Sun Microsystems will be taking one step backward and two steps forward with its new generation of low-power microprocessors, which the company will unveil during a technical presentation at the Hot Chips symposium in Palo Alto, California, on Tuesday.
The first of these new processors, code-named Gemini, will be Sun's first UltraSparc chip to contain a dual-processor core, but it will be based on the older, simpler UltraSparc IIi design and not the UltraSparc III or IIIi designs that Sun is currently shipping in its high-end systems.
The chip's design reflects a growing industry trend to improve performance without simply bumping up the chip's clock speed or number of transistors, said Sun Strategy Marketing Manager Harlan McGhan.
"The emphasis, for really the past decade, has been on building more and more complicated cores to achieve higher and higher frequencies and higher and higher levels of instruction processing," McGhan said. "Our belief is that this whole trend toward more and more complexity at the core level ... is really at the point of not just diminishing returns, but greatly diminishing returns."
The Gemini processors, which will run in the 1GHz to 1.2GHz range, will power Sun's next generation of blade, 1U (4.44 centimeters or 1.75 inch thick) and 2U (8.89 centimeters or 3.5 inch thick) server systems. Each processor core on Gemini will have 0.5M bytes of L2 cache and the chips will contain 80 million transistors.
Sun will begin shipping systems based on Gemini in 2004, McGhan said. Because the new chips will be compatible with the UltraSparc IIIi's Jbus system bus interface, Sun will be able to snap them in as upgrade processors to UltraSparc IIIi systems such as the Sun Fire V210 and V240 servers, he said.
"It's pretty advanced in the sense that the only guys who have been shipping chips with two cores on them to date are IBM," said Nathan Brookwood, an analyst with research firm Insight 64. "Nobody else, Intel and AMD in particular, has done a dual-core design, so Sun is going to be among the leaders in taking two processor cores and putting them on a chip"
With its two processor cores, Gemini will spend less time waiting for data to be transferred from the computer's memory to the chip itself. Today's processors can spend as much as three quarters of their time waiting for data to be pulled from the computer's memory to the chip's cache, according to Brookwood. With a dual-core processor, however, one core can keep working while the other is waiting for data.
"The whole idea of a multicore design is that some of those processes will be able to run, while the other core is stalled and waiting for its process to run," Brookwood said.
Gemini will have a maximum power consumption of 32 watts when running at 1.2GHz, McGhan said, but he expects the chips to ship in more low-power configurations. "The typical number (will be) lower, more like 25 watts," he said.
This low power consumption would make Gemini an ideal candidate for blade servers, and possibly even laptop computers, like those manufactured by UltraSparc OEM (original equipment manufacturer) Tadpole Computer, he said.
"By choosing UltraSparc II as the core here, they fundamentally get to keep the chip running at 30 watts, which is a lot less than other people doing dual-core design," Brookwood said.
Gemini will be followed by a much more advanced, eight-core processor code-named Niagara, which will incorporate technology Sun picked up in its acquisition of Afara Websystems Inc. Niagara-based systems are expected by the first half of 2006, McGhan said.