, and vector quantization. Our experimental results indicate that a 32-bit QCPX version achieves speedups ranging from 205% to 562% compared with that of a 32-bit baseline RISC version and 90% to 100% over the 32-bit MDMX-like version on identically configured, dynamically scheduled ILP superscalar processors. In addition, the QCPX version reduces the energy consumption from 69% to 83% over the baseline version and 47% to 50% over the MDMX-like version due to the significant reduction of executed instructions and cache accesses.