iRISC for Graphics: A Survey and Analysis of Multimedia Extended Instruction Set Architectures

The recent explosion of computing applications rich in graphics and sound has placed new and taxing demands on today’s microprocessors. These processors, designed with the intent of performing operations on integer and floating point numbers, have shown difficulty servicing requests from multimedia applications such as MPEG video on top of servicing requests from the operating system and other processes. Vendors have begun to take advantage of tremendous gate counts on their dies to implement a minimal set of multi-media extensions capable of accelerating media-intensive applications at little cost. In this paper, we survey and analyze several such implementations. We look at Hewlett-Packard’s Multimedia Architectural Extensions (MAX-2), Intel’s Multimedia Extensions (MMX), MIPS Technologies ’ MIPS V instruction set and Digital Multimedia Extensions (MDMX), and Sun Microsystem’s Visual Instruction Set (VIS). Finally, we look at both a qualitative and quantitative performance analysis of these media enhanced processors by modifying some code for several applications to take advantage of an extension set. We find that while certain types of applications may yield a siginificant increase in performance with only modest coding effort, applications reliant on system libraries offer little or no opportunity for such improvement. In the latter case, porting system libraries to take advantage of these new instruction sets can offer the greatest benefit to the largest cross-section of applications in a transparent manner. Because of the lack of disadvantages in implementing multimedia extensions, those vendors who have not implemented similar technologies in their microprocessors have placed themselves at a competitive disadvantage in the marketplace. i