eWEEK at 30: Multicore CPUs Keep Chip Makers in Step With Moore's Law
Atiq Bajwa, director of microprocessor architecture for Intel's Platform Engineering Group, said changes had to be made. "We were pushing frequency very, very hard," Bajwa said in an interview with eWEEK. "It was clear that thermal limits would be an issue if we kept up on that trend." In 1965, Gordon Moore, a co-founder of Intel, said that the number of transistors on a chip will essentially double every year, a statement that became Moore's Law. It later was amended to about every 18 months, to refer to the chip's performance. However, Moore's Law over the past few decades has becoming a driving principle behind chip development, and many expect this trend to continue for at least a couple more decades. According to Intel's Bajwa, frequency was the primary way of increasing performance, but not the only way. The micro-architecture could be manipulated—instructions tweaked, more cache added and data paths widened, for example. Other changes could be made as well, such as improving the bandwidth and reducing the latency to memory. Superscaler architectures—enabling a single-core chip to execute multiple instructions—also were used by Intel, AMD and RISC chip makers.IBM, looking to push past such rivals as Sun, Hewlett-Packard and Digital Equipment Corp. in the Unix server space, in 2001 introduced the Power4 chip, a 1GHz processor that was the first to offer two cores on a single die. The first system to run Power4, a system called Regatta, more than doubled the performance of competing systems at half the price, according to IBM officials. Sun also rolled out multicore UltraSPARC chips, eventually putting as many as eight cores into the architecture by 2007. Intel and AMD each launched their first multicore chips in 2005. Intel launched the dual-core 3.2GHz Pentium Extreme Edition 840 processor and 955X Express chip set in April of that year, followed later by dual-core versions of its Xeon and Itanium server products. AMD, which had become a more formidable competitor to Intel two years earlier with the first release of its 64-bit x86 Opteron server chips, rolled out its dual-core Opteron 800 and Athlon 64 X2 processors within a week of Intel's dual-core processor announcements.
However, as the chips got smaller and faster, the issues of power, heat and efficiency continued to grow. By the late 1990s, chip designers were mapping out ways to put two or more processing cores on a single piece of silicon. The idea was that chip makers could continue pushing forward the performance of the chip by adding additional cores, while reducing the frequency of those cores and keeping power consumption in check.