The lower-end versions are chips that have some manufacturing defects but that still are useful, said David Yen, executive vice president of Sun's Scalable Systems Group, which designs and sells servers using Sparc processors and the Solaris operating system.
"As part of the manufacturing process, there are some processors with less than eight cores but still with very impressive performance," Yen said in a meeting with reporters here at the. "We will be offering the Niagara-based boxes primarily with eight cores and six cores, and we may start with four cores."
The option for six- and four-core Niagara chips was first reported by The Register.
is a crucial processor for Sun, a chip intended to send a message about Sun's commitment to the Unix server market, where it has been losing share. It's important enough that Sun will release Niagara before a more conventional processor, the , for lower-end Unix servers.
"We are executing very well on the Niagara program. We would really like to show all the evidence we have, not just some virtual benchmarks," Yen said. At the same time, servers with the UltraSparc IIIi are selling fine and aren't crying out for the IIIi+ upgrade, he added.
Sun has more than 100 Niagara prototype machines installed at customer sites so far, Yen said. The company has committed to ship them by early 2006, but Yen hinted they might arrive a little sooner: "We'd like to beat that schedule."
Niagara is the opening salvo in a radical overhaul of Sun's Sparc processors, a family that competes with IBM's Power, Intel's Xeon and Itanium, and Advanced Micro Devices' Opteron. Niagara employs a technology called chip multithreading (CMT) that uses numerous processor cores, each able to execute multiple instruction sequences called threads.
CMT is designed to sidestep a persistent and worsening problem in microprocessor design: Chip performance increases faster than memory system performance, so chips spend a larger and larger fraction of their time idle as they await data from memory. CMT sidesteps this problem by juggling among different threads, switching to a new thread when another stalls to await memory.
Sun has publicly discussed two other CMT designs: Niagara II, which will work in multiprocessor configurations, and Rock, which is designed for back-end server tasks such as databases, where threads must execute swiftly.
Niagara can execute as many as 32 threads, but not at top speed. Niagara II will be able to execute more threads, Yen said, but declined to share further details. He also said Niagara II will be followed by "subsequent Niagara families."
Sun scrapped two more conventional designs, the lower-end dual-core Gemini processor and the high-end, to concentrate on the CMT designs. In the meantime, Sun signed a deal to sell an "Advanced Product Line" designed with Fujitsu and using Fujitsu's Sparc64 VI "Olympus" processor.
Sun on Tuesday began selling midrange servers using its newchip, a dual-core model that doubles performance compared with its UltraSparc IV predecessor.
Sun acquired the Niagara design when itin 2002. At the time, the designers had finished the logical design of the processor but had only just started on the physical design, Yen said. The physical design is always a difficult step as engineers run into space limitations on the silicon die.
"At the time we acquired Afara, Niagara was probably one-third done," Yen said.