Sun frowns on HyperTransport expansion

A leading AMD proponent rejects technology that could increase the importance of communication tech built into AMD chips.

MENLO PARK, Calif.--Sun Microsystems has rejected a technology that would give computers with Advanced Micro Devices processors a new, externally available high-speed communications link.

AMD chips incorporate technology called HyperTransport, which connects processors with each other and a computer's input-output subsystem. Some companies advocate an adaptation called HTX that would let network adapters or other external devices be plugged into a computer and communicate directly with processors.

Sun is a leading proponent of AMD processors, but its top x86 server engineer said Friday in a meeting here with reporters that there are few situations in which HTX would be useful, and it's better to stick with the industry-standard PCI (Peripheral Component Interconnect) connector.

"We're interested in industry-standard interfaces," said Andy Bechtolsheim, a Sun engineer and co-founder whose Kealia products became the foundation of Sun's "Galaxy" line of x86 servers. "We looked really hard and long at this."

Some Taiwanese motherboard makers will make changes to sell a few thousand more products, Bechtolsheim said, but Sun has a larger-scale business to maintain. And Sun said it didn't want to squander one of the maximum of three HyperTransport connections on each AMD Opteron for the external interface.

Sun's lack of endorsement doesn't bode well for those trying to get HTX to catch on as a standard rivaling the ubiquitous PCI, which is beginning with a new variety called PCI Express, which initially was called 3GIO.

In a white paper, HyperTransport Consortium calls HTX "the answer to new-generation interconnect challenges" and argues it offers greater data transfer capacity and lower communication delays for high-performance technical computing.

Two top HTX advocates are Taiwan's Iwill, which sells HTX-enabled motherboards accommodating four or eight AMD Opteron processors, and PathScale, which makes InfiniBand networking adapters for high-performance technical computing and which is being acquired by QLogic.

HTX will likely be of limited use, though, Bechtolsheim said. "You'll probably see only a handful of chips that plug into HyperTransport directly," he added. "It is pretty hard to design custom chips that really take advantage of it."

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